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MOSBY

Diagnosis and M anagem ent of

Malocclusion and Dentofacial Deformities

Om Prakash Kharbanda

Also Available

Textbookof Oral

Gruber's

textbook of

Orthodontics |

Basic Principles and Practice

]

Editor

Anil Govindrao Ghom

cE-di+ecf b y

P V e m k u m a f*

........... - r

Pediatric Dentistry

For enquiries, contact:

Elsevier Health Sciences

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Phone: +91-124-4774444, Fax: +91-124-4774100, e-mail: indiacontact@elsevier.com

I

1

K^ rm oaonncs


M alocclusion and D entofacial Deform ities

(Dedicated to

My mother and father

who taught me: %nowCedge is the most precious possession one can ever acquire

(Renu andSidharth

fo r their patience, strength and armour

My patients

who gave me the opportunity to serve

students

who are the very purpose o f this 600^

K^ynnoaonncs


M alocclusion and D entofacial Deform ities


BDS, MDS (Lucknow), M Orth RCS (Edinburgh), M MEd (Dundee), MNAMS, FAMS

Prof and Head, Division of Orthodontics and Dentofacial Orthopaedics

Centre for Dental Education and Research

All India Institute of Medical Sciences

New Delhi 110 029, INDIA

Adjunct Professor and Coordinator

KL Wig Centre for Medical Education and Technology


New Delhi 110 029, INDIA

Fellow, Indian Board of Orthodontics Honoris Causa

Fellow, International College of Dentists

Fellow, Pierre Fauchard Academy

ELSEVIER

A division of

Reed Elsevier India Private Limited

Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities

Kharbanda

ELSEVIER

A division of

Reed Elsevier India Private Limited

Mosby, Saunders, Churchill Livingstone, Butterworth Heinemann and

Hanley & Belfus are the Health Science imprints of Elsevier.

© 2009 Elsevier

First Edition 2009

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or

mechanical including photocopy, recording or any information retrieval system without the prior written permission from the

publisher and the copyright holder.

ISBN: 978-81-312-1568-5

Medical knowledge is constantly changing. As new information becomes available, changes in treatment, procedures, equipment

and the use of drugs become necessary. The authors, editors, contributors and the publisher have, as far as it is possible,

taken care to ensure that the information given in this text is accurate and up-to-date. However, readers are strongly advised

to confirm that the information, especially with regard to drug dose/usage, complies with current legislation and standards of

practice.

Published by Elsevier, a division of Reed Elsevier India Private Limited

14th Floor, Building No. 10B, DLF Cyber City, Phase II,

Gurgaon-122002, Haryana, India

Commissioning Head: Ritu Sharma

Managing Editor: Anand K Jha

Manager - Publishing Operations: Sunil Kumar

Manager - Production: NC Pant

Typeset by Chitra Computers

Printed and bound at Gopsons Papers Ltd., NOIDA (India).

P reface

A majority of the orthodontic texts are primarily intended for the postgraduate students and are beyond the comprehension

of dental students. This book is mainly intended for the dental students but will also serve as a reference book for the

dental surgeons and those in the beginning to pursue postgraduate orthodontic studies.

The spectrum of clinical presentations on malocclusion is ever changing and so the demand for healthy dentition and

good oral health and aesthetics. Now we have more adults and much younger children seeking orthodontic consultation

and treatment. Scope of orthodontics has greatly widened from straightening of teeth to correction of dentofacial

deformities and congenital defects of the face and jaws such as cleft lip and palate. The science of orthodontics has

advanced in leaps and bounds over the last few decades. There has been tremendous advancement in biomaterials,

technology, diagnostic facilities, communication and the use of digital and computerized equipment. The research findings

through Evidence Based Dentistry (EBD) have changed many of the clinical based concepts. New clinical practices and

concepts are being introduced. Children with fixed appliance under treatment may often need to see the dental surgeons

for the prevention of dental diseases, management of trauma and emergencies due to breakages in fixed appliances. Dentists

are quite often required to undertake aesthetic dentistry procedures and consequently orthodontic aspects could be

overlooked. The need to indulge minor tooth movements in the rehabilitation of occlusion by the Prosthodontist is on

increase.

The book takes care of all the issues mentioned above. It has been organized and presented to dental students with

a blend of text, tables, graphics and clinical case reports as encountered in real life situations in clinical practice. A greater

emphasis is laid on learning the concepts of orthodontic diagnosis of the developing, developed and adult malocclusion

problems, understanding the case selection and rationale of treatment approaches rather than the treatment techniques

alone. The book provides a broad yet in-depth overview on fundamentals in biological basis of orthodontics, current and

contemporary orthodontic diagnostic methods and therapeutic clinical procedures to enable a dental student to be able

to make a reasonable analysis of the clinical situation, communicate with patients, undertake interceptive treatment

procedures and communicate with orthodontic specialist/orthodontist for comprehensive treatment. The chapters on

Diagnosis and Cephalometrics provide norms of Indian ethnic groups.

This book also provides up-to-date information on subjects of day-to-day relevance, but often ignored such as

epidemiology of malocclusion and orthodontic indices, psychological aspects of malocclusion and orthodontics and care

and maintenance of occlusion after orthodontic treatment. Newer innovations on fixed and removable appliances, temporary

anchorage devices/ orthodontic implants, impacted and transposed teeth, interdisciplinary treatment, holistic approach in

the management of cleft lip and palate are also included.

Emerging fields such as Distraction osteogenesis: Obstructive sleep apnoea, not often found in the undergraduate

books, have also been provided with up-to-date clinically relevant information.


opkl5@hotmail.com

A ck n o w le d g e m e n ts

I take this opportunity to sincerely thank all the people who have directly or indirectly influenced me and have been

associated with me in my professional and academic journey of Orthodontics and patient care. I express my heartfelt

gratitude for my mentors, teachers, faculty colleagues, research staff, students, secretary, technicians, nursing and other

staff working with me at AIIMS. This acknowledgement would be incomplete without extending special thanks towards

the backbone of this book, my patients, who have entrusted me with the opportunity to serve them and hence played an

important role to help me bear the fruit of my labour. Over the years my endeavour to achieve excellence in clinical care

and research has been supported by my postgraduate students. Their fertile minds and willingness to learn have

contributed to overall academic and professional development of the department.

I would also like to thank the contributors of various chapters Prof M Ali Darendeliler, Asso Prof Varun Kalra, Drs Parul

Taneja, Lokesh Suri, P Hari, Anurag Gupta, Col B Jayan and Col SK Roychoudhary. I thank my colleagues and residents

Drs Anupama Sharma, Sandeep Sabharwal, Priyanka Kapoor, Mahima Nanda, Priyanka Sethi, Varun Malhotra, Sankalp Sood,

Neeraj Wadhawan, Anurag Negi, Poonam Chaudhary, Anil Nafria, S Raja, Vilas Samrit and Mugdha Mankar for their

contributions at various stages.

The following figures deserve case/photo credits. Dr Sankalp Sood, Figs 1.2, 34.5, 35.1-5, 35.2, 36.2; Dr P Hari, Figs

32.1, 36.1, 36.2; Dr Priyanka Kapoor, Figs 1.7, 8.7, 8.8, 31.6, 38.2 A-C, 38.6-7; Dr Sandeep Sabharwal, Figs 34.3, 37.5, 44.9; 0

Dr Poomima Agarwal, Figs 32.8-10; Dr Vilas Samrit, Figs 32.5, 32.6; Dr Mahima Nanda, Fig. 32.11; Dr Neeraj Wadhawan,

Fig. 38.2D; Prof RK Khazanchi, Fig. 44.12; ORTHOLAB bv, Orthodontic Laboratory, Netherlands deserves special mention

for Figs 7.8, 24.6 A, 27.1, 27.7, 31.1, B, E, F, G, 34. IB, 35.1.

A special thank to Elsevier’s professional team, more so Ms Ritu Sharma, Anand K Jha and Sunil Kumar. All efforts are

made to acknowledge the help received however omissions if any which may have been inadvertently occurred may

please be considered as duly acknowledged.

4

C o n trib u to rs

1. Col SK Roy Choudhary, MDS 5.

Classified Specialist in Oral and

Maxillofacial Surgery

Army Dental Corps

India

B Jayan, MDS

Classified Specialist in Orthodontics

Army Dental Corps

India

2. M Ali Darendeliler, BDS, PhD, Dip Orth, Certif Orth

Prof and Chair (ASO-NSW)

Deptt of Orthodontics, Faculty of Dentistry,

University of Sydney

Head, Deptt of Orthodontics, United Dental Hospital

2 Chalmers Street, Surry Hills, NSW

Australia

6.

Varun Kalra

BDS, MDS, D Orth RCS, DDS, MS

Associate Professor

Department of Orthodontics and

Dentofacial Orthopaedics

School of Dental Medicine

University of Pittsburgh

Pittsburgh, PA

USA

3. Anurag Gupta, MDS

Scientist II, Indian Council of Medical Research 7.

Deptt of Orthodontics

Centre for Dental Education and Research


Ansari Nagar

New Delhi - 110 029

4. P Hari, MDS

Senior Lecturer 8.

Al-Azhar Dental College

Thodupuzha, Idukki

Kerala

Lokesh Suri

BDS, DMD, MS

Associate Professor

Department of Orthodontics

Tufts University, School of Dental Medicine

Boston, MA 02111

USA

Parul Taneja

BDS, DMD, MS

Private Practice

Chelsea, MA 02150

USA

C ontributed , C h ap ters

Chapter 7

Altered orofacial functions on

development of face and occlusion

Om P Kharbanda and Anurag Gupta

Chapter 29B

Orthodontic adhesives and bonding

techniques

Om P Kharbanda and Anurag Gupta

Chapter 22

Chapter 25

Chapter 26

Orthodontic archwires: material and their Chapter 38

properties

Anurag Gupta and Om P Kharbanda

Chapter 41

Alternative anchorage through temporary

anchorage device (TAD)

Om P Kharbanda and P Hari

Chapter 46

Principles of biomechanics and appliance

design

Varun Kalra Chapter 47

Class III malocclusion in growing patients

M Ali Darendeliler and Om P Kharbanda

Ortho-surgical management of skeletal

malocclusions

Om P Kharbanda and M Ali Darendeliler

Maxillomandibular distraction osteogenesis

B Jayan and SK Roychoudhary

Orthodontist's role in upper airway sleep

disorders

B Jayan and Om P Kharbanda

C o n te n ts

Preface

A cknow ledgem ents

C ontributors

v

vii

ix

Section I:

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

Fundamentals of Orthodontics

Consequences of malocclusion and benefits of orthodontic treatment

• Consequences of malocclusion • Benefits of orthodontic treatment • Immediate benefits • Long-term

benefits • Limitations of orthodontic treatment • Aesthetic dentistry procedures complementary to

orthodontics

Psychological implications of malocclusion and orthodontic treatment

• Psychological implications of malocclusion • Psychological factors motivating patient to seek orthodontic

treatment • Motivational factors in adults • Orthognathic surgery patients • Functional factors

• Malocclusion associated with dentofacial deformities • Cleft lip and palate • Malocclusion due to

trauma

Epidemiology of malocclusion and orthodontic treatment needs

• Secular trends in malocclusion prevalence • Prevalence of malocclusion in North America and Canada

• Prevalence of malocclusion in Europe • Prevalence of malocclusion in South Africa • China and

Mongoloid races • Prevalence of malocclusion in India • Malocclusion in south India • Malocclusion in

north India • Malocclusion in Indian tribals • Summary of malocclusion in India • Orthodontic treatment

needs of India

Classification and method of recording malocclusion

• Recognition of malocclusion • Historical review • Classification of malocclusion • Intra-arch malocclusion

• Interarch malocclusion • Systems of classification • Angle’s concept of malocclusion • Simon’s

classification and ‘canine law’ • British incisor classification • Ackerman and Proffit classification • Katz

premolar classification • Classification in primary dentition

Recording the severity of malocclusion: orthodontic indices

• Qualitative methods of recording malocclusion • Quantitative methods of recording malocclusion

• Occlusal index • Treatment priority index (TPI) • Handicapping malocclusion assessment record

• Index of orthodontic treatment needs (IOTN) • Limitations of IOTN • Peer assessment rating • Index

of complexity, outcome, and need (ICON) • ABO discrepancy index

Growth of the craniofacial complex

• Prenatal development • Genetic control of craniofacial embryogenesis • Concepts of skeletal growth

• Concept of mechanotransduction • Methods of studying physical growth • Postnatal growth • Growth

of nasomaxillary complex • Growth of the mandible • Growth trends • Timing of craniofacial skeletal

growth • Clinical implications

Altered orofacial functions on development of face and occlusion

• Orofacial functions and craniofacial development • Transition from infantile swallow to mature swallow

• Pathophysiology of habits • Sucking habits • Classification of orofacial habits • Prevalence of orofacial

13

20

28

46

55

69

Contents

Chatper 8

habits • Non-nutritive sucking habits • Types of thumb sucking • Effects of digit sucking on oral

structures • Interception of habit • Tongue thrusting, swallowing habit or retained infantile swallow

• Causes of tongue thrusting • Diagnosis of tongue thrusting swallow • Interception and treatment of

tongue thrusting • Mouth breathing habit • Effects of oral breathing • Clinical features • Diagnosis of

mouth breathing • Orthodontic implications • Bruxism • Aetiology • Clinical features • Treatment

Biology of orthodontic tooth movement

• Nature of orthodontic tooth movement • Orthodontic and orthopaedic tooth movement • Phases of

tooth movement • Optimal orthodontic forces • Tissue reactions to orthodontic forces • Periodontal

ligament remodelling— histological findings • Pathways of tooth movement • Arachidonic acid metabolites-

prostaglandins and leukotrienes • Mechanical strain as first messenger • Current view of orthodontic

tooth movement • Immediate early genes (lEGs) expression • Pain and mobility with orthodontic

appliances

83

Section II:

Chatper 9

Chapter 10

Chapter 11

Chapter 12

Chapter 13

Orthodontic Diagnosis

Clinical evaluation

• Patient history • Clinical assessment of a child with a potential for malocclusion • Looking for signs of

potential malocclusion in a three-year-old child: characteristics of face and dentition at 3-6 years

• Gross abnormalities of face form • Primate spaces • Signs of potential malocclusion just before

eruption of permanent incisors • Clinical assessment of a child with developing or established malocclusion

• Orthodontic assessment of a child during mixed dentition stage • Examination of face • Dynamics

of smile and its orthodontic implications • Nature of smile • Objective evaluation of smile • Transverse

cant of the maxillary occlusal plane • Functional examination including TMJ • Tenderness on palpation

• Range of motion • Trauma and dislocation • Speech and malocclusion • Parts of speech • Assessment

of speech in relation to malocclusion and dental anomalies • Clinical examination of child for

suspected deleterious habit(s) • Clinical assessment of an adult seeking orthodontic treatment

• Intraoral examination • Examination of soft tissues of oral cavity • Examination of oral health and

periodontium • Examination of dentition and occlusion

Analysis of diagnostic records

• Minimum set of records needed for a detailed orthodontic case analysis • Orthodontic study models

• 1. Evaluation of study models • 2. Analysis of study models • Step by step procedure for use of

probability tables • 3. E models or digital models • Facial photographs • 1. Photographs for functional

shift • Cephalometric evaluation (cephalogram-lateral view) • Orthopantomogram (panoramic radiography

of the maxilla and mandible) • Analysis of diagnostic records for assessing growth • Peak

growth velocity • Chronological age • Skeletal maturation • Cervical vertebrae maturation index (CVMI)

• Dental age • Facial growth spurts • PA view cephalograms • Recent advancements in orthodontic

diagnostic aids • Stereophotogrammetry • Technetium scan • 3D CT and cone beam CT

Introduction to cephalometrics: historical perspectives and methods

• Historical perspective • First cephalostat • 2D to 3D cephalometrics • Cephalometric norms • Bolton-

Brush growth study • Burlington growth study for craniofacial growth • Cephalometric apparatus

• Head holder • Image receptor system • Radiographic apparatus • Types of cephalogram according

to patient orientation • Patient positioning for recording a cephalogram • Technique of taking a

cephalogram • Indications and uses of cephalograms • Features of a good cephalogram • Location of

anatomical structures on a cephalogram • Unexpected findings on a cephalogram • Fundamentals of

cephalometric analysis • Cephalometric norm • Studies on cephalometric norms in India • Tracing a

cephalogram • Cephalometric analysis • Definitions of cephalometric landmarks • Landmarks on

cranial base • Landmarks on mandible • Landmarks on maxilla • Dental landmarks

Downs’ analysis

• Basis of Downs’ analysis • Skeletal pattern • Denture pattern • Population groups

Steiner’s analysis

• Logical use of reference planes and parameters • S-N plane substituted FH plane • NA and NB

planes • Skeletal analysis • Dental analysis • Soft tissue analysis • Steiner’s norms for Indians

• Interpretation and comments • Steiner chevrons/sticks • Cephalometric superimposition • Interpretations

and Summary

99

124

152

167

172

i

Contents

xiii

Chapter 14

Chapter 15

Chapter 16

Chapter 17

Chapter 18

Chapter 19

Chapter 20

Tweed’s analysis

• Development of the diagnostic facial triangle • Cephalometric values effect decision to treat extraction

or non-extraction • FMA and its relationship with IMPA • Head plate correction • Tweed norms for

Indians

Ricketts’ analysis

• Robert Murray Ricketts • Ricketts cephalometric analysis • Skeletal landmarks • Basic reference

planes • Eleven factor summary analysis

Vertical linear dimensions of face and Sassouni analysis

• Vertical linear dimensions and ratio of face • Sassouni’s radiographic cephalometric analysis • Planes

• Jarabak ratio of anterior and posterior facial heights (facial height ratio— FHR) • Signs of vertical

growth rotation

Soft tissue analysis of face

• Need for soft tissue analysis • Methods of obtaining soft tissue profile on a cephalogram • General

appraisal of soft tissue profile • Cephalometric analysis • Indian norms

PA cephalometric analysis

• PA cephalometric analysis • Set-up for PA cephalometry • Evaluation of PA cephalogram • Some

important landmarks used in PA cephalogram • Planes in PA cephalogram • Grummons analysis

• Ricketts analysis • Maxillomandibular differential values and ratio • Limitations of PA cephalometry

Computerised and digital cephalometrics

• Computerised and digital cephalometrics • Computerised cephalometrics vs digital cephalometrics

• Acquisition of digital image • Limitations of conventional cephalometric analysis • Computerised

cephalometrics: advantages • Advantages of digital computed radiography (CR) and direct digital

radiography (ddR) • Cephalometrics without X-rays • Digital cephalometry • Computed radiography

(CR) • Direct digital radiography (ddR) • CR cephalometrics • Design characteristics of photostimulable

phosphor cassettes

Errors in cephalometrics

• Limitations of a cephalogram • Errors during making a cephalogram • Errors during X-ray tracing

• Errors of cephalometric landmark identification

177

181

186

194

204

213

221

0

I Section III: Orthodontic Appliances

Chapter 21

Chapter 22

Chapter 23

Chapter 24

Components of contemporary fixed orthodontic appliance

• Components of fixed orthodontic appliance • Brackets • Bracket material • Bracket base • Bracket

body and slot • The wings • Power arm • Bracket ID • Self-ligating brackets • Aesthetic brackets

• Plastic brackets • Ceramic brackets • Futuristic bracket design • Limitations of current bracket

systems • Treatment customization • Intraoral orthodontic accessories • Orthodontic bands • Orthodontic

wires • Coil springs

Orthodontic archwires: material and their properties

• Wire dimensions • Evolution of archwires from past to present • Stainless steel wires • Cobalt-chrome

wires • Nickel-titanium wires • I3-Titanium wires • a-titanium wires • Nickel free stainless steel and TMA

wires • Dual flex archwires • Supercable wire • Turbo wire or braided nickel-titanium rectangular wire

• Variable modulus orthodontics • Variable transformation temperature • Aesthetic wires • Archforms

and preformed archwires • Effects of oral environment on properties of orthodontic archwires

Rubber and synthetic elastics and elastic accessories in orthodontics

• Rubber and synthetic elastics • Elastics bands • Storage and dispensing of elastics • Instructions on

wearing of elastics • Complications of use of natural latex elastics • Force decay • Elastomeric accessories

• Elastic chains (power chains) • Ligation of archwire to brackets with elastic module

Anchorage in orthodontic practice

• Anchorage • Anchorage loss • Anchorage sources for removable appliance • Anchorage for fixed

appliance • Factors affecting anchorage requirements ‘ Treatment planning

227

238

254

261

*

xiv

Contents

Chapter 25

Chapter 26

Chapter 27

Chapter 28

Alternative anchorage through temporary anchorage device (TAD) 267

• Alternative anchorage • Historical perspective • Definition and classification • Indications for the use

of temporary anchorage devices • Limitations of temporary anchorage device • Complications • Case

report • Treatment options

Principles of biomechanics and appliance design 276

• Basics of biomechanics • Types of tooth movement • Analysis of common force systems produced

by orthodontic appliances • Intrinsic characteristics of materials • Basic properties of orthodontic wires

• Orthodontic archwire materials • Characteristics of ideal appliance • Application of principles and

properties

Role of removable appliances in contemporary orthodontics 289

• Removable appliances (RA) • History of removable appliance • Indications of removable appliances

• Advantages • Limitations and disadvantages • Treatment effectiveness • Hawley appliance and bite

plate • Crozat appliance • Components of a Hawley type removable appliance • Steps in appliance

fabrication and clinical management • Laboratory requisition and appliance design • Appliance delivery

and activation • Bite plane • Activation of the active wire components • Suitability of RA therapy to

specific conditions • Bite opening and unlocking the mandible • Correction of anterior proclination

• Class II division 2 malocclusion • Correction of ectopic canine • Avoidable complications of RA

Invisible removable appliances: alternative orthodontic

treatment systems 304

• Historical development • The Invisalign® system • Indications for the appliance • Steps and treatment

stages with Invisalign® system of clear aligners • Treatment with ClearSmile system

Section IV:

Clinical Orthodontics

Chapter 29A

Chapter 29B

Chapter 30

Chapter 31

Steps and treatment stages in contemporary orthodontic treatment 311

• The first appointment • Diagnostic records • Designing a treatment plan • Discussing the planned

treatment approach • Active treatment stages

Orthodontic adhesives and bonding techniques 317

• From banding to bonding • History of bonding orthodontic attachments on teeth • Ideal bonding

systems • Advantages of bonding • Disadvantages of bonding • Types of bonding material • Fundamentals

of bonding • Etching: the basis of bonding • Bonding technique • Step by step clinical

technique of flawless bonding • Patient evaluation prior to bonding • Instruments required • Direct

bonding procedure • Light cure bonding agents • Alternatives to acid etching • Bonding with selfetching

primer (SEP) • Indirect bonding procedure • Bonding on fluorosed teeth • Bonding on unconventional

tooth surfaces • Bonding to amalgam and Co-Cr/ Ni-Cr alloys • Bonding to porcelain surfaces

Preservation of normal occlusion and interception of malocclusion

during early mixed dentition 327

• Goals of preventive and interceptive orthodontics • Management and preservation of space • Active

space maintainer or space regaining appliance • Resolution of crowding during early mixed dentition:

serial extractions • Historical perspective • Controversies with serial extraction • Benefits and indications

of serial extraction • Extreme facial types and serial extraction • Steps in serial extraction • Anterior

crossbite in deciduous and mixed dentition: differential diagnosis and management • Anterior crossbite

in deciduous dentition • Therapeutic approach • Anterior crossbite in early mixed dentition • Local

causes of anterior crossbite • Treatment of anterior crossbite of local origin • Retention • Unilateral

crossbite with mandibular shift • Dental anomalies and malocclusions during mixed dentition • Orthodontic

aspects of supernumerary teeth • Management of supernumeraries • Hypodontia

Non-extraction treatment 341

• Factors influencing extraction decision • Non-extraction cases • Methods to gain space to resolve

limited crowding and protrusion • Expansion of upper arch • Non-extraction treatment of anterior

crowding by inter-proximal reduction of dentition • Indications • Proximal recontouring and prevention

of relapse due to late mandibular crowding • Precautions and complications • Techniques • Intraoral

molar distalization • Objectives • Appliance design and case reports • Post-distalization • Timings of

molar distalization

*

Contents

xv

Chapter 32

Chapter 33

Chapter 34

Chapter 35

Chapter 36

Chapter 37

Chapter 38

Chapter 39

Chapter 40

Chapter 41

Class I malocclusion: extraction treatment

• Class I crowding extraction cases • Treatment sequence • Levelling and alignment • Incisor retraction

Class II division 1 malocclusion: features and early intervention of

growing maxillary excess

• Prevalence • Clinical findings • Cephalometric findings • Interception of developing class II malocclusion

Class II division 1 malocclusion: functional appliances

• Functional appliances • Historical perspective • Classification of functional appliances • 1. Activator

or Monoblock • 2. Balters bionator • 3. Frankel appliance • 4. Twin block appliance • Case selection for

functional appliance treatment of Class 1malocclusion • Age • General rules for bite registration

Class II division 1 malocclusion: fixed functional appliances

• Fixed functional appliances • Rigid fixed functional appliances • Flexible fixed functional appliance

(FFFA) • Hybrid fixed functional appliance • Herbst appliance • Appliance design • Bite registration for

the Herbst appliance • Appliance fabrication • Clinical manipulation • Cephalometric skeletal and dental

changes with Herbst appliance treatment • Splint type appliance • Herbst appliance for non-surgical

treatment during early and late adulthood • Mandibular protraction appliance by Filho • Short-term

cephalometric skeletal and dental changes with MPA • Hybrid fixed functional appliances • Mode of

correction with FFA

Management of class II malocclusion with fixed appliance

• Treatment of class II division 1 malocclusion with fixed appliance therapy • Class II treatment options

• Teeth of choice for extraction • Treatment sequence * Indications of first premolar extraction in the

upper arch only • Occlusion and profile after extraction treatment • Factors affecting soft tissue profile

changes

Class II division 2 malocclusion or Deckbiss (German) malocclusion

• Facial features • Dental features • Cephalometric features • Aetiology • Treatment considerations

• Issues with stability and retention

Class III malocclusion in growing patients

• Prevalence of skeletal class III malocclusion • Aetiology • Nature of Class III malocclusion and

components of the problem • Early indicators of mandibular prognathism • Treatment options in growing

children • Interception of malocclusion • Maxillary protraction appliance • Bonded or banded

appliance • Retention • Effects of chin cup and protraction face mask therapy on craniofacial skeleton

• Age vs. maxillary protraction

Orthodontic aspects of impacted teeth

• Definition of impacted tooth • Prevalence/incidence of impactions • Maxillary canine • Central incisor

• Mandibular canine • Maxillary canine • Diagnosis of an impacted tooth • Clinical examination

• Maxillary central incisor • Maxillary canine • Radiological examination • Treatment considerations for

impacted teeth • Observation • Intervention ^Relocation of an impacted tooth • Bilateral impacted

palatal canines in an adult female

Transposition of teeth

• Aetiology • Treatment considerations • Case reports

Ortho-surgical management of skeletal malocclusions

• Historical perspective • Pre-surgical orthodontic treatm ent* Motivational factors involved in seeking

orthognathic surgery • Case selection for orthognathic surgery • History and clinical evaluation

• Extraoral examination • Records and investigations • Cephalometric and computer based prediction

technology in surgical orthodontic treatment planning • Newer diagnostic aids • Special considerations

during surgical treatment planning • Steps involved in an orthognathic surgery procedure • Preorthodontic

preparatory phase • Pre-surgical orthodontic treatment phase • Surgical phase • Postsurgical

orthodontic phase • Complications following orthognathic procedures • Complications related

to procedures of orthodontic treatment, anaesthesia or surgical procedures

355

363

369

381

389

396

403

415

436

440

L

xvi ■ Contents

Chapter 42 Postorthodontic occlusion and immediate post-deband care 465

• Goals of orthodontic treatment • Occlusion in non-extraction cases • Class I occlusion in extraction

cases • Orthodontic scars • Developmental white spots vs orthodontic demineralized lesions • Dental

care and protocol for post-orthodontic deband subject • Post-orthodontic extrinsic enamel staining

• Why staining occurs • Management of white spot lesions (WSL)

Chapter 43 Maintenance of the outcome results, retention and relapse 473

• Why retention? • Rules of retention and relapse • Factors influencing relapse and retention

• Relapses in orthognathic surgery cases • Relapse in cleft cases • Retainer appliances • Trutains

• Positioners • Hawley retainer • Fixed lingual retainers • Active retainers • Retention protocol • Class

I cases • Retention schedule • Adjunctive periodontal procedures for successful orthodontic results

• Circumferential fibreotomy • Maxillary frenectomy • Autogenous gingival grafts

Section V:

Expanding Role of Orthodontist and Interdisciplinary Care

Chapter 44

Holistic treatment approach in the interdisciplinary management

of cleft lip and palate

• What is cleft lip and palate? • Incidence • Embryology and classification • Typical facial clefts •

Introduction • Abbreviation of cleft types • Cleft of the lip and primary palate • Secondary palate

• Atypical clefts • Aetiology of CLP • Intrauterine diagnosis of the craniofacial anomalies • Interdisciplinary

team care • Issues with the care of cleft patients • Pre-surgical orthopaedics • Pre-surgical

nasoalveolar moulding (PNAM) • Impression of a cleft child • Primary surgery of cleft lip • Oslo protocol

• Closure of the secondary palate • Speech in cleft patients • Orthodontic management • Orthodontic

intervention during deciduous dentition • Orthodontic intervention during early mixed dentition • Alveolar

bone graft • Primary alveolar bone grafting • Secondary alveolar bone grafting • Pre-bone graft

orthodontics • Post-bone graft follow-up • Comprehensive orthodontic treatment • Distraction osteogenesis

• Orthognathic surgery • Prosthetic management

Chapter 45 Orthodontic considerations of interdisciplinary treatment 517

• Interdisciplinary orthodontics • Objectives of interdisciplinary treatment • Diagnostic set-up • Realistic

treatment objectives • Pre-restorative/pre-orthodontic periodontal status • Conditions commonly

treated with interdisciplinary care • Missing teeth/space management • Malformed teeth • Fractured

teeth • Gingival discrepancies • Communication

Chapter 46 Maxillomandibular distraction osteogenesis 526

• Philosophy of maxillomandibular distraction osteogenesis • Development of intraoral distractors

• Maxillary distraction osteogenesis • Indications • Contraindications • Advantages of distraction

osteogenesis over orthognathic surgery • Disadvantages • Types of distractors based on site and use

• Distractor designs • Anaesthesia • Types of distraction device • Direction of distractor placement

• Surgical approach • Distraction protocol • Orthodontic considerations, treatment planning and protocols

• Orthodontic treatment protocols • Pre-distraction orthodontics • Orthodontic management

during distraction and consolidation • Post-distraction orthodontics • Retention • Future of

maxillomandibular distraction osteogenesis

Chapter 47 Orthodontist’s role in upper airway sleep disorders 540

• Epidemiology • Pathophysiology • Common sleep disorders • Snoring • Sleep apnoea • Symptoms

of OSA • Investigations • Craniofacial anatomy in patients with upper airway sleep disorders • Treatment

protocols • Oral appliances • Appliance fabrication • Sleep bruxism

Index 553

491

■

SECTION I

Fundamentals of orthodontics

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

Chatper 8

Consequences of malocclusion and benefits of orthodontic treatment

Psychology of malocclusion and dentofacial anomalies

Epidemiology of malocclusion and orthodontic treatment needs

Classification and method of recording malocclusion

Recording the severity of malocclusion: orthodontic indices

Growth of the craniofacial complex

Effects of altered orofacial functions on development of face and

occlusion

Biology of orthodontic tooth movement

A

1

Consequences of malocclusion and

benefits of orthodontic treatment

OVERVIEW

• Consequences of malocclusion

• Immediate benefits

• Long-term benefits

• Limitations of orthodontic treatment

• Aesthetic dentistry procedures complementary to orthodontics

• Summary

Consequences of malocclusion

Malocclusions can manifest in a wide range and

variations from simple rotation of a tooth, a

small diastema to more severe forms of crowding,

spacing, superior protrusion and in combinations of several

traits. A large proportion of children and adults may seek

orthodontic treatment primarily with the objective of

improvement in their facial aesthetics.

More severe forms of malocclusion are associated with

facial skeletal malrelations and constitute a group of

dentofacial deformities. The common facial deformities are;

severe mandibular prognathism with or without maxillary

hypoplasia (midface deficiency), mandibular retrognathia,

severe open bite or an abnormally long face (vertical face

syndrome). Facial asymmetry is not a rare feature in children

of developing countries like India, a common cause being

untreated childhood trauma of TMJ which hinders the

growth of the mandible. Other common causes of facial

asymmetry among young adults and adults are facial trauma

and tumour(s) of the condylar cartilage such as unilateral

condylar hyperplasia. Deformities of face can be

manifestations of more severe forms of systemic diseases

°r syndromes. Among the congenital birth defects, cleft lip

and palate are the commonest.

It is obvious that adults and children with malocclusion

do suffer from psychological, social and, to some extent,

physical handicap. Psychological consequences of

malocclusion can manifest as concerns, anxiety and negative

body image.

Malocclusion has been implicated and is associated with

an increase in periodontal disease, dental caries, TMJ

dysfunction and problems with articulation of speech and

mastication, which is an indication of poor oral health.

Presence of malocclusion can affect longevity of dentition

and oral health and therefore the quality of life (QoL).

Having worked in a public hospital, the author has come

across many children and adults seeking orthodontic

treatment for many functional reasons besides concern for

aesthetics and improvement in appearance. Some of the

common concerns are:

1. Inability to keep lips closed, which causes discomfort.

Such patients are usually associated with superior

protrusion or bidental protrusion.

2. Problems with clarity and articulation of speech,

common cause being anterior open bite.

3. Pain in lower anterior teeth or in palate associated with

severe deep bite.

4. Appearance of spacing between teeth. Such patients

are usually adults who have deep anterior traumatic

bite causing periodontal migration of teeth.

5. Hypersensitive teeth and front teeth getting worn down.

These patients exhibit attrition of teeth due to deep bite.

6. Pain in TMJ and non-specific symptoms of pain in

orofacial region.

3

Orthodontics: Diagnosis and management of malocclusion and dentofacial deformities

Benefits of orthodontic

treatment___________________

Immediate benefits

The very purpose of orthodontic treatment varies from case

to case and so would the expected benefits which need to

be derived. The benefits therefore are influenced by the

nature of treatment, severity of malocclusion and

motivational reasons of the patient for undergoing the

treatment. In general, orthodontic treatment is aimed at

improving the aesthetics, self-image and the body concept,

and well-being in a majority of cases. Socially, malocclusion

and its treatment can affect perceived attractiveness by

others, social acceptance and perceived intelligence.

Treatment of malocclusion can offer physical health

benefits such as prevention of dental and gingival trauma

and improvement in the articulation of speech and

mastication.

Early correction of severe superior protrusion in class II

malocclusion helps to reduce risk of trauma of maxillary

anterior teeth. It also prevents teasing and nicknames in

school, and offers significant psychological benefits to the

child. The interventional procedures which are undertaken

to guide the erupting teeth and intercept incipient

malocclusion are primarily aimed to achieve a normal

occlusion, which may not be well appreciated by a child

(Figs. 1.1, 1.2).

However, a recent study has challenged these traditional

concepts of reviewed literature relating to the impact of

malocclusion and its treatment, on physical, social and

psychological health of a patient, i.e. quality of life. They

concluded that evidence to support above claims were

conflicting owing to differences in study designs,

populations studied and methods of assessment of physical,

social and psychological health.1 Hence, this study though

under rates the benefits of orthodontic treatment perceived

in day to day practice, could be interpreted as to suggest

need for further studies through well-planned study designs,

sample size and methods of assessment of physical, social

and psychological health benefits to definitely substantiate

or refute the claims.

Pre-treatment

Post-treatment

Fig. 1.1 : A young girl with long face, superior protrusion, class II malocclusion and acute nasolabial angle, treated with standard edgewise appliance.

This case needed extraction of all first premolars

*

Section I: Consequences of malocclusion and benefits of orthodontic treatment 5

Pre-treatment

Post-treatment

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Pre-treatment

______________

Post-treatment

Fig. 1.2: Benefits of orthodontic treatment; improved aesthetics and self-esteem in a young growing child. Psychological benefits can change the

perspective of one’s life with sense of well-being and confidence. This case was treated with fixed functional appliance to correct class III skeletal

imbalance followed by fixed mechanotherapy for finishing and detailing of occlusion. No extractions were required

re- and post-treatment occlusion of the patient shows improvement in molar and canine relation from class II to class I, and normal overjet


Pre-treatment: An adult with malocclusion and poor periodontal health

Post-treatment: Significant improvement in self-esteem, aesthetics, improved periodental health

Fig. 1.3A: This woman has severe periodontitis, aggravated with crowding of lower and upper anteriors. She was very unhappy with her appearance.

Orthodontic treatment with fixed mechanotherapy was carried out. Crowding in lower arch was resolved with extraction of a lower central incisor which

suffered severe bone loss. Proximal recontouring of the upper anteriors was carried out to minimize proclination of teeth as the crowding was resolved

Long-term benefits

Long-term functional benefits of orthodontics are reduction

in periodontal disease and longevity of dentition, and

therefore QoL (Figs. 1.1, 1.2, 1.3).

Limitations of orthodontic

treatment___________________

Orthodontic treatment essentially entails movement and

adaptations of dental and dentoalveolar structures and the

adaptation of neuromuscular and soft tissue structures

around them. The new positions acquired have to be in

balance with the functional needs of stomatognathic system

which has primary functions of mastication, speech,

deglutition and respiration.

The dentofacial orthopaedic treatment in growing children

therefore can produce more significant changes compared

to orthodontics alone. Its capability to enhance sagittal

repositioning of the mandible brings about changes in oral

cavity volume and skeletal bases, besides dentoalveolar

structures.

i

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Section I: Consequences of malocclusion and benefits of orthodontic treatment

Pre-treatment occlusion: Poor periodontal health

Post-treatment: Improved aesthetics and periodontal health

Pre-treatment occlusion

Fig. 1.3B: Adult patients require a long-term FSW retainers, a regular follow-up and commitment to aggressive oral hygiene measures. A residual

overjet and mid line shift are the major issues with single incisor extration in the lower arch. Retention in such cases is usually prolonged:

it could extend for a life time

Malocclusions that are beyond the possibilities of

treatment with orthodontics alone and patients who are

beyond the age for possible dentoskeletal orthopaedic

growth modifications can be managed with a combined

approach of orthognathic surgery and orthodontics.

The nature of malocclusion, magnitude of the problem

and complexity of the skeletal and dental relationships are

the basis of treatment plan and detriments if the deformity

can benefit from orthodontics alone or would require a

combination of jaw surgery and orthodontics.

Not all malocclusions in growing children can benefit

from dentofacial orthopaedics. A familial type of severe

Class III malocclusion may not respond to conventional

dentofacial orthopaedic treatment, even though diagnosed

8 Orthodontics: Diagnosis and management of malocclusion and dentofacial deformities

Pre-treatment

Post-treatment

Fig. 1.4 : Obvious benefits of interdisciplinary orthodontic treatment in an adult female. Note a consonant smile arc. Improved axial and sagittal relations

of the upper anteriors are contributory to maintenance of healthy dentition. The contours of the incisal edges were lost due to frequent grinding by

the general dentist to prevent migration of teeth with the objectives to relieve occlusion trauma. The orthodontic treatment restored mid line.To manage

excessive space in the canine area, a Maryland bridge with additional tooth has been provided. This maintains the integrity of the arch and serves

as a retention appliance. The lost incisal edges were resorted with tooth coloured composites

early. In these cases, diligent observations and diagnosis

would be needed to ascertain if the malocclusion be

interfered in growing age or should it be treated later with

orthognathic surgery?

Orthognathic surgery of the facial skeleton permits

repositioning of maxilla and mandible in all three dimensions

of space. However, there are biological limits to such

changes which have been classically summarized by Proffit

and Ackerman (Figs. 1.4, 1.5, 1.6).

The amounts of changes possible in three planes of

space have been quantified for both maxilla and mandible,

and for orthodontics alone or orthodontics with

orthognathic surgery.

Table 1.1 summarizes envelop of limits of orthodontic

treatment, dentofacial orthopaedics and orthognathic

surgery. The values shown in the table are extreme limits of

movements and it is not necessary that these treatment

effects are always possible or would be absolutely stable

in the future.

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Transverse envelope of discrepancy

Palatal 4

Buccal

Buccal

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Orthodontic

Orthodontic combined with growth modification

Combined with orthognathic surgery

Transverse envelope of discrepancy

Mandible

Fig. 1.6A

Fig. 1.6B

All numbers in mm.

Fig. 1.5 : Limits of treatment in upper jaw. Possible movements of maxilla/teeth with orthodontics, growth modification and orthognathic surgery in

vertical and sagittal direction are depicted. A. While it is possible to retract the teeth by 7 mm and procline them by 2 mm, its range when combined

with orthopaedic treatment goes to 12 mm of sagittal retraction and 5 mm of mesial movement. With orthognathic surgery combined this range goes

to 15mm of de-impaction and 10 mm of mesial movement. These are the extreme limits of movement which are limited by several other biological

factors and structural considerations which vary case to case. It is also, in general, agreed that structural and biological limitations are also governed

by soft tissue behaviour. In general the range of maxillary movement is slightly more for vertical extrusion than intrusion and retraction than forward.

B. In terms of transverse limits on buccal expansion of the maxilla is quite stringent and these are more so on the mandible

Fig. 1.6: Envelope of discrepancy for possible alterations in the mandible/teeth showing possible movement in vertical and sagittal direction. A. While

rt is possible to bring the teeth forward by 5 mm, with orthopaedic correction up 10 mm and surgery; this limit goes to no greater than 12 mm. The

orthopaedics is more effective on mandible to enhance lower jaw mesial movement or growth rather than restrict growth. While orthognathic surgery

has greater limits on sagittal reduction compared to sagittal retraction. B. The vertical limits on mandible are almost similar to maxilla. However the

transverse expansion and contraction of the mandible is rather smaller than maxilla

Redrawn and modified from Proffit WR and Ackerman JL. Diagnosis and treatment planning. In Graber TM and Swain BF (eds): Orthodontics: Current

Concepts and Techniques, St. Louis, Mosby, 1985

10 ■ Orthodontics: Diagnosis and management of malocclusion and dentofacial deformities

■ I m L I Table L l : Limits of orthodontic, orthopaedic and surgical orthodontic movements in three planes of space (in mm) 1

Jaw Orthodontics Orthopaedics Orthognathic

surgery

Maxilla

Anterior segment Sagittal Palatal movement 7 12 15

Labial movement 2 5 10

Vertical Intrusion 4 6 10

Extrusion 2 5 15

Posterior segment Vertical Intrusion 2 3 10

Mandible

Extrusion 3 4 10

Transverse Buccal expansion 2 3 4

Palatal constriction 3 4 7

Anterior segment Sagittal Distal movement 5 10 12

Mesial movement 3 5 25

Vertical Away from maxilla 2 5 15

Towards maxilla 4 6 10

Posterior segment Vertical Intrusion 2 4 10

Extrusion 3 4 10

Transverse Buccal expansion 1 2 3

Buccal constriction 2 4 5

Source: Proffit WR, Ackerman JL. Diagnosis and treatment planning. In: Graber TM, Swain BF (Eds). Orthodontics: Current Concepts and Techniques, St.

Louis, Mosby, 1985

In general, for mandible and maxilla, range of possible

movements in vertical and sagittal directions is greater

while possibilities of movement in transverse plane, i.e.

expansion and constriction are minimal, more so in mandible.

In the opinion of orthodontists, a positive overjet greater

than 8 mm, a negative overjet of 4 mm or greater and a

transverse discrepancy greater than 3 mm were not

orthodontically treatable.3

The goals of orthodontic treatment and/or combined

orthognathic surgery are to provide functionally and

aesthetically acceptable occlusion which is in harmony with

the functional needs of stomatognathic system. These goals

are not always achievable in situations of severe magnitude

of the deformity and complex nature of malocclusion. Hence,

the outcome of a treatment should be kept in mind and

realistically achievable goals of treatment should be outlined.

The treatment goals and expected outcome should be

explained to the subject seeking orthodontic treatment who

may have expectations beyond what is achievable.

Aesthetic dentistry procedures

complementary to orthodontics

Aesthetic dentistry procedures can compliment outcome of

orthodontic treatment and thereby enhance aesthetic

outcome in well-treated cases. Subjects with minor

aberrations of tooth form and contours can be treated by

selective and judicious grinding or reshaping of the contours

to normal proportions thereby improving aesthetic results.

In other situations, aesthetic dentistry is a useful adjunct

to orthodontic treatment where good proximal contacts

cannot be achieved due to Bolton’s discrepancy (difference

in the ratio of mesiodistal widths of maxillary and mandibular

anterior teeth) or malformations of tooth structures like:

• Microdontic lateral incisor

• Fractures of incisal edges

• Maxillary canines substituted for missing laterals

• Transposition of teeth: most commonly the maxillary

canine/premolar transposition (Figs. 1.7, 1.8).


■

Fig. 1.7 : Bolton discrepancy associated with smaller mesiodistal dimensions of maxillary laterals. Arrows indicate treatment with aesthetic composite

built-up

Fig. 1.8 : Case NJ born with UCLP left side. She had a large alveolar bone defect, oronasal fistula and collapsed maxillary arch. She underwent

pre-bone graft expansion, secondary alveolar bone graft and comprehensive orthodontics. Her missing left maxillary lateral incisor and 2nd premolar

are substituted with a removable partial denture (RPD). The left maxillary canine was moved distally to occupy the space created by the missing

first premolar

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Summary

Orthodontic treatment should be perceived first from patient’s

point of view and the reason(s) for seeking orthodontic

treatment should be clearly identified. The professional’s

goals of orthodontic treatment are aimed towards functioning

occlusion and optimization of oral health, which need to be

blended with patients’ expectations on aesthetic improvement.

Orthodontic treatment should be complemented with other

dental procedures such as periodontal surgery, prosthodontic

rehabilitation and aesthetic dentistry procedures to provide

optimum dental health.

REFERENCES

1. Zhang M, McGrath C, Hagg U. The impact of malocclusion

and its treatment on quality of life: a literature review. Int J

Paediatr Dent 2006; 16 (6): 381-87.

2. Proffit WR, Ackerman JL. Diagnosis and treatment planning.

In: Graber TM, Swain BF (Eds). Orthodontics: Current

Concepts and Techniques, St. Louis, Mosby, 1985.

3. Squire D, Best AM, Lindauer SJ, Laskhi DM. Determining

the limits of overbite, overjet and transverse discrepancy: a

pilot study. Am J Orthod Dentofacial Orthop 2006; 129(6):

804-08.

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OVERVIEW

• Psychological implications of malocclusion

• Psychological factors motivating patient to seek orthodontic treatment

• Motivational factors in adults

• Summary

Face is perhaps the most important component of an

individual’s physical appearance. Since times

immemorial, we have been fascinated by beautiful

faces. Aesthetics apart, ‘the face’ lends a distinctive character

and identity to an individual. A beautiful face has been

associated with a pleasing personality and it permeates our

entire developmental process. Hence, undoubtedly, a major

motivation for seeking orthodontic treatment is to enhance,

the dental and facial aesthetics, besides improvement of

function and status of oral health.

A balanced face is the outcome of intricate proportion

and balance between the hard tissues, i.e. the craniofacial

skeleton and dentoalveolar structures and their soft tissue

drape in function and at rest. A dental and/or skeletal

malocclusion may upset this balance, and hence may lead

to dissatisfaction with life in an individual. The deformities

of the mouth and the face, which comprise the

communicative zone, affect an individual’s self-esteem

more adversely. Therefore, aesthetics comprises of not

only the face, but also the teeth, the jaws and occlusion.

Psychological implications of

malocclusion________________

The adverse effects of poor facial aesthetics, motivating a

person to seek orthodontic treatment can be broadly divided

into:

• Low self-esteem and maladjustment

• Restriction of social activities

• Adverse occupational outcomes.

Low self-esteem and maladjustment. The motivation to

seek orthodontic treatment is strongly related to an

individual’s perception of the extent to which their

dentofacial appearance deviates from the social norm. The

psychosocial handicap imposed by an unaesthetic dental

appearance may have a negative impact on the personality

of children who are often subjected to ridicule in the

form of teasing, name calling and sometimes even

mobbing by their peers.1 This mental anguish imposed in

early life may evoke feelings of inadequacy in the child

which may well sustain for life, leading to a maladjusted

individual.

Restriction of social activities. Attractive individuals are

believed to have more social appeal and attractiveness. It

affects perception of social characteristics like:

• Perceived friendliness

• Popularity among peers

• Academic performance.

Adverse occupational outcomes. Malocclusion may become

a big social handicap, as the affected individual may find

it very difficult to smile, talk in public or interact with

people. Facial appearance may have important implications

in job opportunities, with attractive faces having an edge

over the less attractive ones. Hence, malocclusion is closely

related to an individual’s social performance and well-being.

Psychological factors

motivating patient to seek

orthodontic treatment_________

Motivation according to the social cognitive theory, is a

dynamic and reciprocal interaction of a triad of three

factors:

• Personal factors

• Behavioural factors

• Environment.

Not all of these factors interact equally. For some, social

influences and environment predominate, whereas for others,

personal experiences, feelings and personality traits may

play a major role.

The order and degree to which these factors influence an

individual’s motivation and expectation from orthodontic

treatment is governed by:

• Age

• Gender

• Socio-economic set-up.

However, the degree of psychological distress is not

directly proportional to the severity of the dentofacial

anomaly. Hence, a rotated lateral incisor or a small median

diastema may produce a more negative body image in one

person than a gross anomaly in another.

Motivating factors differ in different age groups. A factor

which is of utmost importance to a teenager may not be all

that significant for an adult in seeking orthodontic treatment.

Teenagers find it difficult not to follow the norms and

values of their desired reference group. These norms are

strongly influenced by the environment, including the media

portrayal of an ideal body image.

The perception for attractive preference is gradually

inculcated under the influence factors such as:

Self and parental perception of malocclusion

Peer pressure

Severity of malocclusion

Self-esteem

Social class/cultural reasons

Affordability

Availability of specialist orthodontic care.

Self and parental perception of malocclusion

The concern for a deviation or a trait of malocclusion does

not directly correlate with the severity of the problem. A

child may be concerned and develop anxiety for a minor

tooth deviation like rotation or diastema while others may

not be concerned for major irregularities. Such perception

and concern would be dependent, to large extent, on

parents’ perception of malocclusion which may get

transferred to a child or else a child may develop his/her

own concerns which to some extent may be linked with

awareness and education, besides child’s own personality

and priority for well-being and self-image.

Gosney (1986),2 in a study among British children

population referred for orthodontic treatment, observed

that some were unaware or relatively unconcerned about a

pronounced malocclusion whereas others showed a great

concern over a relatively mild irregularity. The concept of

self-image and concern for the deformity may vary and

change with age. Many children may not seek orthodontic

treatment in childhood but seek treatment when they grow

to adulthood and become aware of its need for social or

functional reasons.

Parent’s satisfaction with their orthodontic treatment can

be an important consideration in motivation and perceived

need of orthodontic treatment for their children.

Parent’s determinants. Baldwin and Barnes3,4, observed

that mother is usually the mobilising, deciding and

determining member of the family in terms of the decision

for orthodontic treatment. They noted that in such cases the

mother usually came from a higher socio-economic

background than husband, and may have had orthodontic

problems of her own in the past. It has been observed that

father tended to be less involved in the decision for

treatment and if father alone was the main factor it was

usually for the daughter’s treatment.

The following factors among parents were found

responsible for bringing children for orthodontic treatment:

• The parents attempt to resolve problems of their own

self-concepts by way of identification with the child

and his treatment.

• They attempt resolution of an insoluble family health

problem by displacement on to the child’s orthodontic

problem and treatment.

• Feeling of guilt about their own hereditary deformity,

among any of parents.

• View orthodontic treatment as a social status symbol.

• It has been also observed that children living with

divorced mother who often develop psychological

shortcomings are often given orthodontic treatment as

a ‘psychic gift’ in compensation for being deprived of

father.5

The presence of these factors would mean that the child

may be withdrawn from the motivation for treatment or from

participation in the decision to seek the treatment. If this

occurs in a child with a minor malocclusion, the child may

have no incentive for cooperation during treatment and

may turn uncooperative. In view of above factors, it is wise

for the dentist/orthodontist to know about the patient’s

attitude towards treatment and make sure that patient, if

possible, becomes member of the treatment team that

comprises of the patient, the parent, and the orthodontist.

An uncooperative attitude of the patient can lead to several

problems during treatment and to unsuccessful results.

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Section I: Psychological implications of malocclusion and orthodontic treatment 15

Peer pressure

Peer pressure is perhaps one of the reasons for seeking

dental advice. It has been well found that many school

children may seek advice on need for ‘BRACES’ like their

peers. Some school children may consider it as a matter of

excitement while others may take ‘BRACES’ as

embarrassment. There are differences in perception of

wearing ‘BRACES’ in school population and referred

population for orthodontic treatment.

There may be a general problem in acceptance of

‘BRACES’ in a certain class of population while in another

it may be a ‘badge of honour’. Familiarity with appliance

may reduce resistance to wear the appliance. However,

communication among peers and difficulties with chewing

of food, pain due to appliance breakages, difficulties in

speaking, extra efforts in maintenance of oral hygiene and

extraction of a tooth (teeth) may discourage others for

undergoing orthodontic treatment.

Shaw et al6 suggested and it has been my clinical

observation too that exposure to the sight of appliance may

actually stimulate demand for similar ‘objects’ or treatment.

The studies on patients’ perception of orthodontic

treatment needs and professional assessment of orthodontic

treatment needs do vary. There have been some studies that

have used index of orthodontic treatment need (IOTN) as

a professional ruler to assess the need and patients/parents

questionnaire on subjective need. The IOTN has two

components: namely dental health component (DHC) and

aesthetic component (AC). The DHC has to be assessed by

a professional who has been calibrated for the same. A

study by Shue-Te et al,7 conducted at various orthodontic

offices in San Francisco (California, USA) on patients and

their pretreatment study models, confirmed that aesthetic

component was the significant factor for orthodontic

treatment.

Social class, availability and affordability. Certain health

and cosmetic procedures are more valuable and popular in

social classes, which may also be indirectly influenced by

affordability as well as availability. Orthodontic treatment or

braces may be considered in a group of children in schools

of high socio-economic class as a symbol of prosperity.

Those not having braces may think they are missing on

something and should have it, since they can afford it and

also orthodontic specialists are available in their

neighbourhood.

Severity of malocclusion

It is one of the major reasons for seeking orthodontic

treatment, particularly ‘large overjet’ or protruding teeth or

severely irregular teeth. A child with severe malocclusion

is more likely to seek orthodontic treatment (keeping the

Table 2.1: Psychological factors and personality traits affecting cooperation during orthodontic treatment

A cooperative patient

An uncooperative patient

Psychosocial factors

It could be related to their greater concern about

problems/aesthetics

Treatment has been initiated by the child himself and decided

by the parents with child being taken into confidence

Children with excellent family rapport

Those children who have a poor relationship with parents

at home and with teachers and peers at school

Treatment has been decided by the parents without child

being taken into confidence

Children from broken families

Personality traits

Usually around 14 years or younger

Enthusiastic

Outgoing

Energetic

Self-controlled

Responsible

Determined

Trusting

Determined to do well

Forthright

Obliging

Hardworking

Usually around 14 years or above with superior intelligence

Hard headed

Independent

Aloof

Temperamental

Impatient

Often nervous

Individualistic

Self-sufficient

Intolerant

Disregards wishes of others where his decisions are involved

Easygoing

--------------------------------------------------------------- — ------------


other governing factors like the socio-economic status,

affordability, availability of services, parent’s attitude, etc.)

than a child with a mild irregularity of teeth.

The other factors that may influence need for treatment

are the social class, awareness and concern. Anterior or

forwardly placed teeth can be a cause of teasing in the

school and therefore may generate concern and reason for

orthodontic treatment. In a study done in Finland,8 parents

of 473 children were screened for child’s dental/facial

appearance, reasons for seeking orthodontic treatment and

the referral paths. Almost all (85%) of the 313 parents of

children under age 16 years expressed concern about their

child’s teeth of which 44% reported that the child has been

teased about in school. It was the child who first noticed

need for treatment, overjet and malalignment of teeth

being the main reasons for teasing.

Self-esteem

It is obvious that dentofacial deformities can constitute a

source of emotional suffering, varying in degree from

embarrassment to mental anguish. In order to understand

better this somatopsychic factor, one must consider the

concept of body image. Each individual develops a

conscious image of his/her own appearance, which is

usually a pleasing one. When it is not personally pleasing,

the individual develops anxieties about himself, which, if

unresolved, may lead to mental illness.9 Two aspects have

to be considered in relation to dentofacial defects.

The first is the individual’s attitude towards his/her

body—an attitude resulting both from his/her own reaction

to the defect and from what he/she perceives others reactions

to be. A child who is teased about his/her defect will tend

to have a body image different from that of a person

without a dentofacial defect. The second aspect is the

response of others to the disability. This involves the

degree to which one’s relationship with others is altered

because of how they respond to the defect with lack of

acceptance from mild amusement to horror. One’s body

image is rarely identical with an objective representation of

the body, the severity of the disfigurement having no direct

proportional relationship to the degree of anxiety it produces.

Roots1011 stated that the first and foremost psychological

effect of dentofacial deformity manifests itself as inferiority

complex. The sense of inferiority is a complex, painful,

emotional state characterized by feelings of incompetence,

inadequacy and depression in varying degrees. Basically,

feelings of inferiority depends on an individual’s comparison

of himself with others. This sense of inferiority does not

become a serious problem until the child enters school. He/

she is then brought to realize his/her differences from the

others and finds that he/she is not able to enjoy company

of his/her peers. When the individual reaches adolescence,

a sense of despair and a negative philosophy of life, mixed

with all kinds of peculiar personal traits, may have been

established.

In a study by Secord and Backman,12 an attempt was

made to determine whether or not some dentofacial

characteristics related to physical attractiveness drew

consistent stereotypic judgments about the individual. They

studied the protrusion of the maxillary teeth, protrusionrecession

of the chin, and alignment of the teeth. From

their study it appeared that some personality characteristics

are stereotyped because of an individual’s dentofacial

appearance.

Studies have shown that the primary psychological impact

of a malocclusion does not result from the response of

others to the dentofacial irregularity but from the individual’s

own reaction to the deformity. It has also been observed

that children with malocclusion often lack love and attention

from their parents and as a result are frustrated and

depressed. This may lead to introvert tendencies.

Gender

Although the prevalence of malocclusion is equal among

males and females, more girls seem to be seeking

orthodontic treatment than boys. This is the reflection of

the so-called ‘sex stereotyping’ wherein the society has

higher values and expectations on physical attractiveness

in females than males. It has also been found that females

are more critical of their dental appearance and dissatisfied

with appearance of their dentition than males.1314 Bergman

and Eliasi15 studied psychological effects of malocclusion

and the attitudes and opinion about orthodontic treatment

in Singapore and Sweden population groups (Fig. 2.1 A,

B). One of the significant conclusions was that features of

facial esthetics are perceived differentially by females and

males. There is also a difference in males in Singapore and

males in Sweden. In a study, VP Sharma (MDS orthodontics

thesis, University of Lucknow, 1972) et al found that females

were more concerned about their dental defects as compared

to males, and more concern was observed among individuals

belonging to higher socio-economic class.

Motivational factors in adults

Adults seeking orthodontic treatment can be grouped in

three categories:

• Those seeking treatment with the sole objective of

improvement in their facial attractiveness.

• Those seeking treatment because of referral by their

general dentists for reasons such as prosthodontic

rehabilitation, periodontal disease or traumatic

occlusion.

• Those seeking treatment as a part of orthognathic

surgery for correction of dentofacial anomalies.

Adults who seek orthodontic treatment are often selfmotivated.

In a study by Riedman, George and Berg16 to

evaluate course and outcome of orthodontic treatment in

adults from the patients’ and operators’ point of view, it was

found that in 75% of adult patients, dissatisfaction with the


100% -

Which is the most important feature for

facial aesthetic?

1 1 1 1

n% — — i— — i— — i— —

F Sing F Sth M Sing M Sth

■ Hair

■ Nose

1 Jaws

■ Teeth

■ Face shape

■ Complexion

Which is your reason for having treatment ?

100%

50%

F Sing F Sth M Sing M Sth

F Sing — Females Singapore

M Sing — Males Singapore

F Sth — Females Stockholm

M Sth — Males Stockholm

■ Improve chewing

■ Enhance self-confidence

■ Improve dental health

Improve speech

■ Enhance facial appearance

■ Attain straight tooth

Fig. 2.1 : Reasons of seeking orthodontic treatment do vary with ethnic and social factors (Reproduced with permission from Bergman L, Eliasi F1£

dental aesthetics was the prime motive for seeking treatment.

Adults are better and more cooperative patients in

maintenance of oral hygiene, wearing of elastics and keeping

treatment appointments for, they are self-motivated and

have definite objectives in mind. They are also better

patients for they spend their own money and decide their

own orthodontic treatment. Nattrass and Sandy 17 concluded

that adults seeking orthodontic treatment can be excellent

patients with high motivation and cooperation. Rarely

orthodontic treatment of an adult may be imposed by

spouse and in such situations the adult patients’ behaviour

may or may not be the same as the one with self-motivation.

Among adult orthodontic patients, a large group may be

those referred by general dentist or other dental specialists

for interdisciplinary orthodontic care. Prosthodontics is a

common reason of referral which may include either space

closure, or uprighting of a tilted molar or space gain for lost

space in anterior region. Migration of teeth associated with

periodontal disease in adults with traumatic occlusion is a

frequently encountered phenomenon. In such cases,

orthodontics may follow periodontal therapy.

The orthodontic tooth/teeth movement may also be

required for aesthetic dental treatment, and procedures may

include intrusion/extrusion of a tooth, shifting of teeth to

L

correct midline problems, create space for veneers/laminates

to restore microdontic or small sized lateral incisors.

Surgical orthodontic management of dentofacial skeletal

deformities is usually deferred till adulthood except in a

few situations. Early orthognathic surgery is indicated in

cases of extensively growing mandible due to condylar

hyperplasia, or in children with TMJ ankylosis where

condylar cartilage may have to be substituted with

costochondral rib graft.

Orthognathic surgery patients

The adult orthognathic patients display psychological traits

and profiles different from others. Cunningham, Gilthorpe

and Hunt (2000)18 investigated the psychological profile of

orthognathic patients prior to starting treatment and

compared it with controls. The orthognathic patients

displayed higher levels of anxiety and lower body image.

The facial image esteem was also found lower but of

borderline significance. Williams et al (2005)19 studied factors

of patients’ motivation for undergoing orthognathic surgery

in 326 patients. The major motivations for having treatment

was to have straight teeth (80%), prevent future dental

problems (65%), and improve self-confidence (68%). Females

sought treatment to improve their self-confidence and smile

to improve their social life.


Functional factors

Many malocclusions are related to poor function and this

is another major drive for seeking orthodontic treatment in

many individuals. The functional problems are often caused

by malocclusions such as:

• Class II division 2

• Open bite

• Severe crowding or displaced anterior teeth

• Malocclusion associated with skeletal dentofacial

deformities of developmental origin and facial trauma

• Congenital defects of face such as cleft lip and palate.

Traumatic occlusion

Many young adults and children who have a reasonably

near normal face profile may have severe problems related

to occlusion where nature of malocclusion may affect

longevity of dentition. The classical examples are children

with class II division 2 malocclusion who often have a

round squarish face with little irregularity of maxillary

incisors but 100% or more vertical overlap of anterior

teeth. Such a traumatic bite which is deterimental to the

health of periodontium which may cause early loss of lower

anterior teeth.

In other situations, deep bite, if not treated may cause

attrition of teeth and therefore by adulthood, the lower

anteriors may be significantly worn out. It may not be

possible to provide any rehabilitation of lower anterior

teeth due to lack of any clearance for crowns or removable

partial denture.

Articulation of speech

Cases with severely crowded, irregular incisors and lingually

positioned maxillary incisors may cause difficulty in

production of linguoalveolar sounds (t, d).

Hypodontia/missing teeth cause interdental spacing which

may lead to lateral or forward displacement of tongue

during speech resulting in distortion of sounds. Lingualalveolar

phonemes (e.g. S, Z) followed by lingual palatal

phonemes (J, Sh, Ch) are most affected by spaces in the

dental arch.

In class III cases, sibilant and alveolar speech sounds are

most commonly distorted or affected (s, z, t, d, n, 1). In

these cases, there is a difficulty in elevating the tongue tip

to the alveolar ridge.

Many may not be aware of the cause of speech problems

and may end up with speech therapist who may refer such

persons to dentist/orthodontist. In a study in Melbourne

Australia, Coyne, Woods and Abrams20, researched the

community perceived importance of correcting various

dentofacial anomalies. They found that correction of

functional problems such as ‘difficulty in chewing or

speaking’ was considered very important. The correction of

other factors such as ‘top teeth which strike out in front’,

‘bottom teeth which strike out in front’ or ‘crooked or

crowded front teeth’ was also considered important. They

also found a very large percentage of respondents

considered the need for ‘straight teeth and nice smile’ to be

important in their lives.

Inability to close lips

Many others seek orthodontic treatment for reasons such

as inability to keep the lips sealed or excessive tooth

exposure. These are often adults who are conscious of their

body image but there are those too who have genuine

functional problems.

Malocclusion associated with dentofacial

deformities

Others who may seek orthodontic help may be affected by

either abnormal growth of the facial skeleton or may suffer

from abnormal faces due to underlying systemic disease or

genetic disorders. The common causes are Addison’s disease

(anterior open bite), Mongolism (mandibular prognathism)

and Pierre Robin sequence (mandibular deficiency).

Abnormal facial growth in otherwise normal healthy

children is often encountered as an abnormally growing

lower jaw - mandibular prognathism, which may or may

not be accompanied by a flat middle face. Such children if

untreated during childhood may end up as adult patients

who would require a combination of orthognathic surgery

and orthodontics for the correction of facial deformities.

Cleft lip and palate

One such category of children are those of cleft lip and

palate where maxillary growth is often restricted in vertical

transverse and anteroposterior dimensions due to surgical

scaring during repair of cleft of lip and palate. Such children

may also exhibit over growth of the mandible and therefore

would require orthognathic surgery and orthodontics for

the correction of facial deformity.

Malocclusion due to trauma

An injury to face during childhood may affect the growth

of the condylar cartilage. The severity of injury may vary

from hemorrhage in TMJ to fracture of the condyle. Many

such children particularly in developing countries like

India may remain unattended. These children may ultimately

exhibit restricted mouth opening of varying degrees which

gradually may become more severe leading to complete

trismus due to ankylosis of TMJ. The consequences of

injury to TMJ manifest in the form of deviated chin to the

affected side and consequential facial asymmetry. Facial

asymmetry and restricted mouth opening could be a major

reason for seeking orthodontic treatment in such children.

Summary

Orthodontists treat dentofacial deformities that interfere

with the well-being of patient by virtue of their adverse

effect on aesthetics and function. Most patients seek

orthodontic treatment with the primary objective of

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‘improvement in facial appearance’ which may have an

effect ‘on their overall personality’. Hence a concept of

self-body image is involved.

A majority of orthodontic patients are young adolescents

who are developing human beings and hence are highly

emotional and reactive to the environm ent and

circumstances. The orthodontic treatment is quite demanding

on the part of patient not only in terms of extra strain in

maintaining oral hygiene, wearing elastics and headgear

but also in frequent visits to orthodontist for a long period.

The cooperation of patient during treatment is important in

determining its length and success. The cooperation or

non-cooperation is further dependent upon patient’s basic

personality trait, and orthodontic treatment may further

aggravate anxiety of such nervous patients. Hence during

the early course of treatment itself, the orthodontist should

not only accurately plan the timing of treatment and the

choice of mechanotherapy for good and stable results but

also understand the patient and his guardians/parents, as

persons.21

REFERENCES

1. Cunningham SJ, Feinmann C, Ibbetson R. “Disorders of

appearance.” In: Feinmann C (Ed): The Mouth, The Face and

The Mind. Oxford University Press 1999; 7: 131-56.

2. Gosney MBE. An investigation into some of the factors

influencing the desire for orthodontic treatment. Br J Orthod

1986; 13: 87-94.

3. Baldwin DC, Barnes ML. Some psycho-social factors

motivating orthodontic treatment, International Association

of Dental Research, 43, Abstract No. 461, 1965.

4. Baldwin DC, Barnes ML. Patterns of motivation in families

seeking orthodontic treatment, programs and abstracts of

papers, International Association of Dental Research, 44,

Abstract No. 421, 1967.

5. Sims MR. Psychological disturbances associated with a

mutilated malocclusion. J Clin Orthod 1972; 6(6): 341-45.

6. Shaw WC, O’Brien KD, Richmond S. Quality control in

orthodontics: factors influencing the receipt of female

orthodontic treatment. Br Dent J 1991; 170: 66-68.

7. Shue-Te Yeh M, Koochek AR, Vlaskalic V, Boyd R, Richmond

S. The relationship of 2 professional occlusal indexes with

patients’ perceptions of aesthetics, function, speech, and

orthodontic treatment need. Am J Orthod Dentofac Orthop

2000; 118: 421-28.

8. Kilpelainen PV, Phillips C, Tulloch JF. Anterior tooth position

and motivation for early treatment. Angle Orthod 1993;

63(3): 171-74.

9. Silverman M. Orthodontics and body image. Penn Dent J

1971; 38(8): 10-15

10. Roots WR. Consciousness of esthetic defect. Am J Orthod

1949; 35: 57.

11. Roots WR. Face Value. Am J Orthod 1949; 35: 697-703.

12. Secord PF, Backman CW. Malocclusion and psychological

factors. J Am Dent Assoc 1959; 59: 931-38.

13. Shaw WC. Factors influencing the desire for orthodontic

treatment. Eur J Orthod 1981; 3: 151-62.

14. Sheats RD, Me Gorray SP, Keeling SD, Wheeler TT, King

GJ. Occlusal traits and perception of orthodontic need in

eight grade students. Angle Orthod 1998; 68(2): 107-14.

15. Bergman L, Eliasi F. Sociocultural influence on attitudes about

orthodontic treatment and treatment need, Institute of

Odontology, Karolinska Institute, and Huddinge, Sweden.

http://www.ki.se/odont/cariologiendodonti/978/Lisbeth

Bergman Farah Eliasi.pdf page 215-244 accessed on 7-1-09.

16. Riedmann T, George T, Berg R. Adult patients’ view of

orthodontic treatment outcome compared to professional

assessments. J Orofac Orthop 1999; 60(5): 308-20.

17. Nattrass C, Sandy JR. Adult orthodontics - a review. Br J

Orthod 1995; 22 (4): 331-37.

18. Cunningham SJ, Gilthorpe MS, Hunt NP. Are orthognathic

patients different? Eur J Orthod 2000; 22(2): 195-202.

19. Williams AC, Shah H, Sandy JR, Travess HC. Patients’

motivations for normal treatment and their experiences of

orthodontic preparation for orthognathic surgery. J Orthod

2005; 32(3): 191-202.

20. Coyne R, Woods M, Abrams R. The community and

orthodontic care—part II: Community-percieved importance

of correcting various dentofacial. Aus Orthod J 1999; 15: 289-

301.

21. Kharbanda OP. Psychological considerations in orthodontics.

J Indian Orthod Soc 1984; 17: 13-20.

L

CHAPTER 3

Epidemiology of malocclusion

and orthodontic treatment needs

OVERVIEW

• Prevalence of malocclusion in North America and Canada

• Prevalence of malocclusion in Europe

• Prevalence of malocclusion in South Africa

• Prevalence of malocclusion in China and Mongoloids

• Prevalence of malocclusion in India

• Orthodontic treatment needs of India

• Summary

Population-based surveys of dental diseases are a

prerequisite for systematic planning of the oral health

needs of the society and to estimate the efficacy of

the preventive and therapeutic measures introduced. The

earlier surveys on dental diseases were mainly focused on

dental caries and periodontal disease while malocclusion

received comparatively much less attention. The reasons

could be a lack of the uniform criteria in recording the

malocclusion which is not a disease but a variation of the

normal morphology, a large spectrum of its presentation in

several traits and difficulties in assessment of the REAL

treatment needs superimposed with the social and ethnic

curtains. However lately, much information on malocclusion

and treatment needs is being made available from around

the world.

Angle’s classification of malocclusion has been used in

population surveys to report on the prevalence and

distribution of the different types of malocclusion. There

are obvious limitations to this classification in that it does

not reveal the severity of the malocclusion, and it does not

consider the patient’s profile and also the skeletal

relationship. However, Angle’s classification is perhaps the

most well known and simple method of recording the

malocclusion.

Variations in prevalence of malocclusion have been found

between different races or ethnic groups. Only a few

surveys on children and young adults have been done to

record malocclusion using samples representative of the

population in terms of size or distribution. In the past,

accurate comparisons of malocclusion from different studies

were difficult because of several reasons listed in Table 3.1.

It is, therefore, recommended that a malocclusion survey

should be conducted during the late mixed to permanent

dentition stage. By this time facial growth is close to

completion and permanent dentition up to the 2nd molars

are present, while maxillary canines are erupted or erupting,

therefore occlusion or malocclusion is nearly fully

established (Table 3.2).

Secular trends in malocclusion

prevalence

The prevalence of malocclusion varies greatly in different

parts of the world, in different ethnic groups, and among

people of different races.1'20 Certain races are known for

specific traits of malocclusion, like bimaxillary protrusion

is more common in Negroes2 and children in Danger Island

have high prevalence of class III malocclusion.7 Prevalence

of malocclusion is reported high among Whites than Blacks1,

more in urban than rural children3 6 and high in certain

ethnic groups.10

20

Section I: Epidemiology of malocclusion and orthodontic treatment needs ■ 21

Table 3.1: Factors that directly or indirectly contributed to the extreme variations in reporting the prevalence of malocclusior

1. Lack of demarcation between prevalence of malocclusion in population vs frequency distribution of malocclusion among patients visiting hospitals

(some have called it incidence?)

2. Selection procedure employed in identification of the locations in population-based studies

3. Sampling technique

4. Sample size

5. Lack of objective criteria in some studies for recording malocclusion or method of registration of malocclusion

6. The variations in age group

7. Age group combination(s)

8. Ethnic variations

9. Sex difference

10. Inter/intraobserver errors

Table 3.2: Suggested criteria for recording malocclusion/treatment needs of a society

• Age group +10 years

• Sample size Should be calculated on the basis of target population (population size)

and established earlier prevalence (45%)

• Area District/state should be categorically specified

• By whom By trained person who are calibrated on use of recording malocclusion traits

• Criteria and method of registration Uniform and objective criteria, which can be quantified

The prevalence of class II malocclusion in USA was

found to be 34% in whites and 18% in blacks.3 It has been

reported that prevalence of class II malocclusion was 31%

in Danish children population5 while it was as low as 8%

in Johannesburg,9 11% in Kenya10 and 16.4% in Saudi

Arabia.11

Prevalence of malocclusion in North America

and Canada

USA

Estimates of the prevalence, severity, and need for treatment

of malocclusion in youths of 12 to 17 years of age in

United States was published in 1977 by the Division of

Health Examination Statistics.1 The data on which the

report was based were obtained in oral examinations in 40

scientifically selected locations situated in 25 states,

covering designated sections of the country. The statistical

findings were based on 90% of a probability sample of

7,514 youths representative of approximately 22.7 million

non-institutionalized children in the United States. The

study suggested that the prevalence of malocclusion was

46%. About 54 % of those examined were found to have

Lneutroclusions. Proportionately, more black (62%) than

Neutroclusions are characterized among other deviations

by crowding, rotations, spacing, ectopic eruptions, and loss

of teeth. More white (34%) than black youths (18%) had

distoclusion. About 14% of the sample studied were reported

to have mesioclusion. More than 10% were estimated to

have severe overbites of 6 mm or more of the incisor teeth.

Crossbites of varying severity were found in 12% and 38%

had up to three displaced teeth, with the remainder having

four or more teeth displaced.

Proffit et al12 published findings of prevalence of

malocclusion and orthodontic treatment need in the United

States: estimates from the NHANES III survey. About 25%

were found to have definite malocclusion for which

‘treatment’ was considered to be ‘elective’. Treatment was

found to be ‘highly desirable’ in 13% and ‘mandatory’ for

an additional 16%. An estimated 10.2 million young/adults

had specific occlusal defects, such as severe incisor overbites

or open bites, which required ‘evaluation by orthodontists

to determine the need for treatment’.

Canada

Payette and Plante14 on a data from a sample of 1201, 13-

and 14-year-old Quebec school children using Grainger’s

orthodontic treatment priority index (TPI) reported that 32%

of the children were in Angle’s class II molar relation; 18%


had an overjet of 5 mm and above, 50% had one or more

teeth in minor or major displacement. Treatment was

mandatory or highly desirable for 13.7% and only 2.9% of

the students were under treatment.

Prevalence of malocclusion in Europe

The prevalence of class II malocclusion in the Danish

children was found to be 31% 5 which is high comparable

to other Caucasians but very high compared to races from

India, Africa and Arabia.

Prevalence of malocclusion in South Africa 15,16

The prevalence of class II malocclusion among children

from Johannesburg is reported to be 8%, and in Kenya,

11%. Studies on children in Africa have shown that the

proportion of class II malocclusion is much lower (up to

14%) as compared to those found in Caucasian (up to

20%).

The prevalence of malocclusion was 72% in Nairobi

among 919 children aged 13-15 years. The predominant

anteroposterior relationship of the dental arches was neutral

occlusion (93%). Specific malocclusion traits were highest

for crowding (19%), rotations (19%), posterior crossbite

(10%), maxillary overjet (10%), and frontal open bite (8%).

China and Mongoloid races1718

According to Zhang et al, prevalence of malocclusion

among Chinese children was 67.82%. A study by Lew et al

on 1050 Chinese school children (aged 12-14 years) reported

a high incidence of class III malocclusions in Chinese

compared with Caucasians. However, the incidence of

class II malocclusions was quite similar to those reported

in Caucasians. Crowding occurred in about 50% of cases.

Japanese are known to have higher prevalence of class III

malocclusion compared to other races.

Prevalence of malocclusion in

India1926____________________

India is a large country, its inhabitants being multiracial and

multiethnic. Indian population has been largely divided into

seven ethnic groups based on anthropometric measurements

and skin colour. These are Indo-Aryans, Sytho-Dravidians,

Mongolo-Dravidians, Mongoloids, Dravidians, Aryo-

Dravidians and Turko-Iranians. The Indo-Aryans occupy

eastern Punjab and Kashmir, the Sytho-Dravidians inhabit

hilly tracts of Madhya Pradesh. Mongolo-Dravidians are

seen in Bengal and Orissa while Mongoloids are distributed

in a belt along the Himalayan region, Assam and northeastern

states, and Dravidians inhabit southern India

especially Tamil Nadu, Andhra, Kerala, southern Bihar and

coastal Orissa. Aryo-Dravidians are mainly confined to

northern India. Turko-Iranians inhabit Baluchistan and the

Frontier province, which are now in Pakistan. The differences

for craniofacial and denture pattern among these groups are

known.

In India, a few studies have been conducted to estimate

prevalence of malocclusion and orthodontic treatment needs

(Table 3.3).

Malocclusion in south India

The prevalence of malocclusion in southern Indian city of

Thiruvananthapuram in age group 12-15 was reported as

49.2%. Of this, class I malocclusion was 44%, class II

4.9% and class III 0.3%. According to another study from

Bangalore conducted on 1001 school children aged 12-15

years, the prevalence of malocclusion was 49.2%.

Prevalence of class II malocclusion was 4.9% and class III

was 0.3%.

Malocclusion in north India

Kharbanda et al (1995) reported prevalence of malocclusion

in Delhi based on the school survey of 4500 children in the

age group of 5-13 years. The sample size was calculated

based on sampling design to represent entire school going

population of Delhi in three subdivided locations, i.e. urban,

periurban and rural. Two types of schools were considered

the Convent and Government. The schools all over Delhi

were identified and selected according to sample size for

the survey. The numbers of children to be recorded for

representative age group (5-13) were determined by statistical

sampling technique. The sample data were essentially

presented in two major groups: the mixed dentition group

which comprised 2817 school children in the age group of

5-9 years and the late mixed/permanent dentition groups, in

the age group 10-13 years, comprised of 2737 children.

Malocclusion in age group 5-9 years

A majority of Delhi children exhibited class I molar relation

(91.6%), while only 6% exhibited class II molar relation.

The permanent molar relation was in accordance with

deciduous molar relation that was mesial step (90.3%) and

distal step (8.6%). Crowding in mandibular anterior teeth

was the most common trait of malocclusion (11.7%). There

was no difference in the prevalence of malocclusion between

males and females (Table 3.4).

Malocclusion in age group 10-13 years

The prevalence of malocclusion and its traits was 45.7%.

This comprised of class I 27.7%, class II 14.6% and class

III 3.4% malocclusion. Full cusp class III malocclusion

was only 0.2%. The crowding of anterior teeth in maxilla

and mandible was 9.5% and 18%, respectively. Superior

protrusion was 12% and so was the deep bite. There was

no sex affiliation for the prevalence of malocclusion (Fig.

3.1, Table 3.5). However, the crowding in maxillary anterior

teeth was high among girls (Fig. 3.2).

The prevalence of malocclusion in rural children in

Section I: Epidemiology of malocclusion and orthodontic treatment needs 23

Table 3.3: Prevalence of malocclusion according to population-based studies in India

Author & years of study Sample size & city Age group Malocclusion Percentage

Shourie KL (1942) 1057 (Punjab) 13-16 years Class I 21.7

Class II 27.2

Class III 0.5

Miglani (1963) 1158 (Punjab) 15-25 years Malocclusion 19.6

Tiwari A (1965) 2124 (Punjab) 6-12 years Malocclusion 37.52

Class I 36.02

Class II 37.89

Class III 26.09

Jacob PP (1969) 1001 (Trivandrum) 12-15 years Malocclusion 49.2

Class I 45.0

Class II 4.9

Class III 0.3

Prasad etal(1971) 1033 (Bangalore) 5-15 years Malocclusion 51.5

Class I 95.0

Class II 4.0

Class III 0.9

Crowding 22.0

NagaRaja Rao(1980) 511 (Udupi) 5-15 years Class I 23.0

Class II 4.5

Class III 1.3

Jalili, Sidhu, Kharbanda3(1993) 1085/Aof/Vas/children 6-14 years Malocclusion 14.4

(Mandu, MP) Class II 3.8

Overjet 0.4

Overbite 0.3

Crowd max 6.4

Crowd mand 7.8

Kharbanda, Sidhu, Sundaram, 2817 (Delhi) 5-9 years Malocclusion 20.3

Shukla4(1995) Class I 11.7

Class II 6.0

Class III 2.6

Crowd max 4.2

Crowd mand 11.7

Overjet 3.1

Overbite 3.5

Kharbanda, Sidhu, Sundaram 2737 (Delhi) 10-13 years Malocclusion 45.7

et al (1995) Class I 27.7

Class II 14.6

Class III 3.4

Crowd max 9.5

Crowd mand 18

Overjet 11.5

Overbite 12.3

Alka Singh, B Singh, and 1019 (Rural Haryana) 12-16 years Malocclusion 55.3

Kharbanda etal (1998) Class I 43.6

Class II 9.8

Class III 0.6

Bimaxillary

Protrusion 0.5

Crowd max 5.4

Crowd mand 16.1

Overjet 3.5

Overbite 12.9

Orthod = Orthodontic, Max. = Maxilla, Mand. = Mandibular, Ant. = Anterior, Crowd. = Crowding/crowded

Source. Malocclusion and associated factors among Delhi children. Project Report Indian Council of Medical Research, New Delhi 1991. Dr OP Kharbanda,

Principal Investigator.

■ Norm al occlusion

54%

■ Class I m alocclusion

46%

■ Class II m alocclusion m alocclusion

■ Class III m alocclsuion }

Mild malocclusion

Mod-severe malocclusion

Normal occlusion

i

A

n

c T

T

C

b

K

C

C

Fig. 3.1 : Prevalence of malocclusion in Delhi children

Fig. 3.3 : Distribution of normal and malocclusion in tribal children in

India

/

Boys

Girls

Fig. 3.2: Maxillary anterior crowding in boys and girls show statistically

significant difference

Haryana in the age group 12-16 was found to be 55.3%. Of

this, class I malocclusion was 43.6%, class II 9.8%, class III

0.6%, bimaxillary protrusion 0.5% and mutilations 0.8%.

Malocclusion in Indian tribals

Jalili, Sidhu and Kharbanda (1995)26 surveyed 1085 tribal

children of 6-14 years of age living in remote villages of

Mandu in Madhya Pradesh. The tribal children exhibited a

very low prevalence of malocclusion and its traits, as

compared to the urban Indian children. Majority of them

(85.6%) were free from any anomalies of occlusion. The

prevalence of malocclusion was only 14.4%. A majority of

these (10.5%) were of mild malocclusion and a smaller

number (3.7%) had moderate to severe malocclusion. The

‘handicapping malocclusion’ was observed in 0.2% only.

The prevalence of distomolar (class II) relationship was

3.8% of which full cusp distoclusion was 0.6% only. The

overjet and overbite were 0.4% and 0.3%. The crowding of

anterior teeth in the maxillary arch was 6.4% and in the

mandibular arch was 7.8% (Fig. 3.3, Table 3.6).

Summary of malocclusion in India

• The prevalence of malocclusion in north India (Delhi

children) age 10-13 years is 45% (44.97%). Of this, class

I malocclusion is 26% (25.87%), class II 15% (15.2%)

and class III 3.5%.

• The prevalence of malocclusion in rural children in

Haryana (age group 12-16) is (55%). Class I

malocclusion is (44%), class II (10%), class III (0.6%),

bimaxillary protrusion (0.5%) and bilateral mutilations

(0.8%).

• The prevalence of malocclusion in southern India

(Tiruvananthapuram) age group 12-15 is 49.2%. Of

this, class I malocclusion is 44%, class II 4.9% and

class III 0.3%.

There is a definite ethnic trend in the prevalence of type

of malocclusion in India from north to south of India. The

prevalence of class II malocclusion in Bangalore and

Tiruvananthapuram is reported close to 5% which is much

low compared to the 10-15% class II malocclusion in Delhi

and Haryana. In addition, the southern population has

ethnic affinity for bimaxillary protrusion.

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Table 3.4: Prevalence of malocclusion and its traits in Delhi children (n-2877), in age group 5-9 years

Angle’s classification

Total percentage

Class 1malocclusion 11.7

Molar relationship (half cusp) (full cusp)

Class II or distal 3.4 2.6 6.0

Class III or mesial 2.6 0.0 2.6

Total (Class l+ll+lll) 20.3

Traits of malocclusion

Crowding Mild-moderate Severe

(2-<4 mm) (4 mm and >)

Maxilla 3.8 0.4 4.2

Mandible 10.1 1.6 11.7

Overjet (<9 mm) (>9 mm)

2.8 0.3 3.1

Overbite <2/3rd >2/3rd

2.6 0.9 3.5

Anterior crossbite one tooth > one tooth

2.6 1.4 4.0

Table 3.5: Prevalence of malocclusion and its traits in Delhi children (n-2737) in age group 10- 13 years


Total percentage

Class 1malocclusion 27.7

Molar relationship (half cusp) (full cusp)

Class II or distal 7.0 7.6 14.6

Class III or mesial 3.2 0.2 3.4

Total (Class l+ll+lll) 45.7

Traits of malocclusion

Crowding Mild-Moderate Severe

(2-<4 mm) (4 mm and >)

Maxilla 7.51 2.0 9.5

Mandible 16.0 2.0 18.0

Overjet (<9 mm) (>9 mm)

9.2 2.3 11.5

Overbite <2/3rd >2/3rd

7.8 4.5 12.3

Anterior crossbite one tooth > one tooth

2.6 1.4 4.0

Orthodontic treatment needs of

India _____________________

The treatment needs of a society cannot be known from the

data on the prevalence of malocclusion alone. Mere

existence of a dental irregularity like a diastema or rotation

°f a tooth may not warrant orthodontic treatment until there

is a concern for it. The concerns for the similar type of

dental deformity may be least for one individual while it

may cause anxiety in another. The same dental malocclusion

may be of no significance in an individual at a given age

but may be of great concern at a different point of time/age.

The need for the orthodontic treatment is also governed

by the dental health component (DHC) of malocclusion,


Table 3.6: Prevalence of malocclusion and its traits in tribal children in India (Mandu, MP state) total prevalence 14.4%

Trait Mild Mod-severe

9.

Crowding maxilla

5.7

0.7

6.4

Crowding mandible

Overjet

7.0

0.1

0.8

0.1

7.8

0.2

10.

Overbite

0.2

0.1

0.3

Class I molar relation

96.2

11.

Class II molar relation

3.2 (half cusp)

0.6 (full cusp)

3.8

12.

Table 3.7: Suggested method for calculation of sample size for prevalence of malocclusion

The sample size is calculated by using the formula

n = 4pq_

L2

Under the assumption that

p = prevalence of malocclusion, i.e. 45% in the age group of

12-16 Yrs based on previous study (Kharbanda et al)

Selected with cluster sampling technique

13.

14.

q = 100-P, i.e. 55

L = allowable error (10% of p)

15.

which is measured in terms of its effect on the longevity of

dentition and function of the occlusion. Malocclusion like

a severe deep bite in a class II division 2 malocclusion may

be of least aesthetic concern to an individual but would

require a priority in treatment because of its detrimental

effect on the dentition.

To prioritize malocclusion for the treatment point of view,

many indices have been developed especially in Europe.

Several studies are now pouring in from different parts of

the world on orthodontic treatment needs using treatment

priority indices. The index of orthodontic treatment needs

(IOTN)27’28 developed in UK is widely used. IOTN can also

be used in public funded hospitals to prioritize the need for

orthodontic treatment. It is obvious that the handicapping

type of malocclusion (cleft lip and palate, severe deep bite,

reverse overjet, skeletal maxillary protrusion, skeletal class

II) should be given priority for the treatment.

The IOTN may not provide a true picture of orthodontic

needs for a country like India for its limitation in recording

bimaxillary protrusion. The bimaxillary protrusion, which

is prevalent in India especially in southern India, should be

added to the existing recording proforma. In addition, the

dental aesthetic index should also be modified to include

bimaxillary protrusion. We do not have a single study in

the country to point out the data-based treatment needs of

India/state or a city.

Summary

In general prevalence of molocclusion is considered to be

on increase with evolution and civilisation. Although Angle’s

method has been used in recording the malocclusion it

does not reflect the actual orthodontic treatment needs of

the society. In India, class II malocclusion has been reported

to be relatively more prevalent in north Indian children

population, compared to southern India. However its

prevalence in India is low compared to those reported in

Caucasian population.

The frequency of occurrence of class I malocclusion is

greatest followed by class II and class III.

REFERENCES

1. Salzman JA. Malocclusion and treatment needs in United

States youths 12 to 17 years of age. Am J Orthod 1977; 72:

579-81.

2. Gamer LD, Butt MH. Malocclusion in Black Americans and

Nyeri Kenyans: An epidemiological study. Angle Orthod

1985; 55: 139-46.

3. deMuniz Beatriz R. Epidemiology of malocclusion in Argentine

children. Community Dent Oral Epidemiol 1986; 14: 221-24.

4. Kerosuo H, Laine T, Kerosuo E, Ngassapa D, Honkala E.

Occlusion among a group of Tanzanian urban school children.

Community Dent Oral Epidemiol 1988; 16: 306-09.

5. Helm S. Malocclusion in Danish children with adolescent

dentition : an epidemiologic study. Am J Orthod 1968; 54(5):

352-66.

6. Ast DB, Carlos JP, Cons DC. Prevalence and characteristics

of malocclusion among senior high school students in up-state

New York. Am J Orthod 1965; 51: 437-45.

7. Davies GN. Dental conditions among the Polynesians of

Puka Puka Island (Danger Island). J Dent Res 1956; 35(1):

115-31. A „

16.

17.

*


8. Wood B F Qt al. Malocclusion in the modem Alaskan Eskimo.

Am J Orthod 1971; 60(4): 344-54.

9. Hirschowitz AS. Dental caries, gingival health and malocclusion

in 12-year-old urban black school children from Soweto,

Johannesburg. Community Dent Oral Epidemiol 1981; 9: 87-

90.

10. Ng’ang’a PM, Karongo PK, Chindia ML, Valderhaug J.

Dental caries, malocclusion and fractured incisors in children

from a pastoral community in Kenya. East Afr Med J 1993;

70: 175-78.

11. Al-Emaran S, Wisth, PJ, et al. Prevalence of malocclusion and

need for orthodontic treatment in Saudi Arabia. Community

Dent Oral Epidemiol 1990; 18(5): 253-55.

12. Proffit WR, Fields HW Jr, Moray LJ. Prevalence of

malocclusion and orthodontic treatment need in the United

States: estimates from the NHANES III survey. Int J Adult

Ortho Orthognath Surg 1998; 13: 97-106.

13. Johnson M, Harkness M. Prevalence of malocclusion and

orthodontic treatment need in 10 year old New Zealand

children. Aust Orthod J 2000; 16(1): 1-8.

14. Payette M, Plante R. The prevalence of malocclusion problems

and orthodontic treatment needs in 13- and 14-year-old

Quebec school children in 1983-1984. J Dent Que 1989; 26:

505-10.

15. Dacosta OO. The prevalence of malocclusion among a

population of northern Nigeria school children. West Afr J

Med 1999 Apr-Jun; 18(2): 91-96.

16. Ng’ang’a PM, Ohito F, Ogaard B, Valderhaug J. The prevalence

of malocclusion in 13- to 15-year-old children in Nairobi,

Kenya. Acta Odontol Scand 1996; 54(2): 126-30.

17. Fu M, Zhang D, Wang B, Deng Y, Wang F, Ye X. The

prevalence of malocclusion in China—an investigation of 25,

392 children. Zhonghua Kou Qiang Yi Xue Za Zhi 2002;

37(5): 371-73.

18. Lew KK, Foong WC, Loh E. Malocclusion prevalence in an

ethnic Chinese population. Aust Dent J 1993; 38(6): 442-49.

19. Kharbanda OP, Sidhu SS. Prevalence studies on malocclusion

in India - retrospect and prospect. J Ind Orthod Soc 1993;

24(4): 115-18.

20. Prasad AR, Shivaratna SC. Epidemiology of malocclusion -

a report of a survey conducted in Bangalore city. J Ind

Orthod Soc 1971; 3(3): 43-55.

21. Jacob PP, Mathew CT. Occlusal pattern study of school

children (12-15 years) of Tiruvananthapuram city. J Indian

Dent Assoc 1969; 41: 271-74.

22. Kharbanda OP, Sidhu SS, Sundaram KR, Shukla DK. A study

of malocclusion and associated factors in Delhi children. J

Pierre Fauchard Academy 1995; 9: 7-13.

23. Kharbanda OP, Sidhu SS, Sundaram KR, Shukla DK.

Occlusion status during early mixed dentition in Delhi children.

Project Report Indian Council of Medical Research, 1991.

24. Kharbanda OP, Sidhu SS, Sundaram KR, Shukla DK.

Prevalence of malocclusion and its traits in Delhi children. J

Indian Orthod Soc 1995; 26(3): 98-103.

25. Singh A, Singh B, Kharbanda OP, Shukla DK, Goswami K,

Gupta S. Malocclusion and its traits in rural school children

from Haryana. J Indian Orthod Soc 1998; 31: 76-80.

26. Jalili VP, Sidhu SS, Kharbanda OP. Status of malocclusion in

Tribal children of Mandu (central India). J Ind Orthod Soc

1993; 24: 41-46.

27. Roberts CT, Richmond S. The design and analysis of reliability

studies for the use of epidemiological and audit indices in

orthodontics. Br J Orthod 1997; 24: 139-47.

28. Shaw WC, Richmond S, O’Brien KD. The use of occlusal

indices—a European perspective. Am J Orthod Dentofac

Orthop 1995; 107: 1-10.

A

Classification and i

recording ma

OVERVIEW

Recognition of malocclusion

Historical review

Terms used to describe traits of malocclusion

Classification of malocclusion


Simon’s classification

British incisor classification

Ackerman and Proffit’s method

Katz premolar classification

Classification of malocclusion in deciduous dentition

Summary

Recognition of malocclusion

Face has infinite variations of its constitution and

expression. Ethnic isolation on one side and on the

other side, heterogeneous mixing of people from across

the globe, the gene-environment interaction and the genetic

mix up which led to the ‘new look’ faces, wherein jaw size,

dentition and occlusion are significant components. There

are ethnic variations of the profile, e.g. in India the subjects

from north, south and north-east are different ethnic stock

and therefore exhibit significant variations in face form.

In strict sense of definition, any deviations from normal

occlusion can be termed as malocclusion, which may vary

from a very slight deviation of a tooth position in the arch

to a significant malpositioning of a group of teeth or jaws

(Figs. 4.1, 4.2).

‘Norm’, in reference to occlusion, is itself a range and

what quantum of ‘deviation’ constitutes a malocclusion is

sti

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an

me

an

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ini

an

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wc

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be;

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Fig. 4.1 : Class I molar and canine relation, normal overjet and overbite

28

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sy;

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Section I: Classification and method of recording malocclusion ■ 29

as a process of analyzing cases of malocclusion for the

purpose of segregating them into a small number of groups,

which are characterized by certain specific and fundamental

variations from normal occlusion of the teeth; which

variations become influential and deciding factors in

providing the fundamental data for the preparation of a

systematic and correlated plan of treatment.”

Lingual

Fig. 4.2: Overjet labial/buccal overlap overbite: vertical overlap

still not clearly defined. The evaluation and definition of

occlusion is determined by the intra-arch dental alignment

and arch forms, interarch relationship of individual tooth

and their harmony with underlying skeleton bases, i.e.

maxilla, mandible and cranium. The soft tissues integument

and attachments including functional components should

harmonize to produce ‘optimum aesthetics’ and ‘function’.

‘Norm’ therefore includes preservation of health and

function of the components. These functions include speech,

deglutition, respiration and mastication.

The concept of ‘malocclusion’, therefore, is greatly

influenced by the definition of normal and its range. There

are possibilities of innumerable number of deviations that

may be within the defined range while many beyond it

would be termed as ‘malocclusion’.

Malocclusion deviations may be limited to within the

arch and/or as a single or a group of teeth with those in the

opposite arch in anteroposterior (sagittal), lateral (transverse)

and vertical (superoinferior) planes of space.

The concept of aesthetics and beauty varies across the

globe and across races: some features could be ‘peculiar to

ethnicity’. For example, median diastema is considered to

be a sign of beauty in some African races. The concept of

beauty has evolved with evolution and civilization. It

changes with changing times to some extent.

For ease of communication among professionals and

understanding the nature of deviations, terminologies were

coined to categorize malocclusion. A classification is specific

to aim, which includes documentation, and to some extent

approach to treatment plan.

Strang ( 1938)1 suggested that classification of

malocclusion should also include a direction to the

systematic plan of treatment. “I would define classification

Historical review2,3

The earliest scientific description of malocclusion was

given by Samuel S Fitch, in his book ‘A System of Dental

Surgery’ 1829. He was the first to classify malocclusion

into four states of irregularity. Christopher Kneisel (1836)

in Der Scheifstand Der Zahre’ (The oblique position of

teeth) described malpositions of the teeth as general

obliqueness and partial obliqueness when all teeth or only

some teeth in the arch are malpositioned. Jean Nicolas

Marjolin (1832-1839) of France differentiated obliqueness

of teeth and anomalies of dental arch.

George Carabelli (1842) of Vienna described abnormal

relationships of the upper and lower dental arches in

systematic manner and coined the term edge-to-edge bite

and overbite.

His classification was based on the positions of incisors

and canines which he termed as:

• Mordex normalis: normal occlusion

• Mordex rectus: edge to edge

• Mordex apertus: open occlusion

• Mordex prorsus: protruding occlusion

• Mordex retrosus: retruding occlusion

• Mordex tortuosus: zig-zag occlusion.

Norman Kingsley (1880)4, an eminent orthodontist,

contented himself by classifying the malocclusion into two

broad categories based on aetiology:

• Developmental malocclusion

• Accidental malocclusion.

Edward H Angle (1899,1900,1906,1907)5'8 gave a detailed

description of malocclusion into three classes based on the

assumption that position of maxillary first molar and canine

were stable in the maxilla and corresponding lower teeth/

jaw showed deviations in anteroposterior positions. He

classified all malocclusions into class I, class II and class

III malocclusion. Later in his work, he gave a detailed

description of normal occlusion, ‘line of occlusion’, ‘facial

lines’, and quantification of each class, in terms of

relationship of the full cusp deviation to half cusp.

Other classification systems or modifications were:

1. Calvin Case (1908)9,10 evolved a rather complicated

classification in which anatomical groups were

selected to be grouped into five classes from the

treatment standpoint of view.

2 . Lischer (1912)11 gave the terms distoclusion and

mesioclusion.


Buccal

overjet

Reverse

overjet

Fig. 4.3A: Normal buccolingual relationship of the posterior teeth showing

buccal overjet

Fig. 4.3B: Buccolingual relationship of the posterior teeth in bilateral

buccal crossbite. Note reverse buccal overjet

A

B

Fig. 4.6 : Traits of malocclusion: A. Anterior crossbite, B. Posterior crossbite

Fig. 4.7: Traits of malocclusion: A. Left upper premolars in infraocclusion, B. Left upper molar in supraocclusion, C. Severe rotation of right central

incisors in a case of unilateral cleft lip and palate (UCLP), D. Nearly complete rotation: Torsoversion of left maxillary central incisor in a UCLP case

3. Martin Dewey (1915, 1935)12 modified and gave

different ‘types’ for Angle’s classes.

4. Paul Simon (1920)13 16 whose philosophy of

classification of malocclusion was based on

gnathostatics and ‘canine law’.

5. Ballard and Wayman (1964)17'19 gave the British

classification based on incisor overjet, based on

6.

1.

the work o/Backlund, which was further modified

by Williams and Stephens (1992).

Ackerman and Proffit’s classification (1969)20

included a Venn diagram.

Katz (1992)21'23 based his classification using

premolars as a reference landmark.

L

32


S'

a]

re

d

C

4

•tr

&

D

Fig. 4.8 : Traits of malocclusion: A. Deep bite, B. Open bite, C. Open bite, D. Severe open bite

Classification of malocclusion

Intra-arch malocclusion (Figs. 4.3-4.8)

Angle used following nomenclature to describe deviations

from normal tooth positions:

1. Buccal or labial occlusion: A tooth outside of the line

of occlusion.

2. Lingual occlusion: When the tooth is inside this line

3. Mesial occlusion: The tooth is farther forward

(mesially) than normal

4. Distal occlusion: If the tooth is backward (distally)

than normal.

5. Torso-occlusion; If the tooth is turned on its axis.

6. Infra-occlusion: Teeth not sufficiently elevated in their

sockets.

7. Supra-occlusion: Those that occupy positions of great

elevation.

Other tooth malpositions can be described as:

1. Rotations', refer to tooth movements around its long

axis.

2. Transposition: This term describes a condition where

two teeth have exchanged places.

Interarch malocclusion

These can be in sagittal, vertical or transverse planes.

Whereas most of the classification systems described are

in sagittal plane, the other planes are as follows:

Vertical plane malocclusion (Fig. 4.8)

Deep bite or increased overbite. This refers to a condition

where there is an excessive vertical overlap between upper

and lower anterior teeth.

Open bite. It is a condition where there is no vertical

overlap between upper and lower teeth . Thus, a space may

exist between the upper and lower teeth when the patient

bites in centric occlusion. Open bite can be in the anterior

or posterior region.

Transverse plane malocclusions

Transverse plane malocclusions include various types of

crossbites and scissor bites.

Crossbite. The term crossbite refers to abnormal transverse

relationship between upper and lower arches. A crossbite

may affect a single tooth or a group of teeth or an entire arch.

It may affect anterior or posterior teeth alone, or both in

combination. Posterior crossbites can be unilateral or bilateral.

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o

0

n

c

o

0

a

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c

1

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1

2

1

Section I: Classification and method of recording malocclusion 33

Scissors bite. It refers to a condition in which the mandibular

arch is contained within the maxillary arch.

Systems of classification______

Angle’s concept of malocclusion

Edward H Angle considered the first permanent molar

relation as a reference to judge normality and very lucidly

described it as (Fig. 4.9):

“In normal occlusion, the mesiobuccal cusp of the

upper first molar is received in the sulcus between the

mesial and distal buccal cusps of the lower, the slight

overhanging of the upper teeth bringing the buccal cusps

of the bicuspids and molars of the lower jaw into the

mesiodistal sulci of their antagonists, while the upper

centrals, laterals, and cuspids overlap the lower about

one-third the length of their crowns.

The mesial and distal inclines of the mesiobuccal cusp

of the upper first molar are received between the mesial

and distal buccal cusps of the lower first molar, and the

inclines of the distobuccal cusp are received between the

distobuccal cusp of the first lower and the mesiobuccal

cusp of the second lower. ’

Later, Angle (1906)7 published his classic article in Dental

Items of Interest entitled The Upper First Molars as a Basis

of Diagnosis in Orthodontics’ where he espoused the

virtues of the maxillary first molars. He believed upper first

molars were the key to occlusion because they:

1. Are the largest teeth

2. Are the firmest in their attachment

3. Have a key location in the arches

4. Help to determine the dental and skeletal vertical

proportions due to length of their crowns

5. Occupy normal position in the arches far more often

than any other teeth because they are the first permanent

teeth and are less restrained in taking their position

6. More or less control the positions of other permanent

teeth

7. Have the most consistent timing of eruption

8. Determine the interarch relationship of all teeth upon

their eruption and ‘locking’ with the mandibular first

molars.

Angle’s conviction of a constant first molar position in

the maxillary arch was also supported by Atkinson who

suggested a relative constancy of the maxillary first molar

and the bony buttress of the zygoma which he called the

key ridge.

For comparison with the normal, two reference norms

are of particular importance: (i) ‘line of occlusion’ of

dentition and (ii) ‘harmony line’ of the face.

i. Line of occlusion. (<When the teeth are in normal

occlusion the line of greatest occlusal contact will be found

to pass over the mesial and distal inclined planes of the

buccal cusps of the molars and bicuspids and the cuttingedges

of the cuspids and incisors of the lower arch, and

along the sulcus between the buccal and lingual cusps of

the upper molars and bicuspids, hence forward, crossing

the lingual ridge of the cuspids and the marginal ridges of

the incisors at a point about one-third the length of their

crowns from their cutting-edges. This we shall call the line

of occlusion. ”

He continued, “This line describes more or less of a

parabolic curve, and varies somewhat within the limits of

the normal, according to the race, type, temperament, etc.

of the individual ” (Fig. 4.10).

ii. Harmony line. Angle gave great importance to the soft

tissue profile and believed that malocclusion destroyed the

profile. He considered the profile of Apollo, a Grecian

spelling mythological God, as so faultless in form that to

change it in the least would be to mar the wonderful


Maxillary

Mandibular

Fig. 4.10: Line of occlusion: As described by Edward Angle (1899), the line of occlusion is a smooth, parabolic curve passing through, the central

fossa of each upper molar and across along the buccal cusps, and incisal edges of the lower teeth, thus specifying the occlusal as well as interarch

relationship once the molar position is established

harmony of proportions. As Fuseli puts it, “Shorten the

nose by but the tenth of an inch and the god would be

destroyed” (Fig. 4.11).

He also described other parts of the face, “Ideal facial

beauty consists in a short, finely, curved, and prominent

upper lip; a full, round, but less prominent lower lip, and

a strongly marked depression at the base of the lower lip,

giving roundness and character to the chin”. Angle gave

special importance to the lower part of the face so much so

that in handsome profiles he found that a beautiful outline

is a constant feature while the upper half of the face may

show variations.

Fig. 4.11: Harmony line Apollo (Angle Edward H. Classification of

malocclusion. The Dental Cosmos 1899; XII:350-57). Reproduced with

permission from University of Michigan Library, Michigan USA. http://

quod.lb.umich.edu/d/dencos

In perfect profiles, harmony line, is a straight line extending

from the most prominent points of the frontal (glabella) and

mental (chin) eminences, and the middle of the ala of the

nose.

Angle used the Roman numerals I, II and III to designate

the three main classes of anteroposterior arch relationship

viz. class I or normal, class II or distal and class III or mesial

relationship of the cusps of the mandibular first molars to

the maxillary first molars. He employed the Arabic numerals

1 and 2 to denote divisions of the classifications. He termed

unilateral deviations as subdivisions (Fig. 4.12).

a. Class I: Relative position of the dental arches, mesiodistally,

normal with malocclusions usually confined to

the anterior teeth.

b. Class II: Retrusion of the lower jaw, with distal occlusion

of the lower teeth.

i. Division 1: Narrow upper arch, with lengthened

and prominent upper incisors; lack of nasal and lip

function. Seen in mouth-breathers.

ii.

Subdivision: Same as above, but with only one

lateral half of the arch involved the other being

normal. Also seen in mouth-breathers.

Division 2: Slight narrowing of the upper arch;

bunching of the upper incisors, with overlapping

and lingual inclination; normal lip and nasal

function (Fig. 4.13).

Subdivision: Same as above but with only one lateral

half of the arch involved, the other being normal;

normal lip and mouth function (Fig. 4.13B).

c. Class III: Protrusion of the lower jaw by at least one

premolar width, mesial occlusion of the lower teeth;

lower incisors and cuspids inclined lingually.

Subdivision: Same as above but with only one lateral

half of the arch involved the other being normal (Fig.

4.12C).

c

Fig. 4.12: Angle’s classification: A. Class I malocclusion, B. Class II malocclusion, C. Class III malocclusion (Angle Edward H. Classification of

malocclusion. The Dental Cosmos 1899;XLI:248-264)

A

BR

BL

Fig. 4.13: A. Class II division 2 malocclusion: Note deep bite, retroclined upper centrals and proclined upper laterals, B. Class II subdivision malocclusion:

LNote class II molar and canine relation on right side and class I molar and canine on left side

36


Functional class III or pseudo class III (Fig. 4.14)

This condition requires special mention because treatment

of this class of malocclusion is entirely different than true

class III situation. The differentiating feature of this

condition is that the dental occlusion is class III in maximum

intercuspation or habitual occlusion but actually in centric

occlusion it is Class I. Here the disturbance is a functional

one, where, due to some dental interference, the mandible

is deviated anteriorly to achieve a ‘bite of convenience’.

Thus, a static evaluation will give a class III reading but

functional examination in postural rest and at first contact

shows that the mandible is closing in a normal class I

relation.

Important diagnostic features for this condition can be

located on the study models such as obvious occlusal

interference in form of single or multiple tooth crossbite

and severely constricted maxillary arch anteroposteriorly

as well as transversely.

Angle also recognized the existence of cases with one

side class II and other side class III. But he discounted

these as being very rare.

Virtues of Angle’s classification are given in Box 4.1.

L

Box 4.1: Virtues of Angle’s classification

1. Simplicity

2. It is practical, easy to understand and apply in day to day clinical practice

3. Three anteroposterior classes, can also be applied to underlying skeletal classes seen on cephalograms, i.e. class I, class II and class III skeletal

relations; although the dental relation may or may not confirm to underlying skeletal malocclusion or vice-versa

4. Angle, who had a brilliant eye of normality and in the pre-cephalometric era, could identifying dental or skeletal abnormal situations

5. The classification has stood test of time and is the most widely used classification

Box 4.2: Drawbacks of Angle’s classification24'28

Angle’s classification suffers from many limitations:

1. Angle grouped all the possible malocclusions in three classes of anteroposterior deviations. The range of discrimination from class I to class II (disto)

to class III (mesio) which was initially full cusp width of maxillary first molar (1899), was further modified to half cusp width (1904,1907)

2. Angle considered the evaluation of all teeth at harmony line and initially used maxillary first molars and canines as reference points (1899), which later

was modified with greater emphasis on maxillary first molar (1904,1907)

3. Angle’s conviction of maxillary first molar being the most stable landmark, was later found not to be consistently true. There can be anatomical

variations of location of the maxillary first molar in the maxillary arch and the jaw bones24’25

4. Angle presupposed that all malocclusions are predominantly exhibited in anteroposterior direction and accordingly classified them on the basis of

sagittal deviations. Vertical and transverse dimensions were not considered

5. Angle’s classification is based upon criterion of dentition alone and it does not take into account the underlying craniofacial relationship

6. It does not indicate the severity and complexity of malocclusion and hence, does not point out the need for treatment

7. This classification also does not draw attention to the aetiological factors associated with malocclusion

8. This classification cannot be applied to deciduous dentition and requires considerable experience for its correct evaluation in transition and deciduous

dentition stages

9. Not suitable for measuring the orthodontic treatment needs of the society

10. Angle’s classification has difficulties in its application when there is an associated discrepancy between right and left sides or where tooth

movements have occurred because of factors such as crowding and premature loss of deciduous teeth

11. Inter-examiner and intra-examiner errors in categorizing Angle class II, div. 2 malocclusions are relatively high27

12. He did not consider bimaxillary/bidental malocclusions

Despite several limitations (Box 4.2), this system is of

great use in the clinical settings and orthodontic research.

One of the reasons for this is its simplicity, understandability

and practicability in day to day clinical practice. Three

classes of malocclusion also confirm to the skeletal classes

as seen on the cephalogram, i.e. it is possible to find

skeletal class I, class II or class III jaw relations. However,

the dental malocclusion may or may not confirm to skeletal

malocclusion or vice versa.

Angle had a brilliant eye for normality and even those

days when cephalometrics was not known, he could identify

and classify normal and abnormal dental as well as skeletal

situations. Angle had a logical and irrefutable philosophy

on occlusion, on which he based his classification system.

Probably he could not have made such a great philosophy,

simpler than his version of classification, which even after

being criticized and modified by many authors, has stood

test of time.

Controversy of subdivision

It has been found in the literature that there are differing

opinions regarding the designation of the side in subdivision

cases. Clinicians all over the world feel that some room for

ambiguity in classifying subdivision cases is still present

even after decades of use of this classification. According

to Angle, subdivision is the occurrence of unilateral

malocclusion whereby one side is normal and the other is

abnormal but he does not mention whether, subdivision is

the normal or abnormal side.

Siegel in 200228 did a survey in the United States on this

issue and found that about 65 % of respondents thought the

subdivision side was the affected or the class II side, and rest

of the 35 % had differing or non-committal opinions. Vyas et

al in 2006 conducted a survey among Indian orthodontists to

know their perceptions and also reported a similar finding. Author

concur with the above views whereby affected side which is

the ‘defective side’ is designated subdivision*

Fig. 4.15: A. Skeletal class I malocclusion, B. Skeletal class

malocclusion, C. Skeletal class III malocclusion

Skeletal classification (Figs. 4.15A-C)

Skeletal classification is a working classification that has

evolved over the years with clinical experience. In fact, it

derives basis from the classic Angle’s classification and

Strang’s interpretation of the former.

Skeletal class I: Orthognathic face (Fig. 4.15a). Important

features may be:

1. Straight profile

2. Normal ANB angle : 2° ± 2

3. Normal facial angle (Downs): 82° to 95° (mean 87.3D)

4. Angle of convexity (Downs): +10° to -8.5°(mean 0D)

Skeletal class II: Retrognathic face that may be due to

prognathic maxilla or retrognathic mandible (Fig. 4.15B).

Important features may be:

1. Convex profile

2. Increased ANB

3. Reduced facial angle

4. Increased angle of convexity

5. Severe backward rotation of the mandible may also be

present.

Skeletal class III: Prognathic face that may be due to

prognathic mandible or retrognathic maxilla (Fig. 4.15C).

Important features may be:

1. Concave profile

2. Prominent chin

3. Decreased ANB

4. Increased facial angle

5. Reduced angle of convexity.

Bimaxillary protrusion: It is another type of malocclusion

in which both the jaw bases are placed ahead with respect

to the anterior cranial base. Here both SNA and SNB

angles are increased but the angle ANB is in the normal

range.

Bidental protrusion: It is a category often used in clinical

practice to describe the tooth positions in the upper and

lower jaws. In this situation, the anterior teeth in maxillary

and mandibular jaws are proclined. Such situation may be

encountered either in skeletal class I, class II or class III

cases.

Lischer’s modification11

Lischer, 1912 substituted the term class I, class II, class III

given by Angle with the terms neutro-occlusion, distoocclusion

and mesio-occlusion.

He gave the suffix “version” to describe the wrong

positions of teeth as follows:

• Linguoversion

• Labioversion

• Mesioversion

• Distoversion

• Infraversion *

L


• Supraversion

• Torsoversion or twisted tooth

• Perversion or impacted tooth

• Transversion or wrong sequential order.

Dewey’s modification12

Martin Dewey, 1915, divided the Angle’s class I into five

types and Angle’s class III into three types. There were no

modifications for class II. He considered the same molar

relationship as in Angle’s classification.

Modifications of class I

• type I: Crowded anterior teeth

• Type II: Maxillary incisors in labioversion

• Type III: Anterior crossbite

• Type IV: Posterior crossbite

• Type V: Molars are in mesioversion due to shifting

following loss of tooth anterior to first molars, all

other teeth are in normal relationship.

Modifications for class III

• Type I: Normal incisal overlapping present

• Type II: Edge to edge incisor relationship

• Type III: Incisors are in crossbite.

Strang’s modification1

Strang (1938) emphasized that body of mandible should be

the determining factor in classification and not the teeth. He

further clarified that it is difficult to make an observation on

jaw placement alone which would be extremely subjective.

He emphasised six processes of case study and made

classification from the deductions derived from study of six

processes of case study that not only determine the true

classification of each case, but also furnish the data from

which a comprehensive plan of treatment can be outlined.

He suggested visual demonstration of overlap among parts

of a complex structure like malocclusion. A collection or

overlap is called ‘set’ and this set would have some

common properties of both.

These six processes of case study for the purpose of

classification are:

1- A study of the inclined plane relationship

2. A study of the axial inclination of each dental unit

3. An analysis of the relationship of the interproximal line

of the central incisors in the two arches and a

comparison of the relationship of these lines to the mid

sagittal plane of the head.

4. The noting of rotated buccal teeth, especially the

maxillary molars.

5- A study of the intraoral and profile roentgenograms

A study of the facial photographs, both in the frontal

and profile view.

With these fundamental facts in mind, definitions of the

various classes can be given as follows:

Class I: All cases of malocclusion in which the body of the

mandible and its superimposed denture is in correct

mesiodistal relationship with cranial anatomy. Of these two

factors, the position of the body of the mandible is the more

important item.

Class II, division 1: Cases of malocclusion in which the

body of the mandible and its superimposed denture is in

distal relationship to cranial anatomy and in which the

maxillary incisors are in labial axial inclination.

Class II, division I, subdivision: Cases of malocclusion in

which the body of the mandible and its superimposed

dental arch is in distal relationship to cranial anatomy on

one side only and in which the maxillary incisors are in

labial axial inclination.

Class II, division 2: Cases of malocclusion in which the

body of the mandible and its superimposed denture is in

distal relationship to cranial anatomy and in which the

maxillary central incisors are in vertical or lingual axial

inclination.

Class II, division 2, subdivision: Cases of malocclusion in

which the body of the mandible and its superimposed

denture are in distal relationship to cranial anatomy on one

side only and in which the maxillary central incisors are in

vertical or lingual axial inclination.

Class III: Cases of malocclusion in which the body of the

mandible and its superimposed denture arch is in mesial

relationship to cranial anatomy.

Class III, subdivision: Cases of malocclusion in which the

body of the mandible and its superimposed dental arch is

in mesial relationship to cranial anatomy on one side only.

Simon’s classification and ‘canine law’13'16

Paul W Simon (1920) was very critical of the Angle’s

classification since it did not correctly record the relationship

of dental malocclusion in relation to cranium. Angle also did

not record malocclusion in three dimensions of space.

Simon developed technique to demonstrate and record

relationship of teeth, occlusion, and supporting bony

framework based on the instrument and technique of

‘Ganthodynameter’. Simon’s philosophy of classification

of malocclusion was based on the ‘Canine Law’ which

implied that in normal cases the maxillary canines are in a

definite relationship to selected points on cranium. He

described malocclusion in relation to three reference planes

(Fig. 4.16):

1. The median sagittal plane: An anthropometric plane

that passes through nasion-basion in the skull. However,

in living organisms, Simon suggested mid palatal raphe

as a reference to imagine a mid sagittal plane of the

face/cranium.

2. The Frankfort plane: Determined by the eye to ear

points. The eye point is determined by the lowest point

on the inferior margin of the orbits. The ear point is

located at the intersection of the helix and margin of

the tragus of ear. *


The malocclusion is defined and classified in reference

to these three planes in antero-posterior, vertical and

transverse dimensions. In normal arch relationship, according

to Simon, the orbital plane passes through the distal axial

aspect of the canine. This is known as ‘the law o f the

canine\

Simon’s classification is given in the Box 4.3. In addition

to the foregoing differential diagnostic information, the

relation of the vault of the palate to the face and the

cranium also may be determined by means of the three

planes of face.

Fig. 4.16: Simon’s philosophy of classification of malocclusion was based

on “canine law”. He described that malocclusion in relation to three

reference planes: 1. The Frankfort plane, 2. The median sagittal plane,

3. The orbital or Simon plane

3. The orbital or Simon plane: Plane perpendicular to the

interpupillary plane and median plane. It is determined

by the above geometry condition and it passes through

the point where the line joining the orbitale would

intersect the constructed median plane.

Limitations of Simon’s classification

The basis of using canine as a stable reference landmark

was rather much weaker than first molar. The maxillary

canines are the last teeth to erupt in the arch and therefore,

likely to be disturbed by several environmental factors

therefore not to always occupy a stable position. Simon’s

significant and important contribution “Gnathodynameter”

could not sustain for long since a better method of

visualization to study the relationship of occlusion and its

skeletal bases was developed through cephalometrics.

British incisor classification (1964)1719

Ballard and Wayman in 1964 gave the incisor classification

(Box 4.3 and Table 4.3). This classification was based on the

work of Backlund (1963), and concentrated on the overjet

and the overbite relationship of the incisors. The shift from

molars to using incisors as the basis for classification was

felt because the incisors are easy to examine and the overjet

and overbite can be recorded rapidly with basic knowledge

of occlusion. Hence, it was incorporated into the British

Standards for classification for epidemiological usage by

general dentists (Fig. 4.17).

Box 4.3: Basis of Simon’s classification

1. Deviation from the raphe or median sagittal plane: Arch form and inclination of tooth axis are determined from this plane

• Contraction: A part or the entire dental arch is contracted toward the raphe median plane. The abnormality may be mandibular, alveolar, dental,

anterior, posterior, unilateral or bilateral

• Distraction: A part or all of the dental arch is wider than usual from the raphe median plane

2. Deviations from the Frankfort horizontal plane:Jhe angle between the Frankfort horizontal and the occlusal plane, the form of the occlusal curve,

and the inclination of the teeth axes are determined from this plane

• Attraction: The distance between the occlusal plane and the Frankfort horizontal is comparatively shorter than normal. This distance is as a rule

normally shorter in the young than in older persons and in some ethnic groups

• Abstraction: The distance between the occlusal plane and the Frankfort horizontal is comparatively longer than normal

3. Deviations from the orbital plane: sagittal symmetry and inclination of the axes of the teeth are determined from this plane

• Protraction: The teeth, one or both dental arches, and/or jaws are too far forward. Normally, the orbital plane passes through the distal incline of

the canine

• Retraction: The teeth, one or both dental arches and/or jaws are too far retruded. The orbital plane passes too far anteriorly to the canines

A

1. Class I: The lower incisor edges occlude with or lie directly below the cingulum plateau of the upper central incisors. If the overbite is incomplete,

the lower incisors are repositioned along their long axis until they meet the upper incisors

2. Class II: The lower incisor edges lie posterior to the cingulum plateau of the upper central incisors. There are two divisions of class II:

/'.

ii.

Division 1: The upper central incisors are of average inclination or are proclined. The overjet is thus increased

Division 2\ The upper central incisors are retroclined; the overjet is usually within normal limits but the overbite is often increased

3. Class III: The lower incisor edges lie anterior to the cingulum plateau of the upper central incisors

and facial appearance which would require some experience

of careful evaluation of facial structures and occlusion.

Authors have synthesized two schemes, the Angle

classification and the Venn diagram. A Venn diagram offers

a visual demonstration of interaction or overlap among

parts of a complex structure. A collection or group in this

system is defined as a SET, and all elements contained in

the SET have some common properties (Fig. 4.18A).

This classification system follows a definite sequence of

evaluating the various dentofacial characteristics in step 1-

5 and futher their interrelationship (Fig. 4.18B). The overlap

and interrelationship of sets from 3-5, results in Gmps

6,7,8 and 9. Overlap of 3-4 results in trans-sagittal, 3-5

transvertical, 4 and 5 sagittovertical and 3, 4, 5 in transversesagittovertical

groups.

Fig. 4.17: Incisor relationship: A. Class I, B. Class II division 1,

C. Class II division 2, D. Class III

Classification of malocclusion according to

British incisor system (Box 4.4)

Ackerman and Proffit classification (1969)20

This classification system is a holistic approach to recording

malocclusion based on complete diagnostic records like

dental casts, facial photographs, and radiographs including

a cephalometric head film. A classification may be made,

however, by careful observation of the patient’s occlusion

Step 1

Group 1: This is also called the universal group and

consists of malalignment and asymmetry within the dental

arches

Step 2

Group 2 (Profile): The soft tissue profile is considered

here.

Step 3

Group 3 (Type): Deviations in the transverse plane.

Step 4

Group 4 (Class): Deviations in the anteroposterior or

sagittal plane.

Step 5

Group 5 (Bite): Deviations in the vertical plane

Group 6: Deviations in the transverse and sagittal planes

Group 7: Deviations in the sagittal and vertical planes

Group 8: Deviations in the vertical and transverse planes

Group 9: Deviations in the transverse, sagittal and vertical

planes

Thus by various permutations and combinations of the

findings from the above groups nine groups of malocclusion

may be identified wherein group 1 denotes normal occlusion

with good facial aesthetics and group 9 denotes the most

complex malocclusion with deviations in all the above

mentioned categories.

This system has many important advantages over the

Angle’s system of classification (Table 4.1).


- Ideal

- Crowding

- Spacing

Transverse deviation

(lateral)

- Buccal

- Palatal

- Unilateral

- Bilateral

- Dental

- Skeletal

Verticotransverse

Transsagittal

Transsagittovertical

Sagittal deviation (A-P)

- Class I ant. displacement

-C lass Ii division 1

-C lass Ii division 2

- Class lii

- Dental

- Skeletal

Sagitto-vertical

Profile

Vertical deviation

- Open bite anterior

- Open bite, anterior

Collapsed bite, posterior

Dental

Skeletal

- Anterior

divergent

- Posterior

divergent

- Convex

- Straight

- Concave/

INTRA-ARCH ALIGNMENT-SYMMETRY

Fig. 4.18A: The interrelationships of two sets which have no elements are contained in sets X and Y. B. Sets are defined on the basis of morphologic

deviations in representing features of malocclusion using a Venn diagram (Source: Graber TM and Swain BF (eds): Orthodontics: Current Concepts

and Techniques. St. Louis, Mosby 1985)


Table 4.1: Advantages and limitations of Ackerman and Proffit classification

Strengths and advantages

1. Cases with only archlength problems are recognized

2. Influence of dentition on the profile is considered

3. Malocclusion can be recorded in all the three planes of space

4. Skeletal and dental problems can be segregated at

appropriate levels

Limitations

1. Very detailed and therefore time consuming and tedious

2. Does not include aetiology

3. Only static view of occlusion considered

4. Communication is not easy without thorough knowledge

of the system

5. Diagnosis is inherent in this methodology

6. The classification can be modified to be used on computers

for large surveys and data analysis

7. Computer compatibility makes it amenable to data storage,

retrieval and processing

8. Quantification and assessment of severity of malocclusion can

be done in this system

9. Can serve as an aid in treatment planning

10. Useful teaching tool

Katz premolar classification (1992)21'23

Morton Katz (1992) shifted the focus from the molars,

canines and incisors to the region of premolars for the

purpose of classifying malocclusion. He highlighted the

shortcomings of the molar based Angle’s system of

classification in which the subjective assessment of molar

relation led to reduced interexaminer and intraexaminer

reliability.

Additionally, he found that if Angle’s system of

classification is followed rigidly, some cases that fall in the

class I category do not have a proper buccal occlusion.

Hence, he proposed a modified Angle’s system of

classification, based on the premolar occlusion, that used

an objective approach of measuring the anteroposterior

discrepancy with calipers.

Premolar class I: It is identified when the most anterior

upper premolar fits exactly into the embrasure created by

the distal contact of the most anterior lower premolar. This

definition applies when a full complement of premolars are

present, i.e. whether one upper premolar opposes two lower

premolars, or two upper premolars oppose one lower premolar,

or whether only one premolar is present in each quadrant.

In essence, these relationships represent prefect

interdigitations and the value is 0 mm on the calipers (Fig.

4.19 A).

Premolar class II: Here the most anterior upper premolar is

occluding mesial of the embrasure created by the distal

contact of the most anterior lower premolar. The measurement

has a (+) sign (Figs. 4.19B, 4.20).

Premolar class III: Here the most anterior upper premolar

ls occluding distal of the embrasure created by the distal

contact of the most anterior lower premolar. The measurement

has a (-) sign.

For deciduous and mixed dentition cases: In class I

situation, the center axis of the upper first deciduous molar

should split the spell between both lower deciduous molars.

In the event that an upper first deciduous molar is

prematurely lost, a line drawn through the center axis of the

edentulous space should bisect the embrasure between the

two lower deciduous molars.

Advantages

The advantages of the premolar classification system are:

1. This system provides a quantitative treatment objective

that is needed to attain excellent buccal occlusion.

2. It provides some flexibility in terms of finishing a case

in functional class II or class III buccal occlusion, while

keeping buccal interdigitation as the prime goal.

3. In deciduous and mixed dentition cases, emphasis is

shifted from the permanent first molars to the region of

current importance, i.e. deciduous molar region.

Disadvantages

The disadvantages of this system are:

1. Premolars are commonly missing, malformed or

supernumerary, hence measurement is not always

possible.

2. Severely rotated and ectopically erupted premolars

present problems.

3. No consideration for the facial balance and aesthetics.

L

Fig. 4.19A: Katz’s premolar classification exhibiting deviation measuring

0 mm hence, normal class I premolar relation

Fig. 4.19B: Katz’s premolar classification exhibiting premolar relation

deviation measuring 3 mm deviation hence, class II +3 deviation

Fig. 4.20: Katz’s premolar classification: Right side premolar deviation

II deviation

is half cusp class II 4mm deviation and + 8 mm which is full cusp class

In essence, a classification is only a part of the diagnosis

and a means of communication, which could be both oral

or as a transcript, to give a clue about the type of deformity.

Angle’s classification has stood the test of time and perhaps

is still the mosts widely used system.

Classification in primary dentition: Baum (1959)29

Flush terminal plane relationship (Fig. 4.21)

The mandibular deciduous second molar is usually wider

mesiodistally than the maxillary second deciduous molar

giving rise to typical flush terminal plane relationship.

When a line is drawn on distal surface of the upper second

deciduous molar it falls along the distal surface of lower

deciduous second molar. As the first permanent molars

erupt, they will be in end on molar relationship in the

presence of complete deciduous dentition having a flush

terminal plane. This relation develops into class I molar

relationship following exfoliation of lower deciduous second

molar, due to the mesial migration of the lower permanent

first molars.

Distal step

In some cases where the upper deciduous second molar is

ahead of lower deciduous second molar, it gives rise to a

distal step. This can lead to class II molarArelationship in


Fig. 4.21: Occlusion during deciduous phase is classified based on

terminal plane: A. Mesial Step, B. Straight terminal plane,

C. Distal step

permanent dentition.

Mesial step

In some cases, if the lower deciduous second molar is

ahead of upper deciduous second molar, it gives rise to a

mesial step. This can either lead to a class I molar relationship

or class II molar relationship in the permanent dentition.

Summary

Malocclusion is essentially a problem in three dimensions

of space however, it is more often expressed and recognised

first in anteroposterior or disturbance in sagittal relationship.

Angle’s method of three classes has stood the test of time

due to its simplicity and ease of communication.

r e f e r e n c e s

1. Strang RHW. A discussion of the Angle’s classification and its

important bearing on treatment. Angle Orthod 1938; 8: 182-

208.

2. Weinberger BW. Historical resume of the evolution and

growth of orthodontics. In: Anderson GM. Practical

Orthodontics (8th edn). St. Louis, Mosby 1955.

3. Asbell MB. A brief history of orthodontics. Am J Orthod

Dentofacial Orthop 1990; 98: 176-83.

4- Kingsley NW. Oral Deformities. New York, Appleton & Co.

1880.

5- Angle EH. Classification of malocclusion. Dental Cosmos

1899, 41(18): 248-64, 350-57.

6- Angle EH. Treatment of malocclusion of the teeth and

fractures of the maxilla. Angle’s System, 6 online Ed.

Philadelphia, SS White Dental Manufacturing Company 1900;

6-8, 44-59.

7. Angle EH. The upper first molar as a basis of diagnosis in

orthodontics. In: Dental Items of Interest 1906; 28: 421-26.

8. Angle EH. Malocclusion of the Teeth, 7 online Ed.

Philadelphia, SS White Dental Manufacturing Company, 1907.

9. Case CS. Principles of occlusion and dentofacial relations.

Dental Items of Interest 1905; 27: 489-527.

10. Case CS. Techniques and Principles of Dental Orthopedia,

(reprint of 1921 edition), New York, Leo Bruder 1963; 16-18.

11. Lischer BE. Principles and Methods of Orthodontia.

Philadelphia, Lea and Febiger, 1912.

12. Dewey M. Classification of malocclusion. Int J Orthod 1915;

1: 133-14.

13. Simon PW. On gnathostatic diagnosis in orthodontics. Int J

Orthod 1924; 10: 755-58.

14. Simon PW. Fundamental Principles of a Systematic Diagnosis

of Dental Anomalies (translated by BE Lischer), Boston,

Stratford Co., p. 320, 1926.

15. Simon PW. The simplified gnathostatic method. Int J Orthod

1932; 18: 1081-87.

16. Sved Alexander. An analysis of the most important diagnostic

methods used in orthodontia (II). Angle Orthodontist 1931;

1: 139-60.

17. Backlund E. Facial growth and the significance of oral habits,

mouth breathing and soft tissues for malocclusion. Acta

Odontologica Scandinavia 1963; 21: 9-139 Supplement 36.

18. Ballard CF, Wayman JB. A report on a survey of the

orthodontic requirements of 310 army apprentices.

Transactions of the British Society for the Study of

Orthodontics, 1964; 86.

19. Williams AC, Stephens CD. A modification to the incisor

classification of malocclusion. Br J Orthod 1992; 19: 127-30.

20. Ackerman JL, Proffit WR. The characteristics of malocclusion:

a modem approach to classification and diagnosis. Am J

Orthod 1969; 56: 443-54.

21. Katz MI, Sinkford JC, Sanders CF Jr. The hundred year

dilemma: what is a normal occlusion and how is malocclusion

classified? Quintessence Int 1990; 21: 407-14.

22. Katz MI. Angle classification revisited 1: Is current use

reliable? Am J Orthod Dentofac Orthop 1992; 102: 173-79.

23. Katz MI. Angle classification revisited 2: a modified Angle

classification. Am J Orthod Dentofac Orthop 1992; 102: 277-

84.

24. Baldridge JP. A study of the relationship of the maxillary first

molars to the face in class I and class II malocclusion. Angle

Orthod 1941; 11: 100-19.

25. Baldridge JP. Further studies of the relation of the maxillary

first molars to the face in class I and class II malocclusion.

Angle Orthod 1950; 20: 3-10.

26. Rinchuse DJ, Rinchuse DJ. Ambiguities of Angle’s

classification. Angle Orthod 1989; 59: 295-98.

27. Gravely JF, Johnson DB. Angle’s classification of

malocclusion: an assessment of reliability. Br J Orthod 1974;

1(3): 79-86.

28. Siegel MA. A matter of class: interpreting subdivision in a

malocclusion. Am J Orthod Dentofac Orthop 2002; 122: 582-

86.

29. Baum LJ. Developmental and diagnostics aspects of primary

dentition. Int Dent J 1959; 9: 349.

Recording the severity of

malocclusion: orthodontic indices

OVERVIEW

• Qualitative methods of recording malocclusion

• Quantitative methods of recording malocclusion

• Occlusal index

• Treatment priority index (TPI)

• Handicapping malocclusion assessment record (HMAR)

• Index of orthodontic treatment needs ((IOTN)

• Peer assessment rating (PAR)

• Index of complexity, outcome and need (ICON)

• American Board of Orthodontics (ABO) discrepancy index

• Summary

R

2.

3.

4.

5.

ecording of malocclusion and its severity among

population groups is required for the following

.purposes:

To document the prevalence of types of malocclusion

in population groups

To document types and severity of different

malocclusions

Scientific studies on development of malocclusion/

normal occlusion according to age

Measurements of malocclusion/traits of occlusion can

be used to objectively quantify outcome of orthodontic

treatment

Recording of severity of malocclusion can help prioritize

the treatment in a given society, which is particularly

important where provision of orthodontic treatment is

made by public health care setting.

Epidemiologic studies are important for planners to

device mechanism on manpower training/capacity

building and provision of health care services.

Qualitative methods of

recording malocclusion_______

Since the time, EH Angle (1899, 1904, and 1907) gave his

classification of malocclusion to three distinct classes,

several modifications have emerged over the years. It was

soon realized, that qualitative methods of classifications

were not suitable for measuring the severity and hence

treatm ent need. The W H O/FDI’s (World Health

Organisation/Federation Dentaire Internationale) basic

methods for recording of malocclusion (1979)1followed

recording of symptoms of malocclusion with a carefully

defined criteria. This method of recording malocclusion was

essentially derived from the principle developed for defining

and recording individual traits of malocclusion by Bjork,

Krebs and Solow 1964.2

46

Section I: Recording the severity of malocclusion: orthodontic indices 47

Table 5.1: Requirements tor an index of occlusion

1. Status of the group is expressed by a single number which corresponds to a relative position on a finite scale with definite upper and lower limits;

running by progressive gradation from zero, i.e. absence of disease, to the ultimate point, i.e. disease in its terminal stage

2. The index should be equally sensitive throughout the scale

3. Index value should correspond closely with the clinical importance of the disease stage it represents

4. Index value should be amendable to statistical analysis

5. Reproducible

6. Requisite equipment and instruments should be practicable in actual field situation

7. Examination procedure should require a minimum of judgement

8. The index should be facile enough to permit the study of a large population without undue cost in time or energy

9. The index would permit the prompt detection of a shift in group conditions, for better or for worst

10. The index should be valid during time

Derived from: Tang, Endarra LK, Wei Stephen HY. Recording and measuring malocclusion: a review of the literature. Am J Orthod and Dentofac Orthop

1993; 103) ^

Quantitative methods of

recording malocclusion3_______

Efforts to quantify malocclusion by assigning each trait a

score and assigning weightage to the traits of occlusion

(malocclusion), that are detrimental to the oral health or

aesthetics, have evolved over the years.

A major issue with recording a malocclusion in its true

objective sense and severity of the problem lies in its

recording and its validity during mixed dentition period.

The occlusion changes dramatically from mixed to

permanent dentition and on several occasions it may improve

and not necessarily worsen.

The index of recording malocclusion should be 6valid’

with time and should exclude symptoms of normal

developmental changes in occlusion. It should be ‘sensitive’

to record basic orthodontic defect.

Therefore, an index which records a basic defect score

of malocclusion, should exhibit either an increase in score

(worsening of m alocclusion) or remain constant

(malocclusion does not worsen), presuming that selfcorrection

of the basic defect of malocclusion does not

occur from transitional stage to permanent dentition stage.

Some indices were developed prim arily for

epidemiological purpose of recording the malocclusion

while others were developed in order to grade the severity

of malocclusion and to distinguish between malocclusion

requiring urgent treatment or a priority of treatment over

others. Some prominent indices are:

1* Occlusal index by Summers (01) 19664,5 (primarily for

epidemiological purposes)

2- Treatment priority index by Grainger (TPI) 19676

3- Handicapping malocclusion assessment record (HMAR)

by Salzmann 1968.7

The requirements for an index are summarised in Table 5.1.

Occlusal index

It was developed as a valid tool for measuring the occlusion/

malocclusion for epidemiological purposes. A scoring scheme

for each stage of dental development (i.e. deciduous, mixed,

and permanent dentition stages) was developed, and

different scoring forms were used for subjects in each

stage.

A method of scoring nine characteristics included:

1. Dental age

2. Molar relation

3. Overbite

4. Overjet

5. Posterior crossbite

6. Posterior open bite

7. Tooth displacement (actual and potential)

8. Midline relations

9. Missing permanent maxillary incisors.

Table 5.2: Occlusal index o f Summers

Division 1(normal) and division II (distal molar relation)

1. Syndrome A: Overjet and anterior open bite

2. Syndrome B: Distal molar relationship, positive overjet, overbite,

posterior cross-bite, midline diastema and midline deviations

3. Syndrome C: Congenitally missing incisors

4. Syndrome D: Potential tooth displacement

5. Syndrome E: Posterior open bite

Division II (mesial molar)

6. Syndrome F: Mesial molar relation, negative overjet, overbite,

posterior cross-bite with maxillary teeth lingual to mandibular

teeth, midline diastema and midline deviations

7. Syndrome G: Mixed dentition analysis and tooth displacement


Occlusal index (Ol) defines two divisions and seven

malocclusion syndromes (Table 5.2).

The scores of all syndromes were clubbed in arriving at

the final Ol score. The syndrome with the highest score

and the other scores were considered by adding half of the

sum of the remaining scores to the highest score among the

seven syndromes. The absence of any occlusal disorder

would be scored as zero.

Occlusal index had developed different scoring scheme

and forms for patients in different stages of dental

development from dental age 0 and dental age I to VI.

Treatment priority index (TPI)

It was developed by Grainger (1967) to assess the severity

of common types of malocclusion and hence provide a

means of ranking patients according to the severity of

malocclusion, degree of handicap or priority of the treatment

(Table 5.3).

The handicap malocclusion defined by him included:

1. Unacceptable aesthetics and/or masticatory function.

2. Traumatic conditions predisposing to tissue destruction.

3. Significant reduction in masticatory function.

4. Speech impairment due to malocclusion.

5. Unstable occlusion.

6. Gross or traumatic defects.

Table 5.3: Treatment priority index by Grainger (1967)

Eleven weighted and defined measurements

1. Upper anterior segment overjet

2. Lower anterior segment overjet

3. Overbite of upper anteriors over lower anteriors

4. Anterior open bite

5. Congenital absence of incisors

6. Distal molar relation

7. Mesial molar relation

8. Posterior crossbite (maxillary teeth buccal to normal)

9. Posterior crossbite (maxillary teeth lingual to normal)

10. Tooth displacement

11. Gross anomalies

Seven malocclusion syndromes

1. Maxillary expansion syndromes

2. Overbite

3. Retrognathism

4. Open bite

5. Prognathism

6. Maxillary collapse syndrome

7. Congenitally missing incisors

A few manifestations of malocclusion such as midline

diastema and slight asymmetries were rejected as being of

little public health significance. TPI is quite similar to Ol

but the major difference is that it does not consider potential

tooth displacement and also omitted mixed dentition

analysis. Therefore it is deemed inadequate for assessing

the occlusion of the deciduous or mixed dentition.

TPI is a valid epidemiologic indicator of malocclusion.

However values recorded in transitional dentition are not

predictive of severity in permanent dentition.

Handicapping malocclusion assessment record

Handicapping malocclusion assessment record (HMAR)

was developed by JA Salzmann in 1968. The purpose of

developing the HMAR was to provide a means for

establishing priority for treatment of handicapping

malocclusion. Handicapping malocclusion and handicapping

dentofacial deformity were defined as, ‘conditions that

constitute a hazard to the maintenance of oral health and

interfere with the well-being of patient by adversely

affecting dentofacial aesthetics, mandibular function or

speech’ (Table 5.4).

The HMAR allocates scores for dental irregularities and

arch malrelationships, which are multiplied by a weighting

factor before the total score is assigned. The relative point

Table 5.4: Hanicapping malocclusion assessment record by

Salzmann (1968)

Weighted measurements consist of three parts:

1. Intra-arch deviations

a. Missing teeth

b. Crowding

c. Rotation

d. Spacing

2. Interarch deviations

a. Overjet

b. Overbite

c. Crossbite

d. Open bite

e. Mesiodistal deviation

3. Six handicapping dentofacial deformities

a. Facial and oral clefts

b. Lower lip palatal to maxillary incisors

c. Occlusal interference

d. Functional jaw limitation

e. Facial asymmetry

f. Speech impairment


values, which were based on clinical orthodontic experience,

had been tested by orthodontists from various parts of the

United States. HMAR also records and weighs functional

problems unlike any other index. The recording is done on

specially designed forms either on orthodontic models or

during clinical assessment. Additional scores are allocated

for dentofacial deviations such as cleft lip and palate, facial

asymmetry and functional disabilities. The assessment is

quite rapid and does not require special instruments.

The usefulness of any of the indices is judged by the

reliability to produce the same score of measurement

when one or more examiners would assess a case of

malocclusion at any given time or an interval. Research

has shown that Summers occlusal index has the least

amount of bias, is best correlated with clinical standards

and has the highest validity during time.

In recent years, American Association of Orthodontist

has taken a view not to consider rating classification or

coding system as scientifically valid measurement for the

need of orthodontic treatment (AAO bulletin, St Louis,

1990, Fall).

Index of orthodontic treatment needs (IOTN)8,9

It was developed in UK by Shaw et al and is another

mechanism of prioritizing and thereby classifying

malocclusions according to treatment needs. This is

particularly useful where the resources available for

treatment are limited. This index ranks malocclusion in

terms of the significance of various occlusal traits for the

person’s dental health and perceived aesthetic impairment,

with the intention of identifying those persons who would

be most likely to benefit from orthodontic treatment. The

index incorporates a dental health component (DHC) and

aesthetic component (EC).

Dental health component

Of the two parts of the IOTN, DHC is in most frequent

use. This represents an attempt at synthesis of the current

evidence for the deleterious effects of malocclusion and

the potential benefits of orthodontic treatment. Each occlusal

trait thought to contribute to the longevity and the

satisfactory functioning of the dentition is defined and

placed into five grades, with clear cut-off points between

the grades.

Dental health component (Table 5.5) has five grades,

categorizing cases from grade 1 (no need for treatment) to

grade 5 (great need). The DHC may be applied both

clinically and to study casts. When applied to study casts,

there are minor differences in the definition of some traits.

In use, various features of the malocclusion are noted and

measured, with a specially designed ruler.

Dental health component (Fig. 5.1) recognizes most severe

defect/deformity which is used to grade the case rather

than the summing up all the deviations.

Aesthetic component

Aesthetic component consists of a 10-point scale illustrated

by a series of numbered photographs. This scale was

developed based on attractiveness as rated by lay persons

and selected as being equidistantly spaced through the

range of scores. A rating is allocated for overall dental

attractiveness rather than the specific morphologic similarity

to the photographs.

The dental attractiveness (unattractiveness) score provides

an indication of treatment needs on the grounds of aesthetic

impairment, and by inference may reflect the social and

psychological need for orthodontic treatment.

Limitations of IOTN

This index places emphasis on the alignment of teeth

alone. In certain ethnic groups, like in India class I

bimaxillary protrusion is a common finding and treatment

need is essentially for aesthetic reasons, to improve the

profile whereas arch alignment and the intra-arch

relationships are normal. Second major limitation is that all

the children with cleft lip and palate are graded as grade 5,

i.e. the most severe malocclusion irrespective of the type

and severity of the defect. In some instances, a cleft lip and

alveolus case may present only with a minor disturbance in

occlusion like a rotated lateral or central incisor. Such a

minor malocclusion would be categorized to grade 5 owing

to the associated cleft lip and palate deformity.

Peer assessment rating_______

Peer assessment rating (PAR) was developed by a group of

experienced British orthodontists at Manchester, UK, who

agreed that individual features should be assessed to obtain

3

0 1 4 5

2

2 c

3 4

4 ms - 5

5 Defect of CLP

5 Non-eruption of teeth

5 Extensive hypodontia

4 Less extensive hypodontia

4 Crossbite > 2 mm discrepancy

4 Scissors bite

4 O.B. with G + P trauma

3 O.B. with NO G + O trauma

3 Crossbite 1-2 mm discrepancy

2 O.B. >

2 Dev. from full interdig

2 Crossbite < 1 mm discrepancy

IOTN VICTORIA UNIVERSITY OF MANCHESTER

DISPLACEMENT

OPEN BITE

I 1

4 3 2 1

ji'9' 5.1: index of orthodontic treatment need (dental health component) ruler. The scale was first published by the European Orthodontic Society;

Evans, MR and Shaw, WC Eu J Orthod 1987; 9: 314-318

L

1 Extremely minor malocclusions including displacements less than 1 mm

Grade 2 (Little)

2a Increased overjet greater than 3.5 mm but less than or equal to 6 mm with competent lips

2b Reverse overjet greater than 0 mm but less than or equal to 1 mm

2c Anterior or posterior crossbite with less than or equal to 1 mm discrepancy between retruded contact position and intercuspal position

2d Displacement of teeth greater than 1 mm but less than or equal to 2 mm

2e Anterior or posterior open bite greater than 1 mm but less than or equal to 2 mm

2f Increased overbite greater than or equal to 3.5 mm without gingival contact

2g Prenormal or postnormal occlusion with no other anomalies. Includes upto half a unit discrepancy

C a

Tc

Whi

0}

On

1-

3.1

5.1

7.1

Grade 3 (moderate) or borderline need

3a

3b

3c

3d

3e

3f

Increased overjet greater than 3.5 mm but less than or equal to 6 mm with incompetent lips

Reverse overjet greater than 1 mm but less than or equal to 3.5 mm

Anterior or posterior crossbite with greater than 1 mm but less than or equal to 2 mm discrepancy between retruded contact position and

intercuspal position

Displacement of teeth greater than 2 mm but less than or equal to 4 mm

Lateral or anterior open bite greater than 2 mm but less than or equal to 4 mm

Increased and complete overbite without gingival or palatal trauma

Ne

O)

0-

3.1

5.1

Grade 4 (great) or treatment required

Im

4a

4b

4c

4d

4e

4f

Increased overjet greater than 6 mm but less than or equal to 9 mm

Reverse overjet greater than 3.5 mm with no masticatory or speech difficulties

Anterior or posterior crossbite with greater than 2 mm discrepancy between retruded contact position and intercuspal position

Severe displacements of teeth greater than 4 mm

Extreme lateral or anterior open bite greater than 4 mm

Increased and complete overbite with gingival or palatal trauma

A£

O r

the

4h Less extensive hypodontia requiring prerestorative orthodontics or orthodontic space closure to obviate the need for a prosthesis

41 Posterior lingual crossbite with no functional occlusal contact in one or both buccal segments

4m Reverse overjet greater than 1 mm but less than 3.5 mm with recorded masticatory and speech difficulties

4t Partially erupted teeth, tipped and impacted against adjacent teeth

Grade 5 (very great) treatment required 4x existing supenumerary teeth

5a Increased overjet greater than 9 mm

y

2f

Cl

1-

5h

Extensive hypodontia with restorative implications (more than 1tooth missing in any quadrant) requiring prerestorative orthodontics

3.1

5i

Impeded eruption of teeth (except third molars) due to crowding, displacement, presence of supernumerary teeth, retained deciduous teeth and

any pathological cause

5m Reverse overjet greater than 3.5 mm with reported masticatory and speech difficulties

5.1

> '

5p

Defects of cleft lip and palate

5 s Submerged deciduous teeth

Section I: Recording the severity of malocclusion: orthodontic indices

Table 5.6: Discrepancy index

DISC REPANCY i n d e x

Ca s e # f

I

To ta l D.I. S c o r e

White Box for Examinee Score - Shaded Box for Examiner Score

OVERIET

THE AMERICAN BOARD OF ORTHODONTICS

EXAM YEAR

EXAMINEE#

EXAMINERS

0 mm' (edge to edge) = lp t

1 - 3 mm = 0 pts

3 .1-5 mm = 2 pts

5.1 -7 mm = 3 pts

7.1 - 9 mm = 4 pts

> 9 mm = 5 pts

Negative OJ (x-bite) 1 pt per mm per tooth =

OCCLUSION

Class I to end on =

End on Class II or III =

Full Class II or III

Beyond Class II or III =

Total =

0 pts

2 pts per side

4 pts per side

1 pt per mm

Additional

Total =

OVERBITE

0 -3 mm =

0 pts

LINGUAL POSTERIOR X-BITE

1 pt per tooth Total =

3.1 - 5 mm =

5.1 - 7 mm =

Impinging (100%) =

2 pts

3 pts

5 pts

BUCCAL POSTERIOR X-BITE

2 pts per tooth Total =

Total =

CEPHALOMETRICS

ANB >5.5 or <-1.5

4 pts

ANTERIOR OPENBITE

0 mm (edge to edge) =

then 2 pts per mm per tooth

1 pt

Each Additional Degree =

SN-Go-Gn

27 deg - 37 deg =

ip t

0 pts

Total =

> 37 deg =

2 pts per degree

LATERAL OPENBITE

< 27 deg =

1 pt per degree

2 pts per mm per tooth

1 to Go-Gn > 98 deg =

1 pt per degree

Total =

Total =

CROWDING

1~ 3 mm =

lp t

OTHER 2 Points

(See instructions)

3-1 - 5 mm =

5-1-7 mm =

2 pts

4 pts

INDICATE PROBLEM

> 7 mm =

7 pts

Total

-


ANT-POST

0 None

1 < 1/2 unit dis

2-1/2 unit dis

TRANSVERSE

0 None

1 Xbite tend > = 1t

2 1 tooth in xbite

3 > 1 tooth in xb

4 > 1 tooth in sb

VERTICAL

0 None

1 openb 2t > 2mm

CENTRELINE

0 < = 1/4

1 1/4-1/2

2 > 1/2

OVERBITE

0 0-1/3 open b

1 1/3-2/3

2 >2/3

3 > = FTC

4

CONTACT Pt

o-

1 -

2 ------

3 -------

4---- ►—

5 Impacted teeth

THE

PAR INDEX

Victoria University

of Manchester

OVERJET

0

> 2t x b

2 t x b

1 t x b

e to e

Fig. 5.2: Index of treatment standards (PAR) ruler

PRE-TREATMENT TOTAL

Fig. 5.3 : Peer assessment rating (PAR) normogram (Reproduced with

permission from University of Michigan Library, Michigan USA. http://

quod.lb.umich.edu/d/dencos)

an estimate of alignment and occlusion. Their aim was to

quantify the changes that occurred after orthodontic

treatment and therefore, measure the treatment success

based on the initial severity of malocclusion. A weightage

score is given to the various traits of occlusion. The ratings

are applied on the study models and no considerations are

made for improvement in profile, underlying skeletal bases

or functions. The dental casts are assessed with the help of

a specially designed ruler (Fig. 5.2). Perfect occlusion

would have a score of 0 and a worst malocclusion would

have a score of 50 or more. The pretreatment and posttreatment

scores are compared for percentage change. A

normogram (Fig. 5.3) is developed which suggests the

improvement in three major categories:

a. Unchanged or worse

b. Improved

c. Greatly improved.

Index of complexity, outcome,

and need (ICON)_____________

Daniels and Richmond (2000)10 developed ICON, which was

expected to serve as a means to compare orthodontic

treatment thresholds across the world and permit

international comparison and professional standardization

of treatment outcomes (Figs 5.4, 5.5). The ICON was

developed in a joint effort of 97 orthodontists across

9 countries and is arguably more valid than the PAR

index.1011 Several authors have found ICON valid to high

levels of accuracy12 and reliability. 1113

The ICON has a scoring system with weighing for each

problem. It evaluates and weighs:

1. Aesthetic component: weight - 7

2. Upper arch crowding/spacing: weight - 5

3. Crossbite: weight - 3

4. Overbite and open bite: weight - 4

5. Buccal segment AP relationship: weight - 3.

Fi

to

si

ar

41

d«

0

%


~ ~ Specificity

Fig. 5.4: The sensitivity, specificity, and overall accuracy of the index

to assess treatment need is shown for all possible cut-off values. A

suitable cut-off value makes the best compromise between specificity

and sensitivity. For assessment of treatment need the cut-off value is

43. (Reproduced with permission from Daniels C, Richmond S. The

development of the index of complexity, outcome and need (ICON). J

Orthod 2000;27:149-162, http://jorthod.maneyjournals.org)

— S ensitivity C ut-off

— S pecificity

Fig. 5.5: The sensitivity, specificity and overall accuracy of the index to

assess treatment outcomes is shown for all possible cut-off values. For

assessment of treatment outcome acceptance the cut-off value is 31.

(Reproduced with permission from Daniels C, Richmond S. The

development of the index of complexity, outcome and need (ICON). J

Orthod 2000;27:149-162, http://jorthod.maneyjournals.org)

A value greater than 43 defines definite need for

orthodontic treatment. This index is rather simple to use

and faster than separate indexes for various facets of

orthodontic treatment. Onyeaso et al (2007)14 investigated

relationship between ICON, DAI (Dental Esthethic Index

WHO), PAR, and ABO objective grading system. They

found overall good agreement between the ICON and the

other indices. The ICON was reported to appear as a

reasonable means of assessing the standard of orthodontic

treatment in terms of complexity, need, and outcome. It

also eliminates the need of using various indices for a

given malocclusion.

ABO discrepancy index 2004

American Board of Orthodontics (ABO) developed an index

r —

presented for the phase III of ABO examination. The index

was called the discrepancy index or DI. It evaluates case

complexity based on criterion of case difficulty by evaluating

dental models and cephalometric parameters. Case complexity

is defined as “a combination of factors, symptoms, or signs

of a disease or disorder which forms a syndrome.”15

The clinical features of a patient’s condition include

assessment of overjet, overbite, anterior open bite, lateral

open bite, crowding, occlusion, lingual posterior crossbite

and buccal posterior crossbite. Cephalometric parameters

include ANB angle, IMPA, and SN-GoGn angle.

The greater the number of these conditions in a patient,

the greater the complexity and the greater the challenge to

the orthodontist. The ABO is considering several options

for applying the discrepancy index to the phase III clinical

examination. The category of ‘other’ was included to

consider other conditions that might affect or add to

treatment complexity. These included: missing or

supernumerary teeth, ectopic eruption, transposition,

anomalies of tooth size and shape, CR-CO discrepancies,

skeletal asymmetry and an excessive curve of Wilson.

Each variable was given weighings which are depicted in

the DI form (Table 5.6).

The index is being tested on ABO exams and ABO is

intending to report outcome from time to time about its

usefulness in objectivity of phase III examination.

Summary

A quantitative method of evaluation of the extent of

abnormality from a given standard requires grading the

abnormality and assigning a score based on the severity of

problem, which is perceived by the degree of aesthetic/

functional impairment produced. Each index is designed

with a definite purpose and should be valid in its

applications. Significant occlusal changes during transitional

dentition make it difficult to assign an index of potential

tooth displacement. The occlusal index of Summers has a

provision based on stages of dental development. This

index was primarily developed for recording malocclusion

in surveys. The index of orthodontic treatment needs (IOTN)

is practical in clinical settings and possibly could be used

for epidemiological surveys.

REFERENCES

1. Brzroukov V, Freer TJ, Helm S, Kalamkarov H, Sarodoinfirri

J, Solow B. Basic methods of recording malocclusion: a

systematic approach for planning treatment. Bull World

Health Org 1979; 57: 955-61.

2. Bjork A, Krebs AA, Solow B. A method for epidemiological

registration of malocclusion. Acta Odontol Scand 1964; 22:

27-41.

3. Tang, Endarra LK, Wei Stephen HY. Recording and measuring

malocclusion: A review of the literature. Am J Orthod Detofac

Orthop 1993; 103: 344-51.

4. Summers CJ. A system for identifying and scoring occlusal

disorders. The occlusal index. [Doctoral dissertation]. Ann

Arbor: University of Michigan, 1966 *

L


5. Summers CJ. A system for identifying and scoring occlusal

disorders. Am J Orthod 1971; 59: 552-67.

6. Grainger RM. Orthodontic treatment priority index. National

Center for Health Service. Series II. No. 25. Washington:

United States Department of Health, Education, and Welfare,

1967.

7. Salzmann JA. Handicapping malocclusion assessment to

establish treatment priority. Am J Orthod 1968; 54(10): 749-

65.

8. Shaw WC, Richmond S, O’Brien KD, Brook P, Stephens CD.

Quality control in orthodontics: indices of treatment need and

treatment standards. Br Dent J 1991; 170(3): 107-12.

9. Shaw WC, Richmond S, O’Brien KD. The use of occlusal

indices: A European perspective. Am J Orthod Dentfac

Orthop 1995; 107: 1-10.

10. Daniels C, Richmond S. The development of the index of

complexity, outcome and need (ICON). J Orthod 2000; 27:

149-62.

11. Richmond S, Ikonomou C, Williams B, Ramel S, Rolfe B,

Kurol J. Orthodontic treatment standards in a public group

practice in Sweden. Swed Dent J 2001; 25: 137-44.

12. Firestone AR, Beck M, Beglin FM, Vig KWL. Validity of the

index of complexity, outcome, and need (ICON) in determining

orthodontic treatment need. Angle Orthod 2002; 72: 15-20.

13. Liepa A, Urtane I, Richmond S, Dunstan F. Orthodontic

treatment need in Latvia. Eur J Orthod 2003; 25: 279-84.

14. Onyeaso CO, Begole EA. Relationship between index of

complexity, outcome and need, dental aesthetic index, peer

assessment rating index, and American Board of Orthodontics

objective grading system. Am J Orthod Dentofac Orthop.

2007 Feb; 131(2): 248-52.

15. Cangialosi TJ, Riolo ML, Owens SE Jr, Dykhouse VJ,

Moffitt AH, Grubb JE, Greco PM, English JD, James RD.

The ABO discrepancy index: a measure of case complexity.

Am J Orthod Dentofac Orthop. 2004; 125(3): 270-78.

OVERVIEW

• Development • Postnatal growth

• Prenatal development • Growth of nasomaxillary complex

• Genetic control of craniofacial embryogenesis • Growth trends

• Concepts of skeletal growth • Timing of craniofacial skeletal growth

• Concept of mechanotransduction • Clinical implications

• Methods of studying physical growth • Summary

Growth in general has been defined as an increase in

size, which is a physiological process of all

living organisms. Increase in size is associated

with an obvious increase in weight, mass of the extracellular

matrix and spatial dimensions. Growth is also accompanied

by an increase in the number of cells and their sizes.12

At the macroscopic or clinical level, growth is

exemplified by an increase in height and weight. In jaws,

it denotes increasing number of erupted teeth and the

increasing size of the mandibular condyle. Growth in

multicellular organisms is more frequently allometric

(disproportional among adjacent structures) than isometric

(proportional among structures).

Development

Development refers to a stage of growth and maturation

encompassing m orphogenesis, differentiation, and

acquisition of functionality.3 Development at the cellular

level can be described as differentiation and maturation of

cell phenotypes from progenitor cells to terminally

differentiated cells, such as, from mesenchymal cells to

mature osteoblasts or from proliferating chondrocytes to

hypertrophic cells. At subcellular level, it can be exemplified

by self-assembly of immature collagen fibrils into mature

and functional collagen fibres in the extracellular matrix or

mineralization of the osteoid to form mature bone (Table

6.1).

Development means progress towards maturity. At the

clinical level, the increasing capacity of the maturing

mandibular condyle to withstand mechanical stresses can

be viewed as development.

Growth and development are integrated processes and

cannot be separated from each other. While the organism

or organ grows, its tissues develop towards special functions

and mature. Maturation is the stage of stabilization of the

adult stage brought about by the growth and development.

The scope of science of orthodontics involves a number

of growth modulation procedures that are undertaken to

redirect the maxillary and mandibular growth. Growth is a

genetically determined process that does get modulated

with environmental factors. Aberrant environmental factors

can influence the growth abnormally, which may either

precipitate the incipient or existing malocclusion or create

the malocclusion in a normally growing child.

The study of morphogenesis of facial structures, growth,

its variability, timing and direction in general and

craniofacial growth in particular is fundamental to

orthodontic diagnosis, treatment timings and institution of

appropriate interceptive and corrective treatment procedures.

Prenatal development_________

Central nervous system (CNS) arises from the neural plate,

a homogeneous sheet of epithelial cells that forms the

A

55


First

Second arch

Ectoderm

Endoderm

“ I

Branchial

Mesenchyme J arch

Cleft

Pouch

Third arch

Fourth arch

Membrane

Artery

Cartilage

Nerve

Fig. 6.1: Pharyngeal arches

Frontonasal

prominence

Fig. 6.2: Embryo at 4th week of intrauterine life

Olfactory placode

Mesial nasal prominence

nasal prominence

pit

Olfactory placode

Lateral nasal

prominence

Mesial nasal

prominence

Nasal pit

prominence

Fig- 6.3A Fig. 6.3B

A

1 1

Section I: Growth of the craniofacial complex

Lateral nasal prominence

Mesial nasal prominence

Nasal pit

Maxillary

prominence

Fig. 6.3C:

Mesial nasal process -

Lateral nasal process -

Nasal pit----------

- Maxillary process—

----- Stomodeum---------

— Mandibular process

Fig. 6.3D: Development of face from 5th to 7th week of IU life

Secondary palate

Nose

-------Upper lip-------

- Primary palate ■

Secondary palate

__ Alveolus ____

__Hard palate____

Soft palate

| Lateral nasal process Medial nasal process I Maxillary process

Fig. 6.4 : A schematic representation of the processes involved in the formation of lip and palate


Table 6.1: Postnatal growth and development defined at various levels of understanding from genes to clinically visible

growth; mandibular growth (e.g. increases in mandibular length and height) results from changes at cellular, molecular, and

genetic levels

Growth (number and size)

Development (proliferation, apoptosis,

differentiation, and maturation)

Clinical Increase in mandibular length Change in the shape of mandibular condyle

Extracellular matrix

Increase in procollagen production and

secretion by osteoblasts: increase in amount

of collagen molecules in extracellular matrix

Formation of mineralization-competent matrix

Cellular Increase in number of osteoblasts Differentiation of osteoprogenitor cells into

osteoblasts

Genetic Gene regulation of osteoblast proliferation Activation of differentiation marker genes

Cited with permission from Mao JJ, Nah HD. Growth and development: hereditary and mechanical modulations. Am J Orthod Dentofacial Orthop 2004;125:

676-89.

dorsal surface of the gastrula stage of embryo. CNS is

fundamental to the development of the craniofacial complex.

Specific neural crest cells that are destined for the branchial

arches migrate to make the individual structures and build

the composite head in an orderly and an integrated manner.4

The ectomesenchymal neural crest cells then interact with

epithelial and mesodermal cell populations present within

the arches, leading to the formation of craniofacial bones,

cartilages and connective tissues.”1

The differentiation of human face takes place between

the 5th and 7th weeks of intrauterine life. In the 4th week,

the future face and neck region becomes segmented and

located under the forebrain of human embryo. These

regiments appear as rounded and tubular enlargements

called branchial arches. The development of mid and lower

facial regions are contributed by mandibular (1st) and

hyoid (2nd) arches5 (Fig. 6.1).

By the 4th week of embryonic development, the face or

the forebrain is made by frontonasal process in middle and

front, with small laterally placed maxillary process and

caudally placed mandibular process (1st arch), hyoid arch

and glossopharyngeal arch (2nd and 3rd arches) (Fig. 6.2).

By the 5th week, appearance of bilateral nasal pits on the

frontonasal prominence, divides it into medial and lateral

nasal processes. Later in the 5th week, smaller maxillary

prominences grow large toward each other, pushing nasal

prominences medially (Fig. 6.3A-D). The fusion between

median nasal and maxillary processes contributes to the

central part of the nose and the philtrum of the lip. The

lateral nasal processes form the outer parts of the nose and

the maxillary processes form the bulk of the upper lip and

the cheeks (Fig. 6.4).

The clefting of the lip and the palate is the most common

congenital defect involving the face arising out of disturbed

intrauterine development. During the 6th week of

development, clefting of lip can occur because of failure of

fusion between the median and lateral nasal processes and

the maxillary processes. The midline cleft of the upper lip,

although rare, could develop because of the split within the

median nasal process. The cleft of lip is often associated

with the cleft of alveolar ridge.

The secondary palate closure is achieved by elevation of

the palatal shelves which follow that of the primary palate

by nearly 2 weeks. So, the interference with lip closure can

also extend to palate development. The lowering of

developing tongue facilitates elevation of palatal shelves

from lateral walls, failure of which can prevent their

mitiline fusion and hence development of the cleft palate.6

Genetic control of craniofacial embryogenesis

“It is well understood that the mechanisms of craniofacial

development are under genetic control. It is helpful to

consider those genes involved in embryogenesis as

encoding a set of instructions or rules of assembly.

Implementation of these one-dimensional rules, via gene

expression and protein interaction, produces the threedimensional

embryo”.1

The genetic control of craniofacial embryogenesis is via

Hox genes which are responsible for controlling

morphogenesis of the regions of the head and neck.

However, the neural crest destined for the first branchial

arch, from which the maxillary and mandibular processes

develop, does not express Hox genes related to the homeotic

homeobox.7 It is subfamilies of the homeobox genes, which

are more diverged from the ancestral Hox genes, that are

expressed in spatially restricted patterns within the first

branchial arch.8,9

Other homeobox-containing genes which are expressed

in the maxillary and mandibular arches, and developing

facial primordial are, Msx-1, Msx-2, Dlxl-6, and Barx-1.

Members of the Msx gene family, especially Msx-1 and

Msx-2 are prominently expressed in the neural crest derived

mesenchyme of the developing facial prominences, and

there is now a strong evidence for the role of these genes

in specification of the skull and face.10

Members of the multi-gene Dlx (distal-less) family are

expressed in a complex pattern within the embryonic

ectoderm and mesenchyme of the maxillary and mandibular

processes of the first arch.11

Goosecoid (Gsc) is another homeobox-containing

transcription factor which has an important role to play in

the craniofacial development.12 Other important genes of

craniofacial development are Otx (orthodontical), Shh (sonic

hedgehog) and Indian hedgehog (Ihh) genes.

These homeobox genes act by exerting control on growth

factor family and the steroid/ thyroid/ retinoic acid super

family. The regulatory molecules in the mesenchyme, such

as, fibroblast growth factor (FGF), epidermal growth factor

(EGF), transforming growth factor alpha (TGFa), transforming

growth factor beta (TGF(3), and bone morphogenetic proteins

(BMPs), are the vehicles through which homeobox gene

information is expressed in the co-ordination of cell migration

and subsequent cell interactions which regulate growth.13

“This means that different parts of the DNA are activated

in different cells regulating different proteins, enzymes, etc.

produced by different tissues and organs. Thus, these

mechanisms will hold the key to understanding of disease

and dysmorphology, and are the subjects of intensive

research in craniofacial biology (Table 6.2).”14

Table 6.2: Classes of selective genes involved in growth and development of cartilage and bone

Genes

Functions

Cartilage

Marker genes Type II collagen Marker for chondroprogenitor cells

IIA isoform

Marker for differentiated chondrocytes

IIB isoform

Interact with proteoglycans

Type IX collagen

Marker for hypertrophic chondrocytes

Aggrecan

Cartilage-specific proteoglycan

Regulatory genes

Transcription factor 5

Sox 9

Signals chondrocyte differentiation

Growth factor/receptors

Indian hedgehog (Ihh)

Stimulates chondrocyte proliferation and PTHrP

Fibroblast growth factors/receptors (FGF/FGFR) Inhibits ohondrocyte proliferation and hypertrophy

Transforming growth factors/receptors

Stimulates chondrocyte differentiation and

(TGFb/TGFbR)

hypertrophy

Bone morphogenetic proteins/receptors

Stimulates chondrocyte hypertrophy

(BMP/BMPR)

Parthyroid hormone related peptide/receptors Stimulates chondrocyte proliferation

(PTHrP/PTHrPR)

Retinoic acid receptors (RAR)

Stimulates chondrocyte hypertrophy

Bone

Marker genes Alkaline phosphatase Potential Ca2+carrier, hydrolyze inhibitors of mineral

deposition such as pyrophosphates

Type I collagen

Serves as scaffold of mineralization

Bone sialoprotein

Nucleator of mineralization

Osteopontin

Inhibits mineralization and promote bone resorption

Osteocalcin

Inhibits mineralization

Osteonectin

May mediate deposition of hydroxyapatite

Regulatory genes

Transcription factors Cbfal/Runx2 Required for osteogenic commitment and

differentiation

Osterix

Required for osteogenic differentiation

Twist

Positive regulator of osteoblast differentiation

Msx2

Inhibits osteoblast differentiation

Growth factor/receptors Fibroblast growth factors/receptors (FGF/FGFR) Stimulates proliferation and differentiation

Generates survival signalling

Transforming growth factors/receptors

Modulates bone remodelling

(TGFb/TGFbR)

Bone morphogenic proteins/receptors

Increases Cbfal/Runx2 expression and stimulates

(BMP/BMPR)

differentiation

Insulin like growth factor (IGF)

Stimulates cell proliferation, differentiation and

matrix production

Platelet derived growth factor (PDGF)

Signals cell proliferation and recruit progenitor cells

by stimulating chemotactic migration

Cited with permission from Mao JJ, Nah HD. Growth and development: hereditary and mechanical modulations. Am J Orthod Dentofacial Orthop 2004;125:


Craniofacial syndromes due to defective genetic

control

Several syndromes of craniofacial region have their origin

in mutations in fibroblast growth factor (FGF) receptor

genes, two transcription factors, MSX2, core binding factor

1 gene (CBFA1), etc. It is now understood through advance

research on molecular genetics that in cleidocranial

dysplasia, mutations in the core binding factor 1 gene

(CBFA1), results in defects in the membranous bones of

the cranial vault and clavicles due to deficiencies in

signalling between the periosteum and chondrocytes

essential for endochondral bone formation.

Treacher Collins syndrome locus has been mapped to

the long arm of chromosome 5 and numerous mutations,

spread throughout the gene, affecting the production of the

treacle protein can produce the anomaly.14

Apert, Crouzon and Pfeiffer syndromes have their origin

in the mutations in fibroblast growth factor (FGF) receptor

genes which are known to affect suture development in

mice and humans.

Child at birth

The differences between the face of a newborn and adult

are significant and striking.

At birth

Essentially at birth, the cranium to face proportions are of

a bigger head on a smaller face. As the child grows,

postnatal period witnesses more growth of the face which

then stands out of cranium. In terms of proportion,

percentage size, newborn head is about 55-60% of adult

head breadth, 40-50% of adult height and 30-35% of adult

depth. Soon after birth, the soft fontanelles fuse and the

suture bones of skull become closure at edges. The newborn

mandible has immature TMJ, a flat condylar head, wide

gonial angle, nearly no chin, and a small ramus. Chin is

rather recessive. There is a mid-symphyseal cartilage which

eventually disappears during the first year of life with body

of both sides becoming one. The coronoid cartilage also

disappears soon after birth in first few months.15

In short there is much more growth of facial structures

compared to cranial structures during postnatal period.

Concepts of skeletal growth

There are mainly four different concepts that would govern

facial growth mechanism:

1. Cartilaginous growth

2. Sutural growth

3. Periosteal and endosteal growth

4. Functional matrix concept.

Cartilaginous growth

The base of the skull, nasal septum and head of the

mandibular condyles are the main area of the skull where

cartilaginous growth takes place. It seems likely that all

these areas of cartilage play their part in the total growth

of the head at least in early years. Bones in the base of

skull retain the primary cartilage between them and are

known as synchondroses. Growth of the cartilage of the

spheno-occipital synchondrosis would increase the

anteroposterior dimension of the skull base.

Growth of the nasal septal cartilage would bring

nasomaxillary complex more forward from its original

position under the front of cranium. In an experiment by

Samat in which nasal septal cartilage was removed from

rabbit just after the birth, there was a significant deficit in

the growth of the midface.16 In another experiment on rats

in various developmental stages at birth, authors found that

extirpation of the nasal septum has a local effect primarily

disturbing the anterior growth of the upper face and secondly

by the reduced growth of the snout causing a reduction of

lower jaw prognathism.17

Growth of the mandibular condylar cartilage would

increase the total length and height of the mandible. The

mandibular bone can be considered as a long bone shaped

in the horse-shoe fashion.

The condylar head acts as the epiphyseal plate of long

bone and is responsible for the mandibular growth. The

condylar cartilage does not grow interstitially, like the

epiphyseal cartilages, but appositionally from the deepest

layer of the connective tissue cover of the condyle. The

condylar cartilage is very much responsive to mechanical

stimuli unlike epiphyseal cartilage. Experimental studies

on rats have proved that condyles have an independent

growth potential and might, therefore, contribute to

mandibular translatory growth.18

It has been found by experimental studies that the

cartilage in synchondroses and nasal septum can act as

growth centers with intrinsic capacity for initiating growth,

whereas mandibular cartilage is a growth site.

»

Sutural growth

During very early years in life when the bones of the skull

are widely separated from each other, sutural growth is

active in bringing the bones into close proximity. The union

of the different sutures takes place at different stages of life

(Fig. 6.5).

The bony sutures of the head were considered capable

of increasing the size of the head in all dimensions as

independent growth centres. However, there is greater

evidence which suggests that sutures react to tension created

by growing brain and soft tissue pull called ‘functional

matrix’ and will respond by bone formation. Sutures are

considered only as growth sites and not growth centres.

The sutures remain important intramembranous growth

sites of craniofacial skeleton.

It has been suggested that the sutures which separate

the face from the cranium are so aligned that growth at

these sutures would result in forward and downward growth

of the maxilla in relation to cranium. Mean direction of

sutural growth in the upper face, measure^ in the sagittal

pi;

Fig. 6.5: Growth at sutures (after Koski 1968). Essentially two

concepts are in vogue. 1. Three-layer theory whereby the intermediate

connective tissue between the sutures proliferates which makes the

bone grow. 2. According to five-layer theory the ends of bone at sutures

have a two layered periosteal layers where the primary bone growth

takes place. The intermediate connective tissue allows adjustments for

the bony growth. (Reproduced with permission from Koski K. Cranial

Growth center: facts or fallacies. Am J Orthod 1968; 54(8): 566-83)

plane by the implant method, was done by Bjork in a

Danish sample. The direction varied from 0 to 82° with a

mean of 51°.19

Through several experiments on young monkeys, rabbits,

and turtles through radiopaque implants in conjunction

with serial direct gross and indirect radiographic

measurements, Sarnat (2003) concluded that bone growth at

sutures is secondary or compensatory to some other factors

20 and not due to growth at the sutures alone.

Periosteal and endosteal growth

Normal bone comprises an external periosteal layer and

internal endosteal layer. The endosteal bone contains a

mixture of cortical and trabecular bone of varying amount.

The apposition of bone on the selective periosteal surfaces

and simultaneously resorption at some other selective

surfaces, contribute to the growth of the craniofacial sutures.

However, the periosteal growth is not simply a matter of

addition of bone to the outer surface and resorption of

bone from the inner surface. Endosteal resorption and

addition of bone from within the cancellous spaces is also

necessary to maintain the appropriate thickness to the

cortical layer of bone.

The process of balance apposition and resorption

facilitates growth of the skull vault, maintains its thickness

and has a significance on proportional growth as well as

shaping of the nasal, oral cavities and sinuses.

Functional matrix concept 21,22

The functional matrix theory was given by Melvin Moss in

1960s. According to this concept, the face grows as a

resP°nse to functional needs and neurotrophic influences

which are mediated by the soft tissue around the bones,

his concept can be supported by the fact that when the

IParent is suffering from hydrocephaly, the bony cranium

size increases and when size of the brain is small, the

cranium is correspondingly smaller.

According to this hypothesis, the origin, growth and

maintenance of skeletal tissues and organs are secondary

and compensatory responses to events and processes,

occurring in related non-skeletal tissues, organs and

functioning spaces called functional matrices. The functional

matrices include muscles, nerves, glands and teeth.

Two types of functional matrix are recognized, periosteal

and capsular. Skeletal units are also considered as of two

types, macroskeletal and microskeletal units.

The periosteal functional matrices relate to those tissues

that influence the bone directly through the periosteum.

Muscles are attached to the periosteum and consequently

are excellent examples of this kind of matrix. Blood vessels

and nerves lying in grooves or entering or exiting through

foramen can also exert a periosteal influence on the skeletal

unit. The periosteal matrix affects a microskeletal unit,

meaning that the sphere of influence is usually limited to

a part of one bone. The temporalis muscle exerts most of

its action on the coronoid process, a microunit of the

mandible (Figs 6.6, 6.7).

The capsular matrix deals with those tissue masses and

spaces that are surrounded by capsules. The neural mass

is contained within the capsule of scalp, dura mater, etc.

and the orbital mass is surrounded by the supporting

tissues of the eye. The oronasal pharyngeal spaces are

surrounded by a variety of tissues that compose their

capsules. These capsules tend to influence macroskeletal

units, i.e. portions of several bones are simultaneously

affected. The neural mass within its capsule elicits a reaction

on the surface of calvarium that transcends a localized area.

Fig. 6.6 : Growth at capsular neural matrix. The brain/neural tissues

housed in the skull along with dura mater constitute the neural matrix

(Based on the concept of Melvin Moss) *

62


Galea aponeurotica

Pericranium

Cranial bone

muscle

Dura mater

mater

Fig. 6.7 : The expansion of the neurocapsular matrix consequent to increase in the size of the neural tissues housed in skull. The process of the

increase in the size of skull occurs by translation of the bones and remodelling with formation of outer and inner tables and diploic area in between

(Based on the concept of Melvin Moss)

As a result, apposition on the occipital, parietal, temporalis

and frontal bones occur. This sharing of reaction by several

adjacent bones constitutes a macroskeletal unit.

As the tissues grow according to the functional needs

of the body, the matrices enlarge and carry the skeleton

within, leading to growth of face.

Factors affecting postnatal growth:

• Genetic factors

• Environmental factors

• Gene-environment interactions.

The architecture of the face and the soft tissues is under

strong genetic control. Studies based on monozygotic

twins, and on siblings have revealed a strong genetic

influence on the development of orofacial structures.

Development of occlusion is greatly influenced by the

environmental factors including nutrition and the resultant

adult face is the outcome of the combination of geneenvironment

interaction (Fig. 6.8).

It is known that pure racial stocks of genetically

homozygous populations tend to have normal occlusion

while those with heterozygous groups tend to have greater

chances of jaw discrepancies and more malocclusion.

Malocclusion pattern such as class II division 2 and true

mandibular prognathism are known to have familial

occurrence. 23

In general, craniofacial pattern and occlusion traits are

considered polygenic in inheritance and therefore susceptible

to modification under environmental influences be it a

abnormal function such as mouth breathing or tongue

thrust or a force or mechanotransduction.3

Fig. 6.8: Epigenetic factors have a considerable regulatory influence on

the developmental pathway of the structures. The ball represents the cell

of tissue, whose pathways on rolling down are limited by the convoluted

surfaces and ridges (Waddington: New Patterns in Genetics and

Development, New York, 1962, Columbia University Press). (Reproduced

with permission from Am J Orthod Dentofac Orthop King I, Harris EF,

Tiley EA 1993; 104(2): 121-31)

Concept of

mechanotransduction24_________

Mechanotransduction is an external stimulus, like muscular

or exogenous force, magnitude and characteristics of which

are significant in that bone and cartilage cells to respond.

The forces are able to generate ultimate ‘strain’ at cellular

level, the outcome of which is a change measurable at

macroscopic structure. The change is brought about by a

Force

(Muscular or exogenous

such as orthodontic appliance/headgear) j ~ \

i

Tissue strain

Interstitial

fluid flow

Cell membrane strain

causes deformation of the

membrane and cytoskeleton structures.

i

Expresssion of ■

regulator genes

-► Regulation of

marker genes

\ /

Cell differentiation, proliferation

and matrix synthesis

i

Growth and development

Macroscopic change in shape

D

c 2 >

Fig. 6.9: Mechanotransduction pathways from cellular to macroscopic alterations (AJO-DO 2004). (Reproduced with permission from Mao JJ, Nah

HD. Am J Orthod Dentofac Orthop 2004; 125(6): 676-89)

ar

;h

d.

ar

at

process of alteration in interstitial fluid flow, and other

stages eventually affecting the cell behaviour through

expression of regulatory genes and regulation of marker

genes. The genes involved in encoding bone-matrix and

cartilage-matrix proteins are considered as marker genes

and those regulating cellular or other gene activities are

called regulatory genes (Table 6.2). The cell differentiation,

proliferation and matrix synthesis, all are affected, resulting

in a macroscopic alteration of change in shape. An

exogenous force must possess certain characteristics before

it qualifies as a mechanical stimulus, defined as a mechanical

signal capable of eliciting anabolic or catabolic growth

response (Fig. 6.9).

Methods of studying physical growth

There are different methods for studying the craniofacial

growth. Methods of studying growth can be classified into

two as:

1- Quantitative

2. Qualitative.

Quantitative methods

The quantitative methods include the craniometry,

anthropometry, cephalometry and implant methods.

Craniometry

It is the method of taking measurements directly from the

skull. The craniometry study is based on measurements of

skull framed among human remains. It is advantageous

since precise measurement can be taken directly from the

skull.

Anthropometry

Anthropometry method involves the measurement of living

human skull. In this method, certain landmarks are taken

on the soft tissues over the human skull and then direct

measurements are made taking the soft tissue into

consideration. The anthropometric measurement can be

both cross-sectional and longitudinal. Any individual or

group can be studied for several years taking the

measurements of skull and face (Fig. 6.10).

Cephalometry

In this method, the radiograph of the skull is taken in a

standardized setting, and the measurements are made on

the radiographs. Serial cephalograms are taken for the

study of growth and measured. Cephalometrics has been

extensively used in understanding the nature of craniofacial

growth. Classical growth studies on facial growth such as


covalent bonds with protein matrices and are preserved in

situ after decalcification.29

Autoradiography

The radioactive substances that bind with the active growth

metabolites are injected into body. These radioactively

labelled metabolites release emissions which produce an

image in a photographic emulsion. To detect the area of

rapid growth in humans, 99mTc gamma emitting isotope is

used. These isotopes are highly concentrated at the active

sites of growth and inflammation.

Fig. 6.10: Craniometer is used to measure dimensions of human skull

and face including those of fossils

Bolton-Brush study,24 Burlington growth study25, used

cephalograms to measure craniofacial growth.

Implant method19,2627

Bjork in 1960s placed tantalum pins, 1.5 mm long and 0.5

mm in diameter, at selected sites in facial bones and skulls

of children subjects to study growth. Serial cephalograms

were then made and measurements between the implants

were taken to find the relative direction and extent of

growth. The cephalometric superimpositions were done to

observe the changes in one bone relative to another and

changes in the contour of bone. Bjork’s studies on facial

growth are perhaps the most referred scholarly work on

facial growth and growth rotations. Implant methods to

study growth may be difficult to perform in present day

scenario due to ethical reasons.

Qualitative methods

The qualitative methods used for the study of the growth

are by vital staining methods and autoradiography.

Vital staining

Dyes like alizarin red S, trypan blue, and chlortetracycline

have been used to study bone growth. These products

have a greater tendency to react with the calcium/proteins

during the bone mineralization stage and have an inhibitory

influence on bone formation. Injections of alizarin S have

been used to determine rate of calcification of bone and

dentine. These methods of studying bone growth are

feasible only in experimental animals.28 The tetracycline

staining of teeth is an example of vital staining in which

tetracycline reacts with calcium during tooth mineralization

stage and stains it intrinsically.

Dyes of the procion M and remazol group are effective

for vital staining of growing bones. These compounds form

Postnatal growth30-31

The postnatal growth movement of craniofacial structures

takes place due to drift and displacement. Drift is a process

in which the combination of deposition and resorption of

the bone results in growth movement towards the depositary

surface. The primary displacement occurs when bone gets

displaced as a result of its own growth. If the bone gets

displaced as a result of growth and enlargement of an

adjacent bony structures, it is called secondary

displacement.

Cranial vault

The cranial vault is made up of flat bones that are formed

by intramembranous ossification. At birth, cranial bones

are not joined at sutures. Sutures are wide and have open

spaces of loose connective tissue in between called

fontanelles. There are six fontanelles at the time of birth,

which are fused later in childhood. Fontanelles allow

deformation of head and thus help in passage of large head

through birth canal and also help in accommodating rapidly

enlarging brain in early childhood (Fig. 6.11). Postnatal

growth and remodelling of the cranial vault occurs mainly

at the sutures, and it follows the neural curve of growth.

Increase in size of brain creates tension at the sutures

which leads to new bone deposition in the area. Remodelling

of the outer and inner surfaces of cranial bones also occurs,

to allow contour changes with growth.

Cranial base

Cranial base is the platform on which the face develops.

Therefore the growth of cranial base affects the structures,

line angles and placement of facial parts. Bones of the

cranial base are formed by endochondral ossification and

centres of ossification appear in chondrocranium early in

embryonic life. These primary cartilages remain between

centres of ossification after birth and play a significant role

in postnatal growth of cranial base. These bands of cartilage

between the cranial base bones are called synchondroses.

Synchondrosis is similar to two sided epiphyseal plate with

proliferating cartilage cells in the centre and mature cartilage

cells and ossification occurring in both directions away

from centre.

Fig. 6.11: At birth the cranial sutures are wide and skull is comparatively softer to that of an adult

The intraethmoidal and intrasphenoidal synchondroses

close before birth. Intraoccipital synchondrosis closes before

5 years of age. Sphenoethmoidal synchondrosis closes

around 6 years of age (Fig. 6.12).

The spheno-occipital synchondrosis contributes the most

in the growth of cranial base as it is the last cranial base

suture to ossify. The spheno-occipital synchondrosis is

closed by 13-15 years of age. The synchondrosis causes

the elongation of the middle portion of the cranial base as

a result of primary displacement.

Growth due to remodelling process of resorption from

the inside and deposition from outside in the cranial fossa

leads to the cortical drift. The cranial fossae are separated

by elevated bony partition. The elevated partitions are

depository and depression portions are restorative. The

Base of sphenoid Pre-sphenoid Ethmoid

Base of

occipital

bone

Spheno-occipital

close at

13-15 years

Inter-sphenoid

close before

7 years

Frontal

bone

% 6.12: Synchondroses at the base of skull. Growth of anterior

cranial base is complete by 5 years with the fusion of spheno-

Lsthmoidal suture

expansion of the middle cranial fossa has a major secondary

displacement effect on the anterior cranial fossa and floor,

the nasomaxillary complex and on the mandible. The

horizontal enlargement of middle cranial fossa produces

major forward displacement of the anterior cranial fossa

and nasomaxillary complex and only a minor displacement

of the mandible.

Growth of nasomaxillary complex

There are different mechanisms of growth which contribute

to the nasomaxillary growth such as (Fig. 6.13A,B):

• Sutures

• Nasal septum

• Periosteal and endosteal surfaces

• Alveolar processes.

The maxillary complex is attached to the cranium by

zygomatico-maxillary sutures, frontomaxillary sutures,

zygomatico-temporal sutures and pterygopalatine sutures.

The growth at these sutures lead to the growth of the

maxilla. According to the cartilaginous theory, the nasal

septal cartilages also play a significant role in vertical

maxillary growth. Surface resorption and deposition causes

the maxillary drift and growth of the alveolar process along

with the eruption of teeth, causing the increase in height of

the maxilla. The whole nasomaxillary complex moves in an

inferior direction due to new bone addition at the sutures.

As the middle cranial fossa grows, it causes the maxilla to

move in anterior and inferior direction which is called

secondary displacement. The secondary displacement is

an important growth mechanism during primary dentition

period but becomes less important as growth of cranial

base slows down.

The appositional bone growth in the alveolar process

leads to the increase in height of maxilla. The resorption

wmm

O rthodontics: Diagnosis and m anagem ent of m alocclusion and dentofacial deform ities

Fig. 6.13: As the maxilla relocates downward and forward resorption occurs in front and resorption in the rear surfaces which essentially maintains

the shape of the structures (Based on Enlow DH: Facial Growth (3rd edn). Philadelphia, Saunders, 1990)

takes place on the lining surfaces of bony walls and floor

of nasal chamber, lining cortical surface of maxillary sinuses

except the medial nasal wall. The deposition takes place

on oral side of bony palate, alveolar ridge and nasal side

of cribriform plate. So, these regional patterns of remodelling

cause the lateral and anterior expansion of the nasal

chamber and downward movement of palate.

Maxillary width

The median palatal sutures play a major role in the

development of maxillary width. The nasal airway expands

by remodelling process. The width of the maxilla also

increases by the palatal remodelling as the external side of

the whole anterior part of the maxillary arch is resorptive.

The inner side of arch and the palatal vault towards oral

cavity is depository. This palatal remodelling follows the ‘V’

principles of bone remodelling. Similarly, the resorption

from inside surface of maxillary sinus and deposition on

outer side and apposition at zygomatic bone cause increase

in width of nasomaxillary complex.

Maxillary length

The horizontal lengthening of maxilla occurs by apposition

on maxillary tuberosity, primary displacement due to sutural

growth and secondary displacement due to growth of cranial

bones. In maxillary tuberosity area, growth occurs in three

directions. It lengthens posteriorly by deposition on the

posterior facing maxillary tuberosity, it grows laterally by

deposits on the buccal surface. It grows downward by

deposition of bone along the alveolar ridge and also lateral

side. The endosteal side of cortex within the tuberosity is

resorptive which causes maxillary sinus enlargement and

drift of cortex posteriorly. The malar process follows the

growth of maxilla. The zygoma and cheek bone complex is

displaced anteriorly and inferiorly in the same direction and

amount, as the primary displacement of the maxilla. The

remodelling process is required to maintain shape of the

maxilla

Growth of the mandible

The growth of the mandible occurs as a combination of

surface remodelling of the mandible accompanied by forward

and downward displacement from the temporomandibular

interface (Fig. 6.14).

Condylar growth

The mandibular condyle is considered as a major site of

growth. The condylar cartilage is a secondary cartilage of

hyaline type covered with fibrous connective tissue. The

condylar cartilage is phylogenetically and ontogenetically

unique and differs in histologic organization from other

growth cartilages involved in endochondral bone formation.

A capsular layer of poorly vascularized connective tissue

covers the articular surface of the condyle. A

prechondroblastic cell layer lies beneath this connective

tissue layer which proliferates to form the cartilage,

ultimately converting it to endochondral bone. The

proliferating process produces the upward and backward

growth of the condyle. As condylar and ramus growth

proceeds, the mandible becomes displaced anteroinferiorly

as a whole. The rate and directions of condylar growth are

influenced by both intrinsic and extrinsic factors.

Ramus and lingual tuberosity

The ramus remodelling is important as it positions the lower

arch in occlusion with the upper and it is continuously adaptive

to the changing craniofacial conditions. The growth vector

of the mandible is posterior and superior. The ramus

remodelling occurs in a posterosuperior direction. While the

mandible as a whole is displaced anteriorly and inferiorly

which allows lengthening of the corpus and dental arch, the

anterior surface of ramus undergoes resorption and the

posterior surface undergoes deposition. In this manner, part

of the ramus is converted into the horizontal corpus as

remodelling of ramus takes place. The lingual tuberosity

forms a boundary between the ramus and the corpus of the

mandible. It grows posteriorly by deposition on its posterior

facing surface.

Fig. 6.14: Condylar cartilage is considered a major growth site for the

mandible. The mandible grows at four processess: condylar, coronoid,

alveolar and body. Growth at alvelolar process is facilitated with the

eruption of teeth. The growth at the condyle is backward which results

in forward and downward shift. As the mandible translates downward

and forward or relocates, resorption occurs at the front sites (-) and

deposition at the posterior borders (+). This is required to maintain the

distinct shape and anatomy of the structure

Ramus to corpus remodelling conversion

As the lingual tuberosity grows, the ramus is relocated

posteriorly. The posterior ramus movement follows the ‘V’

principle. As it moves posteriorly, it widens. There is a

resorption from the buccal side and deposition from the

lingual side of ramus. The remodelling of coronoid process

also follows the V-principle. There is resorption on the

buccal side and deposition on the lingual side of the

coronoid process. A single field of surface resorption is

present on the inferior border of the mandible at the corpusramus

junction forming the antegonial notch. Mandibular

foramen drifts backwards and upwards as deposition takes

place on the anterior rim and resorption takes place on the

posterior rim of the foramen.

Mandibular arch

As the teeth erupt, the alveolar process grow along. The

height of the alveolar process increases with the eruption

of dentition. However, in anodontia, as in ectodermal

dysplasia, the alveolar process does not develop. Where

there is partial anodontia, the alveolar process growth is

affected.

The chin of the human beings becomes gradually

prominent as individual grows from childhood to an adult.

The deposition occurs at the mental protuberance and

resorption at the alveolar portion which causes the chin to

become prominent.

Growth trends

The facial growth is basically divided into two types:

• Horizontal growth

• Vertical growth.

L

The horizontal or vertical growth trends are not particular

to any malocclusion. In horizontal growth trend, there is

tendency of the mandible to rotate upward and forward. The

lower anterior facial height is less; there are more chances of

deep bite occurrence. Such persons have well-developed

muscles of jaw elevators and so is the biting force.

In vertical growth pattern, the mandible rotates downward

and backward. The anterior facial height is increased, more

so lower anterior face height. There is a tendency for

anterior open bite. The muscular forces of jaw elevators

such as temporalis and masseter are weak compared to

horizontal growers.

These growth patterns also determine the facial type as

long face or short face.

Timing of craniofacial skeletal

growth______________________

Growth is a continuous process from birth till it reaches a

slow rate that characterizes adult size. The most rapid skeletal

growth occurs in pubertal growth spurt and the increase in

height of adolescents at puberty is quite obvious. But the

three-dimensional growth of craniofacial structure reaches

the adult status in a definite sequence. Growth in width is

completed first followed by growth in length and finally

growth in height. Growth in width of both jaws and the

dental arches will complete before the pubertal growth spurt.

Maxillary growth in downward and forward direction can

continue 2-3 years after the attainment of puberty, whereas

mandibular horizontal growth will continue longer than

maxillary complex. Growth in height continues till early

twenties in males and somewhat earlier in females.

Clinical implications

Orthodontic therapeutic interventions and prognosis are

influenced by the growth status and growth trend of the

patient. For all orthodontic patients, the growth assessment

should be carried out as a routine. Physical, skeletal and dental

growth, attainment of pubertal growth spurt and amount of

growth remaining are assessed with the help of various growth

assessment parameters like height weight charts, canine

calcification stages, peak height velocity (PHV), hand-wrist

radiographs, and cervical vertebral maturation index.

It is important to assess the general growth status of

child reporting for orthodontic treatment. Percentile growth

charts can be used for the purpose. It helps in assessing

whether the child’s growth is normal or abnormal. Highly

abnormal growth needs medical attention to rule out any

systemic or hormonal imbalance.

Functional jaw orthodontic therapy takes advantages of

redirection of remaining growth of craniofacial region.

Functional appliances like twin block, bionator, Frankel

appliances are given for class II skeletal correction.

Effectiveness of these appliances to modify skeletal growth

is minimal after pubertal growth spurt.


Other orthopaedic appliances like headgears are also

advantageous to correct maxillary prognathism during

growing stage of the patient. Maxillary horizontal growth is

completed much earlier than mandible and so the use of

headgear to restrict or redirect its growth should be started

much before pubertal growth spurt in mixed dentition

period.

Maxillary expansion procedures in cases of jaw

constriction should be carried out during early mixed

dentition. Growth in width of maxilla occurs by sutural

growth in interpalatine and intermaxillary sutures. Maximum

growth occurs in first 5 years. The skeletal expansion

procedures should be carried out before the fusion of

palatal sutures, i.e. by 10 years. Orthopaedic appliances

like facemask and chin cup are used for the treatment of

skeletal class III malocclusions early during the mixed

dentition period. However, the continuing growth of

mandible and its pubertal growth spurt can lead to

development of malocclusion after early interventions.

Active growth cessation is prerequisite for orthognathic

surgery particularly in cases with mandibular prognathism.

REFERENCES

1. Martyn T. Cobourne construction for the modem head:

current concepts in craniofacial development. J Orthod 2000;

27(4): 307-14.

2. http://www.med.uc.edu/embryology/chapterl2 accessed on

11.05.08.

3. lohnston MC, Bronsky PT, Millicovsky G. Embryogenesis of

cleft lip and palate. In: McCarthy (ed.). Plastic Surgery.

Philadelphia: Saunders 1990, pp. 2515-52.

4. Hunt P, Wilkinson D, Krumlauf R. Patterning the vertebrate

head: murine Hox 2 genes mark distinct subpopulations of

premigratory and migrating cranial neural crest. Development

1991; 112(1): 43-45.

5. MacKenzie A, Ferguson MW, Sharpe PT. Expression patterns

of the homeobox gene, Hox-8, in the mouse embryo suggest

a role in specifying tooth initiation and shape. Development

1992; 115(2): 403-20.

6. Sharpe, PT. Homeobox genes and orofacial development.

Connective Tissue Research. 1995; 32: 17-25.

7. Ferguson MWJ. A hole in the head. Nature Genetics 2000;

24: 330-31.

8. Bulfone A, Kim HJ, Puelles L, Porteus MH, Grippo JF,

Rubenstein JL. The mouse Dlx-2 (Tes-1) gene is expressed in

spatially restricted domains of the forebrain, face and limbs

in mid-gestation mouse embryos: Mechanics Develop, 1993;

40: 129-40.

9. Rivera-Perez JA, Mallo M, Gendron-Maguire M, Gridley T,

Behringer RR. Goosecoid is not an essential component of

the mouse gastrula organizer but is required for craniofacial

and rib development. Development 1995; 121(9): 3005-12.

10. Johnston MC, Bronsky DA. Critical Reviews on Oral Biology

and Medicine 1995; 6: 368-422.

11. Mossey PA. The heritability of malocclusion: part 1—

genetics, principles and terminology. Br. J Orthod 1999;

26(2): 103-113.

12. Evans CA. Postnatal growth, birth through postadolescence.

In Avery JA (ed): Oral Development and Histology (3rd

edn.). Thieme. Stutgart. 2002; 4: 61-70.

13. Bannister LH, Berry MM, Collins P, Dyson M, Dussek JE,

Ferguson MWJ. Gray’s Anatomy. 38th edn. Edinburgh.

Churchill Livingstone; 1995; p 426-42.

14. Samat BG. Effects and noneffects of personal environmental

experimentation on postnatal craniofacial growth. J Craniofac

Surg 2001; 12: 205-17.

15. Mao JJ, Nah HD. Growth and development: hereditary and

mechanical modulations. Am J Orthod Dentofac Orthop

2004; 125(6): 676-89.

16. Samat BG, Wexler MR. Postnatal growth of nose and face

after resection of septal cartilage in the rabbit. Oral Surg Oral

Med Oral Pathol 1968; 26: 712-27.

17. Kvinnsland S. Partial resection of the cartilaginous nasal

septum in rats: its influence on growth. Angle Orthod 1974;

44(2): 135-40.

18. Bemabei RL, Johnston L. The growth in situ of isolated

mandibular segments. Am J Orthod Dentofac Orthop 1978;

73(1): 24-35.

19. Bjork A. Sutural growth of the upper face studied by the

implant method. European J. Orthod 2007; 29: i82-i88.

Transactions of the European Orthodontic Society 1964; 49-

65.

20. Samat BG. Gross growth and regrowth of sutures: reflections

on some personal research. J Craniofac Surg 2003; 14(4):

438-44.

21. Moss ML, Salentijn L: The primary role of functional matrices

in facial growth. Am J Orthod 1969; 55(6): 566-77.

22. Moss ML, Salentijn L. The capsular matrix. Am J Orthod

1969; 56(5): 474-90.

23. Mossey PA. The heritability of malocclusion: part 2—the

influence of genetics in malocclusion. Br J Orthod 1999;

26(3): 195-203.

24. Mao JJ, Nah HD. Growth and development: hereditary and

mechanical modulations. Am J Orthod Dentofac Orthop

2004; 125(6): 676-89.

25. http:// dental.cwm.edu/Bolton-bmsh/index.html accessed on

12.05.08

26. http://w w w .utoronto.ca/dentistry/facultyreserach/dri/

grad_burlington.html accessed on 12.05.08

27. Bjork A. Facial growth in man, studied with the aid of

metallic implants. Acta Odontol Scand 1955; 13: 9-34.

28. Bjork A. Prediction of mandibular growth rotation. Am J

Orthod 1969; 55(6): 585-99.

29. Hong YC, Yen PK, Shaw JH. Microscopic evaluation of the

effects of some vital staining agents on growing bone in

rabbits. Calcif Tissue Res 1968; 2(3): 0171-967.

30. Seiton EC, Engel MB. Reactive dyes as vital indicators of

bone growth. Am J Anat 1969; 126(3): 373-91.

31. Enlow DH. Facial Growth (3rd edn). Philadelphia: Saunders.

1990.

32. http://orthodontics.case.edu/facialgrow th/textbook/

chapters.html accessed on 12.05.08

Altered orofacial functions on

development of face and occlusion

OVERVIEW

• Orofacial functions and development of face • Tongue thrusting swallowing habit

• Pathophysiology of habits • Mouth breathing habit

• Classification of orofacial habits • Bruxism

# Prevalence of habits • Summary

# Thumb sucking habit

Orofacial functions and

craniofacial development______

The orofacial skeletal and dental development are

inextricably linked with the development of orofacial

functions. The orofacial neuromuscular components

in a newborn primarily function for fulfillment of the most

basic needs of feeding, maintenance of the airway and

gratification of emotional needs.

In a newborn, the sucking reflex is very well developed

which takes care of his/her feeding and emotional needs. At

this stage of life, an infant tries to communicate with the

world through the sensory pathways present in the oral

structures of lips and tongue. The lip and tongue act in

unison with an intact palate to perform the act of feeding.

The suckling reflex is the most primitive of all reflexes and

yet it is the most well-developed reflex at this stage.

Sucking is actually a nibbling action of the lips on the

nipples of the mother’s breast that causes smooth muscle

contraction of milk ducts to release the milk. The tongue of

the infant is so closely placed next to the lips and tunnelled

so as to cause the milk to flow into the pharynx and

oesophagus. This phenomenon is called infantile swallow

(Hg. 7.1 A).

Characteristics of an infantile swallow are:

" During the act of swallowing, the jaws remain apart

with the tongue tip interposed between the gum pads.

• The lower jaw is held and stabilized primarily by

contraction of the muscles of facial nerve and the

interposed tongue.

• The swallow is guided, and largely controlled by the

sensory interchange between the lips and the tongue.

The sucking action helps in feeding the infant, and also

creates an emotional bond with the mother which builds the

basic trust for him to the outside world. The lips provide

sensory pathway which endows a feeling of well-being

essential for the normal psychological development of a

child.

69

L

70 m Orthodontics: Diagnosis and management of malocclusion and dentofacial deformities

The sucking reflex and infantile swallowing pattern

normally remain for about a year and slowly diminish as the

child grows and start intake of semisolid food.1

An infant is a natural nose breather and hence the

patency of the airway is important to sustain life. As the

child grows, it develops a mature swallowing pattern that

is conducive to chewing solid food and also helps in

developing speech abilities. This graduation from

unifocused functions to multitasked functions requires a

coordinated development of the neuromuscular apparatus

around face, jaws, oral cavity and structures involved in

deglutition.

Any deviation from this normal course of events such as

prolonged retention of primitive functions or development

of an abnormal function, adversely affects the growth of

the jaw and teeth.

Transition from infantile swallow to mature

swallow

While in an infant, the VII cranial nerve (facial nerve) has

predominant control over the muscles stabilizing the mandible,

during first year with the eruption of deciduous teeth, this

role is overtaken by the structures supplied by trigeminal

nerve (V cranial nerve). With the addition of semisolid and

solid food and gradual withdrawal of breast or bottle feeding,

swallowing act also evolves to a more complex mechanism.

The tongue no longer thrusts into the space between the

gum pads or incisal surfaces of the teeth, which actually

contact momentarily during the swallowing act. The muscles

of mastication take over the role of stabilizing the mandible

as the cheek and lip muscles reduce the strength of their

contraction (Fig. 7. IB).

The tip of the tongue rests near the incisor foramen

during the act of deglutition rather than moving in and out

of the mouth. Minimal contractions of the lips occur during

the mature swallow. Fletcher2 points out that a change from

infantile swallow to mature swallow may be due to

morphologic compulsions of growth. Whereas the general

body dimensions change in the neonate at the ratio of five

to one, the infant tongue only doubles in size. As expansion

in peripheral attachments occurs, the role of tongue

somewhat diminishes during postnatal period. Mature

swallow is normally well developed by 18 months.

Speech

Development of speech is another important function that

occurs in a gradual manner. It also follows the anterior to

posterior pattern of maturation like the swallowing pattern.

First the bilabial sounds like /b/ and /p/ are produced. Later

on, tongue tip consonants /t/, /d/, and sibilant sounds like

/s/ and /z/ are produced, /r/ sound which is produced by

a posterior positioning of the tongue develops very late.

Non-nutritive sucking habits like finger, thumb or pacifier

sucking are seen in many children at this age and these may

continue till 2 years of age. These habits normally stop with

transition to mature swallow but some times these may be

seen till the age of 4 years.

P a th o p h y s io lo g y o f h a b its______

Habit has been defined simply as any task or function that

is done repeatedly, and is a part of the subconscious.

Orofacial habits influence the form of the orofacial structures

because of their repetitive nature and longer duration (Fig.

7.1C).

Su<

Cor

gre*

I

pos

pre;

mu!

sysl

the

ante

fon

bee

this

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ope

fin *

feat

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| nc

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Fig. 7.1 B: Mature swallow Fig. 7.1 C: Persistent infantile swallow A

L

Sucking habits

Continuation of non-nutritive sucking habit beyond 4-5 years

greatly hinders the development of normal orofacial function.

During finger sucking, mouth remains open, tongue is

positioned forward and low in the mouth, and an abnormal

pressure is generated by the contraction of the cheek

muscles which causes imbalance in the intraoral force

system. The unfavourable consequences are narrowing of

the maxillary arch, proclined upper incisors, incompetent

anterior lip seal and forwardly placed tongue that moves

forward to achieve a complete lip seal. The lower lip

becomes trapped under the proclined upper incisors and

this becomes a self-perpetuating problem where the lower

lip keep exerting an outward force on the upper teeth. An

open bite like situation may also be created due to persistent

finger sucking. Thus typical Class II division 1 malocclusion

features are precipitated. The habitual lowering of the

mandible further prevents natural lip seal and the patient

has to activate his/her lips in order to achieve anterior lip

seal. The infantile swallowing pattern is retained (Fig. 7.2).

Tongue thrusting. The repeated anterior positioning of the

tongue, anterior openbite, protruded and spaced anterior

teeth and an incompetent anterior lip seal, all lead to a

tongue thrusting like situation. Tongue thrusting could be

the cause and consequence of anterior open bite.

Mouth breathing. If a child suffers nasorespiratory blockage

due any reason, common ones being enlarged tonsils,

recurrent throat infections, he/she tends to keep his/her

tongue low and forward and is unable to maintain an

anterior lip seal. Such patients develop a mouth breathing

habit with consequent open mouth posture. These children

develop a peculiar face look and craniofacial pattern called

Adenoid facies.

Classification of orofacial habits

Klein (1952)3 believed that the habits fall into broad category

of:

1. Unintentional pressure

2. Intentional pressure: those from orthodontic appliances.3

Fig. 7.2: Pathophysiology of thumb sucking induced class II div 1 malocclusion and tongue thrust swallow

*

L


Within this broad category of unintentional pressure, he

further divided habits into:

1. Intrinsic pressures

2. Extrinsic pressures: example incorrect pillowing

3. Functional pressures: malocclusion seen in musicians.

Intrinsic pressure habits (within the mouth)

1. Thumb sucking

2. Finger sucking

3. Tongue thrust swallow

4. Mouth breathing

5. Tongue, lip, cheek, blanket-sucking

6. Nail, lip, tongue biting

7. Macroglossia, overgrowth of the tongue

8. Incorrect swallowing, anaesthesia throat.

Prevalence of orofacial habits (Table 7.1)

A number of studies have been carried out around the

world to gauge the problem of thumb sucking and pacifier

sucking habits in children. In Delhi, the prevalence of oral

habits in school going children (5-13 years) was found

25.5%.4 Tongue thrusting was seen in 18.1% followed by

mouth breathing seen in 6.6% children (Fig. 7.3).

Non-nutritive sucking habits

Non-nutritive sucking habits include thumb sucking, finger

sucking, lip sucking and rarely the cheek. Thumb sucking

refers to placing the thumb or fingers into the mouth many

times every day and night, exerting a definite sucking

pressure.5 The habit can be repetitive and forceful associated

with strong cheek and lip contractions (Fig. 7.4). Several

theories have been put forward to explain thumb sucking

habit.

Freudian theory of psychoanalysis is linked to

psychosexual development of human. This theory regards

thumb sucking as a symptom of a deeper emotional

disturbance or neurosis.

Eysenck’s learning theory regards it as a form of neurotic

symptom itself and not caused by underlying neurosis. If

the symptom (habit) is eliminated, the neurosis will also be

eliminated. Most of the habit breaking appliances work on

the learning theory.6

Palermo theory regards thumb sucking arising out of a

progressive stimulus and reward reaction which would

spontaneously disappear unless it becomes an attention

getting mechanism.7

Other 0.1%

74.5%

No habit

Thumb sucking

0.7%

Mouth breathing

6.6%

Tongue thrust

18.1%

Lip biting 0.04%

Fig

froi

the

gui

i

c

1

Lip biting 0.14%

Others 0.34%

Thumb

sucking 3%

Mouth

breathing

26%

n

i

L

C

1

Tongue

thrusting 71%

Not

bo^

S ol

Fig. 7.3 : A. Prevalence of various oral habits, and B. relative distribution of various oral habits

L

Section I: Altered orofacial functions on development of face and occlusion 73

Fig. 7.4: Intensive thumb sucking at the age of three years. A to C. The thumb used is cleaner due to frequent use in the mouth. Constant irritation

from the teeth may cause formation of a callus. D. The untoward effects of thumb sucking are influenced by intensity, frequency and duration of

the habit. Thumb sucking leads to protrusion of lips and a recessive chin resulting in Class II malocclusion. E. Interceptive orthodontics and psychological

guidance to the child and family counselling can help to discontinue the habit which may bring about normalization of facial growth at this age

Table 7.1: Prevalence of various orofacial habits: types according to sex

Oral habit Male Female Total

N % N % N %

Thumb sucking 10 0.4 30 1.0*** 40 0.7

Mouth breathing 215 7.8 149 5.3*** 364 6.6

Tongue thrusting 483 17.5 520 18.6 1003 18.1

Up biting 1 0.0 1 0.0 2 0.0

Others 1 0.0 4 0.1 5 0.1

Total 710 25.7 704 25.0 1414 25.5

*** = P<0.001

N°te significant differences in pattern of oral habits in boys and girls. While more girls have thumb sucking habit, mouth breathing was significantly high among

boys.

Source: Kharbanda OP et al. Oral habits in school going children of Delhi: a prevalence study. J Indian Soc Pedo Prev Dent 2003:21(3); 120-24.


Fig. 7.5 : Thumb sucking in a young girl. Placement of thumb and abnormal perioral muscle behaviour. A, B. Thumb sucking caused a retrognathic

mandible and superior protrusion. C. Class II malocclusion caused by thumb sucking. D,E. Note proclination of maxillary anterior teeth and large overjet

contributed by backwardly held mandible by the wrist held against chin. DE - A Class II malocclusion and overjet

Sear’s oral drive theory believes that the thumb sucking

habit is intimately related to the prolongation of

breastfeeding. The longer the baby is breastfed, stronger

will be its oral drive and more prone it is to thumb sucking

(Fig. 7.5).

Types of thumb sucking

How children place the thumb has been studied using

cineradiographic by Subtelny8 who grouped them A-D.

1. Group A (50%). Thumb was inserted in the mouth

considerably beyond the first joint or the knuckle. The

thumb occupied a large portion of the palate pressing

against the palatal mucosa and alveolar tissue. The

lower incisor pressed and contacted the thumb in the

region of first joint.

2. Group B (24%). The thumb did not go completely into

the vault area of the hard palate, however. It entered

the mouth up to and around the first joint or just

anterior to it.

3. Group C (20%). The thumb passed fully into the oral

cavity and approximated the vault of the hard palate as

in group A. However, the lower incisor did not touch

or contact the thumb.

4. Group D (6%). The thumb did not progress appreciably

into the mouth. The lower incisor contacted at a level

near the thumb nail (Fig. 7.6).

Effects of digit sucking on oral structures911

The effect of any pressure habit is dependent upon the

trident of habit factors:

1. Duration

2. Frequency

3. Intensity

Digit sucking results in development of features of class

II malocclusion. Proclination of the upper incisors is the

first and the most common sign of persistent thumb sucking.

The proclination is self-maintaining because of the

cushioning effect of lower lips, and upper lip becoming

redundant. These proclined incisors are prone to accidental

trauma (Fig. 7.6).

1. Exaggerated mentalis activity may be seen because of

the effort of the lower lip to attain a lip seal anteriorly.

2. Maxillary arch shows constriction due to unopposed

pressure from the buccal musculature. Posterior

crossbite tendency may occur.

3. Mandibular incisors may be retroclined or upright.

4. Mandible experiences downward and backward rotation

due to lowered position while sucking.

5. An increase in the ANB angle is seen due to both

maxillary prognathism and mandibular retrognathism.

6. Patient may develop tongue thrusting due to

appearance of spaces in the anterior region.


Table 7.2: Treatment o f thumb sucking

Reminder therapy

Corrective therapy

Indication

In an older child of at least 6-7 yrs who

wants to break the habit but is unable to

do so

These appliances should be used in age

group of 31/2 to 41/2 years

In late mixed or permanent dentition when

the malocclusion has set in

Modalities

Chemical method

Application of a bitter and a malodorous chemical like quinine,

asafetida. Cayenne pepper dissolved in a volatile liquid may

also be used

Restrictive methods

Application of bandages to thumb, finger, elbow may be done.

Bandages on the thumb will take away the pleasure from the act.

Bandaging the elbow will prevent bending the elbow to suck thumb

Intraoral appliances

Palatal cribs, spurs (Graber, ref)

Expansion appliance like quad-helix with spurs

Interception of habit

An initial consultation with the paediatric dentist or the

orthodontist will help in formulating a line of treatment

which is dependent upon the age of the patient and

severity of the condition.

• It is suggested that for children below 2 years nonnutritive

sucking habit is very common. But parents

must be alerted towards any possible deficit in attention

or inadequate feeding for the child. If there is no

obvious cause then, this habit should self-correct with

time.

• For the habits persisting beyond 2 years, i.e. up to 4

years of age, attention must be given towards the child

in terms of love and care. With both parents working,

the child may suffer from attention deficit which

should be taken care of.

• In children older than 4 years, signs of malocclusion

should be treated with a reminder therapy. Mocking

and scolding should be avoided at all times. Attention

diverting activities such as outdoor sports could help.

• In older patients (> 7 yrs) with moderate to severe

form of malocclusion like anterior open bite or posterior

crossbite, definitive appliance therapy should be

initiated.

Methods used for interception of the thumb sucking

habit have been outlined in Table 7.2.

Beta hypothesis (1929)12

Dr Knight Dunlap of Johns Hopkins University discovered

the concept of negative practice. It is interesting to know

that he used to repeatedly make a typographical error in

typing the word ‘the’ as ‘hte’. One day, he decided to start

typing ‘hte’ instead of ‘the’. And after few days, he

serendipitously discovered that his often made typographical

error was self-corrected! Thus was born the concept of

‘negative practice’ or ‘beta hypothesis’. When applied to

oral habits, a child is encouraged to watch himself in a large

mirror while sucking digit. The sight of oneself sucking

thumb will hamper the pleasure derived from the activity,

and the child will slowly avoid indulging in the same.

Tongue thrusting, swallowing

habit or retained infantile

swallow_____________________

The tongue is a powerful muscular organ which exerts

tremendous pressure during swallowing at frequent intervals,

24 hours a day, during the night-time as well as during the

day.

In tongue thrusting habits, a normal-sized tongue or one

that is overdeveloped thrusts between the upper and lower

teeth each time the patient swallows, producing an open

bite. Sometimes, the patient allows the tongue to rest in the

open bite space between the act of deglutition, preventing

the bite from closing. Tongue thrusting also permits the

molars to supraerupt, a condition which further complicates

the problem of correcting open bite cases even if tongue

thrusting habits have been corrected1315(Fig. 7.6).

Rix (1953)16 recognized two sharply contrasting types of

tongue behaviour:

1. Non-dispersing behaviour of the tongue. Those cases

in which the tongue does not come forward to exert

any force on the lingual surface of upper and lower

incisors. The lips may or may not contract excessively.

The upper and lower incisors are upright or retroclined.

2. Dispersing behaviour of the tongue. Those cases in

which the actions of tongue and lips are associated

with a dispersal of upper and lower incisor relations.

L


c

Fig. 7.6 : Anterior open bite caused by tongue thrusting habit

Causes of tongue thrusting

Maturational factors

• Tongue thrusting may develop as a sequela of prolonged

thumb sucking and retained infantile swallow.

• A transitional period from infantile swallow to mature

swallow also exhibits tongue thrusting.

Anatomic factors

• In macroglossia, there is overgrowth of the tongue.

Pressure is exerted against the lingual surfaces of the

teeth, causing them to become spaced. Indentations on

the tongue often appear where the tongue pushes

against the teeth.

• Adenoids and tonsils cause the tongue to be positioned

anteriorly to prevent blocking of the oropharynx.

• Tongue thrusting is also called an adaptive behaviour.

If large spaces are present anteriorly in the upper and

lower teeth, then the tongue will try to move into these

spaces to achieve the anterior seal.

Neurogenic factors. Hypersensitive palate causes the tongue

to be pushed forward.

Types of tongue thrusting

Moyers classified tongue thrusting into three types:

1. Simple tongue thrust: Characterized by teeth together

swallow.

2. Complex tongue thrust: Characterized by teeth apart

swallow

3. Retained infantile swallow.

Clinical features of tongue thrusting swallow

The clinical features seen in the tongue thrusting condition

are dependent on the type of tongue thrusting:

1. The simple tongue thrusting (Fig. 7.6)

• Generalized spacing and proclination may be seen in

the upper and lower anterior teeth.

• Increased overjet, reduced overbite or presence of an

anterior open bite may be seen.

• Exaggerated perioral musculature during the swallowing

action.

2. The complex tongue thrusting

• The teeth are apart during the swallowing process.

• The tongue spreads laterally in between the upper and

lower teeth.

• Lateral tongue thrusting is seen in such cases.

• Unilateral crossbite may also be seen.

Diagnosis of tongue thrusting swallow

1. Extraoral examination shows an exaggerated perioral

contraction during swallowing. Increased vertical

dimension of face due to over eruption of the molars

into the freeway space is evident.


Table 7.3: Treatment of tongue thrusting

Modalities

Reminder therapy

Corrective therapy

Palatal appliances

Palatal cribs, spurs, palatal rolling ball

Removal of obstruction

Surgery for adenoids, macroglossia

Closure of anterior open bite, posterior open bite and/or anterior spaces with either a fixed or removable orthodontic

appliance

Tongue exercises

■ Elastic band swallow

The elastic band is kept on the tip of the tongue and the palate and swallowing is practised

■ Water swallow

To keep water in mouth and a mirror in hand, and swallowing is practised daily

■ Candy swallow

A candy is placed between the tongue and palate and swallowing is practised

■ Speech exercises

Patient practises syllables like c, g, h, k while keeping an elastic band between the tongue and the palate

Lip exercises

Patient practises stretching of lips so as to achieve anterior lip seal

Fig. 7.7 : Mild spacing in the upper anteriors due to abnormal tongue posture. Saliva drooling out during swallowing habit

Intraoral examination shows appearance of open bite,

and spacing between teeth.A forced tongue may

cause gushing of saliva through the spaced dentition

(Fig. 7.7).

Interception and treatment of tongue thrusting

Interception and treatment of tongue thrusting is age and

severity dependent. In children below three years, no active

intervention is instituted while children above this age can

i


j

the

cha

<

Fig. 7.8 : Fixed habit breaking appliances, A. Fixed appliance soldered on molar bands for tongue thrusting / thumb sucking, B. Pearl exerciser fixed

on molar bands for tongue thrusting, C. Lip bumper for lower lip sucking

be trained for tongue swallowing exercises. Tongue thrusting

treatment would necessitate that anatomic obstruction like

macroglossia and enlarged tonsils are also taken care of. An

abnormally enlarged tongue could be due to the tumours/

cysts in the floor of the mouth.These should be investigated

and treated accordingly.

Modalities of treatment of tongue thrusting are outlined

in Table 7.3. Treatment of tongue thrusting requires a

positive attitude and strong desire by the patient to overcome

abnormal habit along with suitable mechanotherapy

instituted by the orthodontist. Some of the commonly used

removable appliances include upper Hawley’s plate with

tongue cribs, roller balls for tongue exercise (Fig 7.8).

Mouth breathing habit

Altered mode of breathing through mouth is an adaptation

to obstruction in nasal passages.17 The obstruction may be

temporary and recurrent. While more often it is partial than

complete. The airway resistance may be enough to force

the subject breathe through mouth.

Causes of obstruction to nasal passages are:

1. Allergenic rhinitis

2. Enlarged tonsils or adenoids (Fig. 7.9)

3. Deviated nasal septum

4. Nasal polyps

5. Enlarged nasal turbinates.

Effects of oral breathing

Long-standing nasal obstruction has adverse effects on the

craniofacial morphology during periods of rapid facial

growth, more so in genetically susceptible children who

have dolichocephalic facial pattern (Fig. 7.10). A nasal

resistance of two to three times of the normal would be

sufficient to alter pattern of respiration from nasal to oral,

especially during night when a person is in a supine

position. Day time borderline cases may become mouth

breathers during night.

A majority of the mouth breather patients develop class

II malocclusion. Some patients may develop class III

occlusion due to anterior displacement of the tongue due to

tonsillar hypertrophy. Oral respiration leads to excessive

Fig. 7.9: Cephalogram of a young girl of 10 years who has been snorer

and mouth breather. She developed Class II malocclsuion. Her

cephalogram shows marked reduction in nasopharyngeal airway space

which has been occupied by the adenoids

vertical eruption of the posterior molars, in response to a

lack of occlusal contact. These overerupted teeth exert a

downward vector of force on the mandible, causing the

lower jaw to rotate down and back in a ‘clockwise’ direction.

According to the ‘compression theory’, given by Norland

(1918),18 constriction of the maxillary arch is related to

lowered posture of tongue which happens due to nasal

obstruction in order to facilitate breathing. A lowered tongue

is less capable of balancing the lateral pressures of the

cheek on the maxillary arch. Pressure differential across the

hard palate in the absence of nasal airflow further contributes

to a narrow, high-arched hard palate. Adenoid facies’ was

ove

nas

pat

ass<

ma

bite

pat

bac

1

obs

req

ske

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res]

ma

air

ma

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fac

obs

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bra

Section I: Altered orofacial functions on development of face and occlusion ■ 79

the term coined by Tomes (1872) to describe dentofacial

changes associated with chronic nasal airway obstruction.

Studies by Linder-Aronsen in the 1970’s and 80’s19"22

over two decades have supported the relationship between

nasal obstruction and craniofacial and dental patterns. These

patients have increase in lower anterior face height

associated with unfavourable ‘clockwise’ rotation of the

mandible in a more vertical and posterior direction, open

bite, crossbite, and retrognathia (Fig. 7.10). In growing

patients' following adenoidectomy, changes could reverse

back to nasal breathing.

Harvold’s23,24 classical study on artificially nasally

obstructed monkeys suggested that neuromuscular changes

required to maintain an open oral airway contributed to the

skeletal and dental changes. These changes showed patterns

of dentofacial adaptations dependent upon the mode of

respiration. Elongation of their face with development of

malocclusion was found in monkeys who maintained their

airway oral breathing by protruding and lowering the

mandible.

Solow and Kreiborg (1977)25put forward the soft tissue

stretch theory in which they suggested that the obstruction

to the airway is a major causative factor in determining the

facial morphology (Fig. 7.11).

According to Cheng,26 impact of the severity of nasal

obstruction may have a varying effect on the adverse facial

development and this may vary in different facial types. A

brachycephalic or broad faced pattern with strong facial

musculature and a deep bite may be less affected by nasal

obstruction, whereas dolichocephalic faces with a narrow,

more elongated pattern may be more susceptible to these

changes.

Clinical features

The term ‘respiratory obstruction syndrome’ was used to

describe the constellation of characteristic features

associated with obstruction of the nasal airway during the

years of facial growth. Other common terms are the ‘long

face syndrome’ and ‘vertical maxillary excess’(VME).27

The clinical features often include:

• Excessive lower anterior face height

• Incompetent lip posture

• Excessive appearance of maxillary anterior teeth,

‘GUMMY SMILE’

• A nose that appears to be flattened, nostrils that are

small and poorly developed

• Steep mandibular plane

• Posterior crossbite

• Open-mouth posture

• A short upper lip and a fuller lower lip

• A narrow V-shaped upper jaw with a high narrow

palatal vault

• A class II skeletal relationship

• Gingivitis of upper anterior teeth.

Frequent respiratory

infections

I

Deviated nasal septum

Constricted m axilla

Reduced nasal breathing

Decreased nasal width

Extended head posture

Fig. 7.10: Pathophysiology of mouth breathing following reduced nasal breathing

A


Soft tissue stretch

t

Postural changes

Differential forces on

the skeleton

i

M orphologic change

t

i

Neurom uscular

O bstruction o f the

feedback < -------------------------- airway

Fig. 7.11: Stretch theory by Solow and Kreiborg illustrating the development of mouth breathing

Diagnosis of mouth breathing

• History

• Clinical features

• Assessment of mode of respiration

1. Water holding test. Patient is asked to hold water in

his mouth. Inability to keep the mouth closed for > 2

min confirms nasal obstructions and therefore mouth

breathing habit.

2. Mirror condensation test. A two-surface mirror is placed

under the nose. If the upper surface condenses, then

breathing is through the nose, but if the condensation

occurs on the lower surface then the breathing is

through the mouth.

3. Cotton wisp test. A small wisp of cotton (butterfly

shaped) is placed below the nostrils in a butterfly

shape. If the upper fibres are displaced then the

breathing is through the nose. If the lower fibres are

displaced then it is mouth breathing habit.

Cephalometric analysis

• Lateral view may show presence of enlarged adenoids

and tonsils

• Cephalometric analysis for nasopharyngeal airway show

altered parameters

• VME cases also exhibit typical cephalometric features

that make a ready diagnosis.

Rhinomanometric examination

• Nasal resistance and airflow are measured with the help

of a rhinomanometer.

• A high value of nasal resistance signifies nasal

obstruction and mouth breathing

• SNORT (Simultaneous nasal and oral respiratory

technique). This is a highly accurate technique for

quantifying respiratory mode, wherein both nasal and

oral respiration are simultaneously recorded and

calibrated. The readings of both oral and nasal

respiration are recorded in waveforms which can be

later converted into a digital format.

Orthodontic implications

Effective orthodontic therapy necessitates elimination of

the nasal obstruction to allow for normalization of the

function of facial musculature surrounding the dentition

and normal development of the facial bones. An orthodontist

must communicate to an otolaryngologist if he/she finds

mouth breathing habit and seek his/her opinion prior to

considering any orthodontic or habit breaking treatment.

The cause and effect relationship between nasal obstruction

and orofacial development has now been clearly documented

although genetic predisposition is now well understood.

Early intervention to enhance nasal breathing is now an

accepted mode of therapy in cases of established cause of

obstruction. If instituted early during childhood much of

the adverse effects of craniofacial growth are reversed.28

Various orthodontic appliances have been designed to

discourage mouth breathing and encourage nasal breathing.

Oral screens have been used previously for this purpose.

ENT perspective

Adenoidectomy with or without tonsillectomy is most

common treatment for nasal obstruction in children in

established cases. Allergic rhinitis with turbinate

hypertrophy should be treated with partial inferior turbinate

resection, either with electrocautery or cryosurgery.

Orthodontic aspects of treatment of mouth breathing

have been illustrated in a table format. Essentially, maxillary

expansion without extrusive mechanism is the answer to

expand the narrow maxilla. Rapid maxillary expansion (RME)

has been reported to reduce nasal resistance and promote

nasal respiration.


Bruxism_______________________

Bruxism in the simplest terms refers to the clenching and

gnashing of the teeth against each other. Ramfjord and

Ash29 described it as nocturnal, subconscious activity but

can occur in the day or night and may be performed

consciously or subconsciously. Sleep bruxism is an entity

that is very common with children. The adults may bruxize

in either day or night.

Aetiology

• Emotional tension seems to be the major cause of

bruxism.

• Occlusal interferences can initiate bruxism.

• Childhood bruxism may be related to other oral habits,

such as chronic biting and chewing of toys and pencils,

thumb-and finger-sucking, tongue thrusting, and mouth

breathing.

• Endocrine disorders, particularly those relating to

hyperthyroidism, may lead to bruxism. Many

hyperkinetic children also have a habit of bruxism.

• Gastrointestinal disturbances from food allergy, enzyme

imbalances in digestion cause chronic abdominal

distress.

• Persistent, recurrent urologic dysfunction may be

responsible for nocturnal bruxism.

• Nutritional and vitamin deficiencies as possible factors

for inducing tooth grinding. Bruxism in allergic children

is known.

• Athletes indulge in bruxism due to increased muscular

activity.

• Allergy plays a definite role in nocturnal bruxism as

evidenced during exacerbations of perennial allergic

rhinitis, asthma attacks, upper respiratory tract

infections, and excessive exposure to pollens, etc.30

• Neurological disturbances like lesions in cerebral cortex,

epilepsy are also associated with bruxism.

Clinical features

• Teeth that are worn down, flattened or chipped

• Atypical occlusal facets — worn tooth enamel, exposing

the dentine of the tooth.

• Increased tooth sensitivity

• Jaw pain or tightness in the jaw muscles

• Ear-ache because of severe jaw muscle contractions

• Headache and chronic facial pain

• Chewed tissue on the inside of the cheek

• Hypertrophy of masseter muscle

• Teeth grinding and clenching, this may be loud enough

to wake the sleep partner.

Treatment

Psychological counselling to identify and treat any

psychological distress, tension or emotional upset.

Correction of any occlusal interference by coronoplasty.

3. Temporary relief can be brought about by occlusal

splints or bite plates that will help in relieving the pain

in the muscles by passively stretching them. On relief

of symptoms, the occlusion is equilibrated to correct

centric relation.

4. Prosthetic replacement of any missing posterior teeth

that could have led to loss of vertical dimension

leading to overcontraction of the closing muscles.

5. Oral analgesics for muscular pain.

6. Physiotherapy has proven useful in relieving the

symptoms of bruxism.

• Low intensity ultrasonic radiation therapy: Used

commonly in orthopaedics for relieving painful

muscular symptoms. It has been useful in bruxism.

• Acupressure/acupuncture treatment for muscular

pain.

• Transcutaneous electrical nerve stimulation (TENS)

has an analgesic effect over sensory nerves.

7. Treatment of allergies which may be required in

children.

Summary

Development of mature and complex orofacial functions

progresses slowly yet meticulously through various age

related phases from the infancy to adulthood. In the

formative years, infantile and altered orofacial functions

may remain for an unusually longer period of time, such

that they become a habit. The deleterious habits should be

managed in a holistic approach based on their aetiology.

The developing malocclusion should be intercepted and

treated accordingly.

REFERENCES

1. Moyers RE. Handbook of Orthodontics (3rd edn). Chicago,

Year Book Medical Publishers Inc 1972.

2. Fletcher SG. Processes and maturation of mastication and

deglutition. ASHA Reports 1970; 5; 92-105.

3. Klein ET. Pressure habits, etiological factors in malocclusion.

Am J Orthod 1952; 38(8): 569-87.

4. Kharbanda OP, Sidhu SS, Sundaram KR, Shukla DK. Oral

habits in school going children of Delhi: a prevalence study.

J Indian Soc Pedo Prev Dent 2003; 21(3): 120-24.

5. Graber TM. Orthodontics: Principles and Practice (3rd edn).

Philadelphia, Saunders 2005; p 255-330.

6. Eysenck HJ. Learning theory and behaviour therapy. J Ment

Sci 1959; 105: 61-75.

7. Palermo DS. Thumb sucking: a learned response. Pediatrics

1956; 17: 392-99.

8. Subtelny JD, Subtelny JD. Oral habit - studies in form,

function and therapy. Angle Orthod 1973; 43(4): 349-83.

9. Warren JJ, Bishara SE, Steinbock KL, Yonezu T, Nowak AJ.

Effects of oral habits, duration on dental characteristics in the

primary dentition. J Am Dent Assoc 2001; 132(12): 1685-93.

10. Svedmyr B. Dummy sucking: A study of its prevalence,

duration and malocclusion consequences. Swed Dent J 1979;

3: 205-10.

■


11. Ogaard B, Larsson E, Lindsten R. The effect of sucking

habits, cohort, sex, intercanine arch widths, and breast or

bottle feeding on posterior crossbite in Norwegian and Swedish

3-year-old children. Am J Orthod Dentofac Orthop 1994;

106: 161-66.

12. Dunlap K. The technique of negative practice. Helen Peak

The Am J Psycho 1942; 55(4): 576-80.

13. Graber TM. The “three Ms”: Muscles, malformation and

malocclusion. Am J Orthod 1963; 49(6): 418-50.

14. Tulley WJ. Adverse muscle forces: Their diagnostic

significance. Am J Orthod 1956; 42(11): 801-14.

15. Tulley WJ. A critical appraisal of tongue thrusting. Am J

Orthod 1969; 55(6): 640-50.

16. Rix, RE. Some observations upon the environment of the

incisors. Dent Record 1953; 73: 427.

17. Bosma JE Evaluation of oral function of the orthodontic

patient. Am J Orthod 1969; 55(6): 578-84.

18. Norland H. Ansiktsformens, spec. Gomhojdens for upplomsten

av kroniska otiter. Jppsala, Sweden, Applebergs Boktryckcri

Ab, 1918.

19. Linder-Aronson S. Adenoids — their effects on mode of

breathing and nasal airflow and their relationship to

characteristics of the facial skeleton and the dentition. Acta

Otolaryngol (Suppl) 1970; 265: 1-132.

20. Linder-Aronson S. Adenoid obstruction of the nasopharynx.

In Nasorespiratory Function and Craniofacial Growth.

Monograph 9. Craniofacial growth series. Ann Arbor,

University of Michigan 1979:121-47.

21. Holmbergh. Linder-Aronson S. Cephalometric radiographs as

a means of evaluating the capacity of the nasal and

nasopharyngeal airway. Am J Orthod Dentofac Orthop 1979;

76: 479-90.

22. Linder-Aronson S, Woodside DG„ Lundstrom A. Mandibular

growth direction following adenoidectomy. Am J Orthod

1986; 89: 273-84.

23. Harvold EP et al. Primate experiments on oral respiration. Am

J Orthod 1981; 79(4): 359-72.

24. Harvold EP, Chiericig vargoruik K. Experiments on the

development of dental malocclusions. Am J Orthod 1972; 61:

38-44.

25. Solow B, Kreiborg S. Soft tissue stretching: a possible control

factor in craniofacial morphogenesis. Scand J Dent Res 1917;

85: 505-07.

26. Cheng MC et al. Developmental effects of impaired breathing

in the face of the growing child. Angle Orthod 1988; 58: 309-

20.

27. Kerr WJ, McWilliam JS Linder-Aronson S. Mandibular forma

and position related to changed mode of breathing - a five

year longitudinal study. Angle Orthod 1989; 59: 91-96.

28. Rubin RM. Mode of respiration and facial growth. Am J

Orthod 1980; 78(5): 504-10.

29. Ramfjord SP, Ash MM, Jr. Occlusion (2nd edn). Philadelphia,

Saunders, 1971.

30. Marks MB. Bruxism in allergic children. Am J Orthod 1980;

77(1): 48-59.

C H A P T E R

Biology of orthodontic

tooth movement

OVERVIEW

• Nature of orthodontic tooth movement

• Orthodontic and orthopaedic tooth movement

• Phases of tooth movement

• Optional orthodontic force

• Tissue reactions to orthodontic forces

• Pain and mobility with orthodontic appliances

• Summary

Nature of orthodontic tooth

movement___________________

Orthodontic tooth movement (OTM) is a complex

biomechanical process which is initiated by the

clinician with the application of a force. The applied

force moves the tooth beyond its range of physiological

tooth movement which occurs during various functions of

stomatognathic system like mastication, lifelong mesial

eruption and active eruption of the tooth into the oral cavity.

Several factors affect and modify the nature and amount

of orthodontic tooth movement. Most significant mechanical

factors are: magnitude, direction and nature of the force.

The inherent biological factors include bone density, age

of the person, systemic health, hormones and factors that

influence the bone turnover.

Orthodontic and orthopaedic

tooth movement_____________

In general, it is said that orthodontic forces are those which

lie between the range of 50 and 300 gm and are capable of

educing movement of a tooth or group of teeth in the

alveolus while forces normally higher than 300 gm are called

Orthopaedic forces.

-----------Bone resorption

Fig. 8.1: Application of orthodontic force results in pressure on certain

areas of the periodontal ligament while tension on the others. Bone under

pressure shows resorption while on the tension side bone deposition takes

place. This is the simplest model of pressure-tension theory of tooth

movement

Conventionally, in a clinical setting, forces that are

measured in grams are denoted orthodontic forces and

those measured in pounds (256 gm and beyond) are

orthopaedic in nature.

83


The orthopaedic forces are capable of generating

alteration in the bony configuration either by inhibiting or

redirecting the growth or by enhancing the growth. These

kinds of effects like orthopaedic redirection and inhibition

of the growth of maxilla are therapeutic needs in children

with skeletal class II malocclusion due to prognathic maxilla

or skeletal class III in growing children.

The growth enhancement is needed in skeletal class II

children; what is called functional jaw orthopaedics, where

we like to enhance the growth of the mandible and its

sagittal repositioning and inhibit the maxillary growth.

Bone is a dynamic organ where a lifelong continuous

remodelling process takes place by osteoclasts and osteoblasts.

The mechanical stimuli are known to alter the remodelling

process and are primarily considered as ‘osteogenic’. The

orthodontic tooth movement requires a remodelling of the

bone through the periodontal suspension, where forces or

mechanical stimuli are transmitted through tooth. The alveolar

bone goes through a process of selective bone formation and

resorption consequent to the application of orthodontic force

while the mechanical stimuli on the skeletal system are

considered as primarily osteogenic in nature.

Orthodontic tooth movement involves remodelling of all

components of the periodontal ligament, i.e. alveolar bone,

gingiva and periodontal ligament and to some extent

cementum. Major implications of tooth movement forces in

bone have been extensively studied, since teeth have to be

moved through the bone. Although the cellular and

biological changes occur in the other components of

periodontium as well and recent research has focused

mainly on the molecular events that control the process.

To understand the mechanics of tooth translation through

bone, traditionally pressure-tension hypothesis was put

forward. The bone gets resorbed in areas perceived to be

subjected to pressure and deposited at sites under tension.

The concept of pressure-tension in orthodontic tooth

Fig. 8.2: Stages of tooth movement. Tooth movement showing the three

characteristic phases: (1) compression early phase (day 1), (2) delayed

hyalinization period (days 4 and 5), and (3) late rapid tooth movement (day

5 to the end of the experimental period) (Reproduced with permission from

Mohammed AH, Tatakis DN, Dziak R. Leukotrienes in orthodontic tooth

movement. Am J Orthod Dentofac Orthop 1989; 95(3): 231-37)

movement was evaluated m a in ly by histologic studies of

the periodontium.

Phases of tooth movement (Fig. 8.2)

Burstone1suggested three p h a s e s of tooth movement by

plotting the rates of tooth m o v em en t against time 1- an

initial phase, 2- a lag phase, a n d 3- a postlag phase.

Initial phase. It is ch a racte rized by rapid movement

immediately after the ap p licatio n of force to the tooth. This

rate is due to the displacement o f the tooth in the periodontal

ligament (PDL) space.

Lag phase. Immediately after t h e initial phase, there is a lag

period, with relatively low ra te s o f tooth displacement or no

displacement. It has been su g g e ste d that the lag is produced

by hyalinization of the PDL i n areas of compression. No

further tooth movement occurs u n til cells complete removal

of all necrotic tissues.

Postlag phase. The third p h ase o f tooth movement follows

the lag period, during which th e rate of movement gradually

or suddenly increases.

Recent research on ex p erim en tal animals agrees with the

pattern of tooth movement p h a s e s described in humans by

Burstone. Study by Pilon e t a l2 performed on beagles,

divided the curve of tooth m o v em en t into 4 phases.

The first phase lasts 24 h o u r s to 2 days and represents

the initial movement of the to o th inside its bony socket. It

is followed by a second p h ase, when the tooth movement

stops for 20 to 30 days. After t h e removal of necrotic tissue

formed during the second p h a s e , tooth movement is

accelerated in the third phase a n d continues into the fourth

linear phase. The third and fo u r th phases comprise most of

the total tooth movement d u rin g orthodontic treatment.

Optimal orthodontic forces

A threshold of force is re q u ire d to sustain orthodontic

tooth movement. Importance o f correct force was given

very early in orthodontic h isto ry .

According to Schwarz (1 9 3 2 )3, ‘optimal force is the force

leading to a change in tissue pressure that approximated

the capillary vessels’ blood p re ssu re, thus preventing their

occlusion in the compressed periodontal ligament.’ (capillary

blood pressure is 20-25 g m /cm 2 of the root surface area).

Optimum orthodontic fo rce should produce fast tooth

movement without any h arm fu l effects to the tooth and its

supporting tissues with least discom fort to the patient. The

optimal force value varies acco rd in g to the root surface area

and the type of tooth m ovem ent. F or example, tipping of the

canine distally requires less f o r c e than the one desired for

translation.

Light and heavy forces

The magnitude of fo rce a p p lie d for orthodontic

mechanotherapy has received significant attention. It lS

generally accepted that light forces produce f a v o u r a b l e

tooth displacement by frontal resorption, i.e. resorptiOy

starting at lamina dura. Various studies^5 demonstrated thS|

Section Biology of orthodontic tooth movement 85

teeth subjected to high forces show hyalinization more

often than teeth experiencing light forces, and the

development of hyalinization zones has a definite

relationship to the force magnitude. When heavy forces are

applied periodontal ligament and cells undergo cellular

dealth, and this zone appears without cells in histological

sections so-called hyalinization. The bone resorption starts

at a distant site extending towards tooth and so-called rear

resorption. However, it was found that the hyalinization

zones have no relationship to the rate of tooth movement.

Once tooth movement has started after the second (arrest)

phase, bone remodelling takes place at a certain rate,

independent of force magnitude. It was found that force

magnitude plays only a subordinate role in orthodontic

tooth movement. But maintaining light forces avoid

deleterious effects of tooth movement to a large level, with

less discomfort to patient.

Continuous, interrupted, and intermittent forces

In order to produce orthodontic tooth movement, force

should be sustained for a considerable percentage of time.

Successful tooth movement requires a threshold of force

duration of about 6 hours per day.6

Force magnitude decreases as the tooth moves and there

is a decline from the desired force level between two patient

appointments. This is called force decay. Orthodontic forces

can be classified as continuous, interrupted and intermittent.

• Continuous force means that the force magnitude is

maintained at almost the same level in the period

between two activations.

• Interrupted force declines to zero between activations.

• Intermittent force falls to zero when the appliance is

removed and it also shows force decay with tooth

movement. Intermittent forces act as an impulse for

short periods with a series of interruptions.

Fixed appliances produce continuous and interrupted

forces. It is not always possible to distinguish between

continuous and interrupted movements. Intermittent forces

are produced by removable appliances and headgears. Light

continuous forces produce efficient tooth movement with

the least harmful effects. Heavy forces are physiologically

acceptable if they act as interrupted ones with a rest period in

between. The rest period between appliance activations is

the time used by the tissues for reorganization. This rest can

promote favourable cell proliferation for further tissue changes

when the appliance is activated again. Light continuous and

heavy interrupted forces are clinically acceptable whereas

heavy continuous forces should be avoided. Orthodontic

appliances should not be reactivated more frequently than 3-

week intervals. A 4-week appointment cycle is more typical in

a clinical practice.7

Tissue reactions to orthodontic forces

Tissue reactions to orthodontic forces were first described

hy Sandstedt (1904,8 19059), and later by Oppenheim (1911,10

1930,11 1935,12 193613).

Sandstedt’s work was on dogs, where he applied force

through an appliance for a period of 3 weeks moving the

crowns of incisors by 3 mm. He showed that bone was

deposited on the tension side of the tooth both with heavy

and light forces while on the pressure side with light forces

alveolar bone was resorbed directly by multinucleate

osteoclast cells, called direct resorption or frontal resorption.

With the application of heavy forces, the periodontal

tissues are compressed leading to a cell free zone, called the

hyalinized tissue, which occurs due to thrombosis of vessels

and cell death. On histological sections, this zone resembles

hyaline connective tissue and hence the term hyalinization.

In hyalinized areas, resorption of the alveolus takes place

far from the cell free zone in the bone marrow spaces and

is called ‘undermining resorption’ or ‘rear resorption’.

Oppenheim studied bone transformation following the

application of force in primary teeth on monkeys several

days after the force was last activated. He continued to

work in this field including root resorption (1930,11 1935,12

193613). Kaare Reitan, a Norwegian orthodontist did extensive

work on tissue response to orthodontic tooth movement.

He conducted research on human models (1957,14 196415)

and dogs (195916). His classical work on human premolars

that were destined for orthodontic extraction demonstrated

that continuous forces as low as 30 gm can produce some

degree of hyalinization particularly when tipping movements

are attempted in contrast to translation where forces get

evenly distributed on a wide area of tooth/bone surface. It

takes about 2-4 weeks to remove this hyalinized tissue by

the phagocytes. It has been shown that the patency of the

blood vessels is required for the direct resorption to be

initiated. Later Per Rygh (1972),17 based on ultrastructral

cellular reactions and vascular changes in pressure zones

in rat molars, demonstrated that during the:

• First 30 minutes: Packing of erythrocytes takes place in

dilated blood vessels, necrotic changes in PDL

fibroblasts such as dilatation of the endoplasmic

reticulum and mitochondrial swellings are seen.

• 2-3 hrs (2-3 days in humans): Fragmentation of

erythrocytes, rupture of the cell membrane and nuclear

fragmentation occurs.

• 1-7 days: Disintegration of the blood vessels walls and

extravasations of their contents.

This is followed by removal of the necrotic hyalinized

tissue by multinucleated giant cells. It has been shown by

Brudvik and Rygh (1994)18that TRAP-positive macrophages

and multinucleated giant cells have a role in the removal of

hyalinized tissues. On reaching the adjacent root surface,

TRAP-positive cells continue to remove the cementum and

subjacent dentine producing resorption lacunae on the root

surface.

Periodontal ligament remodelling—histological

findings

Classic histologic research about tooth movement by

Sandstedt, Oppenheim and Schwarz led to the hypothesis


tha

a ‘

stu

a a

ab<

8.3

Oi

Fig. 8.3A, B: A. Sagittal section, 6 pm thick, of maxillary canine of 1-year-old female cat, after 14 days of distal tipping with 80 gm force R, canine

root; P, canine PDL; B, alveolar bone. Shown is distal side of canine, where PDL had been compressed. Compressed PDL contains necrotic (hyalinized)

zone, which is being removed by cells from surrounding viable PDL; adjacent alveolar bone is undergoing undermining and indirect resorption.

Haematoxylin and eosin staining; X 320. B. Sagittal section, 6 |jm thick, of maxillary canine of 1-year-old female cat, after 14 days of distal tipping

with 80 gm force. R, canine root, P, canine PDL; B, alveolar bone. Shown is mesial side of canine, where PDL had been stretched. New bony trabeculae

are seen extending into widened PDL space in direction of applied force. Haematoxylin and eosin staining; X 320. (Reproduced with permission from

Am J Orthod Dentofac Orthop. Krishnan V, Davidovitch Z. Cellular, molecular, and tissue-level reactions to orthodontic force. 2006; 129:469e.1-460e.32)

Oi

Fig. 8.4A-C: Neighbouring sections from the compressed area of the mesiolingual root of a rat maxillary first molar after tooth movement for 7 days.

The hyalinized zone (H) between the alveolar bone (B) and root (T) reveals a fibrillar structure. Resorption of alveolar bone occurs from the marrow

spaces (arrows). Note the resorption lacuna in the dentine at the periphery of the hyalinized zone (arrowhead). A. Haematoxylin and eosin stain. B.

Tartrate resistant acid phosphatase (TRAP) stain highlighting TRAP-positive cells in the adjacent narrow spaces and at the margin of hyalinized tissue.

C. Compressed area after 10 days. Hyalinized tissue almost removed with resorption lacunae on both the bone and dentine surfaces. The multinucleate

cells within the necrotic tissue (arrows) and lining the surface of the dentine (arrowheads) were shown in adjacent sections to be 1 RAP positive.

Haematoxylin and eosin stain. Bars measure 50 pm (Reprinted with permission from Oxford University Press. Brudvik P, Rygh P. Multinucleated

cell remove the main hyalinized tissue and start resorption of adjacent root surfaces. Eur J Orthod 1994; 16(4):265-73)

ab<

k

Section I: Biology of orthodontic tooth movement 87

that a tooth moves in the periodontal space by generating

a ‘pressure side’ and a ‘tension side.’ Later ultrastructural

studies by Rygh (1972) and Brudvik and Rygh (1994), gave

a very detailed description of events. The findings of the

above research have been meticulously summarized (Figs.

8.3, 8.4) by Krishnan and Davidovitch (2006).6

On the tension side

• Widening of the PDL is observed. In the stretched

PDL, several cellular processes are apparently activated,

along with an increase in the number of connective

tissue cells and increased vascularity. Beyond a certain

level of stress, the vascular supply to the PDL

decreases, with cell death occurring between stretched

fibres.

• The blood vessels in the PDL on the tension site

become distended and there is cellular infiltration of

the tissue by macrophages and leucocytes along with

proteins and fluids, which migrate from the adjacent

PDL capillaries and evoke an inflammatory response.

• Fibroblasts are rearranged in the direction of strain.

These fibroblasts secrete new Sharpey’s fibers in the

PDL and part of these newly synthesized collagen

fibers are incorporated in the newly formed osteoid,

whereas the other part is embedded in the PDL

simultaneously with the deposition of a new matrix on

the adjacent alveolar bone socket wall.

On the pressure side

• There is narrowing of the PDL space and deformation

of the alveolar crest bone. Depending upon the

magnitude of applied force, the reaction at this site

differs; light pressure produces direct bone resorption

and heavy forces produce hyalinization.

• Changes in the compressed PDL are characterized by

oedema, gradual obliteration of blood vessels, and

breakdown of the walls of veins, followed by leakage

of blood constituents into the extravascular space.

• Changes seen in fibroblasts at these sites are moderate

swellings of the endoplasmic reticulum, formation of

vacuoles, rupture and loss of cytoplasm. This

disintegration leaves isolated nuclei, which undergo

lysis over a period of several weeks and the retained

ground substance gives a glossy appearance.

Accumulated erythrocyte breakdown products in

pressure regions might undergo crystallization.

• No tooth movement occurs until the necrotic tissue is

/ removed by the invasion of phagocytosing cells from

peripheral undamaged ligament and bone marrow

spaces. This removal is completed after 3 to 5 weeks,

j

and the post hyalinized PDL is markedly wider than

before treatment, perhaps to withstand greater

mechanical influences’.

Orthodontic literature has traditionally elaborated much

about the pressure tension theory and our thinking has

remained within the confines of this theory. Baumrind19

believed that the periodontal membrane which is enclosed

in a space surrounded by the tight boundaries of cementum

and bone served like a fluid, a hydrostatic system. Therefore,

in accordance to the Pascal’s law, any force should be

distributed equally to all regions of the periodontal ligament.

We know that the periodontal ligament contains several

types of collagen fibres, cells, blood vessels, tissue fluids

and the lamina dura is not a closed wall. The analogy of

‘fluid in a closed vessel’ is not absolutely correct. The

evidence from tooth movement experiments has shown that

within the periodontal ligament ‘differential pressure’ is

generated. Hence, several areas of compression and tension

are seen around tooth surfaces. The morphology of the

tooth surface and lamina dura, direction of the force also

determines the differential pressures.

Pathways of tooth movement

Various hypotheses were put forward to understand the

biological process of tooth movement. Mostafa et al20 in

1983 came with broad outline of various modes of cellular

changes bringing about tooth movement. They proposed

an integrated model for the mechanism of tooth movement

(Fig. 8.5).

According to this model, there are basically two pathways

and both of them work concurrently to cause efficient tooth

movement.

Pathway 1

It is the major biologic response to orthodontic force. It

represents greater physiologic response and may be

associated with normal bone growth and remodelling.

When orthodontic force is applied, bone bending occurs

and it can lead to production of inflammatory mediator

prostaglandins and also creation of positive and negative

charges on bone due to charge polarization of its matrix,

which is due to the phenomenon of ‘piezoelectric response’.

The formation of bioelectric signals following force

application to bone is a well known fact in the current

scientific literature.

Electric effects on bone due to force can be:

• Piezoelectric (dry bone) (Fig. 8.6)

• Streaming potentials (wet bone).

Piezoelectricity. It is a phenomenon observed in many

crystalline materials in which a deformation of the crystal

structure produces a flow of electric current, as electrons

are displaced from one part of crystal lattice to another.

Piezoelectric signals have two characteristics: (i) quick

decay rate, and (ii) production of equivalent signal opposite

in direction when force is released. Sources of piezoelectric

current are hydroxy apatite crystals, collagen and collagenhydroxyapatite

interface.

Streaming potentials. Ions in the fluid that bathe living

bone interact with the complex electric field generated when

L


ORTHODONTIC FORCE

Tissue injury

II

Piezoelectric

response

D

Matrix charge

polarization

Prostaglandin

production

F

< -

V

Membrane

effect

Vascular stasis

C

D V

------Inflammation

V

Vascular &

cellular

invasion

Lymphocytes

monocytes

macrophages

Directional

Influence?

+

H

▼

Osteoclast

recruitment

osteoblast

recruitment

Increase cellular cAMP

Initiate bone cell

differentiation and/or

bone cell activation

H

Hydrolytic enzyme

release

Fi

T

th

el

A

OSTEOCLAST

coupling factor?

OSTEOBLAST

Induce collagenase

activity

K

Bone remodelling < -

Fig. 8.5 : Model of cellular events leading to tooth movement by Mostafa et al 1983 (Reproduced with permission from Am J Orthod. Mostafa YA,

Weaks-Dybrig M, Osdoby P. Orchestration of tooth movement. 1983; 83(3): 245-50)

the bone bends, causing temperature changes as well as

electric signals. The small voltage that is observed is called

the streaming potential. In bone, such potentials could

possibly arise in vascular channels, haversian systems,

canaliculi, microporosities of the structure and as a result

of blood flow and interstitial fluid movement. These voltages

like piezoelectric signals have rapid onset and alterations.

According to Mostafa et al, piezoelectric response acts

by itself and also by the production of prostaglandins.

Electric response gave the directional control to bone

remodelling by bone formation in negative charge areas and

resorption in positive charge areas. It also described the

action of prostaglandins through cell membrane and cAMP.

They described a diffusible product secreted by osteoblasts,

which believed to synchronize bone resorption and

formation, and named it as coupling factor.

Pathway 2

It illustrates the tissue inflammatory response by orthodontic

force and how it affects bone remodelling directly as well

as through formation of prostaglandins.

The role of inflammatory and proinflammatory mediators

and other substances due to tissue injury in orthodontic

tooth movement is well known nowadays. These include

prostaglandins, leukotrienes, neurotransmitters, cytokines,

nitric oxide, and hormones (Fig. 8.7).

1. Arachidonic acid metabolites- prostaglandins

and leukotrienes

Von Euler first discovered the compound (1934) in the

prostate fluid and hence the name. Prostaglandins are

important mediators of inflammation and are synthesized

Fii

ric

fr

le

Fi

cc

V{

to

tb

St

re

in


Fig. 8.6: Hypothetical model of the role of stress-induced bioelectric potentials in regulating alveolar bone remodelling during orthodontic tooth movement.

The force, F, applied to the labial surface of the lower incisor displaces the tooth in its socket, deforming the alveolar bone convexly towards the root at

the leading edge, and producing concavity towards the root at the trailing edge. Concave bone surfaces characterized by osteoblastic activity are

electronegative; convex bone surfaces characterized by osteoclastic activity are electropositive or electrically neutral (Reproduced with permission from

Am J Orthod. Zengo AN, Bassett CA, Pawluk RJ, Prountzos G. In vivo bioelectric potentials in the dentoalveolar complex. 1974; 66(2): 130-39)

performed tooth movement. Comparison of tooth movement

rates with controls suggested that tooth movement was

most decreased when prostaglandins and leukotrienes were

inhibited together; and tooth movement was also decreased

when prostaglandins and leukotrienes are individually

inhibited also. This gives evidence to the role of

prostaglandins and leukotrienes in tooth movement. Among

prostaglandins, PGE has most important role to play. The

binding of these molecules to cell membrane can activate

second messengers.

Fig. 8.7 : Crevicular fluid following application of an orthodontic force is

rich in inflammatory mediators

from arachidonic acid by cyclo-oxygenase pathway, whereas

leukotrienes are synthesized by lipo-oxygenase pathway.

Formation of various prostaglandins and leukotrienes from

cell membrane is a complex process and it happens through

various stages. Prostaglandins are important mediators for

tooth movement and clinical and animal studies suggested

that prostaglandins are important mediators of mechanical

stress, and they have an important role in stimulating bone

resorption.

An experimental study by Mohammed et al21 used PG

inhibitor, leukotriene inhibitor and both together, in rats and

2. Neurotransmitters

Neuropeptides are stored in nerve terminals within the PDL

and are released during mechanical strain. Neuropeptides

particularly substance P, vasoactive intestinal polypeptide

(VIP) and calcitonin gene related peptide (CGRP) have been

shown to affect bone cells directly or through their effects

on the vascular system.22

Neurotransmitters can act centrally also, which elicits

pain sensation. Direct action is on cells causing an

intracellular signalling. It has been demonstrated that

incubation of substance P with human PDL fibroblasts in

vitro significantly increased the concentration of cAMP in

the cells and of PGE2 in the medium within 1 minute.22 On

vascular system they produce vasodilatation and cause the

leucocytes to migrate out of the capillaries, further creating

formation of inflammatory substances. All these can produce

intracellular signalling by the production of second

messengers, i.e. cAMP.


3. Cytokines

Cytokines are small proteins with either paracrine or

endocrine functions involved in local inflammation or immune

regulation. Cytokines exhibit overlapping biological activities

and have multiple biological effects. In the early stage of

orthodontic tooth movement, an acute inflammatory

response characterized by the migration of leucocytes

occurs. This response suggests the presence of specific

chemotactic signals that may play a role in the mechanism

of bone remodelling, in particular in resorption. Cytokines

that were found to affect bone metabolism, and thereby

orthodontic tooth movement, include interleukin-1 (IL-1),

interleukin-2 (IL-2), interleukin-3 (IL-3), interleukin-6 (IL-6),

interleukin-8 (IL-8), tumour necrosis factor alpha (TNFa),

gamma interferon, and osteoclast differentiation factor.11

The most potent among these is IL-1. Its actions include

attracting leucocytes and stimulating fibroblasts, endothelial

cells, osteoclasts and osteoblasts to promote bone resorption

and inhibit bone formation. On application of orthodontic

force, IL-1 is released, which activates the release of

prostaglandins. Prostaglandins act on cells initiating second

messengers, followed by gene expression. Interleukins play

a significant role in differentiation and function of osteoclasts

under the influence of various regulatory genes23 (Fig. 8.8).

4. Nitric oxide 24,25

It was found that nitric oxide (NO) is produced from L-

arginine amino acid by nitric oxide synthase (NOS), which

is present in endothelial cells and other tissues. Three

distinct isoforms of NOS are: a neuronal form (nNOS), an

endothelial form (eNOS), and an inducible form (iNOS).

Both nNOS and eNOS are constitutively expressed and are

collectively referred to as constitutive NOS enzymes (eNOS).

It was found that iNOS plays a role in the response of

periodontal tissue to orthodontic force in rats.

1. Orthodontic forces may elevate NO production from

periodontal ligament fibroblasts, which then activate

guanylyl cyclase in periodontal ligament fibroblasts,

leading to an increased level of cGMP.

This second messenger in cell cytoplasm raises

lysosome membrane permeability, leading to exocytosis

of lysosome content resulting in resorption of organic

and mineral elements of bone.

2. Nitric oxide synthesizes prostaglandins by direct

activation of cyclo-oxygenase.

3. Nitric oxide influences the function of osteoclastic

differentiation and osteoblast function.

Mostafa et al’s model was a simplified version of the

various cellular changes accompanying the application of

force on a tooth. However, it left some unanswered questions

like:

• The lack of directional consideration (whether bone

resorption or deposition) in inflammatory response.

That is how resorption occurs in certain areas and

deposition in either areas, in response to inflammation.

Prostaglandins

i

nSignal molecule

iCell surface receptor

Adenylyl cyclase

Transcription of specific genes

i

t

Stromal cells/preosteoblast

i

• • IL-1

• TNFa

OPG

TGF(3

\

IL-6

M-CSF

IL-1

GM-CSF

RANKL

Ostecoclast progenitors

I ( ^ 1

Active 1 ► Increased

Osteoclasts bone

resorption

*

A r "

Fig. 8.8 ; A model of role of 1L-1G in the process of alveolar bone

resorption during orthodontic tooth movement

• The details of coupling factor and how these bone

bending signals internalized into various bone cells.

The model could not explain the molecular and genetic

regulation of precursor cell differentiation into

osteoblast and osteoclast.

Only inflammation and bioelectric signals were

considered. Recent pathway of direct mechanotransduction

of orthodontic force via cell membrane

receptors was not considered.

Mechanical strain as first messenger

Several mechanisms have been suggested in which cells

can detect mechanical stimulus and react in response. It can

be due to: 6,26,27 *

Section Biology of orthodontic tooth movement 91

^^^L ^S tra in sensitive ion channels and shear stress receptors in

cell membrane. Stretch activated calcium and potassium

channels are present in the plasma membrane of cells.

Channel gating may be caused by direct mechanical

perturbation or secondarily by the activation of stretch

sensitive phospholipase C or D. They respond to mechanical

strain by causing in and out movement of ions, creating

changes in the electric potential. These changes enable the

signal to be propagated intracellularly.

Signal transduction by integrins and focal adhesions. The

cytoskeleton presents a number of possibilities for

transducing mechanical forces acting on cells and/or their

adjacent matrices.

Three main components of the cytoskeleton are

microtubules, microfilaments, and intermediate filaments.

Microfilaments are the best to detect these changes.

They include the major protein actin and other proteins

myosin, tropomyosin, vinculin and talin. Integrins are cell

surface receptors that mediate cell to cell attachment or cell

attachment to extracellular matrix molecules such as

fibronectin, laminin and collagen. Integrins form specialized

sites of cell attachment called ‘focal adhesions’. Focal

adhesions are sites where integrins link actin associated

cytoskeletal proteins and signalling molecules such as FAK

and paxillin to structural molecules of extracellular matrix

such as fibronectin, laminin and collagen. This firm

attachment enables mechanical deformation of the cell to be

recognized by the cytoskeleton and intracellular signalling

pathways, mechanosensitive ion channels, phospholipids

and G-protein coupled receptors in the plasm a

membrane.28The cytoskeletal reorganization and other

events will cause intracellular signalling, gene transcription

and desired cellular differentiation and function for tooth

movement.

Current view of orthodontic tooth movement

There is a growing body of information that explains how

the various events occurring in the periodontium and bone

following orthodontic force leads to tooth movement and

how various stimuli affect cells to become bone resorbing

or bone forming cells.

Application of orthodontic force evokes a cellular

response by the formation of primary stimulus or first

messenger. Mainly three pathways of events follow

orthodontic force application which can evoke a primary

stimulus on cells. These include:

• Tissue injury and inflammation

• Bone bending and bioelectric response

• Direct alteration of cell membrane through

mechanotransduction.

Inflammation is the response to tissue pressure and

injury in periodontium following orthodontic force. Various

mflammatory mediators like cytokines are released and

these can activate the formation of arachidonic acid

metabolites. Injury to nerve endings releases various

neuropeptides which also evoke inflammatory response

and pain. The binding of these signal molecules to cell

membrane receptors may alter cell activity through the

formation of second messengers (Figs. 8.9, 8.10, 8.11).

Two main second-messenger systems are: 29

• Cyclic AMP (cAMP) pathway

• Phosphoinositide pathway.

cAMP pathway involves fluxes of ions, such as Ca2+,

Mg2+ and inorganic phosphate as well as activation of the

membrane-bound enzymes adenylate cyclase and guanylate

cyclase. Within the membrane, these enzymes act upon

their respective substrates, adenosine triphosphate (ATP)

and guanosine triphosphate (GTP), to produce cyclic AMP

and cyclic GMP. These latter substances, together with

Ca2+, are considered to be the intracellular ‘second

messengers9which mediate the effects of external stimuli on

their target cells.

Fig. 8.9: Diagram of integrin receptors and focal adhesions. Focal

adhesions are sites where integrins link actin-associated cytoskeletal

proteins (talin, vinculin, a-actinin) and signalling molecules such as FAK

and paxillin to the structural macromolecules of the extracellular matrix.

Firm attachment at focal adhesions enables mechanical deformation of

the cell to be recognized by (1) the cytoskeleton and intracellular signalling

pathways and (2) mechanosensitive ion channels, phospholipids, and G

protein coupled receptors in the plasma membrane. AC, adenylate

cyclase; FAK, focal adhesion kinase; PKA, protein kinase A; R, G-

protein-coupled receptor. (Reproduced with permission from Eur J Orthod.

Meikle M C. The tissue, cellular and molecular regulation of orthodontic

tooth movement: 100 years after Carl Sandstedt. 2006; 28: 221-40)


Orthodontic force

▼

Bone bending

Bioelectric response

Tissue injury and inflammation

i

Migration of lymphocytes,

monocytes, macrophages

Mechanical strain in

cells through integrins

and focal adhesion,

strain sensitive ion

channels & shear

stress receptors

Release of neurotransmitters

Tumour necrosis ---- >

factors

Interferons---- ^

Release of pro-inflammatory

mediators in the paracrine

area

Interleukins

Growth factors

Enzymes

Altered cell membrane

potential

- > ---------------------------

v

Release of

prostaglandins and leukotrienes

cAMP second messenger pathway

influx of ions Ca2+’, Mg2+and

inorganic phosphate.

cAMP, cGMP, Ca2+act as second messengers

Phosphoinositide second

messenger pathway

Signals internalized

Transcription of immediate early genes (c-fos, c-jun)

t OPG

Cell differentiation into

osteoclasts and osteoblasts

influenced greatly by

RANK, RANKL, OPG

and other factors

t RANK

RANKL activity

Increased osteoclastic activity

Bone resorption

More osteoblasts,

Less osteoclastic activity

0 ©

Bone deposition

Fig. 8.10: Summary of the biological process of orthodontic tooth movement

pi

Section I: Biology of orthodontic tooth movement ■ 93

Osteoclast

precursor

RANKL

M-CSF

Osteoclast

RANKL

Activated

osteoclast

M-CSF

RANKL

1

fusion

1

activation

1

1,25(OH)2D3

4 -

Osteoblast

stromal cell

I

PTH

IL-1

RANKL receptor

| RANKL

dVPG

yOg M-CSF receptor

M-CSF

Fig. 8.11: Roles of receptor activator of nuclear factor k B ligand (RANKL), osteoprotegerin (OPG), and M-CSF in the regulation of osteoclast maturation

and function by osteoblasts/stromal cells. RANKL is found both as a transmembrane receptor and as a soluble cleaved form; OPG has been found

only in secreted form. RANKL and OPG constitute a ligand - receptor system that directly regulates osteoclast differentiation. OPG acts as an inhibitor

of osteoclastogenesis by competing with RANKL for the membrane receptor. M-CSF (CSF-1) acts directly on osteoclast precursor cells to control

their proliferation and differentiation. Stimulators of bone resorption such as 1,25(OH)2 vitamin D3, parathyroid hormone, and interleukin-1 increase

osteoclast formation by stimulating the expression of RANKL by osteoblasts/stromal cells. (Reproduced with permission from Eur J Orthod. Meikle

M C. The tissue, cellular and molecular regulation of orthodontic tooth movement: 100 years after Carl Sandstedt. 2006; 28: 221-40)

In support of the second-messenger pathway involvement

in orthodontic tooth movement, Davidovitch30 reported that

cAMP concentrations were significantly higher in alveolar

bone extracts taken from orthodontically treated cats as

opposed to unstressed alveolar bone samples. Elevations

in cAMP concentrations around orthodontically treated

teeth may result from an increase in the number of active

cells in the periodontal membrane and bone marrow. This

was shown to be the case where mechanically induced

bone remodelling was occurring. The experimental

observations discussed above imply that cAMP may act as

a chemical, second-stage mediator in response to some

hypothetical first-stage chemical effectors present in the

microenvironment. This mediator was postulated to have

the ability to stimulate both bone and collagen resorption.

When an orthodontic appliance is activated, forces

delivered to the tooth are transmitted to all the tissues near

the point of force application. These forces bend bone,

tooth and the solid structures of the PDL. Bone bending

can lead to stress-related bioelectric effects like piezoelectric

effects and streamline potentials.3132 In electronegative

regions, bone formation occurs, whereas bone resorption

Predominates in electropositive areas. Various in-vitro and

m-vivo studies have indicated that areas that have been

Ascribed as predominantly osteoblastic were routinely

electronegative, and areas of positivity or electrical neutrality

Were characterized by elevated osteoclast activity.

Accelerated orthodontic tooth movement resulted when

exogenous electric current was administered in conjunction

with orthodontic forces.33 Cellular activities were enhanced

in the periodontal membranes in response to electrical

stimulation. This suggests that the piezoelectric response

propagated by bone bending incident to orthodontic forces

application can affect the charge of cell membranes and of

macromolecules in the neighbourhood and will act as first

messenger.

Mechanical stress of periodontal ligament produces

compression or elongation of cells and extracellular matrix.

These changes evoke intracellular response through different

mechanisms. Strain sensitive ion channels and shear stress

receptors present in plasma membrane interact with the

mechanical stimulus to cause in and out movement of ions,

creating changes in the electric potential. Mechanical

stimulus is transduced further by the presence of integrins

and focal adhesions. Extracellular matrix/integrin activation

and cytoskeletal reorganization can create intracellular

signal. Once detected, signal is internalized and it is

potentiated in cytosol by generation of second messengers

and protein kinases.

Immediate early genes (IEGs) expression

They are among the earliest responses that can be measured

at the transcription level. The transcription of IEGs (c-fos,

c-jun, and egr-1) is increased, when they are*exposed to

L


cytokines, growth factors or mechanical stimulation. Protein

products from the c-fos and c-jun genes form a heterodimeric

complex named activator protein-1 (AP-1). AP-1 is a

transcription factor; it binds to the promoter region of gene

and then modulates its activity.

Genetic and molecular regulation determines the formation

of osteoclast and osteoblast from precursor cells. Several

genes are involved in the differentiation and functioning of

these cells. Osteoblast differentiates from mesenchymal

stem cells and osteoclast differentiates from haematopoietic

cells. Bone morphogenetic proteins (BMP), Cbfa 1 gene,

GM-CSF and M-CSF are all involved in their differentiation,

development and function.

One of the most important regulatory mechanisms is the

RANK-RANKL-OPG axis.28,34 Bone remodelling and

osteoclast differentiation is controlled by a balance between

RANK-RANKL (receptor activator of nuclear factor-Kappa

ligand) binding and osteoprotegrin (OPG) production.

RANKL is a downstream regulator of osteoclast formation

and activation, through which many hormones and

cytokines produce their osteoresorptive effect. OPG is a

decoy receptor produced by osteoblastic cells, which

compete with RANK for RANKL binding. The biologic

effects of OPG on bone cells include inhibition of terminal

stages of osteoclast differentiation, suppression of

activation of matrix osteoclasts, and induction of apoptosis22

(Fig 8.11). Periodontal ligament and alveolar bone cells

provide hundreds of genes and thousands of proteins for

orthodontic tooth movement. Bone adaptation to orthodontic

force depends upon normal osteoblast and osteoclast genes

that correctly express needed proteins in adequate amounts

at the right times and places. Interpatient variation in

mechanobiological response is most likely due to differences

in bone and PDL cell populations, genomes, and protein

expression patterns.

Pain and mobility with orthodontic appliances

Orthodontic appliances usually cause pain and slight

mobility of teeth. Tooth movement is associated with

remodelling of the adjacent bone, reorganization of the PDL

and so mobility occurs with orthodontic appliance. The

heavier is the force, greater is the mobility.

Mobility associated with orthodontic appliances will

correct itself without any permanent damage. Pain associated

with orthodontic tooth movement is due to the compression

of PDL and associated tissue damage. Heavy forces produce

immediate pain after activation. Therefore, orthodontic forces

should be kept light to reduce pain. Light forces produce

little discomfort immediately after appliance activation. Mild

aching pain in teeth and tooth sensitivity to pressure is

commonly noted for the first 2-4 days.7 This can be reduced

by asking the patient to engage in repetitive chewing of

gum for the first 8 hours after activation. This will increase

the blood flow and earlier removal of metabolic products

that generate pain.

Drugs are used to control pain associated with tooth

movement. Non-steroidal anti-inflammatory drugs (NSAIDs)

inhibit prostaglandins and can thus interfere with tooth

movement. Acetaminophen is preferred to normal NSAIDs

and recent Cox-2 selective inhibitors like naproxen and

nabumetone are found to be effective without having much

influence on tooth movement.35,36,37

Several systemically administered drugs have influence

on the biology of tooth movement.38 Drugs with known

notable influences include PG analogues which can promote

faster tooth movement, bisphosphonates that prevent

resorption process. Orthodontic tooth movement should be

carefully monitored in patients with steroid therapy to

avoid root resorption.

Summary

Orthodontic tooth movement consequent to application of

force is outcome of complex chain of events, eventually

leading to bone resorption and bone formation. What

signals the ‘cells’ in periodontium to perceive orthodontic

force to transform into bone forming and bone resorbing

cells is not yet fully understood. Future research in the field

of molecular biology is expected to unfold many more

secretes of this phenomenon.

REFERENCES

1. Burstone CJ. The biomechanics of tooth movement. In:

Kraus BS, Riedel RA (Eds). Vistas in Orthodontics.

Philadelphia, Lea and Febiger; 1962.

2. Pilon JJ, Kuijpers-Jagtman AM, Maltha JC. Magnitude of

orthodontic forces and rate of bodily tooth movement: an

experimental study. Am J Orthod Dentofac Orthop 1996;

110(1): 16-23.

3. Schwarz AM. Tissue changes incident to orthodontic tooth

movement. Int J Orthod 1932; 18: 331-52.

4. Von Bohl M, Maltha JC, Von Den Hoff JW, Kuijpers-

Jagtman AM. Focal hyalinization during experimental tooth

movement in beagle dogs. Am J Orthod Dentofac Orthop

2004; 125(5): 615-23.

5. Von Bohl M, Maltha JC, Von Den Hoff H, Kuijpers-Jagtman

AM. Changes in the periodontal ligament after experimental

tooth movement using high and low continuous forces in

beagle dogs. Angle Orthod 2004; 74(1): 16-25.

6. Krishnan V, Davidovitch Z. Cellular, molecular, and tissuelevel

reactions to orthodontic force. Am J Orthod Dentofac

Orthop 2006; 129: 469e.l-460e.32.

7. Proffit WR: Contemporary Orthodontics (3rd edn). St Louis,

Mosby, 2000; 311-12.

8. Sandstedt C. Einge Beitrage zur theorie der Zahnregulierung.

Nordisk Tandlakare Tidskrift 1904; 5: 236-256. Taken from

Meikle M C. The tissue, cellular and molecular regulation of

orthodontic tooth movement: 100 years after Carl Sandstedt.

Eur J Orthod 2006; 28: 28-40.

9. Sandstedt C. Einige Beitrage zur theorie der Zahnregulierung.

Nordisk Tandlakare Tidskrift 1905; 6:1-25, 141-168. Taken

from Meikle M C. The tissue, cellular and molecular regulation

of orthodontic tooth movement: 100 years after Carl Sandstedt.

Eur J Orthod 2006; 28: 221-240.


10. Oppenheim A. Tissue changes, particularly of the bone,

incident to tooth movement. Am Orthod 1911; 3: 57-67.

11. Oppenheim A. Bone changes during tooth movement.

International Journal of Orthodontia, Oral surgery and

Radiography 1930; 16: 535-51.

12. Oppenheim A. Biologic orthodontic theory and reality. A

theoretical and practical treatise. Angle Orthodontist 1935; 5:

159-211.

13. Oppenheim A. Biologic orthodontic theory and practice.

Angle Orthodontist 1936; 6:5-38, 69-116, 153-83.

14. Reitan K. Some factors determining the evaluation of force in

orthodontics. Am J Orthod 1957; 43: 32-45.

15. Reitan K. Effects of force magnitude and direction of tooth

movement on different alveolar types. Angle Orthodontist

1964; 34: 244-55.

16. Reitan K. Tissue arrangement during retention of

orthodontically rotated teeth. Angle Orthodontist 1959; 29:

105-13.

17. Rygh R Ultrastructural cellular reactions in pressure zones of

rat molar periodontium incident to orthodontic tooth

movement. Acta Odontol. Scand. 1972; 30(5): 575-93.

18. Brudvik P, Rygh R Root resorption beneath the main

hyalinized zone. Eur J Orthod 1994; 16(4): 249-63.

19. Baumrind. S. A reconsideration of the propriety of the

pressure tension hypothesis. Am J Orthod 1969; 55(1): 12-

22.

20. Mostafa YA, Weaks-Dybrig M, Osdoby R Orchestration of

tooth movement. Am J Orthod 1983; 83(3): 245-50.

21. Mohammed AH, Tatakis DN, Dziak R. Leukotrienes in

orthodontic tooth movement. Am J Orthod Dentofac Orthop

1989; 95(3): 231-37.

22. Davidovitch Z, Nicolay OF, Ngan PW, Shanfeld JL.

Neurotransmitters, cytokines and the control of alveolar bone

remodeling in orthodontics. Dent Clin North Am 1988; 32(3):

411-35.

23. Kapoor P, Kharbanda OP, Duggal R, Rajeswari MR, et al. A

comparative evaluation of interleukin 1-beta in GCF during

canine distraction and retraction, under preparation for

publication.

24. Yoo SK, Warita H, Soma K. Duration of orthodontic force

affecting initial response of nitric oxide synthase in rat

periodontal ligament. J Med Dent Sci 2004; 51(1): 83-88.

25. Akin E, Gurton AU, Olmez H. Effects of nitric oxide in

orthodontic tooth movement in rats. Am J Orthod Dentofac

Orthop 2004; 126(5): 608-14.

26. Sandy JR. Signal transduction. Br J Orthod 1998; 25(4): 269-74.

27. Sandy JR, Farndalo RW, Meikle MC. Recent advances in

understanding mechanically induced bone remodeling and

their relevance to orthodontic therapy and practice. Am J

Orthod Dentofac Orthop 1993; 103(3): 212-22.

28. Meikle M C. The tissue, cellular and molecular regulation of

orthodontic tooth movement: 100 years after Carl Sandstedt.

Eur J Orthod 2006; 28: 221-40.

29. Sandy JR, Farndale RW. Second messengers: regulators of

mechanically induced tissue remodeling. Eur J Orthod 1991;

13(4): 271-78.

30. Davidovitch Z, Shanfeld JL. Cyclic AMP levels in alveolar

bone of orthodontically treated cats. Arch Oral Biol 1975;

20(9): 567-74.

31. Epker BN, Frost HM. Correlation of bone resorption and

formation with the physical behavior of loaded bone. J Dent

Res 1965; 44: 33-41.

32. Zengo AN, Bassett CA, Pawluk RJ, Prountzos G. In vivo

bioelectric potentials in the dentoalveolar complex. Am J

Orthod 1974; 66(2): 130-39.

33. Davidovitch Z, Finkelson MD, Steigman S, Shanfeld JL,

Montgomery PC, Korostaff E. Electric currents, bone

remodeling and orthodontic tooth movement. II—increase in

rate of tooth movement and periodontal cyclic nucleotide

levels by combined force and electric current. Am J Orthod

1980; 77(1): 33-47.

34. Drugarin D, Drugarin M, Negru S, Cioace R. RANK-RANKL/

OPG molecular complex—control factors in bone remodeling.

TMJ 2003; 53: 296-302.

35. Roche JJ, Cisneros GJ, Ais G. The effect of acetaminophen

on tooth movement in rabbits. Angle Orthod 1997; 67(3):

231-36.

36. Polat O, Karaman AI, Durmus E. Effects of preoperative

ibuprofen and naproxen sodium on orthodontic pain. Angle

Orthod 2005; 75(5): 691-96.

37. Villa PA, Oberti G, Moncada CA, Vasseur O, Jaramillo A,

Tobon D, Agudelo JA. Pulp-dentine complex changes and

root resorption during intrusive orthodontic tooth movement

in patients prescribed nabumetone. J Endod 2005; 31: 61-66.

38. Krishnan V, Davidovitch Z. The effect of drugs on orthodontic

tooth movement. Orthod Craniofac Res, 2006; 9(4): 163-71.

___ |M IM J IJP j |l J | l | _ 1 ' *?

~ — -

; , ^ . r *.

SECTION II

Orthodontic Diagnosis

Chatper 9 Clinical evaluation

Chapter 10 Analysis of diagnostic records

Chapter 11 Introduction to cephalometrics: historical perspectives and methods

Chapter 12 Downs’analysis

Chapter 13 Steiner’s analysis

Chapter 14 Tweed’s analysis

Chapter 15 Ricketts’ analysis

Chapter 16 Vertical linear dimensions of face and Sassouni analysis

Chapter 17 Soft tissue analysis of face

Chapter 18 PA cephalometric analysis

Chapter 19 Computerised and digital cephalometrics

Chapter 20 Errors in cephalometrics

OVERVIEW

Patient history

Clinical assessment of a child with a potential for malocclusion

Clinical assessment of a child with developing or established malocclusion

Dynamics of smile and its orthodontic implications

Functional examination including TMJ

Speech and malocclusion

Clinical examination of child for suspected deleterious habit(s)

Clinical assessment of an adult seeking orthodontic treatment

Intraoral examination

Summary

Patient history

Adetailed social, personal, medical and dental history

should precede any clinical examination. It is

important to know the developmental milestones of

a young child. Of great importance is the physical

development of the child in relation to his/her chronological

age, skeletal age and dental maturation. The child’s social

and personal history aims to elicit concern for the dental

and orthodontic care, number of siblings in the family, any

history of orthodontic treatment of parents or siblings,

socioeconomic status, and attitude.

The medical history is taken to rule out any systemic or

l°cal disease, which may adversely affect the growth of

hones, craniofacial structures, muscles and tissues

niorphology of dentition and/or occlusion. History is also

helpful in identifying environmental factors related to

nutrition, growth status, dental/oral health, caries, breathing

Pattern and deleterious habits which might influence the

development of occlusion.

Family history of orthodontic treatment and evaluation

°f parents, siblings for their facial forms, occlusion and

malocclusion may give clues on the child’s facial form when

he/she grows into an adult. The orthodontic assessment of

a child should proceed with evaluation of parents/ siblings.

History of a familial disease which may interfere with normal

development of face, teeth and jaws should be elicited.

Facial forms and malocclusions that have a strong familial

tendency are:

Severe deep bite with class II division 2 pattern

Skeletal open bite

Mandibular prognathism

Bimaxillary protrusion

Mandibular retrognathism

Severe crowding/spacing

Median diastema.

Common problems of familial origin affecting face and

jaws:

• Cleft lip and/or palate

• Ectodermal dysplasia

• Cherubism

99

Common problems of familial origin affecting the dentition:

• Peg-shaped or missing lateral incisors

• Partial hypodontia of premolars

• Supernumerary teeth

• Macro or microdontia.

History of orthodontic treatment in either of parents

should warrant for a potential malocclusion in the offspring

under examination.

Clinical assessment of a child

with a potential for malocclusion

An orthodontist may often be encountered with a common

question by the parents, “Is my child going to have braces

when he/she grows up?”

In a clinical setting, this is a rather simple question asked

by the parents but one that is most difficult to answer even

by a very experienced clinician. To be precise, such a

question can only be answered after obtaining a detailed

history and clinical examination of the child. It is of utmost

importance that the findings elicited on history and clinical

examination be supplemented with diagnostic investigations

to reach at a definitive conclusion. However, in certain

situations where the child is still growing and his/her

occlusion is not fully established, one may not be able to

give a definitive negative answer. In such a situation, you

may like to wait and watch for the occlusion to establish

and the deformity to develop to its fullest extent. Clinical

examination is a critical component of diagnosis. The clinical

assessment of a child with a potential for malocclusion can

be broadly grouped according to the development stages

of the child, his/her face and dentition.

Orthodontic evaluation at any stage of a child’s growth

involves four important aspects:

• Physical development and skeletal growth

• Development of face and jaws

• Development of dentition and occlusion

• Occlusal relationships in centric occlusion and function.

Looking for signs of potential malocclusion in a

three-year-old child: characteristics of face and

dentition at 3-6 years

A newborn child’s face appears flat at birth with the head

occupying a considerably larger dimension compared to the

face and a rather recessive chin. By three years, the child

has a head closer to that of adult size and thereafter the

changes in head are minimal. In contrast, the face grows

rapidly in all three dimensions, i.e. in width (transverse),

length (sagittal) and in height (vertical) between the ages

of 3-6 years. The facial convexity is reduced, while chin is

trying to catch up with the maxilla. This is largely because

condylar growth exceeds that of vertical descent of maxilla,

and therefore mandibular plane does not open. A

cephalogram will show a rather large ANB (close to 5°)

compared to adults (2°), and therefore some facial convexity

is acceptable.

Normally, by 36 months all deciduous teeth have erupted

and deciduous occlusion is fully established. The deciduous

incisors are more upright compared to their permanent

successors and their crowns appear rather wide due to the

relatively short crown height. Overjet and overbite are

minimal. The deciduous molars show a mesial step or a

flush terminal plane. Often spaces of about 2-3 mm are seen

mesial to the deciduous canines in the maxilla and distal to

the deciduous canines in the mandible. These spaces are

known as primate spaces (Fig. 9.1A,B).

A. Primate spaces

B. Spaced deciduous dentition: Normal occlusion

Fig. 9.1: Primate spaces: These are often found distal to deciduous lateral in the maxilla and deciduous canine in the mandible. First described by

Baume 1950

L

L

Section II: Clinical evaluation ■ 101

Fig. 9.2 : Severe retrognathia: Two children with severe retrognathic lower jaw. Such a situation warrants detailed medical examination by the

paediatrician. Pierre Robin syndrome is a common cause of such a clinical presentation. Pierre Robin sequence is associated with cleft palate, mandibular

retrognathia, and glossoptosis. This condition may occur as an isolated malformation complex or part of a broader pattern of systemic abnormalities

Absence of primate spaces, severe proclination or a

large overjet in deciduous occlusion are rather uncommon

features and should be considered as a potential for future

malocclusion.

A reverse overjet in the deciduous dentition stage should

be viewed with a suspicion for the habitual forward posture

of the mandible or a skeletal class III malocclusion.

A child’s face should be examined from the front as well

as from a lateral profile view. A very young child may not

permit a formal evaluation, which can be carried out while

he/she is kept busy with toys and play.

The following characteristics of the facial form, dentition

and/or presence of environmental aetiological factors should

alert for a possible need for detailed examination/ need for

further observation in the future interception for

malocclusion.

Gross abnormalities of face form (Fig. 9.2)

Severe retrognathia (Table 9.1)

Small and backwardly placed chin could exist in isolation or

be a part of a syndrome. Micrognathia is characterized by

mandibular hypoplasia causing a receded chin. It is found

in about 1 per 1,000 births. Common defects associated

with small mandibles are genetic syndromes such as

Pierre Robin and Treacher Collins syndromes. Trauma during

birth like injury by delivery forceps can cause injury to the

TM joint and cause delayed/impaired mandibular growth.

Pierre Robin syndrome. This anomalad includes severe

micrognathia, glossoptosis and posterior cleft palate or an

arched palate. It may be a sporadic isolated finding in about

40% of cases or it may be associated with other anomalies

or with recognized genetic and non-genetic syndromes.

The cleft of the soft palate along with a low and backward

positioned tongue may cause difficulty in breathing and

cyanosis in a newborn. If cyanosis or respiratory problems

persist in a newborn, tracheostomy or surgery to fix the

tongue in a forward position may be required. The growth

of the mandible usually catches up as the child grows.

Treacher Collins syndrome. Important features of the

Treacher Collins syndrome are: a facial appearance

resembling that of a bird or fish, missing malar bone

prominence; eyes have a slant with palpebral fissures

inclined downward. Radiographically, characteristic obliquity

L Table 9.1: Syndromes affecting face and jaws associated with mandibular deficiency and class II malocclusion

Condition Features Aetiology

Hemifacial microsomia

(Goldenhar syndrome)

Pierre Robin complex

Treacher Collins syndrome

Unilateral dysplasia of the ear, hypoplasia of mandibular

ramus, cardiac and renal abnormalities

Micrognathia; cleft palate and glossoptosis. This condition

may occur as an isolated malformation complex or part of a

broader pattern of abnormalities

Dysplastic low set ears; downslanting palpebral fissures;

micrognathia

Most cases sporadic; few familial

instances; pedigrees compatible with

autosomal dominant and autosomal

recessive transmissions

Heterogeneous

Genetic/autosomal dominant

------------------------------------ i----------------------


of orbit, small malar bones and very small maxillary antrum

are seen.

Down’s syndrome. A prominent chin with hypoplastic maxilla

can be a feature of Down’s syndrome. Down’s syndrome is

a group of abnormalities that occur in children who are born

with an extra (third) copy of chromosome number 21 socalled

trisomy 21 in their cells. It is a relatively rest. There

would be a tilt of the occlusal plane, which is higher on the

affected side. Such cases can be sometimes mistaken for

agenesis of the condyle (Fig. 9.3).

Facial asymmetry, with large mandibular length can be a

feature of class III malocclusion with or without a small

maxilla. Congenital hyperplasia of the face is recognized at

birth or soon afterward, establishing an important

differentiation from the unilateral hyperplasia of the condyle,

which is not evident till the age of 10 (Fig. 9.4) (Table 9.2,

9.3).

Cleft lip and palate, especially the operated cases of

complete unilateral cleft lip and bilateral cleft lip may show

certain amount of asymmetry with a large mandible and

smaller transverse width of the maxilla.

An anterior open bite and superior protrusion are often

associated with prolonged thumb sucking or macroglossia

(large tongue). Primary macroglossia is a rare entity.

Macroglossia may be secondary to systemic diseases, the

commonest cause being amyloidosis. A large overjet is

usually a consequence of prolonged thumb sucking with

the wrist resting on the chin.

Primate spaces (Figs. 9.5, 9.6)

Humans have a continuous tooth row (no spaces) in the

adult dentition. In about half of the children, however, there

Fig. 9.3 : A child facial asymmetry/deviated chin with no other abnormality

should be suspected for unilateral ankylosis of the condyle. The ankylosis

side appears normal while the unaffected side shows deviations

are diastemata in the deciduous dentition. These correspond

in location to the ape diastemata. The spaces in children are

known in dental literature as ‘primate spaces.’ In other

words, primate spaces are naturally occurring spaces in the

‘normal’ primary dentition, existing distal to the primary

mandibular canine and mesial to the primary maxillary canine.

These were first described in detail by Baume (1950)13 and

later by Foster and others.47 Primate spaces occur in about

50% of children. Facal-Garcia (2002)5 recorded primate

spaces in 3-year old Caucasians and found that the

prevalence of spacing was high in the primary dentition, it

was more frequent in males than in females. The presence

or absence of spacing was not directly related to occlusion

except in cases of posterior crossbite, where it was less

frequent, and open bites, in which spaces appeared more

often than usual. Ohno et al (1999)6,7 recorded primate

i

i

F

te

a

Fig. 9.4 : Facial asymmetry: A boy reported with chief complaints of gradually increasing asymmetry of the face (ABC). He had unilateral condylar

hyperplasia of the left condyle which gradually caused a shift of the lower dentition and the midline to the right side

Section II: Clinical evaluation 103

Table 9.2: Syndromes affecting face and jaws where midfacial deficiency is a major feature could present as class III

relationship


Apert’s syndrome

Crouzon’s syndrome

Achondroplasia

Craniosynostosis; midfacial deficiency; proptosis;

hypertelorism; downslanting palpebral fissures;

symmetric syndactyly of the hands and feet

Craniosynostosis; maxillary hypoplasia accompanied

by relative mandibular prognathism; shallow orbits; proptosis

Short-limbed dwarfism; enlarged head; depressed

nasal bridge; lordosis; high palate




I Table 9.3: Syndromes associated with mandibular prognathism

j


Basal cell naevus

(Gorlin) syndrome

Klinefelter’s syndrome

Macrocephaly; frontal and parietal bossing; prognathism;

multiple jaw cysts; multiple basal cell carcinomas; bifid ribs

Mandibular prognathism; skeletal disproportion;

gynaecomastia; small testes


Commonly XXY karyotype but XXXY

and XXXXY also occur

Osteogenesis imperfecta Fragile bones; blue sclera; deafness; mandibular prognathism Autosomal dominant (common type)

Fig. 9.5 : Features of deciduous dentition at the age of 6 years. Spacing in the anterior dentition, edge to edge bite, and attrition of the deciduous

teeth are indicators of good alveolar growth and sagittal forward repositioning of the mandible. Such a clinical situation often leads to eruption of normal

alignment of permanent teeth and possibly a class I molar relation

Fig. 9.6: Deciduous dentition and occlusion at 6 years. The dentition has attrition and edge to edge bite. Note the mandibular central incisors have

erupted without any crowding or rotations. The molars are in class I occlusion relation, a sign of early mesial shift which in this case seems to be

facilitated due to the to forward shift of mandible


spaces and interdental spaces in the deciduous dentition

by sex and arch in Indian children from Delhi aged 5-7 years

and the relationship between these spaces and other

morphological characteristics of the deciduous dental

arches. The results were as follows:

• There was a wide variation in the pattern of the

interdental spacing.

• Most common areas of spacing were mesial to the

maxillary primary canine (primate spaces) and mesial to

the mandibular primary canine (developmental spaces)

for all ages.

• The mandibular primate spaces were considerably less

frequent than the maxillary ones.

A lack of primate spacing can be one of the indicators

of the insufficient growth in the dental arches and hence a

tendency for the crowded dentition (Fig. 9.7).

Edge to edge incisor relation/negative overjet

An edge to edge bite during primary dentition may be

habitual or functional. Such an incisor relationship warrants

for a detailed clinical examination to rule out functional

forward shift from a true mandibular excess. It also

necessitates the examination of morphology of mandible

and chin for any signs of true mandibular prognathism. Any

case of class III malocclusion should also be examined for

deficiency of midface, which is not an uncommon finding.

Further evaluation of the parents and siblings is required

for any signs of class III skeletal/dental relationship. Either

parents or a family member may have a class III pattern of

variable severity, i.e. from faint traces of prognathism in

dentition/occlusion in sagittal plane to a well-established

mandibular prognathism.

Posterior crossbite

A posterior crossbite of a single tooth should not be

viewed with suspicion towards incipient malocclusion. A

unilateral posterior crossbite of two or more teeth may be

associated with some amount of deviation of lower jaw to

the affected side, and may show some degree of midline

shift. Unilateral posterior crossbite may be the outcome of

a narrow maxilla associated with prolonged thumb or finger

sucking. Mouth breathing can also cause narrow maxilla

and thereby premature contacts with the mandibular teeth.

The lower jaw tends to avoid the prematurities resulting in

a convenience swing of the mandible occluding in unilateral

crossbite.

Signs of potential malocclusion just before

eruption of permanent incisors

Active growth of jaws coupled with attrition of deciduous

teeth brings about following alterations in occlusion. The

crowns of the deciduous incisors may further shorten

Fig. 9.7: A young girl of 3-year-old with deciduous denitition and occlusion. She has poor oral hygiene, there is presence of visible plaque, and signs

of cervical caries in the lower left canine. She has deep bite and lack of spacing in the dentition. Such an occlusion has greater potential for

developmental malocclusion. High caries susceptibility, if not controlled, will lead to carious teeth if left untreated further aggravate the existing situation

thereby worsening the width to height ratio of deciduous

crowns. The deciduous incisor crowns may appear broad

and short. There may be edge-to-edge bite of incisors, and

lack of overjet, which also brings about a mesial step

relationship of the deciduous molars. The anterior dentition

is spaced. Lack of spacing in the deciduous dentition,

presence of over jet and a straight terminal plane are

indicators of incipient malocclusion. Children with such

an occlusiqn need to be under observation for the potential

of developing class II malocclusion.

There are several factors which could be linked to

predict an optimal permanent dentition from an existing

primary dentition. A number of naturally occurring indicators

must be clinically looked for, such as tooth spacing which

includes primate spaces and spaced dentition, terminal

plane relationship of the deciduous molars (i.e. straight/

mesial step/ distal step), leeway space and incisor liability.

According to Baume, type 1 primary dentitions with open

spacing between the teeth lead to a normal alignment of

permanent dentition more frequently than type 2 dentitions

with closed contacts between the teeth.

It has been reported in a long-term study by Bishara et

al8that straight terminal plane relationship may change into

a class I molar relation in favourable growth pattern cases

or a class II in children with unfavourable growth while

mesial step terminal plane is the most favourable for

developing a normal dental class I relationship in the

permanent dentition. Distal step relationship is an indicator

of future class II molar relationship.

Leeway space amounts to 0.9 mm per side in the maxilla

and 1.7 mm per side in the mandible which plays a significant

role in the development of the Class I molar relation.

Additional space is needed to accommodate the permanent

incisors when compared with the primary incisors and this

is termed as incisor liability. It averages 7.6 mm for the

maxilla and 6 mm for the mandible.

Leeway space is described as excess archlength available

consequent to combined smaller mesiodistal widths of

canines and premolars to their deciduous counterparts.

Clinical assessment of a child

with developing or established

malocclusion________________

Orthodontic assessment of a child during mixed

dentition stage

% the age of 9-10 years, growth of the skull and maxilla is

nearly complete. However, the mandible continues to grow

m length in a downward and forward direction till the

completion of puberty. The maxillary dentition accordingly

descends, to catch up with the mandible while the

mandibular teeth erupt to maintain an occlusion relationship.

Face should be evaluated from both frontal and lateral

aspects. Lateral aspect reveals the profile (convex/straight/

concave) whereas the frontal view indicates the facial form

(broad/oval/thin). In addition, it should also be assessed

for the vertical proportions by measuring the anterior and

posterior facial heights and their relative proportions to

each other. An increase in the anterior lower face height

should be confirmed with the steepness of the mandibular

plane.

Accordingly, the face may be categorized into normal,

vertical or horizontal types. Frontal examination should

include an assessment of the shape of the nose, the size of

the nostrils, a nose tip, and nasal bridge. Lips are examined

at rest and during smiling. The child should be carefully

observed for any deviations and midline shifts during jaw

closure and at rest.

Dentition and occlusion

Rapid changes take place in the face and dentition with the

eruption of permanent first molars (6 years molars) and

incisors. The orchestrated events of shedding of deciduous

dentition, eruption of permanent teeth, growth of the

underlying skeletal bases, maturation and function of

overlying soft tissue integument and functional growth of

the organs of respiration, mastication, deglutition and speech

are all under great genetic control.

The development of a normal occlusion is likely to be

influenced by environmental factors, which influence the

normal physical and skeletal growth of a child and

developm ent of the dentition. Hence a thorough

understanding of physical growth, skeletal growth and their

association with the growth of face is essential. This has

been discussed in detail in clinical application of growth

data.

Other major contributor to the development of normal

occlusion is the integrity of deciduous dentition, which can

be taken as full complement of deciduous dentition free

from dental caries or the one with proper restorations.

Premature extractions due to any reason should be

followed by maintenance of space. This should include loss

of tooth due to trauma. It is essential that a full complement

of permanent teeth are present which are of normal

morphology and size, and these should timely replace the

deciduous dentition. The other major factors that can

influence the development of occlusion are the mode of

respiration and behaviour of the tongue and added insult

from habits such as finger or thumb sucking.

First and foremost, the clinical assessment of a child

begins with a look at his/her physical development and

overall presentation in behaviour. A child who is normal in

height according to his/her chronological age and not

overly overweight or underweight is likely to be free from

any endocrinal/skeletal disorder that may influence facial

growth. (A record of weight and height related to age are

used for evaluation of physical growth).

Extraoral examination per se begins with the face in the

state of rest, in occlusion and in function. The child should


be examined in an environment which is friendly (not

threatening) and conducive to understanding and

enhancement of confidence in dentist /orthodontist. It may

be a good idea to spend a few minutes talking to parents

and child in the waiting room or in consultation room on

things that might interest a child and indulge in conversation.

This would help elicit information on socio-cultural aspects

of the child and his family. Conversations like “How are you

doing?”, “Have you had to miss your work to make this

appointment?”, “How far is child’s school from house?”,

“How did you travel to reach the clinic?” provides threefold

benefits. It gives you time to understand the child and his

parents along with an opportunity to observe the child, his

face, action of lips, posture in smile and in rest. It will give

you information on their concern about the problem, their

attitude, and awareness. The number of siblings and the

nature of job of the parents provide some information on

the parent’s possible m otivation for orthodontic

consultation.

Examination of face

Examination of face should preferably be carried out with a

child sitting upright on a chair/or standing straight and not

on a reclining chair, as it will not give you the best view of

frontal and lateral profile. There are several ethnic/ racial

variations of facial forms. Facial characteristics of each

individual are unique to him in many ways; therefore the

consideration of their ethnic/racial features has to be kept

in mind. For example, a Mongoloid face seen from a front

profile would be certainly different from an African and

both would be different from a Caucasian. In spite of racial/

ethnic characteristics of facial forms, certain ‘common

features’ of a balanced face will be discussed which make

essential components of orthodontic diagnosis.

Occasionally, one needs to examine a face from under the

chin while head is tilted backwards. Such a view is needed

for the evaluation of the facial asymmetry particularly of the

nose, zygoma and upper lip. While examining the child from

the frontal view the child should be relaxed and examiner

should stand in front of the child and look for the following:

Overall shape of face and cephalic index

Overall shape of the face including skull may fall in one of

the three types.

A. Long and thin which is often associated with the

ectomorphic body type,

B. Broad and square could be associated with the

endomorphic body type

C. Ovoid face (between A and B) is usually seen in mesoor

endomorphic body types.

Mongoloid faces are usually broad and flat while Africans

and Islanders may show thick lips and prominent cheek

bones, with the Caucasians falling in between. The shape

of the head can be more objectively evaluated by using the

cephalic index.

Cephalic index. It is a ratio (in percentage) of the maximum

breadth to the maximum length of a skull or head. The

principle employed by Retzius is to take the longer diameter

of a skull, the anteroposterior diameter as length. If the

shorter or transverse diameter (width) falls below 80% the

skull may be classified as long (dolichocephalic), while if it

exceeds 80% the skull is broad (brachycephalic). There are

population differences in head forms which influence the

face form (Figs 9.8, 9.9).

Subjects having a dolichocephalic head form also have

a proportionately narrower and longer face than those with

a brachycephalic head form. Their cranial base flexure is

more open or flat, resulting in a protrusive upper face and

a retrusive lower face. They have a tendency for class II

malocclusion. These features are characteristics of

Caucasians. The opposite, i.e. a closed cranial flexure usually

characterizes the brachycephalic head which embodies a

wider, flatter, more upright type of face. The face appears

broad and flat with a tendency for class III type of

malocclusion and a prognathic mandible or a bimaxillary

protrusion. There are many com binations of

dolichocephalism and brachycephalic head forms.9,10

Some authors have used the term, hyperdolichocephalic,

hyperbrachycephalic, ultrabrachycephalic for extreme facial

types. An example of six types of head form based on

cephalic index is given below.

For example, if your head is 150 mm in breadth and 200

mm in length, then your cephalic index is

100x150

200 - = 75.0

Less than 70 (Hyperdolichocephalic)

Between 70 and 74.9 (Dolichocephalic)

Between 75 and 79.9 (Mesocephalic)

Between 80 and 84.9 (Brachycephalic)

Between 85 and 89.9 (Hyperbrachycephalic)

More than 90 (Ultrabrachycephalic)

Facial symmetry

The important points to be examined are symmetry of the

structures of the right and left side of face. Some degree of

facial asymmetry is seen in nearly everybody and is

considered normal since the right and left sides of the face

are not exact mirror images of each other. It is important that

facial symmetry should be examined both in rest position of

the mandible and in occlusion. Midline of nose, lips, chin

and face should be co-incident. Deviated nostrils and nose

are frequently seen in operated cases of cleft lip and palate.

If deviation of chin appears from rest to centric position, it

is indicative of premature contact on functional closure of

the jaw. An obvious asymmetry can be seen in one of the

following conditions.

Facial asymmetry may exhibit itself as a deviation of chin

to either side. Face usually appears smaller on one side or

larger on other side. Hemifacial microsomia or Goldenhar

IVI

\

Fig. 9,

ectomi

seen ii

L

Section II: Clinical evaluation

Dolichocephalic < 75% Mesocephalic 75%-80%

Brachycephalic > 80%

Fig 9.8: Cephalic index

le

Df

is

iat

of

in

se

te.

it

of

he

% 9.9: Broadly overall shape of the face including skull may fall in one of the three types. Long and thin A , which is often associated with the

ectomorphic body type, Broad and square could be associated with the endomorphic body type C, Ovoid (between A and C) face (Fig. B) is usually

Seen in meso- or endomorphic body types


syndrome is a congenital birth defect characterized by

varying degrees of unilateral underdevelopment of mandible,

ear and orbits.

A deviated chin to either side, both in occlusion and rest

position should alert the consultant to look for either

deficient growth of the lower jaw on one side (which is

usually the side which appears normal) or excessive growth.

Size and distance of eyes from the midline of face is of

significant importance. A decrease in the interorbit distance

hypotelorism or an increased distance hypertelorism should

be carefully noted. In normal subjects, the width of the base

of the nose should be approximately the same as the interinner-canthal

distance, while the width of the mouth should

approximate the distance between the irises.

One of the important parts of facial examination is to

note the relationship between skeletal and dental midline,

since this cannot be determined from the dental casts. The

relationship of the dental midline of each arch to the

skeletal midline of that jaw is recanted, i.e. the lower incisor

midline is related to the midline of the mandible and the

upper incisor midline is related to the midline of the maxilla

and all related to each other.

Examination of profile

The examiner should stand on the side of the patient while

the patient is asked to stand and look straight preferably

into a mirror. An imaginary line is drawn connecting the

bridge of the nose, the base of nose and the chin. Nose can

be a big distracter; smaller noses tend to mask retrognathic

face to look straighter, while a very prominent nose gives

a false feeling of a convex profile in an otherwise normal

profile. The facial profile could fall in one of three types

(Fig. 9.10A-C) (Table 9.4)

Convex profile. The chin is recessive and the upper lip is

prominent. It is obvious that a line drawn from the three

points (nasal bridge, upper lip under the nose and chin)

would make an angle at the base of the nose. A convex profile

may be just a posterior divergent profile when the chin is

recessive. It may make a straight line from the nasal bridge to

the base of the upper lip to the chin. However, if the straight

line falls backwards towards neck, then it is called posteriorly

divergent. Convex and posteriorly divergent profiles are

features associated with skeletal class II malocclusion which

may be present in isolation and/or combination of various

degrees of maxillary protrusion and mandibular retrusion.

j

i

Latere

Profih

Nose

Nasal

Chin

Ears

Nasol

Labio

Vertic

FMA

Gonis

Lowe

Fig. 9.10: A. Posteriorly divergent convex profile, B. Orthognathic profile, C. Concave profile, D. Midface convexity seen with bimaxillary protrusion


Table 9.4: Examination of face

Lateral view

Profile

Nose

Nasal bridge

Chin

Ears

Nasolabial angle

Labiomental sulcus

Vertical

FMA

Gonial angle

Lower border of mandible

Convex/straight/concave/bimaxillary protrusion

Small/normal/prominent

Normal/deep/flat

Recessive/normal/prominent

Their shape, size and any abnormalities. Occasionally ear tags and some minor

malformations of the ear are seen which may need correction with plastic surgery

at appropriate age

Acute/normal/obtuse

Normal/flat/deep

Face height at lower third: Normal/increased/decreased

average/large/small

Large/small (open/close)

Any signs of deformity

Straight profile. Line drawn from the nasal bridge to the

base of the nose and the chin, makes a straight line and is

nearly vertical or slightly posteriorly divergent. This

characterizes a straight profile.

Concave profile. A concave profile is associated with

maxillary protrusion or retrognathic maxilla or both. In

lateral view, a line connecting bone of nasal bridge, bone

of nose and chin makes an obtuse angle at base of nose

outside and acute angle towards face.

William Downs (1948)11felt that there are four types of

faces as viewed on the lateral profile keeping chin

prominence as a significant consideration and a major point

of reference. His classification of profile type was given

essentially in relation to cephalometric analysis.

Retrognathic with recessive chin (convex profile)

Mesognathic with straight profile normal chin (straight

profile)

Prognathic - where chin is prominent

Prognathism when mandible is large (concave profile)

Bimaxillary protrusion. A significant variation of the profile

exists among groups from the southern part of India (mostly

^ravidians/Sytho Dravidrans), negroid, certain races from

^donesia and Islanders. These ethnic groups have

Slgnificant protrusion of the upper and lower dentition, and

thereby of midface, upper and lower lips. The chin may be

n°rmal/retrusive (Fig. 9.10D).

| The profile has to be assessed clinically and can be

subsequently also visualized and reconfirmed on clinical

Profile photographs.

Evaluation in vertical dimensions in lateral

profile

The vertical facial proportions between anterior and posterior

face are essentially grouped as neutral, horizontal or vertical

face types based on direction of lower jaw/ angulations of

lower border of mandible to an imaginary horizontal plane

extending from the external auditory meatus to the

infraorbital ridges called the Frankfort horizontal plane. This

line is also called eye-ear plane. The child sitting or standing

upright with eye-ear plane parallel to floor, try to imagine an

angle between eye-ear plane and the lower border of the

mandible.

An angle greater than 30° points to a vertical grower,

which signifies that lower anterior face height could be

increased (Fig. 9.11).

Similarly a subject with 20° or less angle is grouped as

horizontal grower (Fig. 9.12).

The children falling somewhat between 20-30° are

considered neutral grower.

The vertical or horizontal growth trend is not a unique

feature of a particular malocclusion type but can be seen in

any type of malocclusion; class I, class II, or class III.

A mandibular plane angle smaller than 20° is often

associated with a decreased lower anterior face height,

which is obviously compensated by an increase in ramus

height. Such type of facial pattern is common in class II div

2 type malocclusion. However, these can be also seen in

class I or class III malocclusion.

Gonial angle

The horizontal/vertical type of face would also necessitate

a look at the gonial angle. A large gonial angle would be


Trichion

Nasion

Subnasale

Menton

Fig. 9.11: Facial proportions vertical in height: upper third (trichion-nasion), middle third (nasion-subnasale), and lower third (subnasale-menton). Face

can also be divided in upper face height (nasion subnasale) and lower face height (up to menton)

associated with a short ramus and increase in lower anterior

face height, thus also indicating a steep mandibular plane

angle.

A small gonial angle is associated with good growth of

ramus height, a decreased or normal lower anterior face

height and a rather flat mandibular plane. Closed/smaller

angle can be a feature of class II division 2 malocclusion.

Small gonial angle can be associated with class I deep bite

cases, and occasionally true mandibular prognathism with

extreme horizontal growth pattern. Such a gonial angle has

also been observed in children with hypertrophy of masseter

muscles.

othe

forn

all tl

butt

are i

on d

chee

oftfc

to b

man

Ext

Size

mou

sept

Ext

The

shoi

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Lacl

max

Nm

It is

bore

i.e.

Dec

proc

Vertical facial proportions in front profile

In vertical plane, the face can be divided into three equal

parts: from the hairline - supraorbital margins, supraorbital

margins - base of nose, and base of nose - chin.

The common aberration in facial height as viewed from

front is an increase or decrease in lower one-third of the

face. An increase in lower anterior facial height is often

associated with open bite tendency while a decrease is

often seen in deep bite cases.

Transverse facial proportions. In the frontal view, the

face is divided into five equal segments by vertical lines.

The ‘Ideal’ measurements are:

1. The mid-segment is formed between two vertical planes

passing at the inner canthus of the eyes. In a wellbalanced

face, these planes should pass through the

base of the ala of the nose (Fig. 9.12).

2. The second segment is formed on either side between

the plane passing at the inner canthus of the eyes and

Fig. 9.12: Transverse facial proprotion

the plane passing through the outer canthus of the

eyes. This outer plane usually should be coincident

with the gonial angle.

3. The outer two fifth segments essentially represent ears

and their widths may have to be improved by the

plastic surgeon if the ears are disproportionate with the

rest of the face. The width of the mouth normally

should be equal to the interpupillary distance.

Golden proportions of face12

The mathematical formula for the perfect face has been

defined based on a simple mathematical tatio of 1:1.618,

L

Section II: Clinical evaluation

otherwise known as phi, or the divine proportion. Only one

formula has been consistently and repeatedly observed in

all things which are beautiful, be it art, architecture or nature,

but most importantly in facial beauty. Ideal facial proportions

are universal regardless of race, sex and age, and are based

on divine proportions, if the width of the face from cheek to

cheek is 10 inches, then the length of the face from the top

of the head to the bottom of the chin should be 16.18 inches

to be in ideal proportion. The ratio of phi also applies to

many other facial proportions (Fig. 9.13 A-C).

Examination of nostrils

Size and shape. Very narrow nostrils can be associated with

mouth breathing habit. A child may have a deviated nasal

septum and one side of nose may be totally blocked.

Examination of zygoma or cheekbones

The prominence of the cheekbones and the infraorbital area

should be noted, and so their fullness. A deficient maxilla

is a major contributor to the chin appearing more prominent.

Lack of cheekbones prominence is suggestive of a deficient

maxilla.

Nasolabial angle

It is the angle formed by the tangent drawn along the lower

border of the nose and upper lip with the tip of upper lip,

i.e. upper lip anterior. Range of this angle is 85° to 105°.

Decreased nasolabial angle is seen in patients having

proclination of anterior teeth or a prognathic maxilla whereas

increased nasolabial angle is seen in patients with

retrognathic maxilla or retroclined maxillary incisors. If the

nasolabial angle is open (>105°), retraction of anterior teeth

orthodontically and surgically should be avoided in treatment

planning. Fitzgerald et al (1992)12 worked out a normative

data for the nasolabial angle on a sample of 104 young

white adults at Oklahoma which were determined by the

authors to have well-balanced faces. The study showed the

nasolabial angle to be 114° +/- 10°. No statistically significant

differences were demonstrated between the values for men

and women, but the women did have a slightly larger

nasolabial angle (Fig. 9.14A-C).

The lips

At rest upper lip should normally provide lip seal without

showing signs of excessive muscle movement. With the lips

relaxed, interlabial gap should be in the range of 1 to 5 mm.

Females generally show a larger gap. It is also dependent

on lip lengths and vertical dentoskeletal heights.

Upper lip is considered competent if the lip has a good

muscle tone, is usually not dry and is in gentle contact with

or slightly apart from the lower lip.

Upper lip can be averted, flaccid and short, thus being

unable to provide a good lip seal during respiration and

thereby allow mouth breathing. Such an upper lip is called

incompetent upper lip. Increase in the interlabial gap is

seen with short upper lip and/or maxillary vertical excess

and skeletal open bite. A short upper lip (lip length 18 mm

or less) leads to increased interlabial gap and excessive

i

a-1 , b -1.618

T

1.618

1.618

B

Golden proportions of face. Height of face

to width of face ratio.

Golden proportions of face

Ratio of transverse dimensions of face

D

Golden proportions of face

Ratio of vertical face heights

Fi9- 9.13: Divine proportions have been beautifully illustrated in the drawing of human body by Leonardo DaVinci’s. For example, if the width of face

is 1, then the distance from the top of head to chin is 1.618. There divine proportions are seen in width as well as face heights

A


B

incisor exposure at rest and in smile. A decreased interlabial

gap can be associated with maxillary deficiency, long upper

lip, ageing and mandibular retrusion with deep bite. The

upper lip may be unduly thick or thin (fullness).

Closed lip position

The closed lip position adds support to the diagnostic

patterns. It also reveals disharmony between skeletal and

soft tissue lengths. Increased mentalis contraction (mentalis

strain), lip strain, and alar base narrowing are observed in

vertical skeletal excess. Lip redundancy is seen with vertical

maxillary deficiency and mandibular retrusion with deep

bite. With balanced lip and skeletal lengths, the lips should

ideally close from a relaxed, separated position without lip,

mentalis, or alar base strain (Fig. 9.15).

Fig. 9.15: Incompetent lips

Fig. 9.14: Nasolabial angle: A. Normal, B. Obtuse, C. Acute

Smile position lip level

When examining the patient in smile, different lip elevations

are observed in normal and abnormal skeletal pattern.

Three-quarters of the upper incisors crown height to 2 mm

of gingival display is considered normal/ideal exposure.

The gingival display is slightly more in females than in

males. Variability in gingival exposure during smile is related

to lip length, vertical maxillary length, maxillary anatomic

crown length and magnitude of lip elevation with smile.

Excessive gingival show can be linked either to short upper

lip and vertical maxillary excess, or both. In contrast, some

children have a thin upper lip and short face height with

less than optimum incisor show.

Lower lip

Lower dip should be examined for its position and depth of

mental sulcus. A lower lip may be unduly everted, which is

usually associated with a large lower jaw. A lower lip which

is associated with a small/retropositioned mandible will be

usually trapped in the overjet behind the upper incisors.

The protruding incisors may not permit lower lip to have a

lip seal with upper, which may be falsely interpreted as

upper lip being incompetent. Such a child will also show

excessive muscle strain in the chin and lower lip during

swallowing. Chin has to be looked for its position (prominent

or recessive) and action of the muscles during swallowing.

Anatomically long lower lip can be associated with class III

malocclusions (Fig. 9.16).

Lip posture and prominence

From the analysis of the patients’ profile, lip posture and

incisor prominence should be evaluated. This can be done

by relating the upper lip to the vertical line passing through

the concavity at the base of the upper lip, i.e. soft tissue

poi]

line

chii

line

this

and

Ch

The

pro

cerl

chii

II d

but

La

Lai

low

is i

sul<

low

inc

div

of |

bee

reti

l>

or

Sin

by

hur

a tl

a r

Fig. 9.16: Lower lip trap and deep labiomental sulcus

point A and similarly by relating the lower lip to a similar

line through the concavity between the lower lip and the

chin, i.e. soft tissue point B. If, the lips are forward from this

line, lips are prominent. If on the other hand, lips are behind

this line they are retrusive and if the lips are both prominent

and incompetent, anterior teeth are judged to be protrusive.

Chin button

The chin should be evaluated independent of the lateral

profile. It may be normal, recessive or very prominent. In

certain malocclusions like class I bimaxillary protrusion, the

chin button may be flat while in other situations like class

II division 2, the mandible is placed backwards but the chin

button may be very prominent.

Labiomental sulcus

Labiomental sulcus is the groove between chin button and

lower lip. A thin or no sulcus can be seen when chin button

is recessive while in cases with a prominent chin button,

sulcus is deep. A retrognathic mandible and eversion of

lower lip, which is trapped behind the proclined upper

incisors, will cause a deep labiomental sulcus. In class II

division 2 situations, deep labiomental sulcus is the outcome

of excessive activity of the mentalis muscle whereby chin

becomes more prominent, and there is a deep bite with

retroclined maxillary incisors.

Dynamics of smile and its

orthodontic implications_______

Smile is perhaps the most pleasant and wanted expression

by each one of us. The nature of smile denotes underlying

human expressions which may have far deeper impact than

a thousand of spoken words. Smile of a child is innocent,

a mother is of caring, of youth denotes carelessness and

freedom and of aged a great satisfaction of his life and

achievements. Nature of smile does vary with mood, and it

can only be purely perceived in the backdrop of its emotions.

Facial expressions, posture of lips, occlusion and

arrangement of teeth, buccal corridors, shape of teeth, their

proportions, contours, gingival colour texture, contour and

several other aspects constitute components of the smile.

Some authors have tried to group them as macro, mini and

microcomponents of smile.1316

Subjects with malocclusion obviously do not have a

pleasing smile. Gummy smile is something which is most

obvious to a lay person. A gummy smile is essentially an

excessive show of the incisors and gingiva. Protruded,

proclined and crowded incisors may contribute to unnatural

show of teeth. A child with a narrow maxillary arch would

show excessive dark spaces in the comers of the mouth

(buccal corridors) or similarly an arch, which is too wide,

will encroach upon the buccal corridors and therefore no

show of the buccal corridors. Similarly, a subject with

dentofacial deformity, particularly like the one with unilateral

condylar hyperplasia or like the one with ankylosis, exhibits

a transverse cant of the occlusal plane, which would affect

the smile adversely. It is, therefore, important to recognize

deviations from the normal smile of an individual, locate

and focus on the factors, and visualize a plan of treatment

that will restore the normal smile.

Nature of smile

Nature of smile can be broadly grouped into posed and

spontaneous smile.

Posed smile. It is voluntary and is often controlled and

learnt. It is a fairly reproducible human expression which

can be sustained. In other words, it is a social smile. It is

voluntary and often a professional like the ones posed by

the air hostess/receptionist and public relation personnel.


orthodc

of the

Fig. 9.17: The smile index is determined by dividing the intercommissure width by the interlabial gap during social smile. A. Consonant smile arc,

B. Non-consonant smile arc, C. Obliterated buccal corridors after, D. Excessive buccal corridors or dark spaces

Spontaneous sm ile. It is natural involuntary and

spontaneous, often characterized by far greater lip elevation

than in a posed smile. It bursts forth, comes suddenly full

of emotions, and may be the initiation of laughter.

Objective evaluation of smile

Objective criteria exist for assessing attributes of a smile,

establishing lip-teeth relationship:

• Smile arc

• Smile index Ackerman and Ackerman16

• Morley’s ratio17

• Teeth, their show, shape, size and arrangement

• Gingiva, shape, position, show colour and texture.

Smile can be assessed in frontal, sagittal and oblique

views against TIME.1819 Arch form and transverse arch

dimensions in relation to the buccal tissue have received

considerable attention in totality of smile analysis.

Arch form. An arch which is narrow or collapsed may

present inadequate transverse smile characteristics, i.e. large

buccal corridors or dark spaces. Excessive wide arch can

obliterate these, resulting in a denture-like smile.

Buccal corridors. They have been much researched by the

prosthodontists since long. Its implications in orthodontic

treatment are relatively new. Buccal corridor(s) is defined as

the distance between the lateral junction of the upper and

lower lips and the distal points of the canines during

smiling. The buccal corridor is often represented by a ratio

of the intercommissural width divided by the width from

first premolar to first premolar. The buccal corridors have

less light available as we see from anterior to posterior

teeth, which appear darker and smaller. This is an essential

feature and a consonant of a smile (Fig. 9.17C,D).

Smile arc

A smile arc is normally formed as a smooth curvature of the

lower lip that follows a smooth consonant (Fig. 9.17A)

relationship of arc formed by maxillary teeth on smile. Here

the upper incisors rest on the vermilion border of lower lip

on posed smile.

A non-consonant (Fig. 9.17B), or flat, smile arc is

characterized by a flat anterior arc line than curvature of

lower lip on smile. The maxillary arch may be far from being

flat such as in anterior open bite.

Assessment of smile arc or incisor-smile relationships

both with lips in rest and in smile has considerable influence

on treatment plan and treatment mechanics.

Smile index (Fig. 9.18)

Smile index describes the area within the vermilion borders

of the lips during the social smile. The smile index is

determined by dividing the intercommissure width by the

interlabial gap during smile. It is increased in clinical

situations where decreased incisor show is present and

decreased where increased incisal show is present. During

Teeth

The fac

crowns

teeth,

angulat

crowns

morphc

proport

proport

of centr

ratio ol

proport

the ove

of the ]

Gingi]

High s

Normal

just ab<

vary ao

in worn

smile 1

beyond

combin

1 De

rev

L


2. Muscular: Caused by hyperactivity of the elevator

muscles of the upper lip.

3. Dentoalveolar (skeletal): Due to an excessive

protuberance or vertical growth of the maxilla.

Fig. 9.18: The smile index is determined by dividing the intercommissure

width by the interlabial gap during social smile

orthodontic treatment, we intend not to alter the smile index

of the patient.

Morley’s ratio

The Morley’s ratio depicts the percentage of incisor show

on posed smile with respect to the clinical crown height.

Usually it is 75-100%. A ratio greater would necessitate

measures to decrease the incisor show. Common causes

are:

• Palatal plane tipping downward

• Vertical maxillary excess

• Short lip or greater crown height.

Smaller ratio depicts less than normal incisal show due

to a vertically deficient maxilla, increased length of upper lip

or short clinical crown height.

Teeth and dental arches

The factors affecting the quality of smile are heights of the

crowns and their alignment, contact areas, arrangement of

teeth, spacing and/or crowding. The tip (mesiodistal

angulation) and torque (labiolingual inclination) of the

crowns also contributes to the aesthetics of smile. The

morphology and proportions of individual tooth and relative

proportions of the teeth in the arch contribute to the divine

proportions and therefore the quality of smile. The widths

of central incisor: lateral incisor: canine follow mathematical

ratio of 1:1.618, otherwise known as phi, or the divine

proportion. The colour of teeth also indirectly influences

the overall impression, growing darker towards the comer

°f the mouth.

Gingival display

ffigh smile line (gummy smile), low smile line

Normally, the display of teeth and gums is about 1mm or

just above the cervical margins in posed smile. This may

Vary according to sex and age. On an average, the smile line

ln women is 1.5 mm higher than in men. The nature of a high

snule line, which is characterized by the show of teeth

beyond 2 mm of their gingival lines, can be caused by a

c°mbination of several factors:

Dentogingival: Abnormal dental eruption, which is

revealed by a short clinical crown.

Presence of one or more of the above described factors

in varying severity may affect the gingival display. A high

smile is often influenced by anterior vertical maxillary excess,

greater muscular capacity to raise the upper lip, and

supplemental factors, such as excessive overjet and overbite.

Low smile line is the one where teeth are not visible or

visible less than normal. This may be due to small incisors,

vertical maxillary deficiency or a combination of both.

Transverse cant of the maxillary occlusal plane

(Fig. 9.19)

Transverse cant can be due to differential eruption and

placement of the anterior teeth or skeletal asymmetry of the

mandible resulting in a compensatory cant of the maxilla.

Clinical visualization in frontal and transverse dimension

permits the orthodontist to visualize any tooth-related and

skeletal asymmetry transversely.

Transverse cant can be better appreciated when a subject

is asked to hold a tongue blade (a long ice-cream stick) in

mouth between the premolars of the opposite sides while

keeping his/her head straight and observing the parallelism

between the tongue blade and the interpupillary line.

Lately, interdisciplinary and cosmetic aspects of smile

design and enhancement in combination with orthodontics

is emerging as a new science of smile design. Extensive

recontouring, to teeth build up, laminates and other aspects

of restoration with aesthetic materials and techniques are

Fig. 9.19: Cant of occlusal plane in transverse plane is often seen in

cases of facial asymmetry. This young had a fall and subsequently

ankylosis of right TMJ resulting in restricted growth of the mandible more

so on the right side leading to a transverse cant of occlusal plane


Table 9.5: Clinical analysis of smile (posed smile)

Frontal view

Value

Smile arc

Consonant

Non-consonant

Smile index

Average

Decreased

Increased

Morley’s ratio

Normal

Decreased

Increased

Buccal corridors

Normal

Obliterated

Excessive

Smile line

Normal

High

Low

Transverse cant of occlusal plane

Present

Absent

If yes

Skeletal

Dental

Both

being incorporated along with orthodontics. In addition,

the gingival and periodontal structures are also considered

seriously for alterations/surgery to give near perfect

contours.24'26

The objectives of smile design and implementation

strategies should evolve a 360° review of all possible

parameters including the age of the patient (Table 9.5).

Functional examination

including TMJ

A detailed assessment of a patient with malocclusion would

be incomplete without examination of the TMJ. The

functions of mastication, deglutition, speech, and respiration

depend largely on the movements of the mandible and its

relationship to stable cranial base. The TMJ is classified as

a compound movable articulation between condyle and the

inferior surface of the squamous part of the temporal bone.

Interposed between condyle and articular eminence is the

articular disc, which divides TMJ into two separate joint

cavities. In superior joint, movement is gliding or translatory

whereas in inferior joint, it is rotary or hinge type.

Examination of TMJ requires an understanding and

examination of the articulatory system. The articulatory

system comprises three components:

• The temporomandibular joint

• Muscles of mastication

• Occlusion.

A detailed examination of TMJ should start with a

carefully recorded history from the child and/or parents,

which should include questions such as:

• Has there been any injury to the face or jaw which has

caused chewing difficulties?

• Is it difficult or painful while yawning or around the

ears?

• Do the jaw joints make click, feel stiff, and get stuck or

locked?

• Are there any episodes of being unwell with headaches

and pain on or about the ears?

Tenderness on palpation

Children may complain of pain in or in front of the ear.

Tenderness on palpation of the joint in the area implies

inflammation, generally as a result of acute or chronic

trauma. The pulp of index finger should be placed in the

immediate preauricular area; gently applying pressure on

the lateral pole/head of the condyle while the jaw is closed.

The level of pain and discomfort on each side should be

assessed and compared. The little finger with pulp facing

the condylar head should also be gently placed in the

external auditory meatus to evaluate the motion of the

condyles.

Joint sounds

There are two types of joint sounds to look out for:

• Click — single explosive noise

• Crepitus — continuous ‘grating’ noise.

Click. A joint click represents a sudden distraction of two

wet surfaces, symptomatic of some kind of disc

displacement. Clicks may frequently be felt by the patient

and this may be the reason to seek consultation. Click can

be heard more so with special stethoscope with double

drum heads for simultaneous review of both the joints.

The diagnosis of a joint click, and therefore treatment,

depends upon whether the click is present in one joint or

both sides, is associated with pain or not, is consistent or

intermittent. As the joints are under auscultation, the patient

is asked to open the mouth gently. The timings of click and

so the intensity is recorded. A click heard later in the

opening cycle may represent a greater degree of disc

displacement.

Crepitus. It is the continuous noise heard during jaw

opening and closing movement of joint, often caused by

the worn articulatory surfaces of the joint. This occurs

commonly in patients with degenerative joint disease.

Range of motion27'29

Range of motion is the only truly measurable parameter,

since the others are more subjective. It is important to

Fig

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Fig. 9.20: This female had a fall as a young child and subsequently ankylosis of right TMJ resulting in restricted growth of the mandible. Chin is

deficient and facial midline is shifted to right side of ankylosis. Her lateral cephalogram shows a marked retrognathia of the mandible. Proclination

of lower incisors to compensate for overjet

record jaw movement as means to assess the rate and

degree of improvement, as it is to determine the severity of

symptoms. Movements to be measured are:

• Incisal opening — pain free limit

• Incisal opening — maximum (forced)

• Lateral mandibular excursions

• Mandible deviations on pathway of opening.

Incisal opening. It is measured from the upper incisal tip to

the lower, with the patient opening to his/her maximum,

comfortable, pain free range. This is then compared to the

normal range of motion.

The maximum (forced) limit is also recorded. It is important

to determine whether a limitation of vertical movement is

due to pain or due to physical obstruction.27 Mouth opening

may be restricted due to pain in cases of muscular problems

whereas limited mouth opening due to an obstruction is a

feature of disc displacement.

Lateral excursions. The lateral movement is measured from

midline to midline, when the patient is moving the mandible

to its maximum extent, from one side to another.

Mandibular deviation. When the jaw is opened, the path it

follows should be smooth, straight and consistent.

Deviations from the norm are either lasting or transient, and

are suggestive of internal derangements of different varieties.

The normal range of mouth opening is 53-58 mm. A child

the age of 6 can open his/her mouth 40 mm or beyond,

the incisal mouth opening is less than 40 mm it is

suggestive of restricted mouth opening. In lateral excursions,

an °Pening less than 8 mm is considered as restricted.

Trauma and dislocation

Eternal trauma to the face and jaws can often cause

^dibular or condylar fracture or more commonly traumatic

1 Table 9.6: Summary o f TM J exam ination 1

History of pain/tenderness/click/dislocation/trauma

Palpation: Joint/muscles

Auscultation: Click/crepitus

Range of motion: incisal opening

Right

Left

arthritis, but rarely is a cause of a chronic disorder. In the

absence of an anatomical defect, dislocation is rare and is

usually caused by trauma. If trauma in children causes

fracture of the condyle, mandible is deviated to the same

side whereas in dislocation the mandible is deviated to the

opposite side.

Due consideration should be given to the presence of

any of the symptoms or signs of TMJ disorder while

planning the orthodontic treatment in an adult or a child. A

careful and conscious decision has to be made before

undertaking any orthodontic therapy (Table 9.6, Fig. 9.20).

Speech and malocclusion3033

Speech and language acquisition is a complex, intricate

developmental process occurring most dramatically in the

first year of life. Speech is a motor act of verbal

communications. By means of speech, we are able to

describe our thoughts and feelings and can understand

those of others who employ the same language.

Language is a system of communication. It may be

written, spoken, or gestured. Speech is the means of

associating spoken symbols of language. Scientists have

yet to understand how and why so many languages

developed across different parts of the world and in different

societies.


parts of speech

Speech consists of four parts:

• Voice—sound produced by air passing between the

vibrating vocal cords of the larynx.

• Articulation—the movement of the speech organ used

in producing a sound, i.e. the lips, tongue, teeth,

mandible, palate, and so forth.

• Rythm—variation of quality, length, timing and stress

of a sound, word, phrase, or sentence.

• Language—knowledge of words used in communicating

ideas.

There are three possible mechanisms by which

malocclusion and speech may be inter-related:

1. There may be a cause-and-effect relationship where

occlusal or structural anomalies affect articulation of

speech

2. Problems of articulation may be coincidental to

malocclusion

3. Conditions that affect central nervous system leading

to poor motor control and possible distorted morphogenesis.

These may be genetic or metabolic.

Dental anomalies and malocclusion can affect speech

production to a considerable extent, although the ability of

patient to compensate for abnormal dental relationships

should never be underestimated.

Assessment of speech in relation to malocclusion

and dental anomalies

The assessment of a child with malocclusion and dentofacial

deformities should include an assessment of the speech for

articulation, fluency and voice.

The orthodontist’s responsibility is first to be able to

recognize the defective articulation or speech sound and to

look for the presence of dental structures or malocclusion,

if any, that could have adversely affected the speech.

The clinician while talking to the patient informally

performs the subjective assessment. If speech problems are

suspected, the child is asked to read a paragraph that has

been professionally designed by the speech therapist for

the purpose.

Following factors related to oral cavity and dentition

may affect articulation of speech.

Speech is mainly produced by two valves:

• Articulation components of the oral cavity: palate,

teeth, lip seal and tongue

• Velopharyngeal valve, soft palate and pharyngeal walls

The following conditions may affect production and

quality of speech:30-31

Teeth

Cases with severely crowded, irregular incisors and lingual

position of maxillary incisors may have difficulty in

production of linguoalveolar sounds (t,d).

Hypodontia/missing teeth or similar conditions cause

interdental spacing and may cause lateral or forward

displacement of tongue during speech resulting in distortion

of the sounds. Lingual-alveolar phonemes (e.g. s, z) followed

by lingual palatal phonemes (j, sh, ch) are most affected by

space in the dental arch.

In class III cases, sibilant and alveolar speech sounds

are most commonly distorted or affected (s, z, t, d, n, 1). In

these cases, there is difficulty in elevating the tongue tip

to the alveolar ridge.20,21

Lip seal

A competent lip seal is required for control of air and

production of bilabial sounds. Class II malocclusion with

large overjet may impede lip closure during eating and

drinking. Bilabial sounds (p, b, m) may be distorted, being

produced by the upper incisors articulating with the lower

lip (labiodental manner). Incomplete lip seal is also seen in

children with operated cleft lip, which may be short and

immobile.

Children with anterior open bite tend to move tongue

forwards into the interdental space resulting in lisping/

distortion of speech sounds. Sounds involved are those

that involve the tongue tip to contact alveolar ridge (t, d,

n, 1) and palate (s, z) (sibilants).

Velopharyngeal seal

It is an essential mechanism involved in speech production.

For all vowels and consonants except nasal consonants,

the nasal cavity is cut off from the pharyngeal cavity and

the air stream passes into the oral cavity. This ensures

adequate and constant intraoral pressure during speech.

The velopharyngeal seal is achieved by lifting up of the

soft palate, forward movement of the posterior wall of

pharynx and inward movement of the lateral pharyngeal

walls. Inability to achieve a velopharyngeal seal partially or

completely is called velopharyngeal insufficiency. It is

commonly seen in cleft palate cases due to short and not

so mobile soft palate

A fistula in the palate would cause nasal escape and

nasality as seen in unoperated cleft children or in children

with postoperative fistula following repair.

Anomalies of tongue32

Such as ankyloglossia or tongue tie may hinder free

tongue movements and may result in distortion and

substitution of tongue tip sounds (linguoalveolar). The

sounds affected are 1, t, d, n, s and z because of restricted

elevation of tongue tip.

In macroglossia, the abnormally large tongue may affect

production of all speech sounds involving the tongue such

as dentolingual (e.g. th), linguoalveolar (t, d, n, 1), and

palato-lingual (ch, j, sh.). Primary macroglossia is a rare

condition. It may be associated with conditions like

Beckwith-Wiedemann syndrome.

L


Table 9.7: Stages of development of speech

Stage

I 0-8 weeks Reflexive crying and vegetative sounds

II 8-20 weeks Cooing and laughter

III 16-30 weeks Vocal play

IV 25-50 weeks Reduplicated babbling: consonant -vowel syllables

V, 50 + Weeks Non-reduplicating babbling

VI

Around one year First words

Microglossia, another anomaly of tongue characterized

by an abnormally small tongue may be associated with

syndromes exhibiting hypodactyly. It may lead to abnormal

speech because of the inability of the tongue tip to contact

the teeth, palate or alveolus sufficiently.

Speech in a cleft child33

A child operated for cleft lip and plate may have inadequate

velopharyngeal seal and persistent oronasal fistula resulting

in air escape into the nasal cavity. The child is unable to

maintain adequate intraoral pressure and consequently

speech is impaired. Inability to maintain adequate intraoral

pressure leads to the development of compensatory speech

behaviours. Such responses tend to undermine rather than

enhance speech performance.

Individuals with velopharyngeal insufficiency use greater

respiratory efforts. Their air volumes during speech are

approximately twice those of normal speakers. Another

compensatory change in speech is in tongue carriage. A

child with velopharyngeal insufficiency tends to position

the tongue to reduce the nasal escape of the air stream so

that an adequate and constant pressure can be maintained

in the oral cavity.

Clinical examination of child for

suspected deleterious habit(s)

A potential orthodontic patient may have one of the

following deleterious habits, namely mouth breathing,

tongue thrusting and thumb or finger sucking. Other habits

include finger or nail biting and pencil biting.

While examining a child suspected of having mouth

breathing, one can elicit a lot of information from the

parents about the past medical history of the child. A child

with recurrent throat infection, recurrent allergies may be a

mouth breather. Such a child may show a long narrow face,

and dry upper lip that is often flaccid and everted. The

gingiva in the upper anterior region may appear dry and

mflamed. The nostrils may be relatively small and blocked.

A differential diagnosis of habitual or an anatomical aetiology

°f the causes of mouth breathing will be discussed in the

chapter on deleterious oral habits. An ENT examination can

ascertain cause and location of the blockage in the passages.

In a clinical setting, often it is pertinent to ascertain if the

child is a mouth breather or not.

Tongue thrusting or infantile swallowing or abnormal

swallowing pattern can be responsible for superior

protrusion, spacing in the dentition or bidental protrusion.

A child should be asked to relax, wet his/her lips with his

tongue and swallow his/her own saliva. The doctor should

diligently observe the behaviour of the tongue. Infantile

swallow would require a contact of tongue with the lower

lips to maintain a lip seal. Severe tongue thrusters with

spacing push saliva through the interdental spaces, which

may be seen gushing out in the vestibules while the child

swallows. A severe type of tongue thrusting may be

associated with anterior open bite. Lateral tongue thrusting

with posterior open bite is uncommon but not a rare entity.

Thumb sucking or finger sucking beyond 4-5 years is

considered abnormal and if continued may show its

unwanted effects on dentofacial development. There may

be an open bite with class II tendency, i.e. recessive chin

and protrusion of the upper lip due to proclination of the

incisors. A finger sucker child may not like to reveal his/her

own history, which should be ascertained from the parents/

guardian. Dentofacial alterations of thumb sucking are

governed by the frequency, intensity and the position of

the thumb/finger in mouth. The thumb or the finger being

sucked can also be confirmed as it would appear cleaner

and whiter having been in the mouth longer, compared to

the other fingers. Occasionally a child may have an anxious

habit of excessive nail biting or pencil holding between

teeth. This may lead to some damage of teeth and nails

depending upon the frequency and duration of the habit.

Clinical assessment of an adult

seeking orthodontic treatment

More adults are now seeking orthodontic treatment than

ever before. A number of adults are compelled and motivated

for the treatment for professional and/or personal reasons.

Others are those who are seeking better quality of life and

convinced of the benefits of orthodontic treatment through

friends and relatives. A few may seek treatment for the

reasons of oral health and functional problems. Some of the

adult patients may have been referred by the plastic surgeons

for enhancement of their profile.

The orthodontic assessment therefore needs to be carried

out in view of reasons for seeking orthodontic treatment.

Clinical evaluation in adults is more focused, starting with

the chief complaints of the patient. Growth is complete so

malocclusion is fully established. The examination of the

face follows the same principles as discussed above.

However, the objectives of the treatment may have to be

altered and redefined based on oral health status of

periodontium and aesthetic/functional needs of the adult


seeking orthodontic treatment. The following aspects of

dentition, occlusion and treatment needs are critical in the

evaluation of an adult for orthodontic treatment:

Psychological/social needs of treatment

Periodontal status: need for soft tissue procedures

Caries susceptibility, status of existing restorations

Smile assessment

Assessment of real need and objectives for treatment

Preorthodontic periodontal/restorative treatment

Postorthodontic periodontal/restorative treatment

Interdisciplinary assessment for the above and dental

aesthetic treatment like veneers/laminates.

Intraoral examination

Examination of soft tissues of oral cavity

A thorough examination of the oral cavity should precede

any evaluation of the dentition and occlusion. Any

abnormality in colour/texture or structures in oral cavity,

mucosa and tongue should be noted. Presence or absence

of any growth in the soft tissues and hard tissues may be

recorded and accordingly investigated. In a healthy mouth,

Table 9.8: Summary of intraoral clinical examination

Molar relation Right side Left side

no growths are expected, however bumps, odontome(s) or

dentigerous cysts could be an accidental finding on

inspection and palpation (Table 9.8).

Frenum

Maxillary and mandibular freni should be examined for

number, thickness and levels of attachment. The most

common aberration of frenum is thick upper fibrous frenum

that may be associated with median diastema. The upper

frenum should be looked for its thickness and level of

attachment. A fibrous and a thick frenal attachment that is

low may hinder diastema closure. In such a situation,

further examination should involve a gentle pull of the

frenum along with the upper lip, and one should look for

any signs of blanching at the incisive papilla. A blanching

of incisive papilla indicates a low frenal attachment, which

may have clinical implications during closure of the diastema.

The other freni, buccal (U and L) and labial lower freni

are not of great importance in terms of orthodontic

examination. However, lower lingual frenum is important to

look at and examine the extent to which tongue can be

protruded. A tongue-tie, i.e. thick lower lingual frenum with

low fibrous attachment may hinder free movements of the

tongue to its maximum extent. Although often not of

Deciduous/mixed dentition

Deciduous mixed dentition

• Straight/terminal plane • Straight/terminal plane

• Distal step • Distal step

• Mesial step • Mesial step

Permanent dentition

Permanent dentition

Class I/I I/I II Half cusp/full cusp Class I/I I/I 1 Half cusp/full cusp

Canine relation R L

Class I/I I/I II Cusp/full cusp Class I/I I/I 1 Half cusp/full cusp

Upper anteriors

Normal/proclined/retroclined

Lower anteriors

Normal/proclined/upright/retroclined

Overjet ------------mm Edge to edge

Reverse overjet------------mm

Overbite

Midlines coincident/non-coincident-centric occlusion

<1/3

1/3 -<2/3 Curve of Spee Shallow/deep/normal

>2/3,

3 open bite in mm

Crowding/spacing (mm)

Upper

Anterior

Right lateral

Left lateral

Rotations (specify)

Malpositions of individual tooth

Anterior crossbite (specify tooth/teeth)

if not included in the reverse overjet

Posterior crossbite (specify teeth)

Right

Lower

Anterior

Right lateral

Left lateral

Rotations (specify)

Malposition of individual tooth

Left

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orthodontic significance, tongue-tie may be responsible for

hindrance in proper articulation of speech.

The other common findings in children are presence of

enlarged tonsils and peritonsillar abscess. This will be

discussed in detail in the Chapter 7 on Breathing Habits.

Examination of uvula/soft palate may reveal a notch or

a bifid uvula. Such a finding should alert the orthodontist

for a more detailed examination by palpation to look for a

notched posterior nasal spine or signs of occult cleft of the

palate only.

Any abnormal growth/aberrations of oral mucosa or

such findings should alert the orthodontist for detailed

examination and history.

Palate

From an orthodontic point of view, the examination of the

morphology of the palate and deep palate is often associated

with vertical growth pattern (long thin face, increased

vertical dimension of anterior face). Such a child may also

be a mouth breather. A broad shallow arch or a broad

squarish face may be associated with horizontal growers/ or

situations like class II division 2 pattern.

Tongue

The tongue should be examined for its colour, shape and

size. The lingual frenum and its mobility should be assessed.

A large tongue or macroglossia could lead to lateral open

bite and spacing in the dentition. Swallowing pattern of the

tongue has been detailed in the deleterious oral habits

(refer Chapter 7 on Altered Orofacial Functions on

Development of Face and Occlusion).

Having had an overview of oral cavity and detailed

examination of the abnormality if any, a record should be

made, if any of these findings points towards the presence

of an underlying systemic disease. This should be

accordingly investigated by the concerned specialist.

Examination of oral health and periodontium

The next in order of examination involves assessment of

gingival and periodontal health and the level of oral hygiene,

followed by the status of dental caries and its sequela.

Examination of dentition and occlusion

The mouth should be examined for the eruption status of

teeth with reference to chronological age and skeletal

growth of the child, vis-a-vis shedding of deciduous teeth.

Record should be made of a premature loss of deciduous

teeth, and the need for maintenance of space. In the mixed

dentition, the deciduous second molars should be given a

special importance since they maintain the integrity of the

^ch during the transition from mixed to permanent dentition.

Early loss of the deciduous molars would lead to mesial

drift of the erupting first molar and thereby malocclusion.

Several factors would have to be considered at this stage

including a radiological assessment to evaluate the eruption

status of successor tooth.

Unilateral, premature loss of a deciduous tooth is often

seen with the mandibular deciduous canine, which may

require further examination of a possible or existing midline

shift. A gentle palpation of the dentoalveolar apparatus,

both buccal and lingual, is done to locate teeth that are

close to eruption and may be helpful to sort out extraction

of the retained deciduous teeth. Extremely delayed dentition

requires further radiological assessment.

It is also important to note the presence or absence of

any signs of missing teeth or microdontia. Abnormalities of

tooth number may be seen as supernumerary teeth, which

may be erupted/partially erupted or impacted. The

commonest supernumerary teeth are seen in the anterior

region of the maxilla. Unusual rotation of an erupting

maxillary incisor with abnormal diastema should raise

suspicion about a possible presence of a supernumerary

tooth (Figs. 9.21 A,B and 9.22A,B).

Failure of eruption

Failure of eruption of maxillary anterior even after the loss

of deciduous teeth should also possibly arouse the suspicion

of the possibility of the presence of a supernumerary tooth.

A supernumerary tooth may appear as a dichotomous

tooth, maxillary laterals being the commonest. A record of

the quality and morphology of the dental hard tissues

should be made to exclude the defects of enamel and

dentine like amelogenesis imperfecta and dentinogenesis

imperfecta. A generalized delay in eruption can be seen in

gingival fibromatosis. Physical signs of delay of growth

and development accompanied with delayed eruption of

teeth would need consultation with a paediatrician (Fig.

9.23) to exclude any systematic disease.

Fractured or discoloured teeth that have not been treated

adequately should be noted and may require vitality tests

or X-rays with subsequent consultation with the

paedodontist or endodontist.

Dentition and occlusion

A complete intraoral examination involves recording of

malocclusion and its severity in all the three planes of

space, i.e. sagittal/anteroposterior, transverse and vertical.

The recording can be summarized as in the Table 9.8. It may

be noted that the observations are made while the child is

asked to close in centric relation gently. It is not uncommon

for the child to slide the mandible forward while examination

is in progress, and this may give a false picture of an

occlusal condition, prepared and mounted on an articulator.

In cases where a functional forward shift of the mandible

on closure is observed and where a functional class III

malocclusion is present, it is a good idea to adapt two to

three layers of soft wax bite and manipulate the mandible

to close in centric over the wax bite.

Fig. 9.21: A. Dichotomy of maxillary lateral incisors contributing to crowding in the maxillary arch, B. Erupted mesiodens

Fig. 9.22: An 8-year-old girl showing signs of familial gingival fibromatosis. Fibrosed gingivae make a physical barrier to the eruption of teeth and

hence delayed eruption and crowding

Fig. 9.23: Anterior functional shift/pseudo class III malocclusion in an 8-year-old girl. Top row, initial premature contact which leads to forward slide

of the mandible. Bottom line, centric occlusion in anterior crossbite *

In case .of a lateral shift, ascertain the cause or the

premature contact and try to manipulate the mandible in

centric relation over a softened wax. The clinical

examination o f the face and occlusion should be recorded

with the mandible in the rest position and in occlusion.

To have a better idea of occlusion, the study models

with a wax bite in centric should be prepared.

Any abnormality (ies) in position/deviations of individual

tooth or group of teeth within arch or intra-arch should be

noted. Intraoral examination is usually followed by

preparation of records for further detail analysis and

treatment planning.

Summary

Orthodontic examination and diagnosis starts with first

formal and/or informal meeting with child and parents—

takes a face to face and systematic route of history taking

and detailed intricate examination of physical growth, face,

soft tissues and oral cavity, including functions of

stomatognathic systems.

A close and deligent clinical examination is the most

critical component of orthodontic diagnosis.

REFERENCES

1. Baume J. Physiological tooth migration and its significance

for development of occlusion I. The biogenetic course of

deciduous dentition. J Dent Res 1950;29: 123-32.

2. Baume J. Phbysiological tooth migration and its significance

for development of occlusion II. Biogenesis of accessional

dentition. J Dent Res 1950;29:331-37.

3. Baume J. Physiological tooth migration and its significance

for development of occlusion III. The biogenesis of overbite.

J Dent Res 1950;29:440-47.

4. Foster TD, Hamilaton MC. Occlusion in the primary dentition.

Brit Dent J 1969;26:76-79.

5. Facal-Garcia M, Suarez-Quintanilla D, De Nova-Garcia J.

The diastemas in deciduous dentition: the relationship to the

tooth size and the dental arches dimensions. J Clin Pediatr

Dent 2001 Fall;26(l):65-69.

6. Ohno N, Mizutani Tadasi. The incidence of primate spaces

in 5-7 years old children Indian sample. Abstract Proceedings

of 24th Indian Orthodontic Conference, 1989.

7. Ohno N, Kashima K, Sakai T. A study on interdental spaces

of the deciduous dental arch in Indian sample. Aichi Gakuin

Daigaku Shigakkai Shi 1990; 28 (1 Pt 1): 79-91.

8. Bishara SE, Jakobsen JR, Treder J, Nowak A. Archlength

changes from 6 weeks to 45 years. Angle Orthod 1998; 68(1):

69-74.

9. Warren JJ, Bishara SE, Yonezu T. Tooth size-archlength

relationships in the deciduous dentition: a comparison between

contemporary and historical samples. Am J Orthod Dentofac

Orthop 2003; 123(6): 614-19

!W- Lavater JC. Essays on physiognomy. Vo 1 1-3. London: J&J

Robinson; 1789.

H. Downs WB. Variation in facial relationships: their significance

in treatment and prognosis. Am J Orthod 1948; 34; 812-40.

12. Jefferson Y. Facial beauty — establishing a universal standard.

Inti J Orthod 2004: 15(1): 9-22.

13. Fitzgerald JP, Nanda RS, Currier GF. An evaluation of the

nasolabial angle and the relative inclinations of the nose and

upper lip. Am J Orthod Dentofacial Orthop 1992; 102(4):328-

34.

14. Goldstein RE. Change your smile, 3rd Edn, Carol Stream (111):

Quintessence Publishing; 1997.

15. Ackerman JL, Ackerman MB, Brensinger CM, Landis JR. A

morphometric analysis of the posed smile. Clin Orthod Res

1998; 1(1):2—11.

16. Ackerman JL. The emerging soft tissue paradigm in orthodontic

diagnosis and treatment planning. Clin Orthod Res 1999;

2:49-52.

17. Morley J, Eubank J. Macroesthetic elements of smile design.

J Am Dent Assoc 2001; 132:39-45.

18. Sarver DM, Ackerman MB. Dynamic smile visualization and

quantification: part 1. Evolution of the concept and dynamic

records for smile capture. Am J Orthod Dentofacial Orthop

2003; 124(1):4-12.

19. Sarver DM, Ackerman MB. Dynamic smile visualization and

quantification: Part 2. Smile analysis and treatment strategies.

Am J Orthod Dentofacial Orthop. 2003; 124(2): 116-27.

20. Johnson D R, Gallerano R, English J. The effects of buccal

corridor spaces and arch form on smile esthetics. Am J

Orthod Dentofac Orthop 2005;127(3):343-50.

21. Moore T, Southard KA, Casko JS, Qian F, Southard TE.

Buccal corridors and smile esthetics. Am J Orthod Dentofac

Orthop 2005; 127(2):208-13.

22. Hulsey CM. An esthetic evaluation of lip-teeth relationships

present in the smile. Am J Orthod 1970; 57:132-144.

23. Sarver DM. The importance of incisor positioning in the

esthetic smile: the smile arc. Am J Orthod Dentofacial

Orthop. 2001; 120:98-111.

24. Vig RG, Brundo GC. The kinetics of anterior tooth display.

J Prosthet Dent. 1978; 39:502-504.

25. Sarver DM. Principles of cosmetic dentistry in orthodontics:

Part 1. Shape and proportionality of anterior teeth. Am J

Orthod Dentofacial Orthop 2004; 126(6):749-53.

26. Sarver DM, Yanosky M. Principles of cosmetic dentistry in

orthodontics: part 2. Soft tissue laser technology and cosmetic

gingival contouring. Am J Orthod Dentofacial

27. Sarver DM, Yanosky M. Principles of cosmetic dentistry in

orthodontics: Part 3. Laser treatments for tooth eruption and

soft tissue problems. Am J Orthod Dentofacial Orthop

2005;127(2):262-64.

28. Agerberg G. Maximal mandibular movement in young men

and women. Swed Dent J 1974;67(2):81-100.

29. Vanderas AP. Mandibular movements and their relationship

to age and body height in children with and without clinical

signs of craniomandibular dysfunction Part IV. A comparative

study. ASDC J Dent Child 1992;59:338-41.

30. Biltar Gea. Range of jaw opening in elderly non-patient

population. J Dent Res 1991 ;70: 419.

31. Johnson NC L, Sandy R J. Tooth position and speech—is

there a relationship? Angle Orthod 1999; 69(4): 306-10.

32. Rathbone, John S. Appraisal of speech defects in dental

anomalies with reference to speech improvement. Angle

Orthod 1959; 29(l):54-59 .

33. Oliver RG, Evans SP. Tongue size, oral cavity size and

speech. Angle Orthod 1986; 56(3):234-43.

34. Wildman AJ. The role of the soft palate in cleft palate speech.

Angle Orthod 1958; 28(2):79-86.

Analysis of

diagnostic records

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1.

2.

OVERVIEW

Orthodontic study models

Step by step procedure for use of probability tables

E models

Facial photographs

Cephalometric evaluation (cephalogram-lateral view)

Orthopantomogram (panoramic radiograph of the maxilla and mandible)

Chronological age

Peak growth velocity

Skeletal maturation

Cervical vertebra maturation index (CVMI)

Dental age

Facial growth spurts

PA view cephalograms

Technetium scan

3D CT and Cone Beam CT (CBCT)

Summary

Minimum set of records needed

for a detailed orthodontic case

analysis____________________

Orthodontic study models

The key to achieve good treatment results starts with

proper diagnosis and treatment planning. Orthodontic

records allow the orthodontist to carefully examine

several parameters such as dentition, jaw relationships and

make objective measurements for detailed evaluation and

treatment planning. The study models are the first in the

order of records to be obtained and of greatest importance

in orthodontic diagnosis and treatment planning. Plaster

study models are prepared from well-extended good quality

alginate impressions. These replicas allow the teeth and

associated dentoalveolar segments to be examined from all

possible views, the buccal, lingual and occlusal which may

not be possible clinically.

Good study models will show dentition, dentoalveolar

structures and well-defined sulci, freni and palate. An

impression for a good study model should extend over all

teeth and well into the sulci; if necessary the tray may be

modified by the addition of wax to ensure full coverage of

the oral tissues. Good and accurate alginate impression

showing surface details without distortion or voids are

prerequisites to preparing a good plaster models. Beading

wax is usually applied on the periphery of the orthodontic

impression tray to extend the alginate deep into the sulci.

This provides a better impression and helpg in separating

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Section II: Analysis of diagnostic records ■ 125

the tray from the plaster. To avoid distortion, the impressions

should be poured immediately using orthodontic grade

white stone plaster. Models are mounted on bases and so

trimmed in the laboratory that when placed on their bases,

the teeth are in the patient’s intercuspal relationship.

Orthodontic study models consist of two parts (Figs.

10.1 to 10.2).

1. Anatomic part. The anatomic part of the study model

consists of the actual impression of the dental arch and

its surrounding structures and is usually made in stone

plaster.

2. Artistic part. The artistic part of the study model

consists of a symmetrical plaster base that supports

the anatomic portion and helps in analyzing the

occlusion and orientation of the study models.

The ratio of the anatomic portion to the artistic portion

should be 3:1. Preferably both the anatomic and the artistic

parts should be poured in the same orthodontic grade

stone plaster.

Each set of study models should be trimmed to the most

exacting specifications (American Board of Orthodontics

recommendation), smoothened with fine grade sandpaper,

soaped and polished to a high gloss finish, clearly inscribed

with the patient’s particulars on the back of the model

bases.

• Name or initials

• Age/sex

• Registration number

• Date of impression

• Stage of treatment, i.e. pre-treatment/stage/ posttreatment/follow-up.

The maxillary model should be symmetrical with the top

of the model being parallel to the occlusal plane. The back

of the model should be perpendicular to the midline of the

palate as indicated by the orientation of the mid-palatal

raphe. The model when placed on its back should be such

that the top of the cast or the model should be parallel to

the occlusal plane of the teeth. The anatomical base of the

maxillary model should be 13 mm thick (American Board of

Orthodontics recommendation 1). The total height of the

cast should measure 3.5-4 cm from the occlusal surface to

the top of the model. It is advisable to use mid-palatal raphe

as a guide since the dental midlines are often not coincident

with the skeletal midlines. With the mandibular base in

occlusion with the maxillary base, the bottom of the lower

cast should be parallel to the upper cast. The cast should

he such that the base of the lower model is equal in

thickness to that of the upper model. The total height of

hoth casts in occlusion should be about 7-7.5 cm.

The angle between the lateral surfaces of the maxillary

cast should be 70° to the posterior surface, whereas, it

should be 65° for the mandibular cast. Posterior comers of

cast are perpendicular to a line formed between the

tutersection point of the posterior and lateral surfaces and

the intersection point of the lateral and frontal surfaces of

the cast on the opposite side. Length of the corner segments

should be 13-15 mm.

Pre-treatment study models

Study models are prepared to record the initial /baseline

malocclusion of the patient.

• They enable a more accurate assessment of the

malocclusion and facilitate measurements of the dental

arches, size of teeth, and calculation of the space

required for the correction of malocclusion.

• Pre-treatment study models also serve as a replica of

the occlusion and dentition to objectively record traits

of malocclusion like overjet, overbite, canine relation

and buccal segment relation.

• Study models help in assessing the nature and severity

of the malocclusion and are a valuable aid in total

space analysis, being an essential requisite for this

invaluable diagnostic procedure. Discrepancy in arch

perimeter and tooth size can help us in calculating

amount of crowding or spacing, and further influence

extraction decision.

• They are used to assess and record the dental anatomy,

the intercuspation of the teeth and also to detect the

abnormalities like localized enlargement or distortion of

the arch form.

• Molar relation can be assessed from the lingual aspect

also and this is an advantage, as occlusion cannot be

assessed from the lingual aspect when examining the

patient clinically.

• Dental midlines can be matched with the use of the

study models. For determining the skeletal midline,

facial examination has to be carried out, as this cannot

be determined with the study models alone.

• They also help in explaining the treatment plan to the

patient and parents and are also helpful in the

assessment of the treatment progress and in motivating

the patient.

• Study models also help to give the patients a clear

perspective as to what the prescribed treatment will

accomplish. It is a three-dimensional presentation aid

that allows patients to see their own mouth structure

and more easily identify what is wrong. The patient

can touch it, handle it and see it from all sides rather

than simply looking at a picture. The use of study

models in case presentation allows a ‘co-diagnosis’

approach. We can also explain, using a model of

perfect teeth, the steps that should be undertaken to

rectify the problem.

Progress/stage and post-treatment study models

Orthodontic study models prepared occasionally, as

‘progress’ records during treatment are called ‘stage models’

and those made on the completion of treatment are known

as ‘post-treatment models’. Progress study models provide

a means of recording the sequential progression from pretreatment

through mid-treatment to completion of treatment

and several years thereafter. *

L


Fig. 10.1: Well-trimmed dental study models with a wax bite in centric occlusion are a prerequisite and are the most important orthodontic diagnostic

record

i

Smoothly rounded border

Guidelines for 10 years and above

Fig. 10.2: These figures serve as a guide for preparation of orthodontic study models

Section II: Analysis of diagnostic records 127

The pre- and post-treatment and follow-up models are

used to evaluate treatment outcome, and the follow-up

models are used to record relapse. Numerous research

studies have been conducted using study models as the

records. They also serve as a useful teaching aid.

1. Evaluation of study models

9 The first step in assessing study models involves an

assessment of the symmetry. Any gross asymmetry in

occlusion or dentition would be obvious and should

be recorded.

• Grids and occlusograms are placed over the occlusal

arches of models to determine the exact location and

amount of asymmetry.

• Thereafter, the characteristics of dentition, their number,

mesiodistal width, rotations, crowding, ectopic

positions, or the presence of supernumeraries are

assessed. The findings of intraoral examination on

dentition are reconfirmed on the models.

• This is followed by an assessment of the arch shape

(whether round, oval or tapering, Fig. 10.3), arch widths

(intercanine, interpremolar and intermolar), archlength

and arch perimeter. The arch form, arch widths and

archlength have considerable implications in orthodontic

diagnosis since these govern the effective space

available to accommodate dentition, govern stability of

the treatment outcome and aesthetics to a great extent.

These considerations, in association with anteroposterior

movements of the dentition, will determine

the requirements for extraction or otherwise.

• Palatal depth can be assessed which, may be increased

in certain habits like mouth breathing and thumb sucking.

In case of cleft cases, the type of cleft, its extent, any

palatal fistula should be noted.

• Study models are also used to record the lateral and

excursive paths of the mandible and are important

when restorative dentistry is being planned, as the

contours should accommodate the path of movement.

The study models are mounted on an articulator in

centric relation to evaluate CR-CO (centric relation -

centric occlusion) discrepancies which may exist in a

malocclusion.

2. Analysis of study models

Korkhaus palatal index

Korkhaus2 considered palatal vault depth in relation to

posterior arch width. Palatal height is measured on midsagittal

plane in the region of upper 1st molars at the level

of occlusal plane. The height is defined as the perpendicular

distance from the connecting line between midpoints of

fissures of both upper 1st molars to the palate. The following

formula is used (Fig. 10.4):

Palatal height x 100

Palatal height index = —------:------- ---- —-r-

Posterior arch width

Average index value = 42%

The palatal index values are more/increased when palatal

vault relative to transverse arch development is deep such

as in narrow and deep upper arches in mouth breathers and

it is less/decreased when the palate is shallow.

D

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Fig. 10.3: A. V shaped, B,C. becoming parabolic, D, E. wide/square


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Fig. 10.4: Korkhaus cast measurement instrument is a useful device which is designed to simultaneously measure arch widths and palatal depth

dir

Arch perimeter

Arch perimeter

Fig. 10.5: A. Arch perimeter is measured from mesial of first molar to other side of first molar with the help of a soft brass wire, which is contoured

as a curve following the contact points of teeth in a smooth curve looking at basal skeletal arches. B. Alternatively arch perimeter can be measured

from mesial of first molar to other side of first molar in segments

Arch perimeter analysis

To treat a case with extraction or non-extraction approach

is one of the most critical decisions in orthodontic treatment

planning. The decision is based on several factors; one of

considerable significance is space analysis.

Crowding of teeth usually results from lack of space

within the arches. Space analysis requires a comparison

between the amount of space available for alignment of the

teeth and the amount of space required to align them (total

tooth material or TTM) properly.

Arch perimeter is measured as length of the dental arch

mesial to the first molars on either side.

Arch perimeter can be measured in two ways: 1. By

contouring a piece of soft brass wire to the line of occlusion

such that it passes from mesial first molar of one side to the

other side, over contact points of the posterior teeth and

incisal edges of the anterior teeth (Fig. 10.5A).

2. By dividing the dental arch into segments that can be

measured as straight line approximations of the arch. This

method is preferred because of its greater reliability.

Arch perimeter is the sum of the lengths of the segments

connecting points 2, 4, 6, 8, 10, and 12. Points 2 and 12 are

contact points, mesial to the permanent first molars. Points

4 and 10 are contact points, mesial to the first premolars.

Points 6 and 8 are contact points, distal to the central

incisors (Fig. 10.5A, B).

Space required. The amount of space required can be

determined by measuring the mesiodistal width of each

tooth mesial to first molar on either side and then summing

up the widths of the individual teeth. The mesiodistal width

of each tooth should be measured as close to the contact

point as possible. *


A. Archlength B. Archlength

Fig. 10.6: A. Archlength is measured from mesial of first molar to other side of first molar with the help of a soft brass wire, which is contoured

as a curve following the contact points of teeth in a smooth curve looking at basal skeletal arches in the buccal region and at the base of the maxilla

which is the post treatment position of the anterior teeth. B. Alternatively archlength can be measured from mesial of first molar to other side of

first molar in segments as shown.

pth

The instruments used for the measurement of the tooth

dimensions are:

• A fine pointed divider or a digital calliper.

• A ruler with gradations of at least 0.5 mm.

If the arch perimeter (or archlength) is more than the

space required (as determined by summing of the mesiodistal

width of teeth) then spacing between the teeth can be

expected. On the other hand, if the sum of the width of the

permanent teeth or the space required is greater than the

amount of the space available, there is arch perimeter space

deficiency and crowding would occur (Fig. 10.6).

Archlength vs. arch perimeter

Archlength and arch perimeter are two different entities

which are often misused to denote each other.

While arch perimeter is measured as a geometrical dental

arc, formed by the teeth at their incisal/cuspal edges,

archlength is the one which denotes basal perimeter on the

skeletal bases, where the teeth should be placed in normal

alignment.

In case of a normal occlusion with correct labiolingual

placement of anterior segment the archlength and arch

perimeter would have similar values. While in a case with

proclined maxillary anterior teeth the arch perimeter would

be greater.

Measuring archlength on the maxillary arch requires an

experienced eye to visualize the correct placement of incisors

on the basal arch. It may be a good idea to look at the

dentoalveolar segment and proclination of the anterior teeth,

from a lateral view while holding the model at eye level. One

needs to look at the anterior contour of the alveolus and

A

Fig. 10.7: The vernier caliper is used for the measurement of mesiodistal: A. Width of the individual tooth. The total tooth material is the sum of

mesiodistal widths of teeth mesial to the first molars, B. Curve of Spee is the depth at the lowest tooth on a plane from the incisor to the erupted

last molar

B


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Fig. 10.8A: The OPG is taken to ensure that all successive teeth are present in the dental arch

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Fig. 10.8B: Intraoral radiograph of a child in mixed dentition. The

mesiodistal widths of canines and premolars are directly measured on

radiograph taken by long cone method

locate the deepest point. The maxillary cast is then placed

on a flat base such as a table and viewed from the top of

the occlusal surfaces and palate to make a judgement about

the proclination of the incisors and location of the base of

the maxilla just below the anterior nasal spine.

The archlength is measured by contouring a piece of

brass wire on the occlusal view, such that it is aligned along

the dentoalveolar segments from the buccal to anterior

where the teeth should be ideally positioned. The incisor

edges would be about 2 mm labial to the deepest point on

the labial segment of the alveolus which governs the

anterior limit of the maxilla. In other words, the clinician has

to visualize post-treatment position of the incisal edges and

that is the point of placement of the brass wire in the

anterior segment. In lateral segments, the archwire follows

the contact points on the maxillary teeth. In case the arch

Fig. 10.9: The space available in the arch of a case of mixed dentition

can be measured with a caliper. The space required is the sum of the

mesiodistal widths of unerupted canine + first premolar + second

premolar. The difference is called leeway space

is narrow or wide, adjustments have to be made accordingly.

The length of the brass wire is marked mesial to first molars

and measured on a ruler (Fig. 10.7).

The available archlength implies the actual archlength

o f the dentoalveolar segments on the bony bases where all

the teeth need to be accommodated in normal alignment

without crowding/spacing, with proper mesiodistal

angulation (tip) and labiolingual position (torque).

If there is not enough room on the basal arch to

accommodate all the teeth in proper alignment and position,

the outcome is crowding/protrusion, or a combination of both.

Archlength deficiency

Children exhibit archlength deficiency because either the

archlength is too small to accommodate the size of the teeth

or the child may start with an adequate archlength but may

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Section II: Analysis of diagnostic records

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develop a deficient archlength from a variety of

environmental factors such as caries or early loss of

deciduous 2nd molars. Tooth size archlength discrepancies

can express as premature exfoliation of a primary canines

when the permanent lateral incisors erupt more so in the

lower arch. Eruption of the permanent incisors either too far

labially or lingually outside the line of the arch is indicative

of archlength deficiency. Midline shift due to unilateral loss

of primary canine in the mandible is of common occurrence.

Analysis of archlength during mixed dentition

The permanent incisors of children are much larger in

mesiodistal widths than their corresponding primary

incisors. In some situations eruption of the permanent

incisors results in marked crowding during mixed dentition.

For these children, a tooth size archlength analysis can

provide answers about future crowding and provide the

basis for an appropriate treatment plan. Methods of analysis

of archlength during mixed dentiion are:

1. Radiographic

2. Non-radiographic

3. Combination of above.

1. Radiographic method

In order to analyze the space requirement in mixed dentition,

it is necessary to estimate the size of unerupted permanent

teeth in order to calculate the space required. Traditionally

IOPA radiographs have been used to measure the mesiodistal

widths of the unerupted teeth (Figs 10.8, 10.9).

Disadvantage. The measurement of tooth size from the

radiograph is not free from error due to the inherent

distortion of the radiographic image.

Radiographic methods are based on the principle that if

we measure an object, which can be seen both in the

radiograph as well as on a cast, then we can compensate

for the enlargement of the radiographic image. The amount

of distortion can be calculated and the correct mesiodistal

width of the crown of the unerupted tooth can be calculated

by using the following formula:

X1Y1

X2~Y2

Xl=width of unerupted tooth whose width is to be

determined

X2=width of the unerupted tooth on the radiograph

Yl=width of erupted tooth as measured on the cast

Y2=width of the erupted tooth as measured on a

radiograph.

Since the accuracy of this method is dependent on the

quality of the radiographic image, periapical films are

preferred over panoramic films.

This is a very easy, practical and relatively accurate

method that does not require any prediction tables and can

be used in maxillary and mandibular arches.

2. Non-radiographic method

Researchers have calculated correlation among the size of

anterior and posterior teeth. By measuring size of an erupted

anterior tooth, it is possible to predict the size of the

unerupted canine/premolar from the prediction table. The

main advantage of non-radiographic prediction methods is

that they can be performed by measuring the erupted

mandibular incisor(s) without the need of additional

m easurem ents from radiographs. However, these

measurements are less accurate and have larger standard

error as compared with the correctly adjusted radiographic

methods.

a. Moyer's analysis3

This mixed dentition analysis utilizes Moyer’s prediction

tables and is based on the premise that there is a reasonably

good correlation between the size of erupted permanent

incisors and the unerupted canines and premolars as a

person with large teeth in one part of the mouth will have

large teeth elsewhere also, presumably having been

controlled by the same genetic mechanism (Table 10.1).

Advantages

• It can be done with equal reliability by the beginner

and by an expert

• It is not time consuming and does not require any

special equipment

• It can be done on the mouth as well as on the cast.

• It can be used for both the arches.

Step by step procedure for use of probability

tables

• Measure and obtain the mesial distal widths of the four

permanent mandibular incisors and find that value in

the horizontal row of the appropriate table (sex wise).

• Reading downward in the appropriate vertical column

obtain the values for expected width of the cuspids

and premolars corresponding to the level of probability.

• Moyer used 75% of probability rather than the mean of

50% since of the values distribute normally toward

crowding and spacing. Crowding is a much more serious

clinical problem and 75% predictive values thus protect

the clinician on the safe side.

• Mandibular incisors are used for the prediction of both

the mandibular and maxillary cuspid and bicuspid widths.

The amount of space available for the eruption of

permanent canines and premolars is determined by measuring

the distance between the distal surface of lateral incisor and

the mesial surfaces of first molar.

The predicted value is compared with the available

archlength to determine the discrepancy. If the predicted

value is greater than the available archlength, crowding of

the teeth can be expected. Whereas, if the predicted value

is less than the available archlength, it will result in spacing

of the teeth.

1


1 Table 10.1: Moyer’s analysis probability tables for predicting the sizes of unerupted cuspids and bicuspids

Mandibular bicuspids and cuspids

2 1|1 2 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 23.5 24.0 24.5 25.0 25.5

Males

95% 21.6 21.8 22.0 22.2 22.4 22.6 22.8 23.0 23.2 23.5 23.7 23.9 24.2

Females

95% 20.8 21.0 21.2 21.5 21.7 22.0 22.2 22.5 22.7 23.0 23.3 23.6 23.9

Maxillary bicuspids and cuspids

2 1|1 2 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 23.5 24.0 24.5 25.0 25.5

Males

95% 21.2 21.4 21.6 21.9 22.1 22.3 22.6 22.8 23.1 23.4 23.6 23.9 24.1

Females

95% 21.4 21.6 21.7 21.8 21.9 22.0 22.2 22.3 22.5 22.6 22.8 22.9 23.1

b. Tanaka and Johnston method4

Tanaka and Johnston developed prediction tables that were

similar to those of Moyer’s. While information on correlation

coefficients and standard errors of Moyer’s method, was

not available, the correlation coefficient of Tanaka and

Johnston method were r=0.63 for maxillary teeth and r=0.65

for the mandibular teeth. The standard errors were 0.86 mm

for the maxillary teeth and 0.85 mm for the mandibular teeth

(a coefficient of correlation close to 0.9 is considered very

high).1

• Estimated width of the mandibular canine and premolars

in one quadrant is determined by adding 10.5 mm to the

measured value of half of mesiodistal width of four

mandibular incisors.

• Estimated width of the maxillary canine and premolars

in one quadrant is determined by adding 11 mm to the

measured value.

This is a reasonably accurate method of mixed dentition

space analysis and does not require either radiographs or

reference tables.

c. Staley and Kerber method5'8

This method uses both IOPA X-rays and measurements on

dental casts. A revision of Hixon and Oldfather mixeddentition

prediction method (1958) was undertaken by

Stanley and Kerber on the same group of subjects used

originally by Hixon and Oldfather to develop their prediction.

These subjects were among those who participated in Iowa

Facial Growth Study.

Based on equations and computerised data analysis,

significantly improved prediction equations were developed.

A graph was made for clinical use in the prediction of

mandibular canine and premolar widths in mixed dentition

patients. This prediction graph is accurate to the nearest 0.1

mm. Their method requires measurement of the incisors on

models/clinically and of mandibular premolars on

radiographs.

Step by step procedure for analysis

1. Measure and add up widths of mandibular central and

lateral incisors on one side

2. Measure widths of unerupted premolars from IOPA

radiograph of the same side.

3. Sum of 1+2

4. Use the prediction graph to calculate widths of

unerupted canine and premolars.

For example, in a patient, if the sum of the central and

lateral incisor cast widths and the radiographic widths of

the first and second premolars on the right side are 28.3 mm

one finds 28.3 mm on the horizontal axis and follows it

upward to the prediction line, which runs diagonally across

the graph. From the point of intersection on the prediction

line, one moves left to the vertical axis to find the estimated

sum of the right canine and premolar widths (approximately

22.4 mm) (Fig. 10.10).

If measurements were available for only one side of the

arch, it can be reasonably assumed that the prediction for

one side would be very similar to that of the opposite side

of the arch.

• Measurement of severely rotated premolars on

radiographs is best avoided.

• A long-cone periapical radiographic technique should

be used in conjunction with this method.


E

5 17 I----------- ----------- -----------J— lJ — — — — ---------- ------------ L--------------------

22 23 24 25 26 27 28 29 30 31

«

Sum of 25, 26, X28, X29 or sum of 23, 24, X 29, X21

Standard error of estimate = 0.44mm

Fig. 10.10: Hixon and Oldfather prediction graph: Staley and Kerber developed a prediction chart based on Hixon and Oldfather which is accurate

to the nearest of 0.1 mm. Teeth numbers are according to ADA/Universal tooth numbering system. 20 (lower left 2nd premolar), 21 (lower left 1st

premolar), 22 (lower left canine), 23 (lower left lateral incisor), 24 (lower left central incisor), 25 (lower right central incisor), 26 (lower left lateral incisor),

27 (lower right canine), 28 (lower right 1st premolar), 29 (lower right 2nd premolar), X = X-ray.

The simple computations and the convenient graph

make this prediction method suitable for clinical use. The

standard error of estimate for the prediction graph is 0.44

mm (Fig. 10.10).

All the methods used to predict the widths of unerupted

premolars and canines in the mixed-dentition patient are

subject to some error. Methods and estimates with minimal

error are obviously preferable to those with larger errors.

Staley and Kerber method was comparatively more

accurate than Hixon and Oldfather.

The reasons of improvement were:

• Use of a computer, which employed 16 significant

digits in its computations. Hixon and Oldfather did not

have the use of an electronic computer.

• Oldfather’s measurements were taken on one side of

the arch only most commonly the left side whereas

measurements were taken on both sides of the arch for

Staley and Kerber method.

• Hixon and Oldfather used a Boley gauge that read to

the nearest 0.1 mm, whereas Helios dial calipers read to

the nearest 0.05 mm were used in Staley and Kerber

method.

• Premolars that were rotated on the radiographs were

not measured in Staley and Kerber method but were

measured by Hixon and Oldfather.

Formulation of probability charts and prediction

graphs for mixed dentition analysis in south

Indian children12

Moyer’s prediction tables were formulated primarily for

American whites. Considerable differences in tooth size

measurements have been reported in different ethnic groups.

Keeping ethnic variations in mind Subba Reddy and

coworkers14 formulated probability charts and prediction

tables for south Indian children to predict the mesiodistal

width of unerupted canines and premolars, from the

mesiodistal measurement of the erupted mandibular incisors.

Their sample was derived among school children from

Kerala, Karnataka, Andhra Pradesh and Tamil Nadu. Children

in age of 12-15 years who had fully erupted permanent

mandibular incisors and permanent mandibular and maxillary

canines and premolars, having normal occlusion were

chosen. They reported values of correlation coefficients (r

value) in the range from +0.54 to +0.78, and standard error

of estimate from 0.232 to 0.820. Norms were formulated

which could be used for the Indian population.

3. Combination

d. Nance's analysis9

Nance concluded that the length of the dental arches from

the mesial surfaces of the permanent first molars of the one


side to the opposite always shortened during the transition

from the mixed to the permanent dentition.

Procedure. Actual width of four mandibular incisors is

measured on the cast.

• The width of the unerupted canine premolars is

measured from the radiographs.

• In case one of the premolars is rotated, the width of the

premolar on the opposite side may be used.

• The total value indicates the amount of the space

needed to accommodate all the permanent teeth anterior

to the first permanent molars.

• The space available for the permanent teeth is

determined with a brass wire passing over the buccal

cusp and incisal edges of teeth from first molar to first

molar.

• Subtract 3.4 mm (in mandibular arch) and 1.8 mm (in

maxillary arch) from the total space available to

accommodate a decrease in the archlength as a result

of the mesial drift (late mesial shift—leeway’s space) of

the permanent first molars.

Space required-space available=amount of discrepancy

1 Table 10.2: B o lto n ra tio

Overall ratio (OR)

Factors influencing estimation of the tooth

size-archlength analysis

Several factors may influence overall calculations and

decisions on the true nature of the discrepancy. These are

mainly related to their labiolingual placement or proclination

and curve of Spee.

Incisor inclination and position.10 Orthodontic movement of

lingually inclined incisors in a labial direction increases the

archlength, whereas the lingual movement of the incisors

decreases the archlength. According to Tweed, inclining the

lower incisors one degree labially increases archlength by

0.8 mm and vice-versa. The inclination of the lower incisors

is measured by the angle formed by long axis of the

mandibular incisor with the mandibular plane on lateral

cephalogram. The anteroposterior tooth position can be

determined by measuring the perpendicular distance of the

incisal tip of the mandibular incisor with the nasion-B line.13

Curve of Spee.11 The depth of the curve of Spee is measured

as the greatest depth of the curve on both sides of the arch

in the premolar region. Flattening the curve of Spee can be

achieved either by supraeruption of premolars, intrusion of

Max‘12’ Mand ‘12’ Max‘12’ Mand ‘12’ Max‘12’ Mand‘12’ Max‘12’ Mand‘12’

85 77.6 92 84 99 90.4 105 95.9

86 78.5 93 84.9 100 91.3 106 96.8

87 79.4 94 85.8 101 92.2 107 97.8

88 80.3 95 86.7 102 93.1 108 98.6

89 81.3 96 87.6 103 94 109 99.5

90 82.1 97 88.6 104 95 110 100.4

91 83.1 98 89.5

Anterior ratio (AR)

Max ‘6’ Mand ‘6’ Max ‘6’ Mand ‘6’ Max ‘6’ Mand ‘6’ Max ‘6’ Mand ‘6’

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40.0 30.9 44.0 34 48.0 37.1 51.5 39.8

40.5 31.3 44.5 34.4 48.5 37.4 52.0 40.1

41.0 31.7 45.0 34.7 49.0 37.8 52.5 40.5

41.5 32.0 45.5 35 49.5 38.2 53.0 40.9

42.0 32.4 46.0 35.5 50.0 38.6 53.5 41.3

42.5 32.8 46.5 36.0 50.5 39.0 54.0 41.7

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incisors or acombination of both. Incisor intrusion requires

additional space in the bony bases or otherwise proclination

will result. A curve of occlusion formula is used to determine

the additional space required to flatten the curve of Spee.

The greatest depth of the curve is measured by placing

a rigid plastic square sheet on the occlusal surfaces of a

study model, in contact with the permanent molars and

mandibular incisors. The deepest point between the plastic

plate and the buccal cusps is measured with a Boley gauge.

The depths of the curve on the right and left sides are

added and the sum total is divided by two. An additional

0.5 mm is added to provide the total space required for

levelling the curve of Spee.9

Analysis of permanent dentition

a. Bolton's analysis13

Premise. Bolton’s analysis considers the ratio of the tooth

material of the maxillary arch to the mandibular arch, i.e.

mesiodistal widths of upper and lower teeth by nature have

predetermined proportions to maintain normal occlusion

relationship. An alteration in this balance would lead to

unsatisfactory occlusion which is exhibited as improper

intercuspation, overjet or spacing.

Bolton’s analysis is carried out by measuring the

mesiodistal widths of all permanent teeth (except second

and third molars) and then comparing the summed widths

of the maxillary to the mandibular anterior teeth, and the

total width of the upper and lower teeth with a standard

(Table 10.2).3

Anterior ratio less than 77.2% indicates maxillary anterior

excess whereas anterior ratio more than 77.2% indicates

mandibular anterior excess.

Bolton’s analysis helps in determining disproportion in

size between maxillary and mandibular teeth. If there is a

maxillary tooth material excess then it would lead to a large

overjet whereas if there is a mandibular excess it would lead

to crowding or negative overjet.

The overall ratio of 91.3% is derived by the following

formula:

Sum of mesiodistal widths of mandibular 12 teeth/sum of

mesiodistal widths of maxillary 12 teeth x 100

Mand. (6-6) x 100

Max. (6-6)

An overall ratio of less than 91.3% indicates maxillary tooth

material excess whereas overall ratio of more than 91.3%

indicates mandibular tooth material excess.

The anterior ratio of 77.2% is derived by the following

formula:

Sum of MD of anterior mandibular six anterior teeth/sum

of MD of maxillary anterior six teeth x 100

AR = Mand. (3-3) x 100

Max. (3-3)

discrepancy of less than 1.5 mm is rarely significant, but

larger discrepancies create treatment problems and must be

included in the orthodontic problem list.

b. Carey's analysis14

Discrepancy between the archlength and the tooth material

is a common cause of malocclusion. Carey’s analysis helps

in determining the extent of the discrepancy.

Archlength is determined by contouring a piece of brass

wire touching the mesial surface of first molars, passed over

the buccal cusp of premolars and along the incisors from

one side to the other such that it is aligned along the

dentoalveolar segment where the teeth should be ideally

positioned, i.e. if the anterior teeth are well aligned and not

protrusive the wire passes over the incisal edge of anteriors.

In case the incisors are proclined then the wire is passed

along the cingulum of anterior teeth whereas if the anterior

teeth are retroclined, the wire in the anterior segment

passes labial to the teeth.

The tooth material is determined by sum of the mesiodistal

width of the teeth anterior to the first molars (i.e. 2nd

premolars to 2nd premolars).

• If the difference between the archlength and the tooth

material is between 0-2.5 mm, it indicates minimum

tooth material excess and proximal stripping can be

considered to reduce the tooth material.


material is between 2.5-5 mm, it indicates the need to

extract 2nd premolars.


material is more than 5 mm, it indicates the need to

extract 1st premolars.

3. E models or digital models

E Models are three-dimensional digital models that help to

eliminate the need for traditional plaster models in

orthodontic practice.15

There are essentially two different technologies to

produce digital models:

1. 3D scanner-based which can work either on models or

directly mouth.

2. 3D CT-based uses alginate/rubber base impressions of

the dental casts.

Methods of making E models

3D Scanners. In order to make E models, the orthodontist/

laboratory uses 3-D images that are recorded through laser

scanner. This laser scanner uses a flashing white light,

much like a video camera which digitally maps the teeth or

plaster models into precise, high resolution, threedimensional

electronic records. These pictures of teeth are

sent to the computer to build a complete model of the

patient’s teeth and are stored on the computer’s hard disk

which can be assessed like any other digital picture. The

models are viewed as 3D images on the screen and are fairly


acci

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Fig. 10.11: A,B. Current technology makes use of ultra sophisticated computed tomography to radiographically scan dental impressions and reconstruct

the study models using highly advanced computer softwares. Others use hand held 3D scanners, C. Digital models with anatomical part prepared

from scan of alginate impressions, D. Space analysis on digital models. Alternate methods include hand held 3D scanner which can be directly used

in mouth, E. Digital models are virtual reality models. Moldels can be moved and rotated to visualize it on screen. (Courtesy: OrthoPrpof Netherlands)


I

accurate in dimension. The E models can be transported as

files from one orthodontist to another, and to the patients

or can be put on web.

3D CT.18 In this method, the alginate impressions of a

patient are transported in a special tray to an industrial

scanner which like a CT scan of the skull scans the

impressions and uses highly sophisticated software to

construct a 3D image of the dentition/oral structures. The

artistic portion of the models are then superimposed for the

purposes of presentation and aesthetics. These models can

be viewed from all possible views on the computer screen.

“OrthoProof” of Holland utilises this method. This service

is commercially available in Europe, USA and Australia. E

Models have dimensional accuracy, high *resolution and

great life like clarity (Fig. 10.11A-E).

Advantages of E models

Digital models deliver significant benefits that leverage the

power of digital technology to advance the practice of

orthodontics.

• E models eliminate the production, storage and archiving

costs of plaster models, freeing up space and allows

online digital file storage with 24-hour access.

• They eliminate the geographic barriers of plaster models

and paper files for multiple site practices and empower

dental professionals with access via the Internet from

any location.

• Digital models allow easy and seamless communication

between orthodontists, general dentists, oral and

maxillofacial surgeons, and patients and therefore

facilitate comprehensive interdisciplinary treatment

planning.

• Most of the digital models viewing software include

analytical tools to facilitate quick and easy measurements

of teeth and archlength.

• Since E models can be measured directly on screen,

this is time saving, and therefore enhances the efficiency

in orthodontic diagnosis, treatment planning and patient

education processes.

The orthodontist can use the 3-D virtual model of teeth

and then plot the precise individual tooth movements for

the entire course of treatment.

Digital set-up

• When using digital models treatment planning occurs

on the computer, where the orthodontist is able to

precisely map out the entire treatment sequence.

• There are also options available to design custom

archwires that work more efficiently and thus require

fewer wire changes and adjustments throughout

orthodontic care and thus reducing treatment time.

These commercial options are now available through

several services in USA and other countries.

Disadvantages of E models

Digital models have some inherent disadvantages:

• Digital models are technique sensitive as the whole

procedure of making the E models depends upon the

proper scanning of the teeth and adjacent hard and

soft tissues. There should be no vibration or shaking

of the hand while scanning and also there should be

no patient movement. Although this may not be

applicable to 3D CT-based methods, time lost in

transporting impressions and resultant distortion could

be a contributor to inaccuracy if not taken care of.

• A personal touch or feel is absent with the use of

digital models, since a digital image can only be seen

on a computer or printed on paper. There are no actual

study models.

• Conventional study models made from plaster are better

appreciated as these can be seen and felt by the

patient.

• With digital models, there are chances of data loss as

all the information is stored on the computer.

Validity of tooth size and arch width measurements using

conventional and three-dimensional virtual orthodontic

models has been evaluated by Zilberman et al16 and Santoro

et al.17 Results showed that measurement with digital caliper

on plaster models showed the highest accuracy and

reproducibility.

Authors compared measurements made on digital and

plaster models to evaluate the reliability of the OrthoCAD

system. The results showed that the digital measurements

are smaller than the manual measurements. However, the

magnitude of these differences ranged from 0.16 to 0.49 mm,

and the authors concluded it to be not clinically relevant.

Facial photographs

Evaluation of facial photographs essentially involves

recording of the findings on clinical examination for future

reference and confirmation of the clinical observations

though a detailed analysis. It may be noted that conventional

photographs are two-dimensional pictures of the threedimensional

structures. Therefore, these do not substitute

a keen and close examination of face by the clinician.

Photographs are static images, though the recently

introduced video imaging and analysis overcomes this

limitation to a great extent.

The clinical facial photographs are essentially grouped

as extraoral and intraoral.

Extraoral photographs

Extraoral facial photographs should be taken with the frame

from slightly above the scapula, at the base of the neck.

This permits visualization of contours of the neck and chin

area. The superior border should be slightly above the top

O rthodontics: Diagnosis and m anagem ent of m alocclusion and dentofacial deform ities

Fig. 10.12: The standard set of extraoral photographs required for complete diagnosis. Additional views such as bird’s eye view may be needed for

patients with facial deformities, and cleft lip and palate patient

of the head and the right border slightly ahead of the nasal

tip in lateral profile. The left border ends just behind the left

ear. Hair should be pulled behind to permit visualisation of

the whole face.

The following views are routinely taken for orthodontic

diagnosis and treatment planning (Fig. 10.12).

1. Frontal photographs

2. Profile photographs — left and right lateral, in natural

head position.

The facial photographs are taken with the subject in

natural head position and in a relaxed mood. Some clinicians

prefer to take photos with the Frankfort plane orientation

and using the cephalostat head frame. The cephalostat

head holder permits repeated orientation of the face during

and after treatment, and thereby may permit a standardised

comparison. The differences perceived in profile due to the

head tilt can be eliminated by taking an extraoral photo in

the same orientation as before in a head holder.

In order to evaluate the relationship of the lips and teeth

during smile, following views can be added:

• Frontal smile

• 45-degree smile view.

Photographs for subjects with facial deformities. In addition

to the standard photos mentioned above, children with

facial deformities need to be evaluated from various other

views. These include:

• A three-quarter view photo of the face helps in the

evaluation of midface deformities particularly nasal

deformity.

• Photographs of 34 view of the smiling face provide the

best impression of a person’s facial appearance. Also

3A views can be used to judge the patient’s facial

profile.

• A submental view or a bird’s eye view helps to evaluate

the upper lip, nose and chin deformities. This view is


Fig. 10.13: The standard set of intraoral photgraphs required for records and complete diagnosis

often required for evaluation of the lip contour and

nasal deformity in cleft lip and palate children.

Intraoral photographs (Figs. 10.13-10.14)

Intraoral photographs supplement clinical findings of

occlusion which are also recorded through the dental study

models. In addition, the intraoral photos help review hard

and soft tissue findings that exist before treatment. These

include white spot lesions, fluorosis, hyperplastic areas,

and gingival clefts. The following views are essential:

• Frontal

• Right and left buccal views

• Occlusal view of the maxilla and mandible.

1. Photographs for functional shift

In case of a midline shift and facial deviation which can be

observed during closing and opening, additional views may

be recorded. These include:


• Extraoral view: Face at rest and in centric occlusion

• Intraoral views: Frontal view at initial contact on closing,

and frontal view with centric relation.

These views are most useful in differentiating jaw

deviations or skeletal malocclusions (arising due to

premature occlusal contacts) from the true skeletal deviations

particularly in the growing children.

A child in early mixed dentition may develop functional

forward or lateral shift of the mandible due to premature

contacts with the erupting tooth or a retained deciduous

tooth resulting in difficulty in closing the jaw. The closing

mandible would therefore be guided to an abnormal centric

position to avoid the premature contact and hence may

shift laterally or forward. A forward shift would result in a

pseudo-class III pattern, while lateral shift appears as a

deviation of the jaw. A photographic record can be made of

the initial contact and centric positions that will help to

analyse the case for treatment planning.

The analysis of the facial photographs is covered in the

examination of the face itself.

Analysis of face heights

Frontal examination. Divide the face vertically into facial

thirds-horizontal lines at the hairline, nasal base and menton.

In the middle third, philtrum height is important in its

relationship to the incisors and commissures of the mouth.

The commissure height should not be more than 2-3 mm

greater than the philtrum height in adults. In adolescents,

philtrum height could be several mm short. A short philtrum

height in adults makes the maxillary lip line unaesthetic.

The base of the nose has a ‘Gull in flight’ contour. Nares

should be barely visible when the head is in natural head

position. The columella should be slightly lower than and

parallel to the alae when viewed in any direction. The

contour of the alae from the base of the nose to its tip

should be in the form of an S.

The lower third of the face comprises the upper lip which

makes the upper one-third and the lower lip and chin which

make up the rest of the lower two-thirds.

Transverse relationships. The transverse facial proportions

follow the rule of fifths, i.e. the face is divided into five

symmetric and equal parts, and each segment should be of

one eye width.

Central fifth o f face. It is delineated by inner canthus of

the eye. A line from the inner canthus should coincide with

the ala of the base of the nose, i.e. the intercanthal distance

should be equal to the alar base width. This is, however,

influenced by ethnic characteristics.

Medial fifth o f face: Width of the mouth and interpupillary

distance should be the same. Line from the outer canthus

should coincide with gonial angles of the mandible, i.e. the

bigonial width should equal the outer canthal distance.

Outer fifths o f the face. From the outer canthus of the eye

and gonial angles to the helix of the ear. Racial characteristics

influence this proportion to a great extent.

Profile

Lip chin throat angle: Angle between lower lip and deepest

point along the neck chin contour), i.e. R point should be

approximately 90°. An obtuse angle is unaesthetic and

becomes more so as the angle increases. This often reflects:

Chin deficiency

Retropositioned mandible

Lower lip procumbency

Excessive submental fat

Low hyoid bone position.

N eck chin angle. Cervicomental angle should be

approximately 90°. The angle is more obtuse in females as

compared to males. Soft tissues sag in older individuals

A

Fig. 10,15: Skeletal pattern and profile: A. Class I, B. Class

B

large ANB, and C. Class III negative ANB

i


A

Fig. 10.16: High angle and low angle skeletal pattern: cephalograms of two class II malocclusion patients

B

contribute to less than ideal submental form.

Bird’s eye view photographs

It is a supplemental aid in diagnostic photographic records.

It is taken with the patient’s head hyperextended to about

45°. It is useful to assess asymmetry and projection of

anterior cranial vault, orbital areas and cheeks. Nasal

deformities are also well documented and studied in this

view. It is especially recommended in cleft lip and palate

patients where bony deformities of one or both sides

become comprehensible. The deformities of the soft tissues

of the lip and nose area are also well studied from this view.

Cephalometric evaluation (cephalogram-lateral

view) (Figs. 10.15-10.18)

The clinician needs to carefully evaluate the lateral

cephalogram of the head for any gross abnormalities and

pathology which may be accidental findings in an otherwise

normal child. These include radio opacities in the cranium,

lack of union of sutures, stones in the submandibular gland

or bony pathologies in the radiograph which may be

radioopaque or radiolucent lesions in the jaw bones,

supernumerary tooth/teeth, and odontome.

The other important feature that needs to be related to

the clinical examination is the slope of mandibular plane and

gonial angle. A close look at a lateral cephalogram should

reconfirm the clinical observations of ‘face’ in terms of

growth pattern, i.e.

• Skeletal sagittal relationship, i.e. normal/class ll/class

m

• Horizontal or vertical or normal growth pattern

• Proclination of maxillary and mandibular anterior

dentition.

These observations are further confirm ed by

cephalometric analyses which are given in detail in the

Chapter 11 on Cephalometrics: Historical Perspectives and

Methods.

Another important consideration in the evaluation of

lateral cephalogram is to know the nature and severity of

malocclusion and to know its components, i.e. skeletal or

dental, within these two categories we further try to diagnose

which jaw is more affected.

Lateral cephalogram also help the clinician in examining

the respiratory passage which may be very narrow due to

inherent anatomical variations or blocked partially or fully

with enlarged adenoids. Cephalograms should also be

evaluated for the assessment of soft tissues particularly

thickness at chin.

In a nutshell, a cephalogram helps the clinician to

diagnose the components and the severity of malocclusion

along with the growth trend (Fig. 10.16).

Orthopantomogram (panoramic radiography of

the maxilla and mandible)

Orthopantomogram (OPG) or the panoramic view of the

mandible and maxilla provides a host of information on a

single film. It provides an overview of the bony structures

of the jaws and teeth including the TMJ and dentition

which may be useful, particularly in growing children with

mixed dentition where host of information is needed on

L


Deep labiom ental sulcus

Thick chin

Fig. 10.17: Typical skeletal pattern of Class II division 2 case. Bony chin is retrognathic, the soft tissue chin is thick, and there is a deep labiomental

sulcus. The mandibular plane is flat and there is a lack of antegonial sulcus

Fig.

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Fig. 10.18: A 13-year-old young girl with the chief complaints of protrusion of front teeth. On routine investigations, a cystic radiolucency was

accidentally discovered in the midsymphyseal region. It is somewhat visible on a lateral cephalogram and obvious on OPG

eruption status, shedding, number of teeth and so on (Fig.

10.19).

The technique of making an OPG involves the rotation

of the film in a cylindrical cassette and radiograph tube

simultaneously around the structures to be radiographed,

i.e. mandible and maxilla. The inherent technique produces

an image, which is somewhat magnified and distorted than

the conventional radiographs. Also, the magnification may

be unequal in different parts. The midline structures of the

face and dentition show greater variation than the lateral

parts. The information gathered from the OPG can be

reconfirmed by other radiographs needed for the estimation

of the size and length of root, location of the carious

lesions like proximal caries and size of the bony lesions

which may appear larger than their actual size.

An OPG should be oriented on a viewer with the left of

the face to the right of the clinician as if the patient is facing

the clinician. Then an overview of the film for any gross

abnormalities or areas of excessive densities or radiolucent

lesions, may be considered. A good diagnosis can be made

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Section II: Analysis of diagnostic records ■ 143

Fig. 10.19: Normal bony architecture seen in a panoramic view, Fully digital OPG of a 18-year-old woman (Courtesy of Dr. Brigitte Kasmayer,

dental surgeon, private practice, Baden, Austria, SIRONA Dental Systems Bensheim, Germany)

from a film which has been taken and developed correctly.

With the availability of the digital OPG, it is now possible

to easily adjust the contrast and brightness of the film.

Evaluation of the OPG involves an assessment of:

1. The bony structures and symmetry (mandible, midface

and TMJ)

2. Dentition and associated structures

3. Vertebra and parts of skull

4. Soft tissues.

The bony structures and symmetry (mandible,

midface and TMJ)

Evaluation of the mandible can begin with the examination

of the temporomandibular joint (TMJ) and its compartments.

Abnormal situations that can exist include an abnormal

flattening of the condyle or articular eminence, or a forward

position of the condyle.

It is necessary that a comparison be made between left

and the right side structures. Abnormal findings of common

occurrence in condyles include unilateral condylar

hyperplasias, flat condyle heads and signs of trauma to the

condyle. The condylar fractures/haematomas are relatively

common findings in younger children, which may manifest

as malunited fractures, healing fracture lines, flat condyle

heads or condyles with decreased or absent disc space,

which is a sign of ankylosis.

While examining the body of the mandible, one should

look for the anatomical structures like the external oblique

ridge, the mental foramen, and the mandibular canal. From

an orthodontic point of view, the right and left sides should

be symmetrical for ramus height, corpus length, gonial

angle and overall shape of the mandible. An unusually

short ramus is often associated with a vertical growth

pattern and skeletal open bite. The other signs of vertical

growth tendencies would be large gonial angles, and flatter

border of the mandible (the one without a sweep).

Presence of a sharp and accentuated antegonial notch is

an indicator of the hampered growth of the mandible. A

prominent antegonial notch is often seen in the cases of

ankylosis of the TMJ. A large gonial angle (open gonial

angle) is seen in the skeletal class III subjects.

Evaluation of the midface involves an assessment of

symmetry of the structures between the left and right side.

A gross asymmetry will appear on the OPG. The structures

that are readily seen on the OPG are:

• Contours of the maxilla (which limits at the tuberosity

in the 2nd/3rd molar region)

• Pterygomaxillary fissure

• Zygomatic buttress/zygomaticomaxillary sutures

• Orbital rims and infraorbital foramen

• Maxillary sinus

• Floor of the midnasal septum and the conchi.

Any abnormality or pathology that is readily seen on the

OPG should be recorded. The abnormalities that may be

specifically looked for in an otherwise normal OPG include:

• Symmetry of the structures between left and the right

side for the shape and size

• Any deviation of the nasal septum, which may be

responsible for the partial or full obstruction of the

nasal passages

• Thickened concha in the nasal floor blocking the nasal

passages


• Prominence of the orbital rims (a hypoplastic maxilla

may show absence of rims)

• Level of the rims (an abnormal transverse cant of the

maxillary plane can be an indicator of the maxillary

deformities)

• A discontinuity of the maxillary alveolus and cleft can

be indicators of the bony cleft seen in the cleft lip and

palate patients.

Dentition and associated structures

• An OPG provides a bird’s eye view of the entire

dentition and its supporting bone. It is extremely helpful

during the mixed dentition stages, where it is important

to ascertain the number, size, eruption status of the

teeth or the presence of root abnormalities, missing or

supernumerary teeth.

• An orthodontist should attempt to move teeth only if

sufficient amount of bone is available. Then the

complement of teeth present should be ascertained,

which becomes all the more important if the patient is

in mixed dentition stage so that one can relate it to the

chronological age. This helps in the decision to maintain

space in cases where there is premature loss of

deciduous teeth. Further, the decision of serial

extractions depends upon the stage of eruption of

premolars and canines, which can be assessed on the

OFG.

• The stage of root development of mandibular canine

can also be helpful in the assessment of skeletal age

of a child. It indicates whether peak growth is complete

or is remaining and helps in deciding whether

orthopaedic corrections can be attempted or not.

• The OPG X-ray may also aid in identifying the state of

eruption of third molars so that we can predict relapse

of crowding in future.

• OPG gives an overview of the presence of caries,

restorations, periapical pathoses, bone loss, furcation

involvement, impacted/unerupted teeth, internal/external

root resorption, retained roots and marginal bone height

and also the path of eruption of teeth. Evaluation of

impacted teeth hold great importance as the angulations

and position of the impacted tooth can determine their

prognosis.21

• OPG is extremely helpful in monitoring the eruption of

the permanent teeth, particularly in cases of suspected

maxillary canine impactions.

Analysis of diagnostic records

for assessing growth_________

1. Physical growth

2. Hand-wrist radiograph to get information on skeletal

age.

3. Cervical vertebrae maturation index

The examination of the orthodontic patient should include

Age in years

Fig. 10.20: Scammon growth curve

an assessment of the growth status of the individual

especially that of the craniofacial complex since different

parts of the face grow at different rates and times. The

developmental status of a child can be assessed using

growth indicators such as the peak growth velocity in

standing height, chronological age, radiographic assessment

of skeletal maturation, and staging of dental development.

Skeletal maturational status can have considerable influence

on the diagnosis, treatment goals, treatment planning, choice

of mechanotherapy and the eventual outcome of the

orthodontic treatment.

Peak growth velocity

Annual measurements of an individual’s stature over a long

period of time can be used to illustrate growth in one of the

following two ways:

1. Distance curve or cumulative curve

2. Velocity curve or incremental curve.

The distance curve is drawn by plotting the stature of

a child against age to indicate the height achieved at each

age. Velocity curve indicates the rate of growth of a child

over a period of time. Height velocity is expressed as

centimetres per year. The distance curve shows the actual

size of a particular parameter, and the velocity curve indicates

the rate of change in that parameter.

Richard Scammon20 summarised the growth curves of the

tissues of the body to four basic curves. The curves cover

the postnatal period of 20 years and assume that during

that span of life, adult dimensions have been achieved and


have 100% of their values, starting at birth with zero per

cent. For each year, each curve has a certain percentage of

its adult value. He proposed four curves, namely lymphoid,

neural, general and genital curves. When increments of

growth are plotted on a chart to form a velocity curve, the

rate of growth is seen to decrease from birth to adolescence,

at which time a marked spurt in height growth is seen in

both sexes at puberty. This is known as the adolescent

spurt, the prepubertal acceleration or the circumpubertal

acceleration. The spurt begins at the age of about 10.5 to

11 years in girls and at age 12.5 to 13 years in boys. The

spurt lasts for about 2 to 2.5 years in both sexes (Fig. 10.20).

Chronological age

There can be variation in the developmental status of the

child with respect to the chronological age because of the

nutritional status, metabolic and endocrine disorders and

environmental factors. Hence, chronological age by itself is

not an accurate indicator of the stage of development of the

child.

Skeletal maturation

The standard age old, reliable and perhaps the most widely

used method for skeletal age evaluation is the hand-wrist

bone analysis which is performed on a radiograph. However,

for an orthodontic patient, assessment of hand-wrist

radiograph entails additional ionic radiation exposure to a

growing child in addition to the routine radiographic records.

Greulich and Pyle reported a precise sequence of hand and

wrist bone ossification on hand-wrist radiographs. Since

their work in 1950s, it has remained one of the most

standard work on skeletal growth and its association with

chronological age with the update of their atlas in 1959.21,22

1 Table 10.3: Skeletal maturity indicators (SMI) 1

Width of epiphysis as wide as diaphysis

1. Third finger— proximal phalanx

2. Third finger— middle phalanx

3. Fifth finger— middle phalanx

Ossification

4. Adductor sesamoid of thumb

Capping of epiphysis

5. Third finger— distal phalanx


7. Fifth finger— middle phalanx

Fusion of epiphysis and diaphysis

8. Third finger— distal phalanx

9. Third finger— proximal phalanx


11. Radius

Fishman (1982)23 developed the system for the evaluation

of skeletal maturity on hand-wrist radiograph, and

investigated its association with craniofacial growth. He

called it skeletal maturation assessment (SMA) which is

based on skeletal maturity indicators.

The system uses only four stages of bone maturation:

1. Epiphyseal widening of the phalanges

2. Ossification of the adductor sesamoid of the thumb

3. Capping of epiphyses over their diaphyses

4. Fusion of epiphyses and diaphysis.

These stages of bone formation are found at six

anatomical sites located on the thumb, third finger, fifth

finger and radius.

Eleven maturity indicators of skeleton are depicted in

Table 10.3.

He simplified SMI as given in the above scheme. One

needs to first look for presence of adductor sesamoid on

thumb. If adductor sesamoid is seen, SMI applicable will be

of sesamoid or an SMI-based on fusion or capping (Table

10.3).

If adductor sesamoid is not seen applicable, SMI will be

of early epiphyseal widening.

Fishman found that alterations in maturational

development are directly related to growth velocity.

Accelerations and decelerations in the rate of general

growth are accordingly seen in maturational development in

hand-wrist radiographs.

Maximum growth velocity for stature height occurred

when capping of epiphysis over diaphysis takes place in

middle phalanx of third finger in males and in distal phalanx

of third finger in females.

Both, mandible and maxilla reached maximum growth rate

when capping of epiphysis over diaphysis occurred in

middle phalanx of fifth finger in the male group and in

middle phalanx of third finger in case of females.

The growth of the maxilla and mandible continues late

after completion of the statural height. It was mandible that

showed much later maximum completion compared to maxilla.

Females tend to show greater growth velocities and earlier

maturation in stature in the maxilla while mandibular velocities

are higher in males. After the growth completion, growth

velocities diminish more rapidly in females than in males.

Cervical vertebrae maturation index (CVMI)

The size and shape changes in the bodies of five cervical

vertebrae (second through sixth) are a good indicator of

skeletal maturity. These can be assessed on a lateral

cephalogram. Since the pioneer work of Lamparski, much

research has been done in this field, and its association

with skeletal maturity and craniofacial growth.24

It is now well established and proven through a series

of studies that changes in the shape of vertebrae represented

by concavity of the inferior edge and vertical height can

help determine skeletal maturity and residual growth


j

potential.25"27 Lately, it has been demonstrated that this

method was valid regardless of the race of the subjects

analyzed. 28

Baccetti, Franchi, McNamara29 have modified (2002) the

CVMI method to five cervical vertebral maturational stages

(CVMS) on the basis of shape and size through 2nd to 4th

vertebrae and related the stages to mandibular growth.

• CVMS I: Lower borders of all the three vertebrae are

flat, with the possible exception of a concavity at the

lower border of C2 in almost half of the cases. Bodies

of both C3 and C4 are trapezoid in shape (superior

border of the vertebral body is tapered from posterior

to anterior). The peak in mandibular growth will

occur not earlier than one year after this stage.

• CVMS II: Concavities are present at the lower borders

of both C2 and C3. Bodies of C3 and C4 may be either

trapezoid or rectangular, horizontal in shape. The peak

in mandibular growth will occur within one year

after this stage.

• CVMS III: Concavities are now present at the lower

borders of C2, C3, and C4. The bodies of both C3 and

C4 are rectangular horizontal in shape. The peak in

mandibular growth has occurred within one or two

years before this stage.

• CVMS IV: Concavities at the lower borders of C2, C3,

and C4 are still present. At least one of the bodies of

C3 and C4 is squared in shape. If not square, the body

of the other cervical vertebra is still rectangular and

horizontal. The peak in mandibular growth has

occurred not later than one year before this stage.

• CVMS V: The concavities at the lower borders of C2,

C3, and C4 are still evident. At least one of the bodies

of C3 and C4 is rectangular vertical in shape. If not

rectangular vertical, the body of the other cervical vertebra

is squared. The peak in mandibular growth has

occurred not later than two years before this stage.

It has now established that the CVMs method can be

considered as an efficient and a repeatable procedure. This

method presents the advantage of using the lateral

cephalogram, and hence obviates need for an additional

hand-wrist radiograph.

Dental age

The Dental age has been based on two different methods

of assessment. The most commonly used method is the

observation of age at which the primary or the permanent

teeth erupt. The second method involves the rating of the

tooth development from crown calcification to root

completion by using radiographs of the unerupted and

developing teeth. The commonly used method of dental

development stages are given by Demirijan et al30 as follows:

Stage D: Crown formation is completed down to the

cementoenamel junction. The superior border of the pulp

chamber in the uniradicular teeth has a definite curved form,

being concave towards the cervical region. Projections of

the pulp horns, if present, give an outline shaped like an

umbrella top. Beginning of root formation is seen in the

form of a spicule.

Stage E: Walls of the pulp chamber now form straight lines

whose continuity is broken by the presence of the pulp

horn, which is larger than in the previous stage. Root

length is less than the crown height.

Stage F: Walls of the pulp chamber now form a more or less

an isosceles triangle. The apex ends in a funnel shape. Root

length is equal to or greater than the crown height.

Stage G: Walls of the root canal are now parallel and its

apical end is still partially open.

Stage H: The apical end of the root canal is completely

closed. The periodontal membrane has a uniform width

around the root and the apex.

The canine stage F indicates the initiation of puberty

and stage G is indicative of peak height velocity (PHV). The

use of dental age as a means of evaluating the developing

age of the child is not very accurate because of the wide

variations in the timing of eruption, the influence of local

and environmental factors, and the fact that several or no

teeth may erupt during the same time interval.

Facial growth spurts

Both boys and girls experience growth spurts in linear

dimensions of the cranial base, maxilla, and the mandible. It

has been reported that maximal overall vertical facial growth

(N-Me) is coincident with maximum standing height growth

velocity.31

A modest correlation has been found between mandibular

growth rate (Ar-Po) and standing height growth velocity

during the pubertal growth spurt in males and females.

Peak mandibular growth velocity was preceded by the

appearance of sesamoid by 0.72 years in males and 1.09

years in females. Hence, appearance of adductor sesamoid

on hand-wrist can give a definite clue on the mandibular

growth.

Hence, peak height velocity, the state of skeletal

maturation assessment and the dental development could

provide a reasonable clue to the facial development.

Peak height velocity shows maximum correlation with the

craniofacial growth. Thus, in clinical practice, the successive

height of the patients attending the orthodontic clinic

should be measured. That would be helpful in identifying

the period of growth spurts of the patients especially with

reference to the craniofacial growth.

PA view cephalograms32'34

Besides taking lateral cephalograms for diagnosis and

treatment planning of an orthodontic case, a posteroanterior

cephalogram is required for the assessment of dental and

skeletal widths and skeletal asymmetries.32


PA cephalogram holds unprecedented importance in

i I planning for orthognathic surgery (when taking lateral and

‘ frontal VTOs), in treatment of facial deformities, TMJ splint

therapy, functional jaw orthopaedics and evaluation of the

improvements in facial or dental proportions or symmetry in

transverse dimensions.

Common clinical conditions that warrant need for P-A

cephalograms for detailed analysis include:

; Ankylosis of the temporomandibular joint. It has been

t associated to undiagnosed injury to the TMJ, malunited

fracture(s) of the TMJ and injury to TMJ during forceps

delivery.

The growth of mandible on affected side is restricted;

thus on PA cephalogram a small ramus and corpus can be

r visualized with the deviation of the chin to the affected

i side. There would be a cant in the occlusal plane, which is

higher on the affected side. With bilateral ankylosis of the

TMJ both the sides are affected resulting in a small chin,

obliteration of the TMJ spaces and small ramus and corpus

length. Such cases can be sometimes mistaken for agenesis

probably because it may be impossible to identify the

J condyle. In agenesis of the condyle, the mid line of the jaw

is also deviated towards the abnormal side, but the actual

development of chin is normal.

Unilateral condylar hyperplasia* Unilateral condylar

hyperplasia is a slow and progressive enlargement of the

j* condylar head resulting in excessive growth of the mandible

t on the affected side and dentoalveolar and skeletal

i compensations of the maxilla. It is usually seen after 10

i j years of age. The PA cephalogram reveals deviation of the

chin to opposite side. The effected side exhibits a large

r mandibular corpus and ramus. Condylar hyperplasia may

j manifest itself as a bilateral condition with excessive growth

of mandible on both the sides, presenting as an increased

transverse dimension with bulbous condyles.

Facial asymmetry. Facial asymmetry with large mandibular

length can be a feature of class III malocclusion. Large

mandibular length may be accompanied by a small or

normal maxilla.

1 Congenital hyperplasia of the face. It is recognized at birth

or soon afterwards, establishing an important differentiation

from the hyperplastic condyle, which is not evident till the

age of 10 years. The characteristic feature of this condition

* is a progressive asymmetry of jaws. On serial cephalograms,

I it is seen that the affected jaw grows in size at a faster rate

i than the opposite side. Though enlargement is present but

the shape and structure of the bone are normal.

L

Cleft lip and palate. The most common cause of asymmetry

seen in PA cephalograms is cleft lip and palate. Clefts may

he unilateral or bilateral. It may be cleft of lip, palate or

alveolus, complete or incomplete. In every case, certain

amount of asymmetry is present which can be objectively

evaluated on a PA cephalogram.

Radiography ascertains the margins of the cleft. When

unoperated, a radiolucency may be detected between the

central or lateral incisor area or lateral incisor or canine area,

wherever the cleft is situated. It is possible to analyze the

precise alteration in outline of the maxilla and facial bone

and to localize region of collapse of the dental arch and

adjacent maxilla. Usually there is no alteration in lateral extent

of maxillary antrum in cleft cases. Operated cases of unilateral

and bilateral cleft lip and palate exhibit smaller transverse

widths of the maxilla and a comparatively large mandible.

Congenital and chromosomal abnormalities. They affect

the craniofacial region usually present with some kind of

facial asymmetry and therefore, would need a detailed

examination on PA cephalogram and possibly 3D CT scan.

Evaluation of the PA cephalogram

A PA cephalogram would require a careful and attentive

evaluation of the dentofacial and associated structures.

This is usually followed by a detailed cephalometric analysis.

A detailed analysis of the PA cephalogram can be performed

with the tracing of the bony and dental structures to be

studied (refer to Chapter 11 on Cephalometrics).

Recent advancements in

orthodontic diagnostic aids

Stereophotogrammetry

The most promising method of soft tissue recording the

stereophotogrammetry image-based capture system. This

procedure involves the use of a pair of stereo-video cameras

to capture a stereo-image pair of each side of the face.The

software then allows the construction of a photorealistic 3D

facial model. The model can be rotated, translated and dilated

on the computer screen. In order to register and superimpose

by CT scanners and data generated by the 3D image-based

capture system, the two sets of data have to be converted

into a common 3D file format, which is able to handle 3D

models with or without associated texture files.

During the planning procedure, the bone and teeth

position can change, accompanied by a corresponding soft

tissue coordinate change. The generic mesh would then be

draped with a cartograph of the patient’s face to produce

a texture-mapped image of the face. Stereophotogrammetry

has surgical and orthodontic prognostic implications though

the accuracy of the soft tissue generic mesh to the 3D CT

model has not been assessed using this method of 3D

planning.

Technetium scan35

This technique involves imaging the skeleton using gamma

emitting isotopes or labelled radio-pharmaceuticals which

when injected into the bloodstream, gets concentrated in

the bone, especially in areas of active proliferation or areas

high in cellular activity (Fig. 10.21).


The subject under investigation is given injection of

20mCi of 99mTc-labelled hydroxyethyledene diphosphonate

(HEDP) in 1-2 ml of sterile saline solution. Patients are

instructed to drink a large amount of fluids during the

interval between the injection and scanning. The patient is

then scanned by means of Gamma cameras. Gamma camera

provides much better counting statistics as they detect and

record all photons arising from the field of view. The

radiation dose is comparable to that of standard radiological

investigations.

In case of inflammation, there is increase in blood flow

and an increased metabolic activity due to reactive bone

formation. The bone scan reflects this reactive process by

locally increased concentration of gamma emitting isotope

or labelled radio-pharmaceuticals recorded as hot spots.

Conventional radiographs can only detect a trabecular

bone destruction if greater than 1-1.5 cm in diameter or loss

of approximately 50% of bone mineral, but bone scan can

detect before any radiographic abnormality is visible. A

radiograph indicates radiolucency and radiodensity which

is suggestive of the bone destruction and repair. A bone

scan indicates the dynamic response of bone to the turnover

processes, be it physiologic or pathologic such as neoplastic,

traumatic or inflammatory which can be detected much

before it is visible on a radiograph.

Indications for bone scan in orthodontics

In orthodontic practice, scan is usually recommended in

cases of abnormally growing facial bone(s), the commonest

condition being unilateral condylar hyperplasia. Technetium

scan is indicated in condylar hyperplasias to confirm the

Wwksjia*# MIHMft tMHM I f * W. BOW ItOU * ! ! • « .

S K / w *t/ r , j/H/twm « ; s *

Fig. 10.21: Technetium scan of a boy who reported with progressive

deviation of chin to one side and increasing asymmetry of face

activity of the condylar active growth site. Some surgeons

would like to confirm the cessation of the activity of

condylar hyperplasia by a scan before surgery is planned.

Technetium scan can also be useful in skeletal class III

cases to reconfirm the cessation of the active growth before

undertaking orthognathic surgery.

Precautions

• Not to be done within 10 days of menstrual cycle in

females of child bearing age

• Not to be scheduled within 48 hours of another nuclear

medicine procedure utilizing technetium.

3D CT36 and cone beam CT

Cone beam computerised tomography was developed as an

evolutionary process of conventional computerised

tomography whereby 3D reconstruction of the objects is

attained at not so high doses of radiation. CBCT utilises

single rotation of the radiation source which captures the

area of interest on a two-dimensional detector. However, in

a conventional CT, multiple slices are obtained and stacked

to obtain a 3D image.

CBCT has many applications in orthodontic diagnosis

and treatment planning particularly in cases of facial

asymmetries, jaw deformities, cleft palate and canine

impactions. It is a very useful aid in assessing bone

abnormalities such as ankylosis, dysplasia, growth

abnormalities, fractures, and osseous tumours. Cone beam

CT with 3D reconstruction is a valuable diagnostic

advancem ent for complex cases needing major

reconstructive surgery.

In certain canine impaction cases where clinical

examination and palpation may not provide sufficient

information on the exact location of the impacted tooth, a

combination of various 2-D radiographic images and clinical

examination may not be adequate. 3-D imaging provides

invaluable additional information on its location, relation to

the adjacent tooth structures and root resorption. This

information helps in planning effective surgical procedures

that minimize the risk of damage to contiguous vital

structures and prognosis of the treatment (Figs. 10.22).

The main advantage of CBCT over the conventional CT

is its low radiation dosage which is 20% of the conventional

CT or equivalent to that of full mouth radiographs.

Summary

Diagnosis in orthodontics is a rather complex issue. In

orthodontics, it is inseparable from treatment planning. The

diagnosis starts with the history itself whereby social

history, socioeconomic status of the parents, family values,

number of siblings, history of orthodontic treatment in the

family, and such information on would provide clues on the

concern for the problem, attitude towards treatment and

expected level of cooperation during treatment.

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vital structures and other teeth

11

12

These factors often superimpose the total planning and

considerations for the treatment.

Growing

patient

Data base/Problem list

Prioritise the problems

Possible solution

Non-growing

patient

The assessment of the malocclusion should include the

analysis of the soft tissues and underlying skeletal

structures both at rest and in function.

The malocclusion should be looked in terms of its

aetiology and possible presence of the environmental

factors. The physical and skeletal growth of the child has

a direct bearing on the facial growth and eruption of the

dentition. The remaining prediction of growth, occlusion

and facial form at maturity is the most difficult and yet the

most essential component of the orthodontic diagnosis.

New added dimension to the diagnosis is growth of the soft

tissue integument of the face, particularly lips, chin and

nose which show sexual dimorphism.

Based on the clinical observations, analysis of diagnostic

records and history, patient’s problem list is generated. A

number of factors would influence the timings and approach

to treatment of malocclusion. Accordingly, |he problems list

13

14

15

16

17.

18.


would have to be revised and a treatment strategy is

devised to suit the individual needs. No two children with

similar malocclusion would require similar treatment

approaches.

REFERENCES

1. www.americanboardortho.com/professionals/clinicalexam/

casereportpresentation/preparation/casts.aspx. Accessed on

6.04.08 at 1.44AM.

2. Korkhaus G (1939) cited from Thomas Rakosi, Irmtrud

Jonas, Thomas M Graber. Orthodontic Diagnosis Thieme

Page 218, 1993.

3. Moyers RE. Handbook of Orthodontics for Students and

General Practitioners. Chicago, Year Book of Medical

Publishers 1958;195:369-72.

4. Tanaka MM, Johnston LE. The prediction of the size of

unerupted canines and premolars in a contemporary

orthodontic population. J Am Dent Assoc 1974; 88: 798-801.

5. Staley RN, Kerber PE. A revision of the Hixon and Oldfather

mixed-dentition prediction method. Am J Orthod 1980; 78(3):

296-302.

6. Staley RN, Hoag JF. Prediction of the mesiodistal widths of

maxillary permanent canines and premolars. Am J Orthod

1978; 73(2): 169-77.

7. Staley RN, Shelly TH, Martin JR Prediction of lower canine

and premolar widths in the mixed dentition. Am J Orthod

1979;76: 300-09.

8. Hixon EH, Oldfather RE. Estimation of the sizes of unerupted

cuspid and bicuspid teeth. Angle Orthod 1958;28(4): 236-

240.

9. Nance HN. The limitation of orthodontic treatment. I. Mixeddentition

diagnosis and treatment. Am J Orthod Oral Surgery

1947; 33(4): 177-223.

10. Tweed CH. The Frankfort mandibular incisor angle in

orthodontic diagnosis, treatment planning, and prognosis.

Angle Orthod 1954; 24(3): 121-169.

11. Balridge DW. Leveling the curve of Spee: Its effects on

mandibular archlength. J Pract Orthod 1969; 3: 26-41.

12. Reddy Subba VV, Basappa N, Philip P. Formulation of

probability charts and prediction graphs for mixed dentition

analysis in south Indian children. J Ind Orthod Soc 1996; 27:

41-54.

13. Bolton WA. The clinical application of tooth size analysis.

Am J Orthod 1962; 48: 504-29.

14. Carey CW. Linear arch dimension and tooth size. Am J

Orthod 1949; 35(10): 762-75.

15. Rheude B, Sadowsky PL, Ferriera A, Jacobson. An evaluation

of the use of digital study models in orthodontic diagnosis

and treatment planning. Angle Orthod 2005; 75(3): 300-04.

16. Zilberman O, Huggare JA, Parikakis KA. Evaluation of the

validity of tooth size and arch width measurements using

conventional and three-dimensional virtual orthodontic models.

Angle Orthod 2003; 73(3): 301-06.

17. Santoro M, Galkin S, Teredesai M, Nicolay OF, Cangialosi

TJ. Comparison of measurements made on digital and plaster

models. Am J Orthod Dentofac Orthop 2003; 124(1): 101-

05.

18. Industries involved in Digital Model/ E models. I Ortholab

BY, Orthodontic Laboratory, Dorpsplein 8, Postbus 65, 3941

JH Doom, The Netherlands, www.ortholab.nl. II OraMetrix,

Inc. MCD-500066, USA.www.suresmile.com.

www.geodigmcorp.com III Cadent, 640 Gotham Parkway,

Carlstadt, NJ 07072-2405 USA, sales @orthocast.com-.

www.cadent.co.i, IV ORTHO CAST, INC,99 North Main

Street, High Bridge, New Jersey 08829 USA,

orthocast@earthlink.net- V GeoDigm Corporation, 1630 Lake

Drive West, Chanhassen, MN 55317 USA, www.geodigmcorp.

com.

19. www.americanboardortho.com/professionals/clinicalexam/

casereportpresentation/preparation/photo.aspx. Accessed on

6.04.08 at 1.44AM

20. Scammon RE. The measurement of the body in children. In:

Harris JA et al (Eds). The Measurement of Man, Minneapolis,

The University of Minnesota Press. 1930.

21. Greulich W, Pyle S. Radiographic Atlas of Skeletal

Development of the Hand and Wrist. Palo Alto, Stanford

University Press; 1959.

22. Pyle SI, Waterhouse AM, Greulich WW. A radiographic

standard of reference for growing hand and wrist. Pres of

Case Western Reserve University. Chicago, 1971.

23. Fishman LS. Radiographic evaluation of skeletal maturation;

Angle Orthod 1982; 52: 88-112.

24. Lamparski DG. Skeletal age assessment utilizing cervical

vertebrae [Master of Science dissertation]. Pittsburgh, The

University of Pittsburgh (PA); The University of Pittsburgh;

1972.

25. O’Reilly M, Yanniello GJ. Mandibular growth changes and

maturation of cervical vertebrae. Angle Orthod 1988; 58: 179—

184.

26. Hassel B, Farman AG. Skeletal maturation evaluation using

cervical vertebrae. Am J Orthod Dentofac Orthop. 1995; 107

(1): 58-66.

27. Franchi L, Baccetti T, McNamara JA Jr. Mandibular growth

as related to cervical vertebral maturation and body height.

Am J Orthod Dentofac Orthop 2000; 118(3): 335^4-0.

28. Garcia-Femandez P, Torre H, Flores L, Rea J. The cervical

vertebrae as maturational indicators. J Clin Orthod 1998;

32(4): 221-25.

29. Baccetti T, Franchi L, McNamara JA. An improved version

of the cervical vertebral maturation (CVM) method for the

assessment of mandibular growth. Angle Orthod 2002; 72(4):

316-23.

30. Demirjian A, Goldstein H. New systems for dental maturity

based on seven and four teeth. Ann Hum piol 1976; 3(5):

411-21.

31. Grave KC, Brown T. Skeletal ossification and the adolescent

growth spurt. Am J Orthod 1976; 69: 611-19.

32. Cheney EA. Dentofacial asymmetries and their clinical

significance. Am J Orthod 1961; 47: 814-29.

33. Hewitt AB. A radiographic study of facial asymmetry. Br J

Orthod 1975; 2: 37-40.

34. Chebib FS, Chamma AM. Indices of craniofacial asymmetry.

Angle Orthod 1981; 51(3): 214-26.

35. Brody KR, Hosain P, Spencer PP, et al. Technetium-99m

labelled imidophosphate: an improved bone-scanning

radiopharmaceutical. Br Radiol 1976; 49: 267-69.

36. Kau CH, Richmond S, Palomo JM, Hans MG. Threedimensional

cone beam computerised tomography in

orthodontics. J Orthod 2005; 32(4): 282-93.

I

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Introduction to cephalometrics:

historical perspectives and methods

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OVERVIEW

• Historical perspective

• Cephalometric norms

• Cephalometric apparatus

• Fundamentals of cephalometric analysis

• Definitions of cephalometric landmarks

• Summaiy

The science of orthodontics began with straightening

of teeth. With the advent of civilization and the ever

going process of evolution, face, the most noticeable

part of the human body and the centre of communication

both with words and without words, gradually assumed

increasing importance.

As the human fascination with beautiful faces tooks a

further stronghold, the focus of the orthodontist shifted

from teeth to the overall facial framework comprising of the

craniofacial skeleton and dentoalveolar structures enveloped

in the soft tissue drape which constitute the face.

During Angle’s era, orthodontists assumed that the mere

alignment of the full compliment of teeth on their respective

jaw bones was sufficient to create a state of balance and

harmony of the face. However, it was soon realized that this

may not be always true.

A good occlusion with full set of teeth does not

necessarily guarantee a pleasing face which is especially

true in cases with underlying skeletal dysplasia. The horizon

of orthodontics expanded further to encompass the

underlying jaw bases, their relationship to each other, and

the dentition and their orientation with respect to the

cranium. It became apparent that a beautiful face was the

outcome of a harmonious balance of its constituent parts.

The science of jaw proportions and measurements became

much more relevant to orthodontics. This was made possible

with the advent of cephalometrics, the origin of which can

be traced to 19th century anthropometries and physical

anthropology.

Anthropologists devised and used several instruments

to measure variations in the dimensions of the human body.

To measure the height and breadth of skull, they used an

instrument called craniometer.

Simon successfully tried to orient the dental study

models to the cranium and developed an instrument called

the gnathometer (1928-34).1-3 Simon tried to orient and

relate the dentition and the jaws with the help of dental

study models to the cranium. His work was to give the

orthodontist a real insight into the orientation of the

dentition to the facial skeleton in three planes of space

thereby help modulate the treatment plan in the direction of

restoration of facial balance.

Historical perspective_________

The use of radiograph to photograph the human skeleton

on a special film is perhaps one of the most useful

applications of physics in medicine. Hofrath, a

prosthodontist in Germany and Broadbent an American

orthodontist independently, yet in the same year (1931)

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Section II: Introduction to cephalometrics: historical perspectives and methods 153

devised the ‘head holder’ which was used to orient the

head and face to a predetermined standardized position to

make an standardised radiograph of the skull.

Bolton added a scale to the head holder, converting it

into Broadbent-Bolton cephalometer. Earlier Piccani, an

anthropologist had laid its foundation by the using lateral

skull radiograph in his anthropologic craniometrical studies.

Keeping anthropological landmarks in mind, a ‘head position’

was desired which could be reproduced. That would mean

that'head holder could be used to orient head in the same

predetermined position and if a radiograph was taken,

repeatedly in the same position, measurements would not

be distorted.

The other factors that were also standardized included

distance between radiograph film and head. The radiograph

film was always kept on left side of face close to the head.

The distance between the radiograph film and source of

radiographs was kept constant at 5 feet. The voltage (kVp)

and MA which would influence the image quality were also

standardized.

A conventional cephalogram is taken with the Frankfort

horizontal (FH) plane (i.e. ala-tragus line) oriented parallel

to the floor. The Frankfort horizontal plane is essentially an

anthropological landmark which has been extensively used

in craniometry. The Frankfort horizontal plane which extends

from upper margin of external auditory meatus to lowest

point on the infraorbital ridge was essentially called as Yon

Ihering line (1872). This plane was accepted by the

Anthropological Congress held in Frankfort 1884 and become

popular as Frankfort plane.

The instrument capable of taking standardized X-ray of

the skull and face is called cephalostat and the radiographs

film with image recorded with this technique is called

cephalogram. Cephalogram is a standardized radiograph of

the skull which is obtained by orienting the skull parallel to

the FH plane or a predetermined position, which is

reproducible.

The science of study and analysis of cephalogram(s) is

called cephalometrics.

First cephalostat4-6

The Brodbent cephalometer soon became popular and it

was extensively used to study infinite variations of the

human face. The instrument which was initially used as a

research tool to study growth of the face and jaws was

quickly inducted into orthodontic practice. The research

findings have had significant clinical implications in

diagnosis and treatment planning of growing and nongrowing

children with deviations of teeth, face and jaws.

Cephalometrics soon become the language in which the

science of orthodontics began to be written.

2D to 3D cephalometrics

The lateral cephalogram as conventionally used is a 2D

image of a 3D skull (Fig. 11.1). The lateral cephalometric film

allows left halves of the face. Efforts were made to construct

a 3D model of face using lateral and PA cephalograms.

Development of the computed tomography (CT) scan

permits evaluation of any part of the bony tissue at any

depth in all the three dimensions of space. Later research

has focused on 3D reconstruction of face from CT scans

(Figs 11.2, 11.3). Latest cone beam CT (CBCT) systems

supported with sophisticated computer software have

capabilities to generate virtual reality models of any parts

of the body including face and jaws.

Cephalometric norms_________

The cephalograms were measured for the lengths, heights

and proportions of the craniofacial and dentoalveolar

structures. Numerous angles were drawn from bony

landmarks in skull, which were used to analyse the

orientation of jaw bones to their respective bases and to

the skull. These parameters helped to assess the direction

and amount of growth.

Cephalometrics added a much deeper dimension to the

study of growth of human face. The findings from serial

cephalograms of a group of subjects on longitudinal studies

over a number of years provided information on timing,

velocity and direction of cranium and of facial growth.

These have direct clinical implications in treatment planning

and institution of orthodontic treatment modalities.

It was soon to be discovered that there were significant

variations of the human face not only from those with

dentofacial deformities but also among those called ideal or

normal faces. Hence, it became apparent that there was a

need to develop norms based on ideal/normal faces which

could be used as a standard template to compare and study

deviations. These norms were to be developed specific to

age, sex and race. Research continued for several years to

establish norms in several countries. In India too, studies

were carried out with similar objectives.

Im portant cephalom etric studies where serial

cephalograms were taken in a group of children over the

years are:

1. Bolton-Brush growth study7

2. Burlington growth study.8

No more such studies are now permitted because of

ethical considerations related to harmful effects of ionizing

radiation.

Bolton-Brush growth study

The Bolton-Brush growth study comprises the world’s

most extensive source of longitudinal human growth data.

The Bolton-Brush study began in 1928, as two closely

aligned but independent medical research projects. While

the Brush study, looked at physical and mental growth of

healthy children, the Bolton study focussed on the normal

development of the head, face and neck.

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Vertical adjustment

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Fig. 11.1: A conventional cephalometric apparatus

The Brush enquiry was the first project of the Brush

foundation, established by Chartes Francis Brush, the

renowned inventor, scientist and owner of General Electric

Company, in memory of his son who died of blood poisoning

at the age of 34.

The Bolton study originated as an outgrowth of the

work of B Holly Broadbent Sr, an orthodontist and was

funded by the late Frances Payne Bolton - a congress

woman and her son Charles Bingham Bolton and hence, the

name. The research tool primarily comprised of annual serial

cephalograms of 4631 children aged 5-18 years. They also

recorded nutritional, dental, medical health and yearly

batteries of psychological and mental tests.

Testing for the Brush enquiry ended in 1942, while

recruitment for the Bolton Study ended in 1959. The two

collections were officially merged in 1970 into a massive

pool of information comprising of 22,000 physical reports,

90,000 mental and psychological reports, and over 50,000

radiographs of head and neck plus many others of the

major bones of the body.

Dr Broadbent Jr developed cephalometric standards for

understanding and assessing the growth of the craniofacial

Section II: Introduction to cephalometrics: historical perspectives and methods ■ 155

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complex in* 1975. It was found that face and skull continue

to grow and change all throughout life. The researchers

also learned that women undergo a little growth spurt

during pregnancy due to hormonal changes.

Burlington growth study for craniofacial growth

The study was conducted by Dr Frank Popovich, at the

Burlington Growth Centre, established in 1952 at the

University of Toronto, Canada. It comprised of longitudinal

data collected over a time span from 1952-72. The original

sample size comprised of 1380 children aged 3, 6, 8,10 and

12 years and 312 parents. The goal initially was to develop

parameters to study the success of orthodontic treatment.

Complete orthodontic records were taken for all children

consisting of:

• Study models

• Profile and frontal photographs

• Lateral (rest and occlusion), posteroanterior, 45° oblique

cephalograms

• Carpal radiographs

• Anthropometric measurements.

These records were obtained annually for the 3-year-old

children; at ages 9, 12, 14, 16, 20 years for the original 6-

year-old children and at 12 and 20 years for the original 12-

year-old children. Recently, the sample was extended to 40

years for the original 3-year-old sample and to 70 years for

the original parent sample. To date there are 8,000 sets of

records and 46,746 cephalograms on file. The sample is thus

one of the world’s most important collections of longitudinal

craniofacial growth and development data.

Probably, the biggest contribution made by Dr Frank

Popovich to the science of orthodontics was the

development of the Burlington craniofacial growth templates.

These templates plot the amount and direction of craniofacial

growth that occurs in males and females from the age of 4

to 20 years. These templates are used as a diagnostic tool

in orthodontics to aid in cephalometric analysis.

Transverse, anteroposterior and vertical measurements

from the templates provide information related to the skeletal

unit size and spatial orientation of the maxilla, mandible and

the cranial base. These measurements also provide

information related to the position of the molars and incisors.

AH of these facts become an important part of orthodontic

^gnosis.

Cephalometric apparatus (Fig. n.i>

The basic components of the equipment comprise:

f A cephalostat/head holder

• An image receptor system

• A radiographic apparatus.

holder

Th, ie cephalometric ‘head holder’ is the key device which is

to orient the head in a specific relation to the

‘Radiograph film’ in superoinferior (vertical) and rotational

(right to left - mid sagittal) plane. The head holder consists

of adjustable ear rods. These are made of metal/acrylic/and

lately carbon fibre, which provide additional strength and

are radiolucent.

Components of head holder/cephalostat

• Adjustable ear rods

• Nasal support

• Film holder

Fundamentals of head orientation

The film and head (object to be imaged) should be oriented

to each other in such a manner so as to avoid distortion of

the structures recorded on the film in all possible ways. It

is desired that radiograph cassette holder be kept close to

the left side of face, as close as possible within the

mechanical limits of the equipment. The radiograph cassette

is placed parallel to the mid sagittal plane of the head. The

head holder which consists of two ear rods, when inserted

in the external auditory meatus aligns the head so that X-

rays pass through the head without any rotation and

hence, strike the radiograph film at 90° passing through

transmeatal axis of head. The structures which are closest

to the film show maximum sharpness and least magnification.

When exposed from the right side, the magnification factor

is highest for the right side structures and least for the left

side. Modern cephalometric machines are equipped with

laser beams that indicate the true vertical and horizontal

planes.

Orbital pointer

The superoinferior orientation of the head is achieved by

making the anthropological Frankfort horizontal plane parallel

to the floor. This is achieved through the ear rods and the

orbital pointer. The head holder is so devised that on

insertion of ear rods gently in the external auditory meatus

with the orbital pointer kept at the orbitale, the FH plane is

achieved parallel to floor. The modern cephalostat has

somehow got away with orbital pointer. Therefore, the

superoinferior orientation is to be judged by the technician.

To prevent movement from the desired position, head is

supported with a ‘nasal support’ which is aligned to the

nasal bridge. The cassette holder is moveable and is aligned

to the left of the head.

Image receptor system

The complex arrays of parts comprising the image receptor

system for a cephalometric technique are:

The extraoral film

Cassette

Intensifying screens

A grid

Soft tissue shield.


Cassette

Cassette is a light-tight box used to pack the intensifying

screens and the film.

Intensifying screens

Intensifying screens reduce patient exposure dose and

increase image contrast by intensifying the photographic

effect of radiographs.

Grid

Grid filters out secondary radiation. It consists of alternate

radiopaque strips of lead and radiolucent strips of plastic.

The radioopaque strips absorb the secondary radiations

whereas the radiolucent strips allow the primary beam to

pass.

Soft tissue shield

Soft tissue shield consists of an aluminium wedge placed

over the cassette or the window of the radiograph apparatus

and serves as a filter to reduce over-penetration of

radiographs into the soft tissue profile.

Radiographic apparatus

The radiographic housing comprises:

• Radiographic tube

• Filters

• Collimators

• Transformers

• A coolant

The radiographic tube consists of the cathode, the

anode and an electric power supply. Anode is oriented at

15-20° to the cathode to decrease the size of the effective

focal spot to (lx l) mm2 or (1x2) mm2 (Enron Line Focus

principle). Long wavelengths are filtered out by aluminium

filters. The beam now passes through a rectangular

diaphragm (collimator) which determines the shape and the

cross-sectional area of the beam.

B

Fig. 11.2: A modern digital cephalostat machine combined with OPG.

A. Digital cephalostat, B. Image on screen. Cephalostat seen in the

picture has X-ray radiation originating from left side of face, right side

being closest to the sensor, which is in contrast to standard film based

cephalostat

Extraoral film

Extraoral film consists of emulsion of silver halide crystals

suspended in gelatin coated over a base of cellulose

acetate. Size of the film is standardized at either (8" x 10"),

i.e. (203 x 254) mm or (10" x 12") i.e. (254 x 305) mm.

Principles involved

• X-ray exposure is always on the right of the patient, so

that the structures nearest to the radiographic film (left

side) show the least amount of magnification, i.e.

maximum sharpness.

• Distance between radiograph source and mid-sagittal

plane is standardized at 5 feet.

• The distance between the mid-sagittal plane of the

patient and the radiograph film is 15 cm or less.

• Radiographic beam is directed perpendicular to the

mid-sagittal plane of the subject, centered at the external

auditory meatus, usually passing within 4 cm of it.

• The kVp, mA and exposure time are usually standardized

for the adult patient. However, these are usually

adjusted according to the age, race and nutritional

status of the patients and other such factors which

may alter the bone density.


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accommodate up to 6.5' of patient height.

It may be worth mentioning that, in Europe and Australia,

a different version of cephalostat is used. The European

system has a larger distance of radiograph source to MSP

of the subject, which is 2 meters and patient exposure is

done from the left side, right side being nearer to the

radiograph film.

Types of cephalogram according to patient

orientation

The two common cephalometric views are:

1. Lateral cephalogram (Fig. 11.3)

2. PA cephalogram.

In addition, the cephalometric equipment can also be

used for taking:

1. Waters’ view

2. Submentovertex (base) projection.

The most commonly used cephalogram in orthodontics

is the lateral cephalogram, followed by PA cephalogram.

The other views are more useful for assessing specific

structures like maxillary sinus (Waters’ view), zygomatic

arch (submentovertex view, jug handle view).

Patient positioning for recording a cephalogram

It is important to explain to the child the procedure of

recording the cephalogram to allay apprehension usually

experienced before undergoing a medical investigation. An

apprehensive child/person is more likely to move from an

established position and thereby produce an error in the

cephalogram.

There are essentially two schools of thought with regard

to head positioning for cephalogram:

1. Orientation along FH plane. Anthropological Frankfort

horizontal plane is defined as a line connecting the superior

border of external auditory meatus with the infraorbital rim.

This plane is usually 10° inferior to the canthomeatal line,

which runs from the outer canthus of eye to the tragus of

the ear.

2. Orientation according to NHP. The second school of

thought believes in recording the cephalogram in natural

head position (NHP). The natural head position is adopted

by an individual in everyday stance, where pupils are

centered and individual looks straight forward defining the

true horizontal. This position is said to be reproducible for

an individual9 within a range of 4° which justifies its use for

recording the cephalogram.

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Fig. 11.3: Lateral cephalograms: A. Cephalogram taken on a conventional film based machine. Soft tissue profile has been recorded using barium

paint on face profile, B. Taken on a digital cephalostat machine.


Technique of taking a cephalogram

1. Conventionally, a cephalogram is taken along the FH

plane. The subject is asked to stand in a relaxed

position under the cephalostat head holder, which is

first raised beyond the height of the subject, with ear

rods at maximum opening and orbital pointer/nose

support turned upward to avoid injury to the patient.

2. The cephalostat is brought down gently to a level to

gently place the ear rods in external auditory meatus.

At this stage, it is necessary to look for any strain on

neck. The cephalostat height should be adjusted for an

unstrained neck position and not vice versa, where at

times the head holder may be slightly high or low with

the subject trying to either extend his neck or slap

down. Once ear rods are in place and the subject is

comfortable, the FH position is gently manoeuvred- by

tilting the chin/forehead up and down, rotating

superoinferiorly around the transmeatal axis.

3. The earlier models of head holders were provided with

an orbitale pointer. The orbitale, the thickest portion of

inferior orbital rim is gently palpated and the orbitale

pointer is then moved to touch the skin in the region.

Having oriented the head, this position is secured by

a nasal support, which rests gently on the nasal bridge.

4. Child is asked to relax and a centric occlusion position

is checked before making exposure. All cephalograms

are taken in centric occlusion if not indicated otherwise.

5. It is also important to ask the child to keep the lips in

relaxed position while holding the teeth in centric

occlusion. Trying to keep teeth together with strained

lips would provide incorrect information on soft tissue

parameters.

6. It goes without saying that patient’s information for

the documentation should be readily available on the

film, critical being the name, hospital registration number

(which enables an easy track of the patient’s details)

and the date of cephalogram.

7. Cephalograms can also be obtained with the mandible

in rest position/on first tooth contact in certain

situations where there is a functional shift of the

mandible. Functional shift can be in protrusive or in

lateral excursions. In case of anterior functional shift,

it is important to make a cephalogram at first tooth

contact or in a forced centric occlusion, which may be

possible to attain in some cases. Such cases can be

supported with a wax bite to obtain a cephalogram. A

cephalogram taken in a functional forward shift position

would provide incorrect information on sagittal and

vertical relation of the mandible to the cranium.

8. Once all possible patient related parameters are set, the

film is exposed.

Submentovertex projection (jug handle view)

The jug handle view is indicated for visualization of the

facial asymmetries and extent of displacement of the

condyles or mandibular rotations following maxillofacial

trauma or in evaluating the outcome of orthognathic surgery.

The patient is placed in head holder with ear rods, gently

and in place but, face towards the X-ray source. The

subject is asked to extend the neck so that the canthomeatal

line makes an angle of 10° to the radiographic cassette

holder. The X-rays pass perpendicular to film or image

receptor passing below the mandible. This view also

provides a good view of zygomatic arches, in cases of

fracture, if the film is under exposed.

Waters’ projection

Waters’ projection is indicated for evaluation of maxillary

sinus diseases, thickening of sinus mucosa, polyps, and

carcinoma of maxillary antrum and pyramidal fractures of

the maxilla. The radiograph is taken with the patient facing

the image receptor, chin touching the image receptor and

the head titled backward to the extent of canthomeatal line

making a 37° angle. The X-ray beam would pass through

the area of nasal cavity and maxillary sinuses.

Indications and uses of cephalograms

Cephalometrics was originally developed as a research tool

to understand the growth of human face. The understanding

of facial growth, racial variations of dentofacial structures

and understanding the locations, severity and aetiology of

malocclusion has enabled better treatment options, helped

to design appropriate interceptive orthodontic/orthopaedic

procedures and predict prognosis, and evaluate treatment

outcome and results.

A pretreatment/diagnostic cephalogram is indicated to

evaluate growth trend in a child and his/her potential for

malocclusion.

Pre-treatment cephalogram of a case of malocclusion

helps to establish the:

1. Severity of dental malocclusion

2. Severity of skeletal malocclusion

3. Identify the location of dysplasia

4. Evaluate soft tissue integument of face and its

relationship to the dental hard tissues and skeleton of

face

5. Evaluate nasopharyngeal airway, soft palate and

position of tongue

6. Aids in treatment planning, decision on extraction/

growth modifications/surgical orthodontics and the

type of mechanotherapy to be employed

7. Design and plan retention strategy

8. Stage and post-treatment ceophalograms are taken to

monitor progress of treatment and treatment outcome.

Posteroanterior cephalogram

A posteroanterior cephalogram (PA Ceph) is essentially

used to evaluate cranium, face, jaws and dentitions in

transverse and vertical dimensions. It is used to evaluate

Section II: Introduction to cephalometrics: historical perspectives and methods Ll 159

facial asymmetry or symmetry, in children with

developmental deformities like:

• Arrested growth of the mandible due to injury to the

TM joint.

• Excessive growth of the mandible as in unilateral

condylar hyperplasia.

• Facial asymmetry due to hemifacial hypertrophy/

atrophy.

• Facial asymmetry due to trauma

• Developmental or congenital face asymmetry.

PA cephalograms are also used to evaluate transverse

maxillary deficiency or excessive width of the mandible.

Outcome of maxillary expansion can also be evaluated on

PA cephalograms.

Features of a good cephalogram

A good radiograph film . Besides the blend of sharpness,

contrast and density which constitute a good radiograph

film, the other essential features of a cephalogram are those

related to head positioning. A cephalogram is taken with the

objectives in mind that there should be a minimum amount

of magnification of the cranium and dentofacial structures

with the left and right side showing a perfect overlap, i.e.

single shadow. A cephalogram provides highest possible

projectional resolution in which structures smaller than 0.1

mm can be discerned. This projectional resolution with

cephalogram is higher than that of conventional computed

tomograph (CT).

Smooth curve o f cervical spine. A cephalogram which is

taken without straining the neck would show 6-7th vertebra

of cervical spine in a smooth curve.

Concentricity o f ear rods. The radiopaque metallic rings of

the ear rods present as two shadows in the region of

external auditory meatus. The ring of right side appears

slightly larger in diameter compared to left side due to the

magnification factor. However, it is the concentricity which

is important. The rings apart in anteroposterior direction

suggest that radiographs are not passing perpendicular to

the mid-sagittal plane. It signifies rotational error of head

positioning in a cephalostat. Similarly, there may be a

superoinferior discrepancy in the concentricity of rings

which would suggest a right or left side tilt of the head. A

combination of superoinferior and anteroposterior

discrepancy would also exhibit double shadows of

craniofacial structures on a cephalogram.

Minimal discrepancy in horizontal and vertical overlap

°f right to left side structures. A discrepancy of the

condylar heads coupled with a marked discrepancy or large

separation of the posterior border of the ramus of the

mandible and lower border of body of mandible suggest

improper head positioning. A cephalogram with large

discrepancy may have to be discarded and a repeat

radiograph is advised. However, while asking for a repeat

radiograph, consideration of risks and cost associated with

radiation vis-a-vis, actual benefit of a more accurate

cephalogram should be kept in mind.

Some cephalometric systems have a small metal palette

embedded in the centre of plastic ear rod which would

appear in the radio opaque rounded shadows in the centre

of external auditory meatus. Ideally these two shadows

should absolutely coincide, but it is a rare phenomenon to

be seen in day to day life.

Teeth in centric occlusion. A child may quite often move

his/her jaw from centric occlusion position; or open the

mandible. It is always better to check the occlusion clinically

and reconfirm on his cephalogram. The easiest would be to

match the overjet seen on a cephalogram with one measured

in mouth or on dental study models mounted in correct

occlusion. Separation of teeth would appear as double

shadows of molars in vertical direction or a radiolucent

shadow on to the occlusal surfaces of teeth.

A slightly distal placement of the posterior border of the

ramus and superior placement of the lower border of the

mandible on the right side compared to the left side

structures is a normal finding.

Other structures which can help in determining the

accurate positioning of the head while recording a

cephalogram are shadows of orbital rims and the

pterygopalatine fissure.

Good soft tissue contrast. A soft tissue shadow of facial

contour is essentially achieved by limiting the radiation

intensity in the region with the use of soft tissue filters.

Unstrained lips. A cephalogram taken in a relaxed posture

of lips would show a natural outline of the face from

frontella down to the region of hyoid bone. Similarly, a

cephalogram taken with care would also exhibit soft palate

and anatomical contours of the upper airway.

PA view

It is important to mark (L) or (R) side of the head while

taking a PA view radiograph. A cephalogram taken in

correct position in the head holder should exhibit external

auditory meatus (EAM) shadows (either rings or around

radio-opaque marker) in a horizontal plane. However, this

aspect may have to be ignored in children with gross

craniofacial deformities. PA cephalogram would exhibit

temporal bones, orbits, frontal and ethmoid sinuses, maxilla

and its antrum, nasal cavity, palatal floor, and the mandible

from the condyle to the symphysis.

A PA cephalogram is indicated for the evaluation of

symmetry of right and left sides and efforts should be made

to distinguish any apparent difference from true deformity

from left to right side. The rotation of head around a

transverse axis may exhibit itself as facial asymmetry.

160

i

■


Location of anatomical structures on a cephalogram

(Figs. 11.3-11.6)

1. Calvarium and base o f skull. The boundaries of the

skull are readily visible as radio-opaque shadows

extending from the nasal bridge, frontal bone, parietal

and occiputs encircling the brain. The mastoid region

shows air spaces. At the base of the skull, the sella

turcica would appear as a rounded radiolucent shadow

which has anterior and posterior boundaries limited by

anterior and posterior clinoid processes.

2. The sphenoid sinus. It appears below the anterior

cranial base.

3. The frontal sinuses can be readily seen as a pearshaped

radiolucent shadow just above the nasal bone.

4. The orbital ridges. It appear as thick radiopaque

margins surrounding the radiolucent orbits. Dense

radio-opacity is seen at the inferior orbital margins and

the orbitale point.

5. The maxillary sinus. It is a radiolucent shadow whose

inferior border is formed on the cephalogram by the

superior border of hard palate, which extends anteriorly

to make anterior nasal spine and posteriorly to merge

with the soft palate. A shadow of posterior wall of

nasopharynx is easily discernable and so is the anterior

wall.

6. The mastoid sinus. It is seen as a large radiolucency

usually slightly posterior to the location of the auditory

meatus which appears just above and distal to the

condyle of the mandible. Just below the occipital bone,

an anterior triangular shadow seen in the cervical spine

is the anterior arch of the first cervical vertebra.

7. The cervical column. It would show below the vertebra

and their process.

8. The pterygopalatine fissure. It appears as a long tear

drop radiolucent shadow below sphenoid sinus and

posterior to the posterior wall of the maxillary sinus.

Occasionally, it may be possible to discern foramen

rotundum in the cranial part of the pterygopalatine

fissure. The most caudal point on the base of the

sphenoid makes the anterior boundary of the foramen

magnum which makes the basion.

9. The condyles. They appear just below the petrous part

of the sphenoid and they may be seen as a single

shadow on a good radiograph or appear as two slightly

separated radiopaque shadows. The opaque shadow

extends inferiorly and anteriorly from the condylar

head forming the neck of the condyle and extending

anteriorly as the coronoid process of the mandible. The

posterior border of the ramus may appear as a single

line (rarely) or the slightly separated border of the right

hand side may be seen posterior to left with the two

shadows gently merging down at the gonion and lower

border of the mandible.

10. Mandibular symphysis. It shows dense boundaries

with dense radiopaque shadows of the genial tubercles.

Hyoid bone is clearly visible below the mandible in a

lateral view.

Unexpected findings on a cephalogram

A cephalogram should be grossly evaluated for normal

anatomy as well for any possible pathology which may be

an expected or incidental finding.

1. Signs of either excessive or poor bone density of

generalized nature could be suggestive of systemic

disease such as osteopetrosis or rickets.

2. An unusually large sella may be as suspected for a

pathology of pituitary gland

3. Fibrous dysplasia is not uncommon in children and

cotton wool radiopacities may appear in radiographs

much before their clinical presentation and could be an

accidental finding on cephalogram taken for orthodontic

purposes.

4. The shadows of maxillary antral polyps, the sinusitis

and large turbinate in nasal cavity could be readily

seen in lateral cephalograms as well as any radiopacities

or fluid levels in the sinus.

5. Narrow nasopharynx may be the outcome of enlarged

adenoids which should be looked for.

6. The other commonly seen incidental findings on lateral

cephalograms are supernumerary or missing teeth,

odontomas and cysts of the maxilla and the mandible.

7. A prominent antigonial notch is often suggestive of

hampered mandibular growth.

8. A marked decrease in the joint space in the condyle

should warrant for more investigations such as

radiograph of the TMJ.

Fundamentals of cephalometric

analysis____________________

Cephalometric analysis involves location of certain landmarks

on the cephalogram, which are used to make measurements

of either angular or linear variables. The angular variables

reflect spatial relationship of the anatomical parts. The

changes measured on the serial cephalograms with treatment

or without treatment indicate alterations in the spatial

relationship and therefore directions and sometimes, the

amount of change that has occurred.

Linear measurements may be in anteroposterior or vertical

direction on a lateral cephalogram, and in transverse and

vertical direction on a PA cephalogram. They can be used

as absolute values to measure dentofacial/ cranial structures

in sagittal, transverse and vertical directions. Ratio can be

calculated for certain measurements and changes in ratio

with time (growth) or treatment would be indicative of their

relative alterations.

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Numerous cephalometric analyses have been suggested

in the literature by several authors and researchers. The

limitations and benefits of one analysis over others have

been analysed and researched. Some analyses are more

useful for research purposes while others are used for

clinical applications in day to day practice. We intend to

limit our discussion to some practical aspects of

cephalometric analysis. For more detailed and extensive

reading a book on cephalometrics is recommended.

Cephalometric norm

It is known that most biologic variables like height, relative

proportions of body parts, and other biological parameters

are distributed according to some ‘normal values’. There

are deviations from these norms which are called ‘range’.

Values beyond the range of normal are considered as

abnormal.

There are infinite morphological variations of the

biological parameters. Some of them can be attributed to

ethnic groups/race/age and gender. Since malocclusion is

not a disease but a morphological variation of facial

structures, in many instances orthodontists have tried to

treat malocclusion to ‘normal occlusion’ and also used

facial skeleton as a template to achieve normal balance of

dentofacial structures. They devised a ‘norm ’ template of

dentofacial structures using cephalogram as a tool of

subjects with pleasing profile, well-balanced facial

proportions and normal occlusion. The ‘norm’ values are

being used to formulate treatment objectives for cases of

malocclusion.

Soon it was realized that there was a need to develop

‘norms’ for the different races. Several studies from across

the world were devoted to development of cephalometric

norms. The earliest available ‘norms’ were available for

Caucasians.

Studies on cephalometric norms in India

The earliest cephalometric studies in India were conducted

at Bombay as a part of MDS Dissertations on Gujrati

population by Kotak (1961), Seshadri (1964), Mathur (1964))

on M aharashtrians; Shetye (1962), on Parsis and

Maharashtrians by Sidhu (1969). Cephalometric studies in

India were being done lately till 90s.1011

The first comprehensive study on cephalometric norms

of north Indians was published by Nanda and Nanda

(1969).12 Since then, a number of studies have been

conducted across India and these have been compiled as

a booklet which has been published by the Indian

Orthodontic Society. Detailed and comprehensive

cephalometric norms for north Indians were developed by

Kharbanda et al which are now used in day to day clinical

practice.10,11

Floating norms

It has now been realized that a case of malocclusion cannot

be treated to a template of NORMS which have been

derived from mean values of a certain select group of

subjects with excellent occlusion and harmonious facial

proportions. There are several limitations to treating

individuals to match with ideal norms especially with those

of skeletal type of malocclusion.

Attempts were therefore made to derive ‘norms’ for an

individual based on his skeleton and dental pattern.

Floating norms are individual norms that vary (float) in

accordance with the variation of the correlated measurements

(guiding variable). Each cephalometric variable is not

independent but guided by underlying craniofacial pattern.

Hence, its deviation from a ‘norm’ alone would not be an

indicator of a dysplasia. In certain situations, a deviation of

a cephalometric variable may be acceptable if a certain

relationship is maintained.

Tracing a cephalogram

The cephalogram is labelled for a subject’s initial hospital

identification number and date of radiograph. The hospital

ID number can be used to track all other details of the

patient. The cephalogram, like other radiographs should be

handled properly and cared for to prevent any scratches,

marks and wrinkles. It should be kept in its paper cover

sleeve and envelop without any folds, stored in a cool

place away from direct sunlight or excessive light exposure.

The following equipment are required for a good tracing

to be performed:

1. An X-ray illuminator/mounted on a tracing table with

soft light. The tracing table should be mounted in a

room with minimal brightness. The tracing table should

also have a control switch for controlling the intensity

of light.

2. Tracing paper of good quality. Pre-cut sheets are

available in 8"xl0" size from orthodontic suppliers

3. Sharp 7H pencils, HB pencil.

4. Geometric set squares and protractor.

5. Tooth templates, usually supplied by orthodontic

suppliers.

6. Good quality dust free eraser and transparent adhesive

tape.

The cephalogram, is usually traced with a tracing paper

mounted, keeping the face profile on right side of the

operator. Mount tracing paper using adhesive tape, on the

left hand border of the cephalogram.

Following information is recorded on the corner of a

tracing paper:

• Name of patient

• Registration no

• Date of birth

• Age and sex

• Date of X-ray

• Stage of treatment.

1


The tracing

1. Clean the tracing table, make it dust free using soft

cotton cloth

2. Switch on the illumination

3. Radiographic film should be cut to proper size in

accordance to tracing paper (8"xl0").

Tracing paper should be mounted on the radiograph film

in such a way that the lower border of the paper extends

about one inch below the chin point. Where only lateral film

is being used it is more convenient to fold the left hand

periphery of the paper to the corresponding side of the

head plate. This permits moving the tracing paper up or

back frequently to directly check structural details on the

film while tracing. The use of an opaque matte of blotting

paper to mask all portions of the film except the immediate

areas being traced reduces eye strain and allows far more

accurate tracings in ‘faded’ areas. Excess light can be

reduced in areas of delicate, darker facial structures by

looking through a black paper cone. Fine detail may be

revealed by lifting the tracing paper from the film for an

unobstructed view of the section to be studied.

All tracings should be done with a pencil with a chisel

point.

Distinction between the left and right sides in bilateral

structures is difficult and is a common source of error

particularly in the dental region. Hence, it is an acceptable

practice to go by the middle of right and left structures if

asymmetry is not involved. On the lateral film, most

structures are bilateral and if symmetrical they double the

resistance to X-ray penetration hence a better contrast.

Practically, even if the face is perfectly oriented and if the

bilateral structures are symmetrical, they are not necessarily

superimposed because the radiations are not parallel but

divergent. Therefore, if a double image is seen on the film,

it does not mean asymmetry. It is recommended to trace the

left side routinely since it is less magnified and more

accurate.

An orientation cross is marked on the cephalogram at

the top left corner of the film with the help of a sharp

pointed tool. This orientation cross is transferred to the

tracing paper. The transfer guide helps to correctly orient

the tracing paper back on to a cephalogram.

Accurate tracing of a cephalogram is an art and requires

considerable experience in identification of the skeletal and

dental structures. I prefer to start tracing with the soft

tissue profile of the patient which starts at forehead going

down to the contour of the neck. Use of soft tissue filters

has greatly enhanced the visualization of soft tissue

contours. One should not attempt to make their own

judgement about any of the contours. Smooth lines which

are visible should be followed. The next structure which

needs to be carefully traced is the bony Nasion. Outer

cortex of frontal bone is traced towards the nasal bone. It

follows the nasal bone anteriorly and complete its joining

back to the frontal bone. The frontonasal suture is often

visible which should be traced for better anatomical

presentation of the tracing.

Sella appears as a sharp radiolucent shadow, except at the

anterior clinoid process. However, it is possible to demarcate

the boundary of sella by virtue of its sharp outline

overshadowed by rather less dense anterior clinoid process.

Trace the anterior cranial base starting cranial side of frontal

bone, going backwards to anterior clinoid process, sella, and

posterior clinoid process and follow the sphenoid bone - up

to the spheno-occipital suture which gives a faint outline.

The porion is located either as machine porion which is

the outer border of the metal rings seen in ear rods or

anatomical portion which is an elliptical shadow seen

superoposterior to the condylar fossa in the body of

sphenoid bone. This is a difficult area and considerable

experience is needed to locate it accurately.

The next important anatomical structure to be traced are

the orbital rims which appear as condensed arc like

shadows below the anterior cranial base, descending

downwards and anteriorly where they often get more radioopaque.

Orbitale is located here, as the inferior point on the

orbital rim.

The maxillary sinus is seen as a radiolucent shadow

just below the orbital rims. The superior boundary of the

palatal shadow is traced anteriorly to form anterior nasal

spine which merges anteriorly into the anterior alveolar

process, the deepest point here being point ‘A’. The oral

side of palate can be traced starting at the cingulum of the

maxillary incisor backwards smudging on to the soft palate.

The posterior nasal spine is often not clearly demarcated

due to the overlying shadow of the developing third molar.

The pterygopalatine fissure which appears as an inverse

teardrop-shaped structure marked by sharp dense radioopaque

line surrounding a grayish radiolucent shadow, the

thin hair-like part of the shadow merges down often into the

superior border of the palate.

The dense triangular shadows below the orbital arches

are maxillary process of the zygoma making a radiopaque

buttress descending down and backwards towards maxillary

first molar, can be traced gently as it signifies the key ridge.

Further, the condyles’ superior border is traced, continue

anteriorly which extends into pterygoid fossa which is

often not clearly demarcated. Further if one continues

mesially the coronoid process is traced. It is not possible

to see and trace anterior border of the ramus. The condyle

is traced posteriorly and inferiorly which completes the

posterior border of the mandible ramus. The inferior border

of the body of the mandible is traced next. In case, two

borders are seen, both the borders are traced and a dotted

line is used to draw a border average of two.

The mandibular symphysis is traced from the junction of

alveolus with the mandibular incisor, going downward into

a deeper point (B), following the contour of chin (pogonion)

turning around (gnathion) and completing the lingual

boundary of the mandible.


The first molars and most prominent incisors are traced

in both jaws.

Cephalometric analysis

Cephalometric analysis is the process of evaluating skeletal,

dental and soft tissue relationship of a patient by comparing

measurements performed on the patient’s cephalometric

tracing with population norms for respective measurement(s),

to come to a diagnosis of the patients’ orthodontic problem.14

Essentially cephalometric analysis involves evaluation

of the patient’s:

1. Skeletal pattern

2. Dentition and its pattern (denture pattern)

3. Soft tissue pattern of face

4. Nasopharyngeal airway

5. Growth trend.

Definitions of cephalometric

landmarks

Landmarks on cranial base

1. Sella(S): It is defined as a constructed point in the

medial plane and is defined as the centre of sella turcica

2. Entrance to sella (Se): It is defined as the mid point to

the entrance of sella turcica.

3. Nasion (N/Na): Defined as the most anterior point of

the frontonasal suture in the mid sagittal plane.

4. Pterygomaxillare (Ptm): It is defined as a point located

at the intersection of the nasal line (NL) and the

pterygomaxillary fissure.

5. Pterygomaxillary fissure (Pt): The pterygomaxillary

fissure is a vertical fissure which descends at right

angles from the medial end of the inferior orbital fissure.

It is a triangular interval formed by the divergence of

the maxilla from the pterygoid process of the sphenoid.

6. Porion (Po): Po point is anthropological landmark

identifiable on the skull on the superior border of the

external auditory meatus. Of the two main approaches

to its definition, one was anatomical [Blair (1954), Craig

(1951), Higley (1954)] and the other was pragmatic

(machine porion) [Moorees (1953), Baumrind (1954)].

a) Machine porion: Baumrind defined it as the

superior point of the image of the cephalostat

ear rod.

b) Anatomical porion: Savara and Tkeuchi15 (1979)

defined it as the most superior point on the roof

of the external auditory meatus at the border of

the external cartilaginous ear canal, it being

identical to the most superior point of the

cephalostat ear rod.

7. Articulare (Ar): Ar is defined as the point of intersection

of the images of the posterior border of the ramal process

of the mandible and the inferior border of the basilar

part of the occipital bone. In 1947, Bjork introduced the

term articulare16.

8. Basion (Ba): Defined as the most anterior point on the

anterior margin of the foramen magnum where the

midsagittal plane of the skull intersects the plane of the

foramen magnum.17

9. Orbitale (Or): Defined as the most inferior point of

each infraorbital rim.

Nasion

Porion

Condylion

Orbitale

Anterior nasal spine

Subspinale

Gonion <*-

Apex of upper incisor

Supramentale

Pogonion

Gnathion

Menton

Fig. 11.4: 3D CT reconstructed image of a skull marked with landmarks commonly used on a lateral cephalogram

A


Entrance to sella

Sella

Basion

Posterior nasal

spine

Supra

pogarion

Frontal sinus

Nasion

Sphenoidal sinus

Spheno-occipital

synchondrosis

Anterior nasal spine

Subspinale


Tip of lower incisor

Tip of upper incisor

Infradentale

Supramentale

Apex of lower incisor

Centre of symphysis

Pogonion

Gnathion

Menton

Fig. 11.5: Multiplanar reformatted image of the skull. Image from slice in the midline of the skull. The condyle, ramus and body of the mandible are

not seen since they lie lateral to midline

Anatomical

porion

Bolton

point

PNS*

Centre of

ramus

Condylion

Centre of condyle

Orbitale

Root apex of upper molar

Mesial limit of upper molar

Mesial limit of lower molar

Root apex of lower molar

Menton

Fig. 11.6: Multiplanar reformatted image of the skull from slice at condyle and ramus of the skull. The condyle, ramus and body of the mandible

are seen; however structures such as sella, sphenoid and nasal spine are not seen at its entire anteroposterior length being in the midline (Figs.

11.5, 11.6 Courtesy Dr Tina Chowdhary and Prof NK Ahuja, Subharti Dental College, Meerut) 4

wmm

10 Bolton point (Bo): The highest point of the curvature

between the occipital condyle and the basilar part of

the occipital bone and located behind the occipital

condyle.

Landmarks on mandible

I

Condylion (Co): Defined as a point located on the

superior posterior contour of the mandible.18

2. Centre of ramus (Xi): Defined as the geometric centre

or the centroid of the ramus by Ricketts in 1972. The

deepest point on the subcoronoid incisures (Rl) is

selected, and a second point (R2) is selected directly

opposite to that on the posterior border of the ramus.

R3 is picked at the depth of the sigmoid notch; R4 is a

point directly inferior in the lower border of the ramus.

By using these four points, the centroid of the ramus

(Xi) is selected by forming a rectangle and joining the

corners.19

3. Centre of condyle (Dc): It is defined as the geometric

centre or the centroid of the mandibular condyle.

4. Gonion (Go): Gonion is defined as a point on the external

angle of the mandible projected in a lateral cephalogram

by bisecting the angle formed by tangents to the

posterior border of the ramus and the inferior border of

the mandible.20The most posterior and inferior point

on mandible corpus is also called anatomical gonion.

5. Menton (Me): Defined as the most inferior point on the

mandibular symphysis.21

6. Gnathion (Gn): Defined as the most antero-inferior point

on mandibular symphysis.

7. Pogonion (Pg): Defined as the most anterior point on

mandibular symphysis.

8. Centre of symphysis (D): It is defined as the geometric

centre or the centroid of the mandibular symphysis.

9. Protruberance menti (suprapogonion) (Pm): Defined

as the superoposterior point on mandibular symphysis

changing from concave to convex.

10. Supramentale (B): Defined as the the deepest point on

the profile curvature from pogonion to infradentale.

11- Infradentale (Id): Defined as the most anterosuperior

point on labial aspect of mandibular alveolus or the

apex of the septum between the mandibular central

incisors.

Landmarks on maxilla

Anterior nasal spine (ANS): Most anterior midpoint

of the anterior nasal spine of maxilla.

2. Posterior nasal spine (PNS): It is defined as the sharp

and well defined posterior extremity of the nasal crest

of the hard palate.

3. Prosthion (Pr): It is defined as a craniometric point that

is the most anterior point in the midline on the alveolar

process of the maxilla.

4. Subspinale (A): Craniometric point that is deepest and

the most posterior point in the midline on the alveolar

process of the maxilla.

Dental landmarks

1. Tip of lower incisor (TLI): Defined as the incisal tip of

the most prominent mandibular central incisor.

2. Tip of upper incisor (TUI): Defined as the incisal tip of

the most prominent maxillary central incisor.

3. Apex of lower incisor (ALI): Defined as the root apex of

the most prominent mandibular central incisor.

4. Apex of upper incisor (AUI): Defined as the root apex

of the most prominent maxillary central incisor.

5. Labial surface lower incisor (LLI): It is defined as the

anterior most point on the labial surface of the most

prominent mandibular central incisor.

6. Labial surface upper incisor (LUI): It is defined as the

anterior most point on the labial surface of the most

prominent maxillary central incisor.

7. Cusp tip of upper molar (TUM): It is defined as the

mesiobuccal cusp tip of upper first molar.

8. Root apex of upper molar (AUM): It is defined as the

root apex of the mesiobuccal cusp of the maxillary first

molar.

9. Cusp tip of lower molar (TLM): It is defined as the cusp

tip of the mesiobuccal cusp of the mandibular first molar.

10. Root apex of lower molar (ALM): It is defined as the

root apex of the mesiobuccal cusp of the mandibular

first molar.

11. Anterior point on occlusal plane(OpA): It defined in

the following ways:

a) The anterior point of the bisecting occlusal

plane is defined as the point bisecting the

vertical overlap of the upper and lower central

incisors.

b) In case of the maxillary occlusal plane the

anterior point on the occlusal plane is the

incisal edge of the most prominent maxillary

central incisor.

c) When the mandibular occlusal plane is taken

into consideration the anterior point is the

i


incisal edge of the most prominent mandibular

central incisor.

12. Posterior point on occlusal plane(OpP): It is defined

in the following ways:

a) The posterior point of the bisecting occlusal

plane is the point where the mesiobuccal cusp of

the maxillary molar meets with the mandibular

molars.

b) In case of the maxillary occlusal plane the

posterior point on the occlusal plane is the

mesiobuccal cusp tip of the maxillary first

molars.

c) When the mandibular occlusal plane is taken

into consideration the posterior point is the

mesiobuccal cusp tip of the mandibular first

molars.

REFERENCES

1. Simon PW. On gnathostatic diagnosis in orthodontics. Int J

Orthod 1924;10:755-58.

2. Simon PW. Fundamental principles of a systematic diagnosis

of dental anomalies (translated by BE Lischer), Boston,

Stratford Co, p. 320, 1926.

3. Simon PW. The simplified gnathostatic method. Int J Orthod

1932;18:1081-87.

4. Broadbent BH. A new radiograph technique and its application

to orthodontia. Angle Orthod 1931; 1: 45-66, reprinted in

Angle Orthod 1981; 51:93-114.

5. Hofrath H. Die bedentung der rontgenfern und abstan

dsaufnahme fur die diagnostik der kieferanomalien. Fortsch

Orthod 1931;1:232-36.

6. Bolton CB. First roentgenographic cephalometric workshop—

proceedings of 1st roentgenographic cephalometric workshop

(sponsored by the American Association of Orthodontists)

March 24-26, 1957. The Bolton Fund Headquarters, Western

Reserve University, Cleveland, Ohio. Am J Orthod 1958;

44(12): 899-900.

7. http://dental.cwru.edu/bolton-brush/index.html. Accessed on

13.04.08.

8. http://w w w.utoronto.ca/dentistry/facultyreserach/dri/

grad_burlington.html.accessed on 13.04.08.

9. Solow B, Siersback-Nielsen S. Cervical and craniocervical

posture as predictors of craniofacial growth. Am J Orthod

Dentofacial Orthop 1992;101:449-58.

10. Kharbanda OP, Sidhu SS, Sunadram KR. Cephalometric

profile of Aryo Dravidians part I. J Indian Orthod Soc 1989;

20: 84-88.


profile of Aryo Dravidians part I I . J Indian Orthod Soc 1989;

20: 89-94.

12. Nanda R, Nanda RS. Cephalometric study of dentofacial

complex of north Indians. Angle Orthod 1969; 39: 22-28.

13. Franchi L, Bacetti, T, McNamara JA (Jr). Cephalometric

floating norms for North American adults. Angle Orthod.

1998; 68:497-502.

14. Glossary of orthodontic terms, published by Dentauram

Germany.

15. Savara BS, Takeuchi Y. Anatomical location of landmarks on

temporal and sphenoid bone.Angle Orthod 1979; 49(2): 141—

149.

16. Bjork A. The face in profile. Svensk Tandlarkare Tidskrift

1947; 40: 30.

17. Seward S. Relation of Basion to Articulare. Angle Orthod

1981 ;51(2): 151—161.

18. Nohadani N, Ruf S. Assessment of vertical facial and

dentoalveolar changes using panoramic radiography. Eur J

Orthod 2008; 30(3): 262-68.

19. Ricketts RM. A principle of arcial growth of the mandible.

Angle Orthod 1972;42(4): 368-386.

20. Legrell PE, Nyquist L, Isberg A. Validity of identification of

gonion and antegonion in frontal cephalograms. Angle Orthod

2000; 70(2): 157-164.

21. Chang HP, Liu PL, Chang HF.Thin-plate spline (TPS) graphical

analysis of the mandible on cephalometric radiographs.

Dentomaxillofac Rad 2002; 31:137- 147.

Downs’analysis

OVERVIEW

• Basis of Downs’ analysis

• Reference landmarks and planes

• Skeletal pattern

• Denture pattern

• Adams and Vorhies polygon

• Downs Norms for Indians

• Summary

Beauty is skin deep. Beauty is deeper to skin

William Downs introduced a method of recording

the skeletal and denture pattern to measure facial

form on a cephalogram in 1948.1 Although

several analyses have been introduced since then, Downs’

analysis is still in use and gives reasonable information on

the lateral skeletal and denture profile of the subject.

Downs felt that there are four types of faces as viewed

on lateral profile:

• Retrognathic with recessive chin

• Mesognathic with straight profile normal chin

• Prognathic, where chin is prominent

• Prognathism when mandible is large.

Original sample and main reference plane. Downs’ norms

were based on 20 Caucasian subjects of age range 12-17

years of both sexes. All individuals possessed clinically

excellent occlusion. The Frankfort horizontal plane was

used as a reference plane because of its clinical visibility

and its familiarity to clinicians.

Basis of Downs’ analysis

Downs considered sagittal position of the ‘chin’ of greater

importance in determining the four basic facial types. He

felt that the subjects, whose malocclusion skeletal pattern

variation was within the range of his norms, could be

treated to norms. However, subjects whose skeletal and

dental patterns were severely beyond the range could not

be treated to a harmonious balanced face within Downs’

range of deviation. Although facial pattern varied from

orthognathic to a mild state of prognathism, the face was

still considered harmonious and balanced.

Downs’ analysis provides information by which we can

determine whether the individual’s pattern shows

comparatively harmonious relations or not, and whether

dysplasia present in the individual is in the facial skeleton,

the dentition or in both.

His analysis was not presented as the basis for a

treatment goal rather it is a method for examining and

quantifying the relationships of the skeletal components of

the face, i.e. maxilla and mandible and its dentition

essentially the incisors.2,3

Reference planes

Downs used the following reference planes (Figs 12.1-12.3):

1. Facial plane. A line drawn from nasion through

pogonion.

i

Fig. 12.1: Skeletal reference planes and variables according to Downs: Skeletal reference planes: 1. F-H plane Po- Or, 2. Facial plane N-Pg, 3.

Y-axis plane S-Gn, 4. Mandibular plane Go-Me, 5. A-B plane

i. Facial angle; iv. Mandibular plane angle; v. Y axis.

Fig. 12.2: Skeletal reference planes and variables according to Downs: Skeletal angular variables:

i. Facial angle, ii. Angle of convexity, iii. A-B plane angle, iv. Mandibular plane angle, v. Y axis angle

Section II: Downs’ analysis

Fig. 12.3: Skeletal reference planes and variables according to Downs: Dental variables: i. Cant of occlusal plane, ii. Interincisal angle, iii. Incisor

mandibular plane angle, iv. Mandibular incisor to occlusal plane angle, v. Protrusion of maxillary incisors (in mm)

2. Mandibular plane. It is drawn tangent to the Gonion

and the lowest point of the symphysis.

3. Occlusal plane. It is drawn by bisecting the overlapping

cusps o f first molars and the incisal overbite. In cases in

which the incisors are grossly malposed, Downs

recommended drawing the occlusal plane through

overlapping cusps of the premolars and the molars.

4. Y-axis. It is formed by drawing a line from sella turcica

to gnathion.

5. FH plane. It is drawn using superior border of machine

porion and orbitale.

Skeletal pattern (Figs. 12.1, 12.2, Table 12.1)

1. Facial angle. It is measured as posterior inferior angle at

the intersection of facial plane with Frankfort horizontal

plane essentially indicates the degree of recession or

protrusion of the mandible in relation to upper face at the

point where FHP is related to facial plane. Increase in

facial angle is suggestive of chin protrusion.

2. Angle of convexity. This angle measures the degree of

the maxillary basal arch at its anterior limit relative to

the facial profile. It is suggestive mid-face sagittal

positioning. Mean 0°, range -8.5° to +10°.

3. A-B plane angle. A-B plane is a measure of the relation

of the anterior limit of the apical bases to each other

relative to the facial line. Mean -4.6°, range 0° to -9°.

4. Mandibular plane angle (MPxFHP). According to

Downs, mandibular plane is tangent to the gonial

angle and the lowest point of the symphysis.

Mean = 21.9°, range 17° to 28°. High mandibular

plane angle suggests an unfavourable hyperdivergent

facial pattern. High mandibular plane angle complicates

treatment and prognosis.

5. Y-axis. It is also called as growth-axis angle, measured

as posterior inferior angle on S-Gn x FHP. The Y axis

indicates the degree of downward and forward position

of the chin in relation to the upper face. A large Y axis

is indicative of the anticlockwise rotation of the

mandible. Y axis does not give indication of the size

of the lower jaw but the direction in which it is

growing. Mean 59.4°, range 53°-66°.

Denture pattern

1. Cant o f occlusal plane. It is suggestive of

anteroposterior tilt of occlusal plane in relation to the

cranial base. Its importance lies in treatment mechanics

and it should not be alerted unfavourably. Mean =

+9.3°, range = +1.5° to +14°.

2 Interincisal angle. It is indicative of protrusiveness of

upper and lower incisors. Acute angle obviously means

proclined incisors. Small angle is seen in class I

bimaxillary protrusion cases. A large angle is seen in


class II division 2 cases and in cases with deep bite.

Mean = 135.4°, range 130°-150°.

3. Mandibular incisor to occlusal plane. The angle

measured is the complement of the angle formed by the

intersection of the long axis of the lower incisor with

the occlusal plane. Meanl4.5°, range = 3.5° to 20°.

4. Incisor-mandibular plane angle. It indicates inclination

of the lower incisor on to the mandibular plane. The

deviation of incisors is indicated as plus or minus from

the 90° mean. Larger is the angle, greater is its

contribution to the interincisor angle.

5. Protrusion of maxillary incisors. The measurement is

made from upper incisor edge to A-Pg line. This linear

measurement indicates the amount of maxillary dental

protrusion. Mean +2.7 mm, range = -1.0 mm to +5.0 mm.

Graphic presentation

Heilman in 1937 introduced polygonal portrayal of

dimensional values in facial growth. A polygon was

suggested by Vorhies and Adams (1951)4 whereas the

vertical centre-line shows Downs’ norm values. Left side

shows low range and on the right side high range of

standard deviation. The polygon represents anteroposterior

deviation of the face with left side representing more of

class II type and right side representing class III type of

pattern (Fig. 12.4). It is an effective method of quantitatively

and qualitatively illustrating a static cephalometric analysis.

It enables clinician to rapidly assimilate the collective data

and serves as a great aid in case presentation.

Fig. 12.4: Adams and Vorhies polygon with Downs’ norms

Table 12.1: Cephalometric norms for Downs’ analysis for Caucasians, north Indians and south Indians

Skeletal pattern

Caucasians

Downs

20

North Indians

OP Kharbanda

25 M+ 25 F

Keralites

RK Roy

50 F

Norm Range Mean Range Mean Range

1.

Facial angle 87.5° 82°-95° 84.09° 77°-90° 85.0° 76°-93°

2. Angle of convexity 0° -8.5°-10° 4.30° -14°-12° 7.5° -4.5°-18.0°

3. A-B plane to N-Pg angle -4.6° 0°-9° -6° -11°- 6.0° -6.7° -13.5°-5.0°

4. Mandibular plane angle 21.9° 28°-17° 24.22° 13°-35° 26.7° 16.5°-36.5°

5. Y-axis angle 59.4° 53°-66° 62.78° 55°-70.5° 62.0° 53.0°-70.0°

Denture pattern

1.

Occlusal plane angle 9.3° 1.5°-14° 10.67° 3°-28° 11° 0.5°-17.0°

2. Interincisal angle 135.4° 130°-150.5° 128° 110°-141° 119° 113°-148.5°

3. Lower incisor to mandibular plane 1.4° 7°-8.5° 11.00° 9°-27° 13.8° 0-27°

4. Lower incisor to occlusal plane 14.5° 3.5°-20° 14.50° 11°-36.5° 28.8° 9.5°-42.0°

5. Upper incisor to A-P line (mm) 2.7 mm -1 -5 mm 6.41 mm 2-10 mm 8.3 mm 0-14.5 mm

Section II: Downs’ analysis 171

Downs’ norms for Indians were investigated by Kotak

(1964)5,Ravi Nanda (1969)6, Sidhu(1970)7, Valiathan (1975

Indian Residents of Washington DC)8, Kharbanda

(1989,1990)9,10 and in several studies at the Lucknow

University (Table 12.1).11

It was observed that Indian faces possess racial

characteristics more so in dental pattern.

population groups

North Indians possess a facial skeleton which is close to

Caucasians except that they seem to have a slightly higher

value for Y axis and angle of convexity suggestive of slightly

more protrusive midface. They possess a characteristic dental

pattern which is characterized by increase of incisor

mandibular plane angle and interincisal angle.

Keralite Indians exhibit a skeletal pattern which is different

from North Indians and certainly shows greater differences

from Caucasians.

For Keralite Indians, the values for FMA and Y axis are

higher suggesting a more vertical (hyperdivergent) facial

pattern. This group also exhibited increased angle of

convexity, which suggests a midface protrusion. The AB

plane to N-Pog angle is also more for them which is

contributed by a retrusive mandible due td vertical pattern

and superior protrusion. They exhibit a decreased value of

interincisal angle (119.0) and increased values of lower

incisor mandibular plane (+13.8) which is suggestive of

proclined upper and lower incisors which contribute to

their bidental facial profile. Increased linear distance of

maxillary incisor A-Pog line (8.3 mm) among them further

contributes to superior protrusion.

Summary

Downs’ analysis essentially gives an indication of skeletal

profile of the subject with ‘Nasion’ as the reference point.

The facial angle suggests anteroposterior positioning of

mandible, whereas angle of convexity would suggest relative

protrusion of maxilla, to the mandible, while AB plane to

N-Pg gives information on how maxilla and mandible denture

bases are oriented in relation to skeletal facial profile (N-Pg)

line. The Y axis provides information on the direction of the

lower jaw in relation to the cranium and the mandibular

plane angle would provide information on the vertical

relation of the jaw bases. The occlusal plane angle

supplements information arrived from skeletal patterns in

terms of inclination of dental occlusal plane with skeletal

pattern.

The interincisal angle gives information on relative

proclination of anterior teeth. The dental protrusion

measured as interincisal angle can be contributed by lower

incisor proclination which is evaluated through incisor

mandibular plane angle. The sagittal position of the upper

incisor is assessed by measuring the distance of the tip of

upper incisors to the A-Pg line.

Hence, by evaluation of the above 10 parameters it may

be possible to assess skeletal pattern of a subject in terms

of skeletal convexity of the profile, position of mandible

and maxilla, in anteroposterior and vertical direction to the

cranium. The relative protrusiveness of the dentition on

their respective denture bases, and the relative

anteroposterior position of maxillary incisor in relation to

maxilla is assessed.

REFERENCES

1. Downs WB. Variation in facial relationships: their significance

in treatment and prognosis. Am J Orthod 1948; 34: 812-40.

2. Downs WB. The role of cephalometrics in orthodontic case

analysis and diagnosis. Am J Orthod. 1952; 38: 162-82.

3. Downs WB. Analysis of the dentofacial profile. Angle Orthod

1956; 26: 191-12.

4. Vorhies JM, Adams JW. Polygonic interpretation of

cephalometric findings. Angle Orthod 1951; 21: 194.

5. Kotak VB. Cephalometric evaluation of Indian girls with

neutral occlusion. J All Ind Dent Assoc 1961; 36: 183-97.

6. Nanda R, Nanda RS. Cephalometric study of the dentofacial

complex of North Indians. Angle Orthod 1969; 39: 22-28.

7. Sidhu SS, Shourie KL, Shaikh HS. The facial skeletal and

denture patterns in Indians - a cephalometric study. J Ind

Orthod Soc 1970; 2: 27-38, 52.

8. Valiathan A. Downs cephalometric analysis on adults from

India. J Ind Dent Assoc 1974; 46: 437-41.


profile of Aryo Dravidians part I. J Indian Orthod Soc 1989;

20: 84-88.


profile of Aryo Dravidians part II. J Indian Orthod Soc 1989;

20: 89-94.

11. Kapoor DN. Cited in Indian Cephalometric Norms. Official

publication of Indian Orthodontic Society. 1996.

Steiner’s analysis

OVERVIEW

• NA and NB planes

• Skeletal analysis

• Dental analysis

• Soft tissue analysis

• Steiner’s norms for Indians

• Steiner chevrons/ sticks

• Cephalometric superimposition

• Summary

Steiner approached and propagated cephalometrics for

effective use in treatment planning and not merely a

diagnostic tool.1'4

Steiner was greatly influenced by the works of Downs,

Wylie and other prom inent workers in the field

cephalometrics at that time, and their influence is clearly

reflected in his analysis. He selected parameters from

various analysis developed by several authors, critically

evaluated, modified and included them in his analysis.

Steiner’s composite analysis is supposed to provide

most useful clinical information from several studies using

only a few parameters from each one of them, for better

treatment planning. Steiner proposed the appraisal of various

parts of the skull separately as:

• Skeletal analysis

• Dental analysis

• Soft tissue analysis

Logical use of reference planes

and parameters_______________

S-N plane substituted FH plane

Steiner highlighted difficulties in accurate location of the

porion point and its relative variation, which could be

observed in successive radiographs. This in turn, affected

the orientation of the Frankfort plane. Although, Frankfort

horizontal plane was traditionally the logical choice of

anthropologists (as porion and infraorbital points were

easily visible in dry skulls, unlike S and N points), they

could not be easily and accurately located on a cephalogram.

On the contrary, S(Sella) and N(Nasion) were easily

discemable in a lateral cephalogram and could be located

with relatively higher accuracy. Moreover, S and N points

had another advantage, of being located in the mid-sagittal

A

172

Section II: Steiner’s analysis 173

plane of the head, and move minimally with any deviation

of head from true profile position. Hence, keeping these

above findings in mind,* Steiner considered S-N plane as a

better, more accurate and predictable alternate plane to the

FH plane.

Angle ANB. Impressed by Dr. Richard Riedel5, Steiner

used SNA and SNB angles to compare the position of the

chin in the lower jaw to the other structure of the cranium

and the upper jaw and ANB angle to compare the relative

discrepancy between the upper and lower jaws.

NA and NB planes

Steiner suggested, assessment of the upper and lower

incisors by comparing their relative position and angulations

to the NA and NB planes as a guide. He felt there were

more direct reference planes than the mandibular plane,

which is not a straight line reference plane, but a curved

one and that too a highly variable one. Although he cited

the above limitation, he continued to use mandibular plane

angle as a reference for evaluating the lower incisors.

Originally, even the distance of the upper molars (6’s) was

measured from NA to be used as a reference at a later date

to determine if any migration of molars (6’s) had occurred

over time.

Downs’6method of measuring the interincisal angle was

retained as a supplementary method of appraisal of the

angulation of these teeth to each other. Moreover, Downs’

philosophy of evaluation of the occlusal plane to determine

the position of teeth in occlusion to the face and skull was

also retained.

Wylie7 and Johnson’s method to determine any

malformation of the mandible was incorporated and Riedel’s

Go-GN plane was used to represent the body of the

mandible.

According to Steiner, mandibular plane is drawn between

gonion and gnathion and occlusal plane is drawn through

the region of the overlapping cusps of the first premolars

and first molars.

Skeletal analysis (Fig. 13.l)

The skeletal analysis entails relating the upper and lower

jaws to the skull and to each other.

Angle SNA. Riedel inner angle on SN plane to N-A line

Mean 82°.

Angle SNB. Inner angle on SN plane to N-B line-mean 80°.

Mandibular plane angle. The inclination of MP to SN

represents (Go-Gn x S-N) vertical relation of the mandible

with the cranium. Excessive high or low angles are

unfavourable for treatment. Mean 32°.

SL distance (Wylie). A perpendicular is dropped from

pogonion to S-N plane and the point is designated as ‘L’.

The linear measurement of SL (Mean 51 mm) represents

effective size of the mandible.

SE distance (Wylie). It is the linear measurement from a

point E to S. A perpendicular is drawn on S-N from most

distal point of mandibular condyle and this point is

designated as ‘E’. S-E (Mean 22 mm) represents the most

distal location of the condyle with the teeth in occlusion.

SL and SE are useful in assessing the changes in position

and effective length of the mandible.

SND is angle formed on SN plane and line from N-D. D is

the centre of mandibular symphysis.

Dental analysis (Fig. 13.2)

Lower incisor to chin. It is measured according to Holdaway.

The discrepancy of the distance between the labial surfaces

of lower incisor to N-B and the distance between N-B line

and Pog is measured. According to Holdaway, up to 2 mm

discrepancy is acceptable, 3 mm discrepancy is not desirable

and 4 mm or more would require corrective measures.

Maxillary incisor position (Wylie). Maxillary incisor position

is measured in terms of its inclination and linear distance to

NA line. Mean angulation of the long axis of maxillary

incisor to NA line is 22° and linear distance is 4 mm.

Mandibular incisor position (Wylie). It is measured in

angulation and linear distance to NB line. Mean angulation

of mandibular incisor to NB line is 25° and linear distance

of lower incisor to NB line is 4 mm.

Interincisal angle (Downs)7. It is a measure of relative

position of upper incisor to lower incisor and its interpretation

as given by Downs. Mean = 131°.

Occlusal plane angle (Downs). Same interpretation as given

by Downs. Mean 14.5°.

Upper incisor to S-N plane. Provides information on

proclination/retroclination of the maxillary incisors in relation

to the SN plane independent of the interincisal angle.

Clinically, this measurement is particularly important in the

evaluation of the torque of upper incisors. Mean-104°.

Mandibular incisors to mandibular plane. Mean: 93°. Same

interpretation as Downs except that Steiner considers it its

actual measurement unlike Downs.

Maxillary permanent first molar to N-A line (Wylie). This

measurement is useful in the evaluation of molar position

in the maxilla which may be necessary to evaluate loss of

anchorage following mechanotherapy. Mean: 27 mm.


Mandibular permanent first molar to N-B line (Wylie).

This measurement is similar to maxilla and is useful in

determining whether the lower molar has moved in relation

to N-B plane during the treatment. Mean: 23 mm. The

maxillary and mandibulor first molars measured at their

contact points.

Soft tissue analysis

The soft tissue analysis provides a means of assessing the

balance and harmony of the lower facial profile. The facial

contour line called ‘S’-line of Steiner. A line is drawn on

the soft tissue contour of the chin to the middle of the ‘S’

formed by the lower border of the nose. In a well-balanced

face, the lips should touch the line. T heS line partially

excludes the effect of nasal growth on the soft tissue

profile.

Steiner’s norms for Indians

Steiner’s norms for Indians have been developed by several

authors. The important ones for north India being by

Kharbanda et al (1989)8,9 Parsees and Maharashtrians by

Sidhu (1970),10 Kerala Population by Valiathan and John

(1976)11 and others at the university of Lucknow12 (Table

13.1).

Interpretation and comments

Mean values of various parameters of Indian population are

some what different in some aspects more so the dental

parameters, compared to the norms compiled by Steiner.

However, on close look, Indians were observed to have

slightly larger value of angles ANB suggesting that Indians

possess slightly retrusive mandible.

Increased values of angular and linear measurements of

maxillary incisor to NA and mandibular incisor to NB line

suggest proclined incisors and forward placement of incisors

in relation to NA and NB lins. These findings are more

prominent among population group from Kerala.

Steiner chevrons/sticks

Steiner found that some acceptable dental compromises

naturally occur in different skeletal maxillomandibular

relations, i.e. ANB values. Based on his observations, he

gave a novel method of treatment planning for non-growing

patients.

He concluded that in non-growing patients in whom

skeletal relations cannot be altered, it may not be possible

that dentition is corrected according to ideal norms. Here it

becomes imperative to treat the dentition to acceptable

compromise situation that will mask the underlying skeletal

Table 13.1: Steiner’s cephalometric norms for Caucasians, north Indians and south Indians

SN

Age group

Caucasians

CC Steiner

North Indians

Kharbanda

Lucknow 18-25 yrs

South India

Kanappan

Madras 18-20 yrs

Keralites

John and Valiathan

Sex

19M

26F

100 (M+F)

1 SNA0 82 82.92 82.28 82.6 84.14

2 SNB0 80 79.9 78.52 79.9 81.85

3 ANB0 2 3.02 3.52 2.7 2.27

4 SND° 76 - - 77.3 79.36

5 SN x Go-Gn° 32 27.24 26.83 31.0 27.91

6 SLmm 51 54.83 52.50 50.9 59.66

7 SEmm 22 21.12 19.84 22.2 21.46

8 1 to NA° 22 23.96 23.17 23.5 27.44

9 1 to NA mm 4 6.23 5.65 4.2 7.46

10 T to NB° 25 27.73 27.80 26 30.75

11 T to NB mm 4 6.82 6.02 5.2 7.50

12 1 to T° 131 124.34 124.07 128 119.69

13 1 x SN° 104 104.83 104.88 - -

14 T x MP° 95 -

-

15 OP-MP0 x Or-SN° 14.5 - 11.79

16 6 - NAmm 27 23.01 23.13 -

17 6- NBmm 23 17.53 18.52 -

Section II: Steiner’s analysis 175

Fig. 13.1: Skeletal variables used by Steiner

Fig. 13.2 : Dental variables used by Steiner

deformity as much as possible. For these, Steiner’s sticks

were given and calculations are carried out for a particular

ANB value. These calculations define our orthodontic goal

and also help us decide on extraction and non-extraction

decisions.

Cephalometric superimposition

Steiner evolved his own method of cephalometric

superimposition for the purpose of evaluation of changes

that occur due to growth and orthodontic treatment. He

suggested superimposition of lateral tracing on S-N plane

registration at ‘N’ thus causing the lines NA to superimpose.

The record of anteroposterior growth is thus expressed

posterior to these lines.

To evaluate changes in the maxilla alone, the tracing is

moved vertically parallel to the S-N plane till drawings of

maxilla, like palatal contour is superimposed as best fit.

The movement of maxillary teeth can now be visible.

The movement of teeth within mandible is assessed by

superimposition of the mandible over the best-fit crosssection

of symphysis of mandible, keeping the lower border

parallel.

For registering the changes in the location of the mandible

and its relationship to craniofacial structures, the tracings

are superimposed on line S-N, registered at ‘S’.

Distances between points ‘L’ and ‘E’ represent the

anteroposterior lengths of the mandible. This measurement

is an indication and not an accurate measurement of change

in the length of the mandible because these measurements

do get affected with change in inclination of occlusal plane

with the opening of bite.

Interpretations and Summary

The method of cephalometric analysis by Steiner is intended

and designed for application of cephalometric data for

clinical practice.

For example, a case with high values of angles SNA and

SNB and yet an ANB of normal value would be considered

an average/normal sagittal jaw relationship with a unique

facial type. Steiner laid greater emphasis on position of

incisors and its inclination in relation to denture bases. He

considered it as one of the most vital indicators of

malocclusion and important in diagnosis of a case.

The measurement of upper molar position to N-A line

serves as a reference for the future use to analyze amount

of anchorage loss. Similarly, the position of the lower molar

to NB line is measured as a reference for the evaluation of

future lower molar position. A standard norm of these lines

is useless because of the number of teeth intervening

variations in their size and also likely hood of their

malposition which would influence the measurements.

In order to locate mandible for comparison purposes

during and after treatment, pretreatment SL and SE distances

are used as reference measurements. The change in these

measurements represents alteration in its anteroposterior

position as well as change in effective length of the

mandible.

Steiner also locates the centre of the condyle in occlusion

and at rest position of the mandible. He then transferred

these tracings on each other to locate path and distance of

opening of mandible at gnathion and centre of condyle.

The distance measured at Gn-Gn’ varies great deal in

different individuals and often varies considerably during

treatment. This parameter may represent freeway space to

a great extent and hoped that it is likely to gain greater

importance in future for treatment planning.

REFERENCES

1. Steiner CC. Cephalometrics for you and me. Am J Orthod

1953; 39: 729-55.

2. Steiner CC. Cephalometrics in clinical practice. Angle Orthod

1959; 29: 8-29.

3. Steiner CC. The use of cephalometrics as an aid to planning

and assessing orthodontic treatment. Am J Orthod 1960; 46:

721-35.

4. Steiner CC. Cephalometrics as a clinical tool. In: Kraus BS,

Reidel RA (eds): Vistas in Orthodontics. Philadelphia: Lea

and Febiger; 1962, p. 131-61.

5. Riedel, Richard A. An analysis of dentofacial relationships.

Am J Orthod 1957; 43: 103.

6. Downs WB. Variations in facial relationships-their significance

in treatment and prognosis. Am J Orthod 1948; 34: 812-40.

7. Wylie, Wendell L. Assessment of anteroposterior dysplasia.

Angle Orthod 1947; 17: 97-109.

8. Kharbanda OP, Sidhu SS, Sundaram KR. Cephalometric

profile of Aryo-Dravidians part I. J Indian Orthod Soc 1989;

20: 84-88.


profile of Aryo-Dravidians part II. J Indian Orthod Soc 1989;

20: 89-94.

10. Sidhu SS, Shourie KL, Shaikh HS. The facial, skeletal and

denture patterns in Indians - A cephalometric study. J Ind

Orthod Soc 1970; 2: 27-38, 52.

11. Valiathan A, John KK. A comparison of the cephalometric norms

of Keralites with various Indian groups using Steiner’s and

Tweed’s analyses. J Pierre Fauchard Acad 1991; 5(1): 17-21.

12. Kapoor DN. Cited in Indian Cephalometric Norms. Official

publication of Indian Orthodontic Society, 1996.

Tweed’s analysis

OVERVIEW

• Development of the diagnostic facial triangle

• Cephalometric values effect decision to treat extraction or non-extraction

• FMA and its relationship with IMPA

• Head plate correction

• Tweed’s norms for Indians

• Summary

Tweed’s analysis (1954) is essentially based on the

inclination of the mandibular incisors to the basal

bone and its association with the vertical relation of

the mandible to the cranium.1,2’3

Development of the diagnostic facial triangle

Tweed’s cephalometric analysis has its beginning in clinical

orthodontics where he found that the cases of malocclusion

with pleasing outcome, harmonious profiles and stable

occlusion following orthodontic treatment had a common

consistent feature of occlusion: their mandibular incisors

were upright on their skeletal bases.

The clinical observations supplemented and quantified

on cephalograms led to the development of the diagnostic

triangle. Tweed’s diagnostic triangle is simple and basic,

yet provides a definite guideline in treatment planning.

Landmarks used in the construction of Tweed’s triangle.

Tweed used FH plane, mandibular plane and long axis of

the mandibular incisor to construct a triangle.

Cephalometric values effect

decision to treat extraction or

non-extraction________________

Angle’s philosophy of orthodontic treatment was based on

the assumption that if the cuspal interdigitation of the teeth

was made normal, the stimulation occasioned by orofacial

function would result in growth of the basal bone structures,

i.e. maxilla and mandible, which would accommodate full

complement of teeth and result in a balanced harmonious

face. Hence, little or no thought was given to the inclination

of mandibular incisors and to the mesiodistal relationship

between the teeth and their respective jaw bones. In the era

of Angle, Tweed also strictly adhered to the philosophy of

non-extraction.

However, in the years following, Tweed realized his

inability to create balance and harmony of face in more than

a few patients. Also he noticed significant relapse in quite

a few of his treated cases thus casting doubt over the longterm

stability of the results. So he started analysis of the

177


treatment records (1934), results of which prompted him to

conduct a study on the features and characteristics of

occlusion, dentition and faces of ‘normal’ people who never

had orthodontic treatment. His initial impression was based

on clinical examinations alone. The relationship of teeth to

the basal bone was carefully noted, especially the inclination

of incisor teeth.

He found that in an average non-orthodontic normals, the

incisal inclination was approximately 90° when related to the

mandibular plane. From the study, he found a variation of 10°

in the inclination of mandibular incisor as related to mandibular

plane in subjects with normal occlusion. Further from his

records of treated cases also noted that in a majority of cases

which showed relapse the incisor-mandibular plane angle

deviated significantly from the ideal of 90°.

He concluded that if the orthodontist is to attain facial

aesthetics and occlusion similar to that found in nonorthodontic

normals, then the mandibular incisors should

be positioned in a range of 85° to 95° with a mean of 90°.

Based on his observations on lower incisor mandibular

plane angle (IMPA) and its association with variation in

Frankfort mandibular plane angle (FMA), he found that a

consistent finding was a resultant 3rd angle of the triangle

which was Frankfort mandibular incisor angle (FMIA).

Tweed found that extraction of teeth was necessary in

patients with FMA more than 30°.

He observed that when the FMA ranges upward from

35°, it was physically impossible to fully compensate the

inclination of the mandibular incisors, i.e. make them less

than upright. Prognosis is not good in such cases and the

orthodontist is limited in his efforts to create stable end

results and establish harmony and balance of facial

aesthetics.

The results of this clinical research established the norm

for FMA as 25° with a normal variation of 16° to 35°. This

resulted in the development of the 2nd angle of the

diagnostic facial triangle. Since the sum of the three angles

of the triangle is 180°, it is expected that in a normal case

with 25° of FMA and 90° of IMPA the 3rd angle which is

FMIA would be 65°.

His clinical observations were further supported by a

cephalometric study. The sample size consisted of 100

people, chosen on the basis of balance and harmony of

facial aesthetics. The average of the three angles is as

follows (Table 14.1):

• FMA-25°

• IMPA-900

• FMIA-65°

c

Fig. 14.1: Planes and angles used in Tweed's analysis

Me

*

Section II: Tweed’s analysis 179

T Z .

Table 14.1: Indian norms for Tweed’s analysis

population Caucasians North Indians Indian adults

Tweed’s norms Kharbanda et al (1991) Valiathan A (1976)

Age group 100 18-26 yrs 20-48 yrs

48(25M+23F)

20(10M+10E)

Mean Range Mean Range Mean Range

FMA 24.57 16-35° 23.49 13-35 21.6 13.5-3.30

FMIA 86.93 56-80 53.87° 36-74.5 51.87 32.5-66.5

IMPA 68.20 76-99 101.7° 81-117 106.5 88-129.5

FMA and its relationship with IMPA

Tweed observed that the patients in whom FMA angle was

more than 30° demonstrate nature’s compensation of

inclination of mandibular incisors when related to mandibular

plane. IMPA angle was found as little as 77°. FMIA angle

was around 65°. The occlusal plane converges toward the

mandibular plane, because of excessive height of mandibular

incisors as compared with molar height.

In patients with FMA angle of 25° ± 4° (21° to 29°),

FMIA angle was found to be 65° - 70°. The occlusal plane

did not converge posteriorly as sharply towards the

mandibular plane as it did in patients with large FMA. The

patients in whom FMA angle was below 20° rarely

demonstrated IMPA greater than 94°. Their FMIA reading

ranged from 68° - 85°. The occlusal plane converged less

sharply towards the mandibular plane. In some cases, it

was parallel to the mandibular plane.

He, therefore, postulated that FMIA is critical, and

hence while planning orthodontic treatment, IMPA should

be compensated for a minimum of 77° for higher FMIA

and to a maximum of 105° for lower FMIA.

Head plate correction

Tweed also utilized IMPA correction on a cephalogram

according to his treatment objectives and called it head

plate correction. He accordingly calculated the space

requirements in the arch based on the amount of change

required to place the lower incisors correctly over basal

arch. Orthodontists across America and Europe treated

cases according to the IMPA goals of Tweed’s triangle. In

India too during 70’s, the treatment planning were based

using Tweed’s objectives of IMPA as guideline.

• FMA > 30°, mandibular incisors are compensated so

that FMIA ranges from 65°-70°. Prognosis - Fair

extraction is usually indicated.

• FMA = 25° ± 4°, effort should be maintained to attain

FMIA of 68°-70°.

• FMA < 20° IMPA should not exceed 94°.

In his analysis, Tweed stressed the importance of FMIA

ai*gle, and recommended that it should be maintained at 65°

" 70°. As an example, a case with FMA-21°, FMIA-51° and

IMPA-108° should be corrected to IMPA of 90° with this

change, FMIA would be 69°, which is within recommended

range. This would necessitate removal of dental units

(Table 14.2).

Table 14.2: Predicting IMPA for a patient for his FMA

(based on Tweed’s norms for north Indian adults)

FMA IMPA L-IMPA U-IMPA

15.000 110.125 105.575 114.675

16.000 109.141 105.017 113.265

17.000 108.157 104.445 111.869

18.000 107.173 103.855 110.491

19.000 106.189 103.239 109.139

20.000 105.205 102.586 107.824

21.000 104.221 101.881 106.561

22.000 103.237 101.102 105.371

23.000 102.253 100.258 104.277

24.000 101.269 99.243 103.294

25.000 100.284 98.147 102.422

26.000 99.300 96.955 101.646

27.000 98.316 95.691 101.941

28.000 97.332 94.375 100.290

29.000 96.348 93.022 99.674

30.000 95.364 91.644 99.084

31.000 94.380 90.247 98.513

32.000 93.396 88.837 97.955

33.000 92.412 87.417 97.407

34.000 91.428 85.990 96.866

35.000 90.444 84.556 96.331

The table is based on correlation of IMPA with FMA which is strong but

negative.

X=124.88-0.9841 Y

L = Lower Limit

L= 95% Lower limit U = Upper Limit

Y= 95% Upper Limit

Kharbanda OP, Sidhu SS, Sundram KR. Cephalometric profile of north Indians:

Tweed’s analysis. Int J Orthod 1991 ;29(3-4):3-5.

. .

L


Estimated IMPA

/ ! i i

W/--1------1----- 1---- ,-------1--- ,-------1-------r

80 85 90 95 100 105 110 115

IMPA°

Fig. 14.2: Prediction of IMPA according to FMA of the individual patient

as given by Kharbanda et al based on north Indian subjects

Tweed norms for Indians4

Kharbanda et al reported that in their sample of north

Indian adults with class I occlusion and balanced facial

profile exhibited, FMA close to the Tweed’s norm. They

reported mean FMA of 23.49° (range 13°-35°). The IMPA

values ranged from 81° - 117° with a mean of 101.77°.

Therefore, the values for FMIA were found in the range of

56°-74° with a mean of 53.87°. This study also found a

highly significant and negative correlation between FMA

and IMPA. Using a linear regression analysis, they devised

a table and a normograph to estimate IMPA for individual

patient based on his FMA (Fig. 14.2, Table 14.2).

Interpretations and comments

• In most of the Indian studies, FMA has been found

close to Tweed’s norms.

M

• FMIA value has been found to be around 55° which is

quite low as compared to Tweed’s mean of 65°.

• In all studies conducted on Indian population groups,

IMPA was found to be close to 100°, i.e. 10° more

than the value observed in Caucasians suggesting that

Indians have more proclined mandibular incisors as

compared to Caucasians.

• It has been observed that the correlation of IMPA with

FMA and FMIA were negative and highly significant

indicating that any increase or decrease in FMA was

compensated by an inverse change in the IMPA to

maintain good facial harmony.

Summary

Tweed’s analysis is simple and clinically useful analysis.

His norms should be considered only as a guide and not

absolute achievable objectives. The treatment objectives of

IMPA should be considered according to facial pattern, i.e.

FMA. Racial/ethnic variations of norms cannot be

overlooked while oulining goals and planning the treatment.

REFERENCES

1. Tweed CH. The Frankfort - mandibular incisor angle (FMIA)

in orthodontic diagnosis, treatment planning and prognosis.

Angle Orthod 1954; 24: 121-69.

2. Tweed CH. Was the development o f the diagnostic facial

triangle an accurate analysis based on fact or fancy? Am J

Orthod 1962; 48: 823-40.

3. Tweed CH. The diagnostic facial triangle in the control of

treatment objectives. Am J Orthod 1969; 55(6): 651-57.


profile of north Indians: Tweed’s analysis. Int J Orthod, Fall-

Winter; 1991; 29(3-4): 3-5.

5. Valianthan A, John KK. A comparison o f the cephalometric

norms o f Keralites with various Indian groups using Steiner’s

and Tweed’s analyses. J Pierre Fauchard Acad 1991; 5(1):

17-21.

OVERVIEW

• Robert Murray Ricketts

• Ricketts cephalometric analysis

• Skeletal landmarks

• Basic reference planes

• Eleven factor analysis

• Summary

Robert Murray Ricketts

Dr. Ricketts attended dental school at Indiana and

was a determined scholar in orthodontics at the

University of Illinois. He was a student of Dr. Allan

G. Brodie and follower of Downs. He was the founder of the

American Institute of Bioprogressive Education, and was

instrumental in establishing the Foundation for Orthodontic

Research (FOR). He was an expert and an authority in the

science of human craniofacial development and has done

extensive research work on cephalometrics and prediction

of growth and computer aided diagnosis.

Ricketts cephalometric analysis

Ricketts approach in selection of landmarks and parameters

was essentially based on the pattern of facial growth.1'3The

landmarks used by him are (Fig. 15.1):

Skeletal landmarks

A point. The deepest point on the curve of the maxilla

^

^

between the anterior nasal spine and the dental alveolus.

ANS. Tip of the anterior nasal spine.

BA basion. The most inferior posterior point of the

occipital bone at the anterior margin of the occipital

foramen.

4. PT point. The intersection of the inferior border of the

foramen rotundum with the posterior wall of the

pterygomaxillary fissure.

5. CC (Centre of cranium) point. Cephalometric landmark

formed by the intersection of the two lines BA-NA and

PT-GN.

6. CF (Centre of face) point. Cephalometric landmark

formed by the intersection of the line connecting

porion and orbitale and perpendicular through Pt.

7. DC. A point selected in the centre of the neck of the

condyle where Basion-Nasion planes coincide.

8. GO (Gonion). Intersection of the line connecting the

most distal aspect of the condyle to the distal border

of the ramus (Ramus plane), and line at the base of

mandible (Mandibular plane).

9. PM. A point selected at the anterior border of the

symphysis between point B and pogonion where the

curvature changes from concave to convex.

10. PO (Pogonion). The most anterior point of the

midsagittal symphysis tangent to the facial plane.

11. Xi-point (Fig. 15.2). A point located at the geometric

centre of the ramus. Location of Xi is keyed

geometrically to porion-orbitale (FH) and perpendicular

through PT (PTV) in the following steps:

• By construction of planes perpendicular to FH and

PTV. * •


Fig. 15.2: A. Landmarks, planes and variables used in Ricketts summary analysis, B. Construction of Xi-point

Section II: Ricketts’ analysis 183

• These constructed planes are tangent to points

(Rl, R2, R3, R4) on the borders of the ramus.

• The constructed planes form a rectangle enclosing

the ramus.

• Xi is located in the centre of the rectangle at the

intersection of diagonals.

Steps in the construction of the Xi-point (Fig. 15.2 A, B)

Rl. Mandible. The deepest point on the curve of the

anterior border of the ramus, one-half the distance

between the inferior and superior curves.

R2. Mandible. A point located on the posterior border of

the ramus of the mandible.

R3. Mandible. A point located at the centre and most

inferior aspect of the sigmoid notch of the ramus of the

mandible.

R4. Mandible. A point on the border of the mandible

directly inferior to the centre of the sigmoid notch of

the ramus.

Relevant dental landmarks

1. A 6 (Upper molar). A point on the occlusal plane

located perpendicular to the distal surface of the crown

of the upper first molar.

2. B 6 (Lower molar). A point on the occlusal plane

located perpendicular to the distal surface of the crown

of the lower first molar.

3. TI point. The point of intersection of the occlusal and

the facial planes.

Basic reference planes (Fig, 15.3)

Horizontal reference plane

Frankfort horizontal (FH) plane is constructed by connecting

the porion and the orbitale.

Vertical reference plane

Pterygoid vertical (PTV) is constructed by drawing a line

perpendicular to the Frankfort plane at the posterior margin

of the pterygopalatine fossa.

The intersection of FH and PTV has been found to be

stable, i.e. the change in the location of this point as a

result of patient growth is minimal. Therefore, serial

cephalometric tracings of a patient superimposed at this

point are recommended.

Facial axis

It is a line from PT point through cephalometric gnathion

which normally intersects Basion-Nasion at a right angle.

Cranial base

The border between the face and the cranium can be

defined by a line connecting Basion and Nasion.In a normal

adult Caucasian, the basion-nasion line makes a 30° angle

with Frankfort plane.

Occlusal plane

It is a line bisecting the overbite of the molars and passing

through the overbite of the first bicuspids. In the adult

Caucasian, the plane passes just inferior to Xi-point, nearly

bisecting the angle of lower facial height. The occlusal

plane is nearly parallel to the Frankfort horizontal and

palatal plane.

Maxillomandibular relationship

Horizontally, the maxilla and mandible of the normal face are

in alignment, both falling along the facial plane. Vertically,

the relation of the maxilla to the mandible is described by

the lower facial height and the intersection of two planes,

ANS-Xi and Xi-PM. The norm for this measurement is 45°.

The maxillary first molar normally is 21 mm anterior to the

pterygoid vertical. The relationship of the maxillary to the

mandibular first molars is such that the maxillary molar is 3

mm distal to the mandibular molar.

Eleven factor summary analysis

Eleven factor summary analysis given by Ricketts is a

simplified version of his detailed and comprehensive

cephalometric analysis. It provides an overview of the

patient’s craniofacial and dental growth direction. The

cephalometric norms are based on the research studies of

normally growing individuals and may not truly reflect the

growth of a case of malocclusion with abnormal growth

trend (Fig. 15.3).

Measurements to locate the chin in space

1. Facial axis angle. This angle is formed by the

intersection of basion-nasion line and the facial axis.

The angle describes the direction of growth of mandible

at chin. A larger angle indicates horizontal direction of

mandibular growth while a smaller angle is suggestive

of more vertical growth. Facial axis angle remains stable

in a normally growing child or reduce a little.

2. Facial depth angle. This angle is formed by the

intersection of the facial plane and the Frankfort

horizontal plane. This angle gives the clinician an

indication mandible (pogonion) in sagittal direction.

This facial depth angle increases 1° every 3 years as

the mandible grows forward and downward. In

adulthood, the mean measurement is 90°.

3. Mandibular plane angle. The mandibular plane angle is

formed by the intersection of mandibular plane and the

Frankfort horizontal plane. High mandibular plane angle

is seen in dolichofacial patients with weak musculature

or vertical growth problems. Low mandibular plane angle

is found in brachyfacial types with strong musculature

and deep bites who tend to have square jaws. This angle

tends to decrease 1° every 3 years until maturity, as a

result of growth and adaptive changes that occur to the

mandible during normal development.

Fig. 15.3 : Landmarks, planes and variables used in Ricketts summary analysis

Table 15.1: Ricketts’ norms at 9 years and growth changes

Variable Measurement Norm

Age 9

Clinical Dev.

Mean change/year

1. Facial axis 90° ±3.5° No change with age

2. Facial (angle) depth 87° ±3° Change=+10 every 3 years

3. Mandibular plane to FH 26° ±4.5° Change= -10 every 3 years

4. Lower facial height 45° ±4° No change

5. Mandibular arc 26° ±4° Increases 1/2° per year

6. Convexity of point A 2 mm ±2 mm Change-1 mm every 3 years

7. Mandibular incisor to A-PO plane +1 mm ±2 mm No change with age

8. Mandibular incisor inclination to A-PO 22° ±4° No change with age

9. Upper molar to PTV 12mm ±3 mm Changes=+1 mm/year

10. Interincisal angle 130° ±6° No change with age

11. Maxillary depth 90° ±3° No change with age

Source: RMO® & Diagnostic Services 1989

Section II: Ricketts’ analysis 185

4. Lower facial height. This is the angle formed by the

intersection of a line from anterior nasal spine (ANS)

to Xi-point and the corpus axis (Xi-PM). A larger angle

indicates a divergence of mandible and maxilla or

vertical growth trend. Lower facial height angle does

not usually change significantly with age. However,

this angle would be affected by treatment mechanics,

i.e. it may open or close the bite. Low values of angle

are suggestive of horizontal facial pattern.

5. Mandibular arc. The mandibular arc is the angle formed

by the intersection of the condylar axis (DC-Xi) and the

distal extrapolation of the corpus axis. It describes the

configuration of the mandible whereby a large angle is

indicative of a ‘strong’ and ‘square’ mandible; a small

angle represents a lower jaw with a short ramus and

vertical growth pattern. Smaller angles suggest a short

romus and vertical growth trend. The norm for a 9-yearold

child is 26° + or - 4°. It decreases approximately

0.5° per year with growth.

Measurements to determine convexity

6. Convexity of point A. Facial convexity is the distance

in millimeters from A point to the facial plane, when

measured perpendicular to that plane. The normal growth

trend shows more anterior growth of the mandible than

the maxilla. Thereby a decreases in its measurement

with age. At maturity, the norm is 9 mm, indicating that

A point lies along the facial plane a high convexity

indicates a Class II skeletal pattern; negative convexity,

a skeletal Class III.

Measurements to locate denture in face

7. Lower incisor protrusion. This linear measurement

relates the position of the tip of the lower central incisor

to the maxillomandibular relationship. The plane used to

describe this relationship intersects both A point and

pogonion (A-PO). The distance from the tip of the incisor

is measured perpendicular to this plane. The position of

the lower incisor has been associated both with aesthetics

and stability as suggested by Tweed. Labial or lingual

movement of lower incisors affects archlength.

8. M andibular incisor inclination. The angular

measurement formed by the intersection of the long

axis of the lower central incisor and the A-PO plane is

called the lower incisor inclination. The measurement

also relates the lower incisor to the maxillomandibular

relationship.

9. Upper molar position. Upper molar position is the

linear distance between the most distal point of the

maxillary first permanent molar, and the pterygoid

vertical (PTV) measured parallel to the occlusal plane.

This measurement indicates mesial or distal position of

the upper denture. It is also indicative of whether or

not the upper molar can be moved distally without

impacting the maxillary second and third molars. Norm

is the patient’s age (in years) plus 3 mm. At least 21 mm

of maxilla (+/- 3 mm) is generally needed in later years

for proper eruption of the second and third molars.

10. Interincisal angle. The angle depicts cumulative

proclination of the upper and lower incisors. It does

not quantify the proclination of maxillary/mandibular

tooth.

Measurements to determine the profile

11. Lower lip to E-plane. The lower lip protrusion is

evaluated by measuring the lower lip from an aesthetic

line constructed by joining the tip of the nose and the

tip of the chin.

12. Maxillary depth. This angle is formed by intersection

of FHP to a line from Nasion to A point. The maxillary

depth angle relates horizontal position of maxilla at

point A to cranium (NA).

Summary

Ricketts cephalometic analysis essentialy tries to orient

face and mandible to the cranium. His analysis was

fundamental to this treatment approach whereby he gave

great emphasis to the growth and facial growth pattern. The

ultimate objective was to integrate growth to work out best

possible treatment plan.

REFERENCES

1. Ricketts RM. Cephalometric analysis and synthesis. Angle

Orthodontist 1961;31:141-56.

2. Ricketts RM. Perspectives in the clinical application of

cephalometrics: the first fifty years. Angle Orthod 1981;

51(2): 115-50.

3. Ricketts RM. A principle of archial growth of the mandible.

Angle Orthod 1972;42(4):368-86.

C H A P T E R

Vertical linear dimensions of face

and Sassouni analysis

OVERVIEW

• Vertical linear dimensions and ratio of face

• Sassouni’s radiographic cephalometric analysis

• Jarabak’s ratio of anterior and posterior facial heights

• Signs of vertical growth rotation

• Summary

Vertical linear dimensions and

ratio of face_________________

The vertical proportions of the face are important in

determining the aesthetics and harmony of the face.

The role of the vertical dimension in the aetiology of

various anteroposterior problems was realized relatively late

in the mid twentieth century.

Wylie as early as 19471 , did some commendable

attempts in devising a method for rapid evaluation of

facial dysplasia in vertical plane. He used the following

linear dimensions in the anteroposterior plane to localize

dysplasia of the maxilla and the mandible using the FH

plane as a reference.

1. Glenoid fossa - sella

2. Sella - Ptm

3. Ptm - maxillary first permanent molar (buccal groove)

4. Ptm - ANS (maxillary length)

5. Mandibular length, vertical drawn on mandibular plane

from, posterior condyle surface and pogonion.

If the first four linear dimensions that represent maxilla

and upper face were longer than average dimensions, it is

obvious that upper face would be prognathic and if the

mandible length is large it will make the lower face more

prognathic (Fig. 16.1AJB).

These linear values are not to be judged in absolute

sense but are to be considered in proportionality. The

relative proportions of some dimensions may vary but may

show some proportions and compensate by deviating in an

appropriate direction. For example, a large maxillary length

can be compensated by a short cranial base.

Later, Wylie and Johnson2 used a vertical dimension

approach on anterior and posterior face. The anterior face

height was divided into upper face height, nasion to ANS

and lower face height, ANS to menton. Posterior vertical

height was measured from the summit of the condyle to the

gonial angle. If the mandibular length is large, it will make

the lower face more prognathic (Fig. 16.2).

The anterior face height is divided into upper face height

(N-Ans) and lower face height (Ans-Me). A ratio of 45:55

is considered normal. An increase in lower face height is

suggestive of downward and backward rotation of the

mandible, anterior open bite, short ramus, large gonial angle

or combinations of above two or more features in varying

degrees of severity.

4

186

n

A

B

Fig. 16.1: Rapid evaluation of facial dysplasia according to Wylie and Johnson 1952: A. Parameters and average values for a 11.5 years female:

1. Glenoid fossa-sella, 2. Sella-Ptm, 3. Ptm - buccal groove of first molar, 4. Ptm-Ans maxillary length, 5. Mandibular length, B. In a face with

larger vertical dimensions yet same AP dimensions, a longer mandible will compensate for the maintenance of profile

% 16.2: Analysis of vertical face heights and ratio: N - Anterior face height, N - Ans: Upper anterior face height. Ans - Me: Lower anterior face

height, S - Go: Posterior face height. S - Ar: Upper posterior face height, Ar - Go: Lower posterior face height


A

D

C B A

B

Fig. 16.3: A, B. Landmarks, planes and arcs used by Viken Sassouni

Section II:: Vertical linear dimensions of face and Sassouni analysis 189

Table 16.1: Analysis of vertical facial heights7

All the measurements are perpendicular distances in mm

North Indians

Variable/parameter Males Females

Mean SD Mean SD

Anterior facial height: upper 53.16 mm 3.36 50.65* mm 4.39

Anterior facial height: total 118.48 mm 6.78 111.70**mm 6.31

Ratio of anterior face heights 45.43% 2.82 45.35% 3.03

Posterior lower facial height 58.40 mm 5.74 52.35**mm 5.30

Posterior total facial height 89.56 mm 5.52 79.91 **mm 4.64

Ratio of posterior face heights 64.81% 4.87 65.50% 6.20

Jarabak’s ratio 75.74% 5.16 71.68%** 4.63

* Significant difference, ** P < 0.01

Sassouni’s radiographic

cephalometric analysis35______

Although several authors worked towards understanding

the role and importance of the vertical dimension, and its

effect on the anteroposterior dimensions of the face, Viken

Sassouni’s work (1955) greatly emphasised it in orthodontic

treatment planning.

Sassouni’s analysis was the first cephalometric method

to categorize vertical as well as horizontal relationships, and

the interaction between vertical and horizontal proportions

of face.

Sassouni constructed a series of planes, arcs and axes

on the profile cephalostatic roentgenogram in order to

study the structural configuration of the skull for the

purpose of growth analysis, diagnosis and treatment (Fig.

16.3 A, B).

Planes

1. Mandibular base plane, Og. A plane tangent to the

inferior border of the mandible.

2. Occlusal plane, Op. A plane going through the mesial

cusps of the permanent first upper and lower molars

and incisal edges of the upper and the lower central

incisors.

3. Palatal plane, On. A plane perpendicular to the

midsagittal plane, going through the anterior and the

posterior nasal spines (ANS-PNS).

4- Anterior cranial base. Structurally, the floor of the

anterior cerebral fossa. In the lateral radiograph, there

are two contours: the upper is the roofing of the orbit,

including the lesser wing of the sphenoid, and the

lower is posteriorly the spheno-ethmoid area and

anteriorly the cribriform plate.

5* Anterior cranial base plane or basal plane, Os. A

plane parallel to the axis of the upper contour of the

anterior cranial base and tangent to the inferior border

of sella turcica.

6. Ramus plane, R x \ A plane tangent to the posterior

border of the ascending ramus.

In a well-proportioned face, the under mentioned four

planes meet at point O:

1. Tangent to sella and parallel with anterior cranial base

(Os)

2. Palatal plane (On)

3. Occlusal plane (Op)

4. Mandibular plane (Og).

Based on the point of convergence of these planes,

vertical proportionality of the face can be appraised. The

relation of the four planes to the common point O permits

of the classification of 4 facial types:

1. Type I: Anterior cranial base plane does not pass

through O.

2. Type II: Palatal plane does not pass through O.

3. Type III: Occlusal plane does not pass through O.

4. Type IV: Mandibular base plane does not pass through

O.

Sassouni considered the face to be well proportioned

when axis of these four planes, prolonged posteriorly meet

at a common intersection which is posterior to the occipital

contour ‘O’.

Using O as the centre, Sassouni constructed the following

two arcs:

Anterior arc: It is the arc of a circle, between anterior

cranial base and the mandibular plane, with O as the centre

and O-ANS as radius.

Posterior arc: It is the arc of a circle, between anterior

cranial base and mandibular base plane, with O as centre

and OSp as radius ( Sp the most posterior point on the rear

margin of sella turcica).

Sassouni’s approach was popularized as archial analysis.

Based on his observations and research, he classified all

the malocclusions into 9 types of craniofacial pattern.

These are:

Class I

Class II

Hyperdivergent Neutral Hypodivergent

Hyperdivergent Neutral Hypodivergent

Orthodontics: Diagnosis and management of malocclusion and dentofacial deform ities

Hyperdivergent

Fig. 16.4*. Neutral, hyperdivergent, hypodivergent facial patterns can exist in class I, class II or class III type of malocclusion based on the work of V Sassouni

Fig. 16.4: Neutral, hyperdivergent, hypodivergent facial patterns can exist in class I, class II or class III type of malocclusion based on the work of v sassouni

Downward and backward

rotation of the mandible

or

clockwise rotation

Downward

and

forw ard

Downward and greater forward

(upward) rotation of the mandible

or

anticlockwise rotation

Fig. 16.5: Three types of growth trends of face according to the ratio of total posterior to total anterior face heights (after Siriwat and Jarabak 1985)

1. Class I: neutral, open bite and deep bite

2. Class II: neutral, open bite and deep bite

3. Class III: neutral, open bite and deep bite

Essentially, the neutral or skeletal open bite (vertical

pattern) and deep bite (horizontal pattern) can exist in any

all the three types of anteroposterior dysplasia of jaws.

A well-proportioned face as defined by Sassouni is

expected to possess normal occlusion. To the contrary, of

50 persons with normal occlusion examined, only 16 were

found to have a well-proportioned face. Since the norm

concept cannot be accepted as absolute for the individual,

Sassouni advocates the measurement of proportionality in

the individual as a basis of growth diagnosis and treatment

planning (Fig. 16.4).

Jarabak ratio of anterior and posterior facial

heights (facial height ratio—FHR)6

It has been reported that proportion of anterior to posterior

vertical heights is more relevant and not the absolute

values of the measurements. Jarabak has described facial

vertical pattern on the basis of ratio of anterior to posterior

vertical heights of the face (Figs. 16.5, 16.6 A-D).

He described three types of face pattern in vertical plane:

1- Neutral

1 2. Hypodivergent

| 3. Hyperdivergent.

The hypodivergents are those with square face, low,

Mandibular plane angle. These subjects have either reduced

anterior face height or increase in posterior face height. The

1

subjects with class II division 2 type of pattern fall in this

category. These subjects would exhibit an increased ratio of

posterior to anterior face height.

The hyperdivergent type of subjects show excessive

anterior face height and/or a reduced posterior face height.

These subjects show smaller height of the ramus and an

increase in mandibular plane angle:

Hyperdivergent growth patterns. They are associated with

<59% FHR. The face rotates downwards and backwards

with growth. The anterior face height increases more rapidly

than posterior face height or in other words ramus height

is smaller and gonial angle tends to open, i.e. larger than

normal. These facial patterns are commonly associated with

rotational growth changes and exhibit several other features

on craniofacial morphology like antegonial notch, inclination

of the condylar head, inclination of the palatal plane and

the cranial base.

Neutral growth pattern face types. They are usually

associated with FHR, 59-63%. These are the commonest

face types. The growth of face and mandible follows

downward and forward direction, and there is not much

change in the ratio of anterior to posterior face height.

Hypodivergent growth pattern subjects. They have FHR,

>63%. These children have well-developed ramus height


Downward and backward


or

clockwise rotation

Downward and forward


or

neutral

Upward and forward


or

anticlockwise rotation

Fig. 16.6A-D: Facial growth rotations: A. Vertical, B. Neutral, C. Horizontal differential vertical growth, D. Superimposition of A, B,C

and their gonial angle tends to be on smaller values. These grey zones of overlap may evolve into either type,

subjects have horizontal growth pattern, i.e. low values for The three facial types may exist in association with any

MP to SN plane and could also have small anterior face of malocclusions and anteroposterior skeletal dysplasia,

heights.

‘Siriwat and Jarabak reported that neutral pattern is dominant

The young growing children will fall in one of these in class I and class II malocclusions,

categories and predicatively follow the facial pattern which Hypodivergent pattern is dominant in class II division 2

is established much early. However, some of the children in and class III malocclusions.

Section II:: Vertical linear dimensions of face and Sassouni analysis 193

More males tend to be hyperdivergent while females are

hypodivergent. Facial height ratio (FHR) is strongly

associated with ramus height, gonial angle, mandibular

plane angle, palatal plane inclination and sum of saddle +

articular+gonial angles.

Signs of vertical growth rotation

The signs of vertical growth rotations include:

• A short ramus

• Prominent antigonial notch (a sign of restricted

mandibular growth)

• Large gonial angle, particularly lower gonial angle

• Anterior inclination of the condylar head

• Higher values for sum of cranial base (N-S-Ar), articular

(S-Ar-Go) and gonial angles (Ar-Go-Me).

• An upward swing of palate at ANS is an indication of

posterior maxillary excess causing gonial angle to open.

These findings are obviously reversed in other extreme

of horizontal facial type. The inclination of palatal plane is

another indicator of facial type.

The diversity of facial pattern in height is an outcome of

distorted facial, cranial morphology affecting several bones

and growth rotations of the mandible. For practical purposes,

we consider children with high mandibular plane angle and

low Jarabak’s FHR as vertical growers and low MPA with

high Jarabak FHR as horizontal growers. The ratio of

anterior to posterior height is more relevant than absolute

values. Vertical face pattern has a considerable bearing on

orthodontic treatment planning from the point of view of

anchorage management, extraction/non-extraction decision/

prognosis/treatment outcome, and effect of treatment on

facial profile in particular on the chin.

Summary

A well-balanced face has its good proportions in all three

dimensions of space. We as orthodontists are by tradition

looking at malocclusion in sagittal/anteroposterior

deviations. Alterations in transverse (widths) and vertical

(heights) may contribute to sagittal discrepancy or be

expressed as a sagittal discrepancy.

It has been found that a vertical or a horizontal face type

is established much early in childhood. Within normal range

of occlusion neutral, horizontal or vertical face types do

exist.

The craniofacial structures exhibit certain characteristics

which can be both qualitative and measured in terms of

absolute numerical values of face heights and in ratio.

REFERENCES

1. Wylie WL. The assessment of anteroposterior dysplasia.

Angle Orthod 1947; 17: 97-109.

2. Wylie WL, Johnson EL. Rapid evaluation of facial dysplasia

in vertical plane. Angle Orthod 1952; 22: 165-82.

3. Sassouni V. A roentgenographic cephalometric analysis of

cephalo-faciodental relationships. Am J Orthod Dentofac

Orthop 1955; 41: 735-64.

4. Sassouni V. A classification of skeletal facial types. Am J

Orthod Dentofac Orthop 1969; 55(2): 109-23.

5. Nanda SK, Sassouni V. Planes of reference in roentgenographic

cephalometry. Angle Orthod 1965; 35(4): 311-19.

6. Siriwat PP, Jarabak JR. Malocclusion and facial morphology:

is there a relationship? An epidemiologic study. Angle Orthod

1985; 55: 127-38.

7. Kharbanda OP, Sidhu SS, Sundaram KR. Vertical proportions

of face: a cephalometric study. Int J Orthod 1991; 29 (3-4):

6-8.

Soft tissue analysis of face

OVERVIEW

• Need for soft tissue analysis of face

• Methods of obtaining soft tissue profile on a cephalogram

# General appraisal of soft tissue profile

• Cephalometric analysis

• Indian norms

• Summaiy

Need for soft tissue analysis

Placement of teeth according to the accepted hard

tissue cephalometric criteria does not necessarily

ensure that overlying soft tissue will drape in a

harmonious manner and hence result in a pleasing profile.

It has been recognized over the years that response of the

soft tissue integument may not be judged correctly and

completely by simply analyzing the dental occlusion or the

osseous structures.

Soft tissues of the face require an independent appraisal

in addition to the skeletal and dental analysis in order to

deduce a comprehensive diagnosis and treatment planning

of the face.

Dynamic entity of soft tissue behaviour

The soft tissue integument of the face is a dynamic entity

whose response and behaviour to orthodontic treatment is

not reciprocated in a manner similar to that of osseous or

the dental structures.

Soft tissue varies considerably in thickness, length, and

postural tone and expression and so its response to dental

and skeletal correction is different in different individuals

and at different times, i.e. age of treatment.

Growth is independent of hard tissue of face

Soft tissue growth of the face follows an independent curve

to that of hard tissues. Different parts of the soft tissue of

the face like nose, lips and chin have independent growth

curves, which are age-related and exhibit definite sexual

dimorphism.

These factors should be taken into serious consideration

while planning orthodontic treatment.

Methods of obtaining soft

tissue profile on a cephalogram

A soft tissue cephalometric analysis can only be done on

a good quality cephalogram showing reasonable to excellent

soft tissue details of the facial profile and structures.

194

Section II: Soft tissue analysis of face 195

The cephalogram should have been recorded in a relaxed

lip position with no strain on lips and chin. To obtain a clear

picture of the soft tissue profile on a cephalogram, various

techniques have been adopted and modified over time.

1. Aluminum or copper wedge attached to block X-rays

covering area behind soft tissue profile is the most

commonly used method in day to day practice.1

2. Radiopaque barium meal used as a contrast in abdominal

radiography is painted on the midline structures of

' face. This technique was popular till 1980s but it is not

preferred any more because of its messy nature.

3. Adapting a thin lead wire on the midline of face

extending from forehead to chin also provides a good

profile line on cephalogram. However, it requires

considerable time and experience to accurately form the

wire to confirm to different profiles.

4. Soft tissue could be recorded better by reducing the

kVp of the X-ray unit.

5. Simultaneous exposure of a nonscreen film and a

screen film in the same cassette.

6. Painting an absorbing dye on the intensifying screen.1

7. Jacobson mentioned a reduction in film density over

the anterior bony landmarks when the black paper

technique was used.2

8. Arnett et al have advocated placement of metallic

markers on the right side of the face to mark the

profile.3

General appraisal of soft tissue profile

The soft tissue profile can be evaluated by dividing the

face into the following regions for easy and methodical

analysis:

• Upper one-third

• Middle one-third

• Lower one-third

• Chin/neck region.

Upper one-third of face

Important soft tissue landmarks to be considered are glabella

and the nose. The nose comprises of the following

structures: the radix, nasal dorsum, the supratip depression

and the tip of the nose. It is particularly important to note

the prominence of the glabella, the dorsum hump of the

nose and the tip of the nose (whether tipped upwards or

not).

Middle one-third of face

This is the region that contains the columella, the nasolabial

sulcus and the upper lip.

The upper lip may vary in thickness, length, posture and

tonicity. These factors are vital in determining the response

°f the upper lip to orthodontic treatment. Upper lip strain

and a short lip are common findings in patients with

severely proclinated upper incisors. When the upper lip is

strained then the normal contour of the upper lip is altered

and the lip takes almost equal thickness at the base of nose

as well as vermillion border. Holdaway 4,5 has given an

effective method to identify the upper lip strain and quantify

the same.

Other important features to note are lip thickness and

dental as well as skeletal protrusion or retrusion. Thick lips

may show acute nasolabial angle even in the absence of

dental protrusion. Similarly, thin lips may show obtuse

nasolabial angle in the absence of dental retrusion.

Lip eversion may be present in some individuals and is

often associated with acute nasolabial angles. It may not be

corrected on retraction of teeth.

Lips should be examined for competency of the lip seal

and interlabial gap. If found incompetent, its relationship

with dental protrusion should be looked for.

Lower one-third of face

This region contains the lower lip, the mentolabial sulcus

and the soft tissue chin. The lower lip is notorious in

showing variations in thickness, length, tonicity and posture

(particularly everted lower lips). Everted lower lip gives an

impression of a deep mentolabial sulcus that does not

correct even with the retraction of teeth. Some patients

have a thick soft tissue chin that may mask a retrognathic

mandible to appear normal. Deep mentolabial sulcus may be

associated with a prominent chin. Vertical overclosure

(skeletal deep bite) cases show soft tissue redundancy in

this area which is manifested as deep mentolabial sulcus.

Conversely, a patient with long face shows shallow

mentolabial sulcus. Chin prominence may be reduced in

vertical growers. Changes in the soft tissue chin are amongst

the most predictable orthognathic surgical outcomes and

hence need a careful evaluation.

Chin/neck region

In this region, the contour of the throat is important

specifically from the orthognathic surgery point of view

where mandibular advancement or setback may be planned.

Important features to note here are lip-chin-throat angle,

chin-throat length and cervicomental angle.

Nasolabial angle

This is the angle formed by the upper lip and the base of

the nose. It is constructed at the intersection between the

upper lip tangent and the columella tangent. A big range of

90° to 110° has been reported with a normal value of 102

±4° 6

Scheideman et al7 drew a horizontal line parallel to the

postural horizontal through subnasale and further divided

the nasolabial angle into columella tangent to postural

horizontal and the upper lip tangent to postural horizontal.

The upper angle averages 25° and the lower averages 85°.

In some cases, it may be seen that the nasolabial angle is

normal but oriented abnormally. This angle can be affected

by:


1. Dental protrusion or retrusion

2. Skeletal protrusion or retrusion

3. Lip thickness

4. Nasal tip

5. Upper lip posture.

Upper lip prominence

The upper lip prominence is measured as the perpendicular

distance from labrale superior to the line extending from the

subnasale to soft tissue pogonion. Legan and Burstone6

measured this distance to be 3 ± 1mm.

Bell et al 8 utilize a vertical reference line through

subnasale, in which case the upper lip is estimated to be

1-2 mm ahead of this line.

Lower lip prominence

In normal cases, Legan and Burstone6 have estimated the

labrale inferius to be 2 +/- 1mm anterior to Sn - Pog’ line.

While Bell et al8 have found that lower lip is on the

subnasale vertical or 1 mm behind it.

Interlabial gap

Some amount of vertical gap between the upper and lower

lips has been found to be acceptable by researchers. A

range of 0 to 3 mm for this vertical distance has been given.

Interlabial gap of 2 ± 2 mm is considered as acceptable.6

Horizontal nasal prominence7

This is measured from the glabella vertical as the horizontal

distance from the tip of the nose to this line. It is found that

the nasal prominence and nasal height are in the ratio of 1:3

(G-P: G-Sn =1:3).

Chin prominence

Soft tissue chin prominence is measured as horizontal

distance from a line perpendicular to FHP passing through

subnasale. The mean value is -3 ± 3 mm.

Many other methods of evaluating chin prominence

have also been given. Construction of 0 degree meridian,

which is a line passing through soft tissue nasion and

perpendicular to FHP. This distance has been estimated to

be 0 ± 2 mm.

Chin thickness

Soft tissue chin thickness should be evaluated in relation

to factors of hard tissue such as thickness of chin,

microgenia, micrognathia, retrognathia or prognathia of the

mandible. Soft tissue chin thickness varies in different

individuals and different types of malocclusion. Some

children with class II div 2 malocclusion have significant

chin thickness which masks the retrognathic mandible. Soft

tissue chin thickness has been observed to be thin in class

II div 1 high angle cases and in class I bimaxillary cases.

Middle third to lower third ratio

The ratio of G - Sn and Sn - Me’ is approximately 1:1. The

measurement is done perpendicular to the true horizontal

plane. This proportion also known as the upper to lower

face ratio analyses the anterior proportions in the vertical

dimension.

Upper lip to lower lip height ratio

The length of the upper lip Sn - Strn should be approximately

one-third of the total lower third of the face Sn - Me’. Also

the distance Stm. - Me’ should be about two-thirds. Thus

Sn - Stm /Stm. - Me’ = Vi

S 1

Cephalometric analysis_______

Though there are numerous soft tissue analyses each

having their specific indications and applicability, the authors

feel that a composite of two or more analyses should

provide the information enough to make clinical judgments.

Various important soft tissue analyses that give detailed

information about the soft tissue profile are:

1. E line (Ricketts’ analysis)9

2. Holdaway’s analysis 4,5

3. Merrifield Z angle 13

4. Steiner’s S line 14

5. Inclination of nasal base

6. Mentocervical angle

7. Submental - neck angle

8. Soft tissue cephalometric analysis (STCA).:

Ricketts’ E line - aesthetic plane9 (Figs. 17.1,

17.2)

A quick method to look at one profile is to imagine a line

tangent from the lower chin to the nose tip.

Cephalometrically, Ricketts’ E line is drawn from the tip of

the nose to soft tissue chin. Normal values suggest that the

upper lip is 4 mm behind the E line while the lower lip lies

2 mm behind this reference line. It is important to mention

that this reference line is influenced a great deal by the

growth of the nose and also varies with age and sex.

Ricketts recommended that lip position should be

analysed with the nose-chin reference. These values are for

Caucasians and it is obvious that cannot be applied to all

races.

Holdaway’s analysis4,5

This analysis introduced the concept of Harmony line or

the H line that is drawn as a tangent to the chin and the

upper lip. Holdaway’s analysis contains 11 measurements

which are as follows (Fig. 17.3):

1. Soft-tissue facial angle. This is an angular measurement

of a line drawn from soft-tissue nasion (Na’ or n), to the

soft-tissue chin (Pog’ or pg) measured to the Frankfort

horizontal plane. A measurement of 91° is ideal, with an

Section II: Soft tissue analysis of face

i

y

197

Fig. 17.1: Commonly used soft tissue landmarks on lateral profile

Fig. 17.2: Commonly used soft tissue facial lines: 1. Soft tissue facial line, 2. Steiner's S line, 3. Ricketts E line, 4. Holdaway's H line


Fig. 17.3: Angular measurements used by Holdaway

acceptable range of ±7°. This measurement is helpful in

categorizing whether a case is prognathic (> 91°) or

retrognathic (< 91°). There is large range of ±7° given

that must be carefully correlated with other parameters.

2. Skeletal profile convexity. This is a measurement from 4.

point A to the Downs’ facial plane (N-Pg). As it is

apparent that it is not a soft tissue measurement yet it

provides a good assessment of the skeletal convexity

in relation to the lip position. The ideal measurement

ranges form -2 to +2 mm and provides a guideline for

achieving dental relationship needed to produce facial

harmony.

3. H angle. This is an angular measurement of the H line

to the soft-tissue facial plane (Na’- Pog’). Measurements 5.

of 7 to 15° are in the ideal range and are correlated with

the skeletal profile convexity. Ideally, as the skeletal

convexity increases, the H angle must also increase if

a harmonious drape of soft tissues is to be realized in

varying degrees of profile convexity. H line signifies

that as the skeletal convexity increases so does the

convexity of the soft-tissue profile if the entire facial

complex is to be one of balance and harmony. This 6.

angle measures the prominence of the upper lip in

relation to the over-all soft-tissue profile. H angle

increases as we go from concave to convex skeletal

patterns. Changes in the H angle reflect the direction

of growth, especially of the mandible. This measures

change during treatment or observation periods in the

same patient and helps in quantization of differences

between one patient and another.

Nose prominence. Nose prominence can be measured

by means of a line perpendicular to Frankfort horizontal

and running tangent to the vermilion border of the

upper lip. This measures the nose from its tip in front

of the line and the depth of the incurvation of the

upper lip to the line. Although nasal form is judged on

individual basis measurements less than 14 mm are

considered small, while those above 24 mm are

considered large.

Superior sulcus depth. It is measured as the distance

between the perpendicular from FHP and tangent to

the upper lip. A range of 1 to 4 mm is acceptable, with

3 mm being ideal. During orthodontic treatment or

surgical orthodontic procedures, we should strive not

to allow this measurement to become less than 1.5 mm.

Decreased values are suggestive of upper lip strain

Soft-tissue chin thickness. This is recorded as a

horizontal distance between the hard tissue and soft

tissue facial planes (Pg - Pog’). Average values are

between 10 to 12 mm. In very thick soft tissue chin, it

may be essential to leave the lower incisors in a more

i


anterior position so as to provide the much needed lip

support.

7. Upper lip thickness. This is measured near the base of

the alveolar process, at about 3 mm below point A. It

is at a level just below where the nasal structures

influence the drape of the upper lip. This measurement

is useful, when compared to the lip thickness overlying

the incisor crowns at the level of the vermilion border,

* in determining the amount of lip strain or incompetency

present as the patient closes his or her lips over

protrusive teeth.

8. Upper lip strain. Upper lip strain is a very common

phenomenon seen on cephalograms of patients with

proclined upper lip. In this situation, the patient

habitually tries to close the lips so as to hide proclined

teeth. In doing so, the normal thickness of the upper

lip is not recorded on the cephalogram. While taking

the cephalogram it is always advisable to ask the

patient to relax the lips by licking them and keeping

them in repose.

In situations where lip strain is present, strain

measurement can be done horizontally from the

vermilion border of the upper lip to the labial surface

of the crown of the most proclined incisor. The usual

thickness of lip measured at the vermilion border level

is 13 to 14 mm. This measurement should be

approximately similar to the upper lip thickness (1mm

range). If this measurement is less than the thickness

of the lip (beyond the accepted range) then the lips are

considered to be strained. The difference between the

two measurements is called as the strain factor. It also

reveals the amount of retraction needed to produce

normal lip form and thickness. It is important to note

that inherent lip thickness matters when predicting the

response of the lips to retraction. Thick lips do not

retract significantly. The relationship in change of

position of upper lip and linear retraction of maxillary

incisor is usually 1:3.

When the lip thickness at the vermilion border is larger

than the basic thickness measurement, this usually

identifies a lack of vertical growth of the lower face

with a deep overbite and resulting lip redundancy.

measurement were 8 or 9 mm with no evidence of lip

strain or lack of harmony of facial lines, extraction of

premolars may not be indicated.

10. Lower lip to H line. Lower lip to H line is measured

from the most prominent point on the outline of the

lower lip. Ideal is 0 to 0.5 mm anterior to H line with a

range of - 1 mm to + 2 mm. Lack of chin may be a factor

where the lower lip is very prominent. Sliding

genioplasty surgical procedures can be very beneficial

in some of these cases.

11. Inferior sulcus to the H line. This is measured at the

point of greatest incurvation between the vermilion

border of the lower lip and the soft-tissue chin and is

measured to the H line. The contour in the inferior

sulcus area should fall into harmonious lines with the

superior sulcus form.

Angular profile analysis

Angular profile analysis was given by Subtelny.10 It gives

an analysis of the convexity of the profile. This analysis

makes a distinction of convexity amongst:

• Skeletal profile

• Soft tissue profile

• Full or total soft tissue profile including the nose

Skeletal profile convexity

This is determined by measuring the angle N-A-Pog. Mean

value is 175.°

Soft tissue profile

It is determined by n-Sn-Pog’. Mean value is 161°. Some

authors report that facial convexity is relatively stable after

the age of 6 years, others found it changes till much

later.10*12

Total soft tissue profile

It is measured by N-No-Pog. Convexity of the nose is

included because the nose has a marked influence upon the

total cosmetics of the soft tissue profile.

In men, average value is 137° while in women is 133°.

Bishara found that total facial convexity increases with age.

All male and female subjects demonstrated an increase in

total facial convexity from the age of 5 years to adulthood.

9. Upper lip sulcus depth. Subnasale to H line, this

measures the upper sulcus depth and the ideal is 5 mm,

with a range of 3 to 7 mm. When the skeletal convexity

of a case is from - 3 to +5 mm the lips can usually be

aligned nicely along the H line when the superior

sulcus measurement is at or near 5 mm. With short and/

or thin lips, 3 mm will be adequate. In longer and/or

thicker lips, 7 mm may be in excellent balance. If this

Merrifield profile line: Z angle13

It is the tangent to the soft tissue chin and to the most

anterior point of either the upper or the lower lip whichever

was most proclining and extending this line upwards to the

FHP. Its average value is 80±9°. Ideally the upper lip should

be tangent to the profile line, whereas the lower lip should

be tangent or slightly behind it. This angle expresses the

full extent of lip protrusion in malocclusions.


Steiner’s S line14

S line is drawn from the soft tissue pogonion to the

midpoint of the S-shaped curve between subnasale and

nasal tip. Normally, the upper and lower lips touch the S

line. The lips lying behind this line are too retrusive while

those lying ahead are protrusive (Fig. 17.2).

Inclination of nasal base

This is an important consideration because sometime the

nasal base is tipped upwards thereby increasing the

nasolabial angle and similarly if the nasal base is tipped

down it may lead to decrease in the nasolabial angle.

Mentocervical angle

It is formed by the intersection of the E line and a tangent to

the submental area. The range of average values is 110 to 120°.

Submental neck angle

It is formed by a submental tangent and a neck tangent. It

shows variation among sexes. In males, its normal value is

126° and in women its average value is 121°.

Soft tissue cephalometric analyses

(Fig. 17.4 A-E)

The STCA given by William Arnett et al3 (1999) is a

comprehensive method to analyze the integumental profile.

This method is in continuation with the diagnosis and

treatment planning philosophy given by Arnett and

Bergman. The authors believe that clinical findings of

examination and model analysis are important when

proceeding with STCA.

A novel method of obtaining a good soft tissue profile

has been described, wherein, radio-opaque metallic markers

are used to mark key midface structures. These markers are

placed on the right side of the face on the landmarks such

as orbital rim, cheekbone, alar base and neck-throat point.

After placing the markers, the cephalogram is recorded with

head in the natural head orientation as given by Lundstrom

and Lundstrom.15

The true vertical line (TVL) is established as a line passing

through subnasale and perpendicular to the natural horizontal

head position. The vertical or horizontal position of soft

tissue and hard tissue landmarks were then measured relative

to the Model’s natural horizontal head position or TVL.

The STCA can be used to diagnose the patient in five

different but inter-related areas.

1. Dentoskeletal factors

2. Soft tissue components

3. Facial lengths

4. TVL projections

5. Harmony of parts.

While the first three factors are more common and reader

is requested to refer to the table for the norms, TVL

projection and harmony of parts will be discussed below.

TVL projections

They are anteroposterior measurements of soft tissue and

these represent the sum of the dentoskeletal position plus

the soft tissue thickness overlying the hard tissue landmarks.

The horizontal distance for each individual landmark,

measured perpendicular to the TVL, is termed the landmark's

absolute value (Fig. 17.4A).

The subnasale may frequently be coincident with

anteroposterior positioning of the TVL, but it may not be

so in some cases. For example, the TVL must be moved

forward in cases of maxillary retrusion in which there may

be long-appearing nose, depressed or flat orbital rims,

cheek bones and alar bases, poor incisor support for the

upper lip, upright upper lip, thick upper lip, and retruded

upper incisor. In such cases, clinical examination is necessary

to corroborate cephalometric findings.

Harmony values

They were created to measure facial structural balance and

harmony. It is based on the concept that the position of

each landmark relative to other landmarks determines the

facial balance. Harmony values represent the horizontal

distance between two landmarks measured perpendicular to

the true vertical line.

Harmony values examine 4 areas of balance:

intramandibular parts, interjaw, orbits to jaws, and the total

face.

Intramandibular parts: Here chin projection is assessed

relative to the lower incisor, lower lip, soft tissue B’ point,

and the neck throat point (Fig. 17.4B).

Interjaw parts: Harmony values indicate the interrelationship

between the base of the maxilla to chin, soft

tissue B’ to soft tissue A’ and upper lip to lower lip (Fig.

17.4C).

Orbital rim to jaw harmony values. They determine the

position of the soft tissue inferior to orbital rim relative to

upper jaw ( OR’-A’) and lower jaw (OR’-B’) (Fig. 17.4D).

Total facial harmony values. They determine the interrelationship

of upper face, midface and chin via facial angle

(G’ - Sn - Pog’). Then the forehead is compared to upper

jaw (G’ - A’) and chin (G’ - Pog’) (Fig. 17.4E).

Indian norms16'18

It has been recognized over the years that clinically

significant variations in the craniofacial morphology and

soft tissue are found among the various ethnic groups.

Clinicians and researchers have highlighted redundancy

of applying the same ‘Caucasian’ norms to the people of

different genetic origin. This justified the need to study and

develop ‘Indian norms’ for the Indian population.

A number of studies have been done to develop

cephalometric norms for Indian population for its different

Section II: Soft tissue analysis of face

% 17.4B-E: Harmony

harmony

values in four areas of facial balance: B. Intramandibular harmony, C. Intrajaw harmony, D. Orbital rim to jaw, E. Total face

A


ethnic groups including norms for the soft tissue (Table

17.1).

Indians have a few similarities of soft tissue parameters

vis-a-vis Caucasian norms while they do differ significantly

in many others. Parameters that differ significantly are

profile, lip and soft tissue chin. Soft tissue chin seems to

be deficient in south Indian Tamil population as compared

to the Caucasian norms.

Table 17.1: Cephalometric values for soft tissues of face for Indian racial (ethnic) groups in comparison to Caucasians

Parameters

Caucasian

norm

North India

Grewal, Sidhu,

Kharbanda

30 F

Kashmiri

Menghiet al

Keralities

Haridas R

M&F25

Indian

Valiathan etal

M&F 50 adults

Mean ± SD Mean ± SD Mean ± SD Mean/Range Mean/Range

Angular

1. Soft tissue profile 161° 15873°

145-175

159.5°±5.3

2. Total soft tissue

profile

M133°

F 137°

135.23°

126.5°-148.8°

3. Nasolabial angle 96.5°

70°-112°

4. H angle 7 °-15° 1079°

1.9°-19.5°

9.5°

5°-14°

Linear

1. Thickness of upper lip 15mm 13.4 mm

9.8-16.00 mm

15.8 mm

12-21 mm

2. Thickness of lower lip 14.0 mm

11.6-17.2 mm

3. Length of upper lip 23.0 mm

18.5-29.0 mm

19.4 mm

14-23 mm

21.8 mm

16-26 mm

4. Length of lower lip 35.9 mm

30.0-47.6 mm

46.2 mm

39-53 mm

48.6 mm

42-5 mm

5. Upper lip prominence 3 ± 1 mm 2.7 mm ± 2.06 1-83 mm

6. Lower lip prominence 2 ± 1 mm 2.2 mm±2.18 6-6.2 mm

7. Chin prominence -1 to -4 mm -8.9 mm

8. Upper lip to E line -4 ± 2 mm 2.15 mm

-8.15-8.5

- 5.8 mm± 3.04

9. Lower lip to E line -2 ± 2 mm -0.26 mm

-6.59-5.11

-3.4 mm± 2.92

10. Lower lip to H line Omm 0.77 mm 1.15mm

-2-+2

11. Pg-pog’ 10-12mm 11.47 mm

7.9-14.8 mm

11.8 mm

8-15 mm

13.1 mm

19-18 mm


Summary

The orthodontic treatment objectives are aimed at attainment

of harmonious well balanced face and stable occlusion.

Soft tissue of face shows great variations in thickness

and presentation which may mask the underlying skeletal

pattern.

The current thinking of orthodontics havers around

“Face First” regime. Soft tissue analysis makes integral and

significant component of the orthodontic diagnosis. The

norms are only a guide. Soft tissue analysis should be

viewed with consideration of race, individual pattern, sex

and age of a person.

REFERENCES

1. Tyndall DA, Matteson SR, Soltmann RE, Hamilton T, Proffit

W. Exposure reduction in cephalometric radiology: a

comprehensive approach. Am J Orthod Dentofac Orthop

1988; 93(5): 400-412.

2. Jacobson A, Caufield PW. Introduction to Radiographic

Cephalometry. Philadelphia, Lea and Febiger, 1985: 25-27.

3. Arnett G William et al. Soft tissue cephalometric analysis:

Diagnosis and treatment planning of dentofacial deformity.

Am J Orthod Dentofacial Orthop 1999; 116: 239-53.

4. Holdaway RA. A soft tissue cephalometric analysis and its

use in orthodontic treatment planning. Part I. Am J Orthod

Dentofacial Orthop 1983; 84: 1-28.

5. Holdaway RA. A soft-tissue cephalometric analysis and its

use in orthodontic treatment planning. Part II. Am J Orthod

1984; 85: 279-93.

6. Legan HL, Burstone CJ. Soft tissue cephalometric analysis

for orthognathic surgery. J Oral Surg 1980; 38: 744-51.

7. Scheideman GB, Bell WH, Legan HL, Finn RA, Reisch JS.

Cephalometric analysis of dentofacial normals. Am J Orthod

Dentofac Orthop 1980; 78: 404-20.

8. Bell WH, Jacobs JD, Quejada JG. Simultaneous repositioning

of the maxilla, mandible and chin. Treatment planning and

analysis of soft tissues. Am J Orthod 1986; 89: 28-50.


cephalometrics. Angle Orthod 1981; 51: 115-50.

10. Subtelny JD. A longitudinal study of soft tissue facial

structures and their profile characteristics defined in relation

to underlying skeletal structures. Am J Orthod Dentofac

Orthop 1959; 45: 481-507.

11. Mauchamp O, Sassouni V. Growth and prediction of the

skeletal and soft tissue profiles. Am J Orthod 1973; 64: 83-

94.

12. Chaconas SJ, Bartroff JD. Prediction of normal soft tissue

facial changes. Angle Orthod 1975; 45: 12-25.

13. Merrifield LL. The profile line as an aid in critically evaluating

facial esthetics. Am J Orthod 1966; 52: 804-22.

14. Steiner CC. Cephalometrics as a clinical tool. In Kraus B,

Reidel R (eds): Vistas in Orthodontics. Philadelphia, Lea and

Febiger; 1962, p.131-61.

15. Lundstrom A, Lundstrom F. Natural head position as a basis

for cephalometric analysis. Am J Orthod Dentofac Orthop

1992; 101: 244-47.

16. Grewal H, Sidhu SS, Kharbanda OP. A cephalometric appraisal

of dentofacial and soft tissue pattern in Indo-Aryans. J Pierre

Fauch Acad (India) 1994; 8: 87-96.

17. Kalra JPS, Kharbanda OP. Facial profile changes related to

orthodontic tooth movement-A cephalometric study. J Indian

Orthod Soc 1996; 27: 93-105.

18. Cephalometric norms for use with Indian population. Indian

Orthodontic Society 1996.


OVERVIEW

• PA Cephalometric analysis

• Set-up for PA cephalometry

• Some important landmarks used in PA cephalogram

• Planes in PA cephalogram

• Evaluation of PA cephalogram

• Grummons analysis

• Ricketts analysis

• Maxillomandibular differential values and ratio by Ricketts and Grummons

• Limitations of PA cephalometry

• Summary


The PA cephalogram offers an effective tool in

evaluating the craniofacial structures in transverse

and vertical dimensions. It allows us to look at the

facial skeleton in relative view of the right-left face and

upper-lower face. First attempts towards analyzing the

craniofacial skeleton on PA cephalograms were limited to

absolute linear ^measurements such as face widths and

heights and later ratio and volumetric comparisons were

added to evaluate relative asymmetries.1-4

Set-up for PA cephalometry

Patient’s correct orientation is of utmost importance before

exposing the patient to X-ray radiation. The cephalostat

head holder is rotated 90° so that the subject will face the

X-ray cassette and the central X-ray beam passes through

the skull in a posteroanterior direction bisecting the

transmeatal axis perpendicularly.

Patient is fixed in a headholder with the use of ear rods.

The standard distance from X-ray source to the ear postaxis

is 5 feet. The reproduction of the head position is

crucial because if the head is tilted all vertical dimensional

measurements will change.

Reproducing correct head orientation

1. Conventionally, head can be positioned with the tip of

the nose and forehead in light contact with the cassette

holder. This position is good for evaluation of

craniofacial anomalies which require special attention

to the upper face.

2. The standard method is by keeping the Frankfort’s

horizontal plane parallel to the floor, while the patient

is facing the X-ray film cassette as close as permissible

within the limits of nose prominence.

3. To ensure correct orientation of head in FH plane, a

guided patient positioning as follows: A line is scribed

on the ear rod assembly at a point 1^5 mm above the ear

204

Section II: PA cephalometric analysis 205

rod. The height of the orbit is about 3 cm, and the

lateral canthus is essentially at the centre of the orbit,

or 15 mm. The patient should be oriented such that his

ear canals tuck snugly against the top of the ear rods

with the head positioned so that the lateral canthus of

the eye is located in level with that line.5

Orienting the head in natural head position (NHP).6

Cephalograms are taken with the mouth of the patient

slightly open for cases with significant mandibular

displacement.7

Signs of good head position on PA cephalogram

X-ray film

1. The head position and the intermaxillary occlusal

relationship that appear in X-ray should be first

confirmed using patient’s photographs, study casts or

clinical evaluation as a guideline.

2. In a properly oriented frontal head film, the top of the

petrous portion of the temporal bone will lie near the

centre of the orbit.4

% 18.1: PA cephalogram is developed and so oriented for the purpose of tracing as if it is AP view, i.e. the film is so placed as if one is actually

feeing the patient. This orientation greatly helps the orthodontist to simultaneously have an instant comparison with facial photos and dental casts

while evaluating frontal dysplasia


Left side

MSR

Fig. 18.2: Commonly used landmarks for PA cephalogram analysis. Tracing a PA cephalogram requires a considerable experience. It is a much

more cumbersome process compared to lateral cephalogram. An orthodontist must be fully conversant with the detailed anatomy of skull and all its

structures

Evaluation of PA cephalogram 3.

A PA cephalogram would require a careful visual evaluation

of the dentofacial and associated structures. This is usually 4.

followed by a detailed cephalometric analysis.

Important features 5-

1. Orbits - whether normally inclined or oblique and size

of orbits whether equal or disparate.

^

2. Ramus of the mandible - whether present or absent or

underdeveloped as seen in unilateral or bilateral ^

hypoplasia cases.

Angle of mandible - whether obtuse or acute. Obtuse

angle is usually seen on the unaffected side in ankylosis.

Body of mandible - whether present or absent and

developed on both sides to an equal extent or not. May

be deviated to either side in certain situations.

Chin - whether present in centre or deviated to one

side as seen in cases of asymmetry of mandible.

Malar bones - whether equally prominent on either

sides or one side as in craniofacial syndromes.

Maxillary antra - whether equal on both sides and

whether the development is normal or not.

Section II: PA cephalometric analysis 207

■

8. Width.of dental arches - may be underdeveloped or

over developed on either sides.

9. Cant of occlusal plane - can be compared at a single

glance in PA cephalogram. Cant may be tilted to the

affected side in TMJ ankylosis cases.

10. Nasal widths - may be equal or unequal as in unilateral

hypoplasia.

A detailed analysis of the PA cephalogram can be

performed with the tracing of the bony and dental structures

to be studied. Horizontal and vertical reference planes help

in the determination of facial asymmetry in vertical and

horizontal directions by observing the relative orientation

of landmarks to these planes.

Some important landmarks used in PA

cephalogram (Figs 18.1,18.2)

The posteroanterior cephalogram should be first assessed

in order to exclude any possibilities of pathology of hard

and soft tissues involved or unusual findings. Each

cephalogram should be labelled for patient details with

respect to hospital ID, and date of cephalogram being the

most critical.

The tracing of the PA cephalogram should be carried out

by placing the cephalogram in front of the examiner as if

he is looking at the patient, i.e. patient’s right should be on

the examiner’s left. Tracing may begin with the midline

structures.

The bilateral points marked on the PA cephalogram are

conveniently abbreviated with addition of R and L for the

right and left side.8

1. Z point zygomatic. Bilateral points on the medial margin

of the zygomaticofrontal suture, at the intersection of

the orbits (ZL, left and ZR, right).

2. ZA, AZ. Centre of the roof of the zygomatic arch. It is

abbreviated as ZA as left side and AZ as right side.

3. J point. Bilateral points on the jugal process at the

intersection of the outline of the tuberosity of the

maxilla and zygomatic buttress (left and right).

4 G; gonial point: mandible. Points at the lateral interior

inferior margin of the antigonial protuberance (left and

right). GA-AG

5- Cg. Critsta galli.

6- ANS. Anterior nasal spine. Tip of anterior nasal spine

just below the nasal cavity and above the hard palate.

7- Cd; condylon. The most superior of the condylar head

(left and right).

& Al point. A point selected at the interdental papilla of

the upper incisors at the junction of the crown and

\ gingiva.

9- Bl point. A point selected at the interdental papilla of

the lower incisors at the junction of the crown and

gingiva.

10- M g Point of the inferior border of the symphysis

directly inferior to mental protuberance and inferior to

the centre of trigonium mentali (Figs. 18.1, 18.2).

Most and least reliable landmarks

Some of the landmarks were found to be more reliable than

others. It has been found that the most reliable skeletal

landmarks are menton and point Bl; the mandibular canine

is the most reliable dental landmark.

The least reliable dental landmarks are mandibular first

molars and the maxillary canine. The zygomatic-frontal

suture is the least reliable skeletal landmark.

Planes in PA cephalogram

Various horizontal and vertical planes are drawn in PA

cephalogram in different analyses for the determination of

asymmetry, linear dimensions and angles.

Median sagittal reference (MSR) plane

It has been selected as a key reference line because it

closely follows the visual plane formed by subnasale and

the midpoints between the eyes and eyebrows. The median

sagittal reference plane normally runs vertically from crista

galli (Cg) through the anterior nasal point (ANS) to the

chin area, and is typically nearly perpendicular to the Z

plane (line joining zygomaticofrontal suture of one side to

the other).

If the location of Cg is in question, an alternative

method of drawing MSR is to draw a line from the

midpoint of the Z plane through ANS. The position of

anterior nasal spine will be altered in facial asymmetry

involving the maxilla.

If there is upper facial asymmetry, MSR can be drawn

as a line from the midpoint of the Z plane through the

midpoint of the Fr-Fr line (foramen rotundum of one side

to the other). To avoid any such bias, a best-fit vertical line

is drawn in the center connecting the midpoints of lines

joining zygomaticofrontal sutures (Z-Z), the centres of the

zygomatic arches (ZA), the medial aspects of the jugal

processes (J) and antegonial notch (AG-GA) of both the

sides.

The best-fit line and all lines constructed as

perpendiculars through midpoints between pairs of orbital

landmarks have shown excellent validity.9

Besides vertical reference lines, horizontal best-fit lines

have to be constructed to know the asymmetry in vertical

plane. All horizontal lines connecting bilateral cranial

landmarks can adequately serve as reference lines in the

analysis of vertical asymmetry from PA cephalograms, if

landmark identification error is acceptable.

Grummons analysis (Figs. 18.3,18.4)

Grummons analysis is a comparative and quantitative PA

cephalometric analysis and is not related to normative data.

The analysis consists of different components:

1. Horizontal planes

2. Mandibular morphology

3. Volumetric comparison

4. Maxillomandibular comparison of asymmetry


5. Linear asymmetry assessment

6. Maxillomandibular relation

7. Frontal vertical proportions.

Horizontal planes

Four planes are drawn to show the degree of parallelism

and symmetry of the facial structures. Three planes connect

the medial aspects of the zygomatic frontal sutures (Z-Z),

the centres of the zygomatic arches (ZA), and the medial

aspects of the jugal processes (J). Another plane is drawn

at menton parallel to the Z plane. MSR has been selected

as a true vertical reference line.

Mandibular morphology

Left and right triangles are formed from the heads of the

condylar processes or the condyles (Co), the antegonial

notches (AG), and menton. These are split by the ANS-ME

line and compared. ANS-ME parallels the visual dividing

line from subnasale to soft tissue menton in the lower face.

Linear values and angles can be measured while the

anatomy can be determined. Like the horizontal planes, this

data is quite sensitive to head rotation.

Volumetric comparison

Two ‘volumes’ (polygons) are calculated from the area

Section II: PA cephalometric analysis

Fig. 18.4: Volumetric comparison between left and right side for analysis of facial asymmetry

defined by each Co-GA-ME and the intersection with a

perpendicular from Co to MSR. A computer can

superimpose one polygon upon the other to provide a

percentile value of symmetry.

Maxillomandibular comparison of asymmetry

Perpendiculars are drawn to MSR from J and GA, and

connecting lines from Cg to J and GA. This produces two

pairs of triangles, each pair bisected by MSR. If perfect

symmetry is present, the four triangles become two, J-Cg-

J’ and AG-Cg-GA.

Linear asymmetries

The vertical offset as well as the linear distances

measured from MSR to Co, C, J, AG and ME.

Maxillomandibular relation

To allow tracing of the functional posterior occlusal plane,

a .014" wire is placed across the mesio-occlusal areas of the

maxillary first molars. The wire should extend about 3 mm

buccally to make it easy to recognize on the head film.

Distances are measured from the buccal cusps of the

upper first molars (on the occlusal plane) along the J

are

.


perpendiculars. The AG plane, MSR, and the ANS-ME

plane are also drawn to depict the dental compensations for

any skeletal asymmetries in the horizontal or vertical planes

(maxillomandibular imbalance). Midline asymmetries of the

upper and lower incisors and ME-MSR are also provided.

Frontal vertical proportions

Skeletal and dental measurements are made along the Cg-

ME line with divisions at ANS, A l, and Bl. The following

ratio are calculated.

1. Upper facial ratio— Cg-ANS/Cg-ME

2. Lower facial ratio— ANS-ME/Cg-ME

3. Maxillary ratio— ANS-A1/ANS-ME

4. Total maxillary ratio— ANS-Al/Cg-ME

5. Mandibular ratio— B 1 -ME/ANS-ME

6. Total mandibular ratio— B 1 -ME/Cg-ME

7. Maxillomandibular ratio— ANS-A1/B1-ME

These values can be compared with common facial

aesthetic ratio and measurements.

Ricketts analysis

Ricketts analysis gives a normative data of parameters

measured, which is helpful in determining vertical,

transverse dental and skeletal problems. It has five

components:

1. Dental relations

2. Skeletal relations

3. Dental to skeletal

4. Jaw to cranium

5. Internal structure.

Dental relations

1. Molar relation left (A6-B6).

2. Molar relation right (A6-B6). A differences in width

between the upper and lower molars measured at

the most prominent buccal contour of each tooth.

Used to describe the buccal/lingual occlusion of first

molars.

3. Intermolar width (B6-B6). It is measured from the

buccal surface of the mandibular left first molar to

the buccal surface of the mandibular right first molar.

This is helpful in determining the aetiology of a

crossbite.

4. Intercanine width (B3-B3). It is measured from the

tip of the mandibular right canine to the tip of the

mandibular left canine.

5. Denture midline. It is measured from the midline of

the upper arch to the midline of lower arch.

Skeletal relations

1. Maxillomandibular width right. It is measured from the

jugal process to the frontal facial plane (constructed

from the medial margins of the zygomaticofrontal sutures

to AG point). Used to measure skeletal crossbite.

2. Maxillomandibular width left. It is measured on left

side

3. Maxillomandibular midline. It is measured by the

angle formed by the ANS-ME plane to a plane

perpendicular to ZA-AZ plane.

4. Maxillary width (J-J’). It is measured as transverse

distance from J-J’.

5. Mandibular width (AG-GA). It is measured as transverse

distance from AG-GA.

Dental to skeletal

1. Lower molar to jaw left (B6 to J-GA left).

2. Lower molar to jaw right (B6 to J-AG right). It is

measured from the buccal surface of the lower molars

to a plane from the jugal process to the antegonial

notch. Norm: 6.3 mm, clinical deviation: 1.7 mm.

3. Denture-jaw midline. It is measured from the midline of

the denture to the midline of the jaws(ANS-ME).

4. Occlusal plane tilt. It describes the difference in the

height of the occlusal plane to the ZL-ZR plane.

Jaw to cranium

1. Postural symmetry. It is measured by the difference in

the angles (left and right) formed by a plane from the

zygomatic suture to antigonion and antigonion to the

zygomatic arch. Used to determ ine cause of

asymmetries.

Internal structure

1. Nasal width. It is measured from the widest aspects of

the nasal cavity. May be used to determine the cause

of mouth breathing.

2. Nasal height. It is measured by the distance from the

ZL-ZR plane to the anterior nasal spine.

3. Facial width. It is measured at AZ-ZA points. It

essentially describes width at zygomatic arches and

can be useful in maxillary expansion decision making.

Maxillomandibular differential values and ratio

(Ricketts and Grummons, 2003)

Maxillomandibular differential values and ratios obtained

from PA cephalogram help us in estimating the transverse

deficiency and also the amount of expansion required.

Maxillomandibular differential value is the difference

between mandibular width (AG-GA, antigonion -

antigonion) and maxillary width (J- J’). A differential in

total width of about 20 mm was considered satisfactory.10

A definite ratio exists between maxillary and mandibular

width and also nasal cavity to maxilla, which will help us in

determining the relative transverse problem in the arches.

The value of ratio of maxilla to mandible is about 80%, and

the ratio of nasal cavity to maxilla ranges from 40 to 42%.

Limitations of PA cephalometry

There are some inherent errors associated with cephalometry

S.No. Variable Norm Clinical deviation

Dental relations

1. Molar relation left (A6-B6) 1.5 mm 2 mm

2. Molar relation right (A6-B6) 1.5 mm 2 mm

3. Intermolar width (B6-B6) 55 mm 2 mm

4. Intercanine width (B3-B3) 22.7 mm 2 mm

5. Denture midline Omm 1.5 mm

Skeletal relations

1. Maxillomandibular width left (ZL-GA) 11 mm 1.5 mm

2. Maxillomandibular width right (ZR-AG) 11 mm 1.5 mm

3. Maxillomandibular midline 0 degree 2 degree

4. Maxillary width (J-J’) 61.9 mm 2 mm

5. Mandibular width (AG-GA) 76.1 mm 2 mm

Dental to skeleton

1. Lower molar to jaw left (B6 to J-GA left) 6.3 mm 1.7 mm

2. Lower molar to jaw right (B6 to J-AG right) 6.3 mm 1.7 mm

3. Denture-jaw midlines Omm 1.5 mm

4. Occlusal plane tilt Omm 2 mm

Jaw to cranium

1. Postural symmetry 0 degree 2 degree

61.9 mm 2 mm

76.1 mm 2 mm

Internal structure

1. Nasal width (C-C’) 25 mm 2 mm

2. Nasal height (ZL-ZR to Ans) 44.5 m 3 mm

3. Facial width (AZ-ZA) 115.7mm 2 mm

that are more pronounced in PA cephalogram. There may be

variations in X-ray projection, measuring system as well as

landmark identification. Errors may also be associated with

faulty head positioning, e.g. excessive tilt of the head,

which is more difficult to control in posteroanterior than in

lateral cephalograms.

Summary

PA cephalogram is an essential diagnostic aid in cases with

facial symmetry. It can answer the important aspects of

facial symmetry like maxillomandibular width, occlusal

plane level, dental to skeletal midline, skeletal midlines

and chin location. It is helpful in determining true asymmetry

from the apparent.

The PA cephalogarms are used to assess location and its

quantification of transverse problem, skeletal class III, and

for prediction of upper canine impactions.

PA cephalogram is used to measure the amount of

maxillary expansion required and that has occurred with

treatment.

REFERENCES

1. Chebib FS, Chamma AM. Indices of craniofacial asymmetry.

Angle Orthod 1981; 51: 214-26.

2. Grummons DC, Kappeyne MA. Frontal asymmetry analysis.

J Clin Orthod 1987; 448-65.


3. Rigketts RM, Grummons D. Frontal cephalometrics: practical

applications, part 1.World J Orthod 2003; 4: 297-316.

4. Grummons D, Ricketts RM. Frontal cephalometrics: practical

applications, part 2.World J Orthod 2004; 5(2): 99-119.

5. Bench R. Provocations and perceptions in craniofacial

orthopedics. Denever. Rocky Mountain Orthodontics 1989.

Quoted from Ricketts RM and Grummons D. Frontal

cephalometrics: practical applications, part 1.World J Orthod

2003; 4: 297-316.

6. Lundstrom F, Lundstrom A. Natural head position as a basis

for cephalometric analysis. Am J Orthod Dentofac Orthop

1992; 101: 244-47.

7. Faber RD. The differential diagnosis and treatment of

crossbites. Dent Clin North Am 1981; 25: 53-68.

8. RMO diagnostic services. Course Syllabus. 1989 Chapterl,

Pages 14-18, 33-40 Chapter 3, Pages 23-35.

9. Trpkova B, Prasad NG, Lam EW, Rabound D, Glover KE,

Major PW. Assessment of facial asymmetries from

posteroanterior cephalograms: validity of reference lines. Am

J Orthod and Dentofac Orthop 2003; 123: 512-20.

10. Vanarsdall RL Jr. Transverse dimension and long term stability.

Semin Orthod 1999; 5: 171-80.

Computerised and

digital cephalometrics

OVERVIEW

Computerised and digital cephalometrics

Computerised cephalometrics vs digital cephalometrics

The acquisition of ‘digital image’

Limitations of conventional cephalometric analysis

Cephalometrics

Advantages of digital computed radiography (DR) and direct digital radiography (ddR)

Digital cephalometry

Computerized radiography (CR)

Direct digital radiography (ddR)

Summary

Computerised and digital

cephalometrics______________

Computerised cephalometrics essentially means use

of computers to make cephalometric measurements

for quick and accurate analysis and store data for

ease of retrieval and transfer. There could be several versions/

levels of computerized cephalometrics depending upon the

capabilities or options of the supporting analysis ‘software’

used for cephalometric analysis.

The simplest version is the one, which substitutes the

Use of protractor and ruler to make measurements of

eraniofacial angular/linear measurements and ratios without

taking any lines on a cephalogram. These computerized

Cephalometric systems that were developed in 70-80’s used

^OS’ (disc operating systems) and had limited capabilities

F data analysis and treatment planning. These systems

Were then upgraded to be compatible with Windows.

Computerised cephalometrics has since advanced with

newer developments in computer hardware technology;

image capture (scan) and image transfer, and on-screen

image quality on monitors. Development of computer

softwares for architecture and for use in industry CAD

CAM technology have also been inducted in cephalometric

analysis. Specific softwares have been now developed for

reconstruction of 3D images for the 3D analyses of face and

craniofacial structures through CT scan and lately CBCT.

On the other hand, research and knowledge on growth

of craniofacial structures, growth prediction and soft tissue

changes that occur due to ageing, orthodontic treatment

and following orthognathic surgery have been integrated in

cephalometric diagnosis soft systems.

Robert M urray Ricketts was the pioneer and spent a lot

of his lifetime in the development of computerized

cephalometric systems and integration of growth prediction


data.and visual treatment objectives (VTO) into the

system.1'5The systems were developed in collaboration with

Rocky Mountain Orthodontics, at Denver, Colorado, USA.6

The advancements in computer technology helped to

render quality, accuracy and speed to image (cephalometric

image) management. The enhanced knowledge in growth

and soft tissue behaviour following orthodontic treatment

and orthognathic surgery has been of immense help in

orthodontic treatment planning, predictions of growth and

simulation of orthognathic surgery. The technological

advancements both in computer technology, digital image

quality manipulation and research in orthodontic literature

continue to pour in and are being constantly used to

update and enhance the ‘capabilities’ and quality of

computerized cephalometrics.

Computerised cephalometrics vs digital

cephalometrics

Computerized cephalometrics is often confused with digital

cephalometrics. Digital cephalometrics essentially involves

recording of cephalometric image on a non-film medium as

a ‘digital image’ which is manipulated through computers

and viewed on screen. It substitutes analogue film to digital

image and it is possible to do simultaneous analysis of this

image with cephalometric softwares.

Computers are a medium to store and retrieve ‘digital

image’ taken through either CMOS/CCDS sensors or storage

orthophosphor plates (Fig. 19.1). Digital radiology image

achieved through photostimulable orthophosphor plate

(PSP) is called computed radiography (CR) while radiology

image obtained on CCD/CMOS sensors, and processed on

screen is called direct digital radiography (ddR).

Acquisition of digital image (Fig. 19.2)

The digital image of a cephalogram can also be obtained by

either scanning a cephalogram X-ray film or capturing an

image of X-ray film using a digital camera. This image can

be transferred to a computer and made available on screen.

This digital image of analogue X-ray film can be used for

cephalometric analysis using cephalometric analysis

software. Such a process is called indirect acquisition of

digital image.

Direct digitization

The cephalometric software essentially locates X and Y

coordinates of a cephalometric point. This can be done

through a ‘digitizer’ by using the digitizing tablet and a

cursor. The cephalogram is placed on digitizer which is back

lit, using soft light. The points are digitized using a cross bar

or a digitizing pen. Such a process is called direct digitization.

■— O vercoat

— Phosphor layer

— Estar support

I— Black cellulose acetate

|— Lead backscatter control

— A lum inium panel

Fig. 19.1: Structure of phosphor screen cassette used in computerised radiography (CR)

X-ray

Fig. 19.2: The principle of horizontal scans used in direct digital radiography (ddR)

ll

e

e

e

y

n

Indirect digitization

It will involve location and digitization of cephalometric

points on computer screen with a mouse cursor. The onscreen

image may be obtained either through indirect

acquisition (scan or digital picture of a cephalogram) or

direct acquisition methods, i.e. digital radiography (dR) /or

direct digital radiography (ddR).

Modem computer softwares are capable of dynamic

manipulations of digital images through processes like

changing algorithms and windowing that permits alteration

of the contrast and density of the image without permanently

changing the original file. Hence raw data image can be

preserved.

Optimization is the key word in digital imaging which

means that digital computerized radiographic imaging and

direct digital imaging has superior capabilities by virtue of

possibilities to optimize each function from image production,

image display, archiving, and image retrieval as independent

developments. The synergetic and multitask outcome of

these capabilities has greatly enhanced diagnostic

capabilities in radio diagnosis.

For all medical applications, image quality standards

have been set up. These standards are called ‘DICOM’ or

digital imaging and communications in medicine.

Limitations of conventional cephalometric

analysis

1. Requires tracing of cephalogram on a tracing paper

2. Needs precise calibrated measuring hand instruments

3. Chances of errors of calculations

4. Measurement accuracy is dependent on the accuracy

of lines and accurate drawing of planes and angles.

5. Measurement accuracy is sensitive to human errors

6. Measurement accuracy is governed by the sensitivity

of measuring hand instruments.

7. Requires several calculations to be performed on a

single tracing.

8. Therefore it is a time consuming process which can be

cumbersome and boring

9. Many practitioners avoid cephalometric calculations

for it encroaches up clinical time and efforts required

to perform the analysis.

10. Storage of data and records needs space.

11. Retrieval is not easy.

12. Results may not be reproducible.

Computerised cephalometrics: advantages

1- There is no need to make a tracing of the cephalogram

2. The need to draw lines and planes and angels is

eliminated since the computer software calculates it

from the digitized points

3- Measurements are quick

4- Measurements are accurate

5- Multiple analyses can be done in a short duration.

6. The output can be generated with instant comparison

to norms.

7. Saving of time.

8. Growth prediction can be added.

9. Graphic display can be generated.

Advantages of digital computed radiography

(CR) and direct digital radiography (ddR)

(Fig. 19.3)

1. X-ray exposure can be greatly reduced (upto 70%).

2. Need for the X-ray film developing and processing is

eliminated and therefore all the technique and chemical

related errors associated with it.

3. Multiple ‘original images’ can be made and made

available to multiple stations simultaneously without

intermediate copying of the images as with screen-film

radiographs.

4. Digital images of X-rays can be transmitted to the end

user from the place of radiography within hospital setup

using local area network (LAN) or wide area network

(WAN) without any deterioration in any details of

image spatial frequency.

5. The image can be saved on a CD-ROM and mailed. The

images can also be transferred through internet, and

tele-radiology.

6. The digital image can be manipulated and enhanced

through image processing algorithms and postprocessing

functions of software.

7. Digital data storage saves space.

8. Ease of data retrieval.

9. Superimposition of cephalograms/on photographs is

possible.

DIGI-CEPH7

It is a cephalometric analysis software. It is the first

indigenous cephalometric system in India developed at

AIIMS in collaboration with the Department of Biomedical

Engineering, IIT, New Delhi. The system has following

hardware components (Fig. 19.4A-C):

1. A computer CPU with a good monitor.

2. A hipad digitizer, which is backlit with uniform soft

light.

3. A printer and graphic plotter.

Cephalometrics without X-rays8'10

Sonic digitization is the process of digitization of face/skull

without making the cephalogram. The system uses sound

waves to record the position of a landmark. Since this

system does not make use of X-rays the hazards of radiations

are eliminated.

This concept was first introduced in orthodontics by

Dolphin Imaging System (USA). The system makes use of

a headholder like the one used in cephalostat to orient the

skull/face. A camera grabs the digital image of the face in


errors of tracing and distortion of X-ray images are

eliminated. The DIGIGRAPH sonic digitization is more

accurate for soft tissue surface landmarks and values of

linear measurements but relatively less accurate than

cephalometric for other skeletal and dental parameters.

A

B

Fig. 19.3: Contemporary cephalometric digital machine: A. Digital

cephalostat, B. Image on screen

lateral view. The face is digitized with a hand held digitizer

for the landmarks like orbitale, nasion and porion. For the

other landmarks like Sella/root apex, their position and

spatial localization is calculated by mathematical algorithms.

The system of sonic digitization is relatively less accurate

for skull/hard tissue parameters because it is not possible

to exactly locate all the landmarks although the errors

associated with identification of cephalometric landmarks,

Digital cephalometry

Digital cephalometry and radiography implies acquiring a

digital image rather than an analogue image. It is used for

diagnosis and treatment planning on the computer screen

and, if required, several analogue copies can be printed

from the digital image.

Main advantage of digital imaging is reduction in radiation

dose from 40-50%1112 instant image availability, besides

image archiving, its transport to a multiuser locally or

remote areas.1314

Digital radiography has slowly evolved from use of

photostimulable phosphor plates (Computed radiography-

CR) to direct digital radiology (ddR). Eastman Kodak

Company (1975) patented a device that used

thermoluminescent infrared stimulable phosphors thereby

releasing a stored image. Its application was to improve

microfilm storage. FUJI Photo Film Company made use of

photostimulable phosphors to record a reproducible

radiographic image and patented the technology in 1980.

Thus digital radiography was born.15

Computed radiography (CR)

It makes use of photostimulable phosphors which replace

silver halide crystals of a conventional film. The

photostimulable phosphors when contacted by radiation

energy cause them to fluorescence, releasing a high fraction

of the absorbed energy, while some remnant energy is

stored in the phosphors, essentially as a latent image.

When stimulated with infrared, high frequency heliumneon

laser or white light, photostimulable phosphors release

light proportional to the stored energy which can be detected

by a photomultiplier tube (PMT) to generate an electrical

signal that is ultimately reconstructed into a digital

radiographic image. An optical filter is used to filter out the

laser light from the luminescent light of the CR screen

during read-out. Electrical signal from the PMT is sent to

the analog-to-digital converter where it is converted to

digital bits or binary coded numbers. In addition to

converting image data to digital data the converter may

manipulate the data and correct any deviations in it using

an input look-up table.

Each CR screen must be erased after use or before use

if the cassette has not been used in over 24 hours. The

reader erases the plate using fluorescent white light.

Direct digital radiography (ddR)

It is based on amorphous silicon technology that uses a

cesium iodide scintillator to perform X-ray detection. These

*

A. On screen menu of DIGI-CEPH

wi- »#tH MWM

B. A digitizer is used to locate X Y coordinate which is

connected to a computer. The points to be digitized are

chosen for the required analysis on screen through

software function. Point mode allows placement of a

single point while stream mode is used to draw profile

or contours. Cephalometric software such as DIGI-CEPH

calculates the variables and stores the data. The data is

retrieved either on screen or printer in a tabular form. A

plotter or laser printer can print graphic display of the

profiles

Cephalogram

Screen cursor LR

Digitization

Exit/over any button

Close-up of Backlit Digitizer showing switches for different

modes of digitization. The crossbar of the digitizer cursor

is used to locate the cephalometric points either on the X-

ray tracing or directly on the film placed on a backlit box

Patient Record Sheet

- 0 . Cl. No, ; 06805

SI. No, ;

Nane :

- Sex :

ASHITA

F

0. 0. B. :

0. 0 , Ceph.:

ftge :

Ethnic Gr. : Indo-Aryan

C. Graphic display of skeletal and facial contours, generated

through DIGI-CEPH

Fig. 19.4: Computerised cephalometrics using direct digitization


systems are called charged coupled device (CCD) or

complimentary metal oxide semiconductor (CMOS) systems.

These sensors are also used in digital cameras.

Charged coupled device (CCD)

It converts light image into a form that can be stored on a

tape. An integrated circuit is made up of a grid, which is

constituted of ‘pixels/electron well’. On exposure, stored

electric charge is converted into values of brightness and

location which makes a digital image. The data is sent to a

computer, processed and displayed.

Complimentary metal oxide semiconductor

(CMOS) system

It is an integrated circuit like a CCD. However, image quality

is poorer than CCD. Improved versions like CMOS/APS

system have been developed by ‘NASA’ and ‘JET

propulsion laboratories’ in 1993. The active pixel sensor

(APS) allows embedding of microprocessors and other

circuits right in the sensor chip itself. It offers several

advantages over CCD which include possible smaller

individual pixels, less power requirement, lower cost and

long lasting sensors.

Scintillator

It is an essential component of CCD device which helps to

detect X-ray signals. It converts X-ray radiation into photons

which are conducted through a fibreoptic layer. CCD

converts these photons to electronic signals which convert

the analogue signal to a digital signal.

Direct digital radiography (ddR) offers full resolution

images that are displayed and stored in about 8 seconds

and therefore have greater advantages over CR which

requires plate processing.

The ddR is compatible with digital imaging and

communications in medicine (DICOM) standards. DICOM

standards have been developed by the American College of

Radiology Manufacturers Association to define the

connectivity and communication protocols of medical

imaging devices and therefore can be connected on

workflow through LAN (Local area networking) or WAN

(Wide area network). WAN is a geographically dispersed

telecommunications network. The term distinguishes a

broader telecommunication structure from an LAN.

Conventional digital cephalometry systems had to scan

a patient’s head for up to 8 to 18 seconds. The major

disadvantage of this technique was that if the patient

moved during the exposure the image had to be taken again

(Fig. 19.2).

Newer technology captures the image in just over one

second, drastically reducing the risk of blurred images and

significantly improving patient’s comfort. With ‘one shot’,

the entire skull is exposed in a single shot, in a fraction of

a second (just like film), so that movement of head is no

longer a problem. The image is clearer and patient comfort

is improved. There is no need for the user to change

working practices, as the methods are exactly the same as

systems using silver halide films - but with none of the

disadvantages.

Advance digital cephalometric systems now use 3D

volumetric images. The advanced slicing windows can help

display any slice of choice within 3D volume (Fig. 19.5A,B).

CR cephalometrics

It uses conventional cephalostat machines that are modified

to receive PSP plates.

Hardware components of CR system

1. Photostimulable phosphor plate and cassettes,

2. Cassette reader,

3. Bar code scanner

4. Remote operator panel for entering patient data,

5. Printer and/or workstation.

PACS is a network of computers into which a CR unit may

input data for display and storage. The CR imaging system

consists of clinical workstation for reviewing and printing

from PACS.

Steps of using CR system

Once the study is selected, i.e. cephalogram/panorex and the

cassette is bar-coded, the radiology technologist may proceed

using the cassette just as they would a screen-film cassette.

1. Patient information data is entered into the CR unit (it

can be accessed through barcode of the patient if

provided by the hospital records)

2. The appropriate algorithm of the X-ray is selected

(cephalogram/OPG/TMJ)

3. It may also be essential to enter cassette’s unique

barcode into the CR system so the reader can identify

the image and process it according to the pre-selected

algorithm.

4. Patient is correctly positioned in the apparatus and

exposed to X-rays.

The chronology of the image processing following

exposure is as follows:

1. The exposed cassette is placed on the reader where the

cassette is mechanically opened and the photostimulable

plate removed.

2. Inside the reader, a laser is passed over the plate in

raster fashion using a wavelength of 633 rpi to stimulate

luminescence of the phosphors.

3. This stimulated luminescence releases the latent image

in the form of light that is filtered and collected on to

a photomultiplier tube (PMT).

4. The PMT converts the light signal to an electrical

signal that is then converted from analog-to-digital

data bits by a special converter.

5. The raw data is subjected to algorithms and look-up

tables (LUT) that interpolate data points and allow for

Section II: Computerised and digital cephalometrics 219

Fig. 19.5A: Cephalogram lateral view made on advanced 3D digital ceph

machine, Cephalogram of an 18-year-old woman (Courtesy SIRONA

Dental Systems, Bensheim, Germany)

Fig. 19.5B: Cephalogram in open mouth with a slice of TMJ superimposed.

X-ray views A, B are made on SIRONA GALILEOS (Courtesy SIRONA

Dental Systems, Bensheim, Germany)

manipulation of digital information. It is optimized

through a process of image segmentation.

6. Finally, the image is presented on the CRT monitor.

All of this takes place in a matter of seconds rather

than minutes as in conventional screen-film image

processing

7. Once the image is acquired to the satisfaction it can be

stored as digital image or processed for printing.

8. Image can be available in the archives and retrieved as

and when required for computerized cephalometric

analysis.

Design characteristics of photostimulable

phosphor cassettes

The basic component of CR image capture is the

photostimulable phosphor screen and cassette. The cassette

front is made of carbon fibre and the backing of aluminum.

The structure of a photostimulable phosphor screen from

within outward is: Aluminum panel, lead layer, black cellulose

acetate layer, estar support, phosphor layer, and an overcoat

to protect the phosphor (Fig. 19.1).

BaFBrEu2+

Phosphor is coated on to the base (estar) using polymers

^at act as glue to hold it. Then a clear coat solvent is

coated over the phosphor to seal it, protecting it from

Physical damage. A black reflective base under the phosphor

helps improve image resolution by reducing dispersion of

%ht as the laser exposes the phosphors at reading; the

hlack base also allows for a thicker phosphor layer into

which photon energy is trapped. These are all mounted on

to a lead sheet that absorbs excess photons and reduces

backscatter, and to an aluminum panel that is mechanically

removed from the cassette during scanning.

On the back of the panel, there is a label which indicates

the speed of the cassette, which in CR imaging is the

brightness of the phosphor. Speed is also used in calculating

the exposure index (Fig. 19.1).

How PSP works

Photostimulable phosphor screens are composed of

europium-activated barium fluorohalide crystals (BaFX:Eu2+)

where X is a halogen of iodine or bromine. Photostimulable

phosphors generate fluorscence from radiation energy just

as do analog screens; however, to release the latent image

contained in the storage phosphors the screen must be

subjected to light from a finely collimated laser beam. The

equipment utilizes light in the wavelength of about 633 rpi

to release a storage phosphor’s latent image. During

photostimulation of the storage phosphor screen, light is

emitted which has a wavelength of 400 rpn. Light emitted

from CR screens during photostimulation is filtered and

collected by photomultiplier tube(s) (PMT) and converted

to an electrical signal that can be digitized.

Advantages of CR systems or storage phosphor

plate

1. Existing X-ray apparatus can be modified for use with

PSP

A


2. PSP is reusable

3. Wider exposure range and fewer retakes

4. Reduction in radiation exposure

Disadvantages

1. Costly

2. Less spatial resolution than film

3. Phosphor tends to decay with time

4. Images may initially appear different from film based

images

Summary

In near future the film base technology will be extinct.

Digital caphalometics has eased out much of errors and

limitations associated with film processing and storage.

The quality of digital images should follow DICOM

standards. The digital images can be instantly viewed on

screen and thus save time. The cephalometric analysis

softwares have automated process of cephalometric analysis

to great extent. The options of proper prediction and

treatment outcome may not be accurate and should be

interpreted with a great caution.

REFERENCES

1. Ricketts RM. The evolution of diagnosis to computerized

cephalometrics. Am J Orthod Dentofac Orthop 1969; 55(6):

795-803.

2. Ricketts RM, Bench RW, Hilgers JJ, Schulhof R. An overview

of computerized cephalometrics. Am J Orthod Dentofac

Orthop 1972; 61(1): 1-28.

3. Ricketts RM. The value of cephalometrics and computerized

technology. Angle Orthod 1972; 42(3): 179-99.

4. Ricketts RM. An update on the status of computerized

cephalometrics. Aust Orthod J 1978; 5(3): 89-104.


cephalometrics: the first fifty years. Angle Orthod 1981;

51(2): 115-50.

6. RMO diagnostic services Course Syllabus. Denver, Colorado,

USA. 1989.

7. Kharbanda OP, Sdhu SS, Guha SK, Anand S. DIGI -CEPH

Manual AIIMS IIT, New Delhi, 1990.

8. Chaconas SJ, Engel GA, Gianelly A A, et al. The DigiGraph

work station. Part 1: basic concepts. J Clin Orthod 1990;

24(6): 360-67.

9. Alexander RG, Gorman JC, Grummons DC, Jacobson RL,

Lemchen MS. The DigiGraph work station. Part 2: clinical

management. J Clin Orthod 1990; 24(7): 402-407.

10. Chaconas SJ, Jacobson RL, Lemchen MS. The DigiGraph

work station. Part 3: Accuracy of cephalometric analyses. J

Clin Orthod 1990; 24(8): 467-71.

11. Visser H, Rodig T, Hermann KP. Dose reduction by directdigital

cephalometric radiography. Angle Orthod 2001; 71(3):

159-63.

12. Nessi R, Garattini G, Blanc M, Marzano L, Pignanelli C,

Uslenghi C. Digital cephalometric teleradiography with storage

phosphors: comparative study. Radiol Med (Torino) 1993,

85(4): 389-93.

13. Forsyth DB, Shaw WC, Richmond S. Digital imaging of

cephalometric radiography, part 1: advantages and limitations

of digital imaging. Angle Orthod 1996; 66: 37-42.

14. Forsyth DB, Shaw WC, Richmond S. Digital imaging of

cephalometric radiographs, part 2: image quality. Angle Orthod

1996; 66: 43-50.

15. http://www.ceessentials.net/articlel 1 .html

1

Errors in cephalometrics

OVERVIEW

• Limitations of a cephalogram

• Errors during taking a cephalogram

• Errors of tracing

• Errors of landmark identification

• Errors of cephalometric analysis

• Summary

Limitations of a cephalogram

It must be well appreciated and realised that a

cephalogram is an X-ray taken with a standard

orientation of the head and with a standardized

technique. A cephalogram is a two-dimensional view of

three-dimensional structures of the dentition, face and

head.

It is presumed that structures of right and left side of

face/head would be exactly overlapping each other when

X-rays traverse perpendicular to mid-sagittal plane at

transmeatal axis of the head, which has been oriented

parallel to the X-rays. However, the fact that the structures

of head on left side of face are closer than the right side

and hence show less magnification compared to right side

should be taken into account. Appearance of double shadows

on cephalogram would be a routine and not an exception.

Most of the cephalometric machines accept 5% enlargement

as an acceptable limit. Magnification is an inherent

limitation of a cephalogram.

Errors during making a cephalogram

Sources of errors at random in taking a cephalogram are

mostly associated with improper positioning or orientation

of head in cephalostat. A common problem is either head

tilted downward or upward.

1. Strain on neck. Cephalostat machine needs to be

adjusted to patient’s height whether the patient is

standing/sitting in a relaxed posture. The ear rods

should gently be placed in the external auditory meatus.

Should there be small discrepancy in height either the

child has to strain up the neck or more commonly

bends the neck.

2. Axial rotation of head. It is not uncommon and appears

as double shadows in anteroposterior direction while a

tilt of head to right or left side would appear as double

shadows in vertical plane.

3. Teeth aparts. They are not uncommon and so is excessive

strain on lips in an effort to close the lips. A cephalogram

in centric occlusion should be taken with lips in a relaxed

posture. The way patient poses during exposure would

effect soft tissue measurements (Fig. 20.1 A,B)

Errors during X-ray tracing

Other sources of error in cephalometric measurements could

be contributed to improper tracing of the X-ray film. Several

factors could contribute; these include contrast and

sharpness of X-ray film which is in turn dependent upon

the speed of film, exposure parameters, use of intensifying

screen and processing of X-ray films. With the development

221

222

:

■


A

B

Fig. 20.1: A. Common error while making a cephalogram with posterior teeth out of occlusion. B. Same patient with buccal teeth in centric occlusion.

Occlusion on cephalometry should always be double checked with centric occlusion relation in mouth

of digital radiography most of such factors can now be

controlled with image processing capabilities of the computer

softwares through the process of optimization.

Errors of cephalometric landmark identification

It has been reported that variability of landmark identification

is five times greater than measurement variability. Observer’s

experience in locating a landmark and his understanding of

the precise definition of landmarks are important factors

that influence landmark identification errors. Studies on

reproducibility of landmark identifications have reported

that each landmark has its own envelop of landmark

identification error. Some landmarks are more consistent

and accurate to be located while others show consistent

variability. This variability is independent of observers, i.e.

those landmarks with inconsistent variability show similar

trend of error of placement by the same operator or number

of operators. Some landmarks show consistent variability of

placement identification in X axis, while others exhibit in

vertical. Some landmark show inconsistent pattern.14

The errors of cephalometric measurement have been

classified as systematic errors and random errors.

Systematic errors (or bias) are those which occur due to,

e.g. a different concept of a landmark by a single operator or

by two different operators. Mr. X, who consistently locates

‘Or’ point slightly superior would add an inherent systematic

intraoperator error to all the cephalograms traced by him.

Similarly, two operators may consistently locate the point

‘Or’, based on their judgment in a different location and

hence a systematic error is introduced. Such an error of bias

for comparison of studies can arise between two operators

or a single operator over a time.

Random errors occur due to difficulties in landmark

identification or guessing.

These are classified as intraoperator and interoperator

errors. Single operator over the time may improve or change

landmark location identification with experience (Table 20.1).

T a b le 2 0 .1 : Cephalometric landmark accuracy

(meta analysis of six studies)5,7

X Coordinate

Orbitale (2.8+- 0.24)

Bolton point

Menton

ANS

P

Xaxis

B

Ptm

S

Go

Ar

Na

High error possibilities

Y Coordinate

A

B

Pog

Least error possibilities


Apex of lower incisor

Yaxis

ANS

Ptm

S

N-Me

Me-Go

A

Section II: Errors in cephalometrics 223

In general, up to 0.6 mm of discrepancy in location of the

landmark in considered acceptable. It is precisely 0.56 for X

coordinates and 0.59 for Y coordinates.5

Richardson6 in his study had two judges register

cephalometric landmarks, lines, and angles on ten

cephalograms at an interval of 10 weeks. He found that

ordinary cranial landmarks have a margin of error of 1 mm.

• Orbitale and Bolton points show higher variability.

• Vertical deviations are more on landmarks which are

, on curves like points A and B.

• Horizontal deviations have been observed in particular

for menton(M e), spina nasalis (ANS) and

pterygomaxillary fissure (Ptm).

Midtgaard et a l7 conducted a study on reproducibility of

15 commonly used landmarks and measurements of errors

in seven cranial distances. When a clinician was asked to

mark the same landmark on two consecutively taken lateral

cephalograms the differences were apparent, which varied

from landmark to landmark. Roughly, the same variance in

values was observed in estimating the positions of landmarks

on the same cephalogram on two occasions with an interval

of one month.

• The greatest difference was found for landmark orbitale

with a mean of 2.08 mm + 0.24.

• On an average, difference of 1mm was observed for

landmarks supramentale (1.27), pogonion (1.20), spina

nasalis anterior (1.17), apex of upper incisor (1.12) and

lower incisor (1.09).

The means of the differences in cephalometric

measurements accounted for most of the part dependent

upon uncertainty of observer in exactly locating the

landmarks whether on two consecutive films of a subject or

on the same cephalogram film at one month apart.

• The greatest degree of certainty has been found for

landmarks sella turcica (0.41 mm) and articulare (0.52

mm).

• The greatest inaccuracy has been found in estimating

accuracy of n-ss and n-sm, while greatest accuracy

was seen for Me-Go and N-Me.

Trpkova5 et al conducted a m eta-analysis of

cephalometric landmark, identification and reproducibility.

Only six studies fulfilled strict inclusion criteria. They

reported:

• B point and Na point for X coordinate and ANS and

A point for Y coordinate are the landmarks that showed

greatest consistency among six studies.

• On X coordinate Ar and Or and on Y coordinate P and

Or showed significant bias. According to their

conclusions, authors recommend that 0.59 mm of total

error for X coordinates and 0.56 mm error for Y

coordinates are acceptable levels of accuracy.

• The landmarks B, A, Ptm, S and Go on the X coordinate

and Ptm, A and S on Y coordinate presented with

insignificant mean error and small values for total error.

Therefore, these measurements may be considered to

be reliable for cephalometric analysis of lateral films.

Every effort should be made to minimize error of

measurement of cephalometric variables which could affect

judgments in diagnosis and quality of research.

Summary

Much of cephalometric errors are related to head positioning

in the cephalostat, strain on neck, occlusion and strained

lips. The quality of film processing and chemicals, exposure

control are significant factors that influence the contrast

and sharpness of X-ray film.

With digital technology much of these issues have been

taken care. Accurate identification of landmarks holds the

key to accurate measurements. Experience of the operator

has considerable influence on landmark accuracy, specially

certain landmarks which are not so easily identificable on

the X-ray.

Some landmarks show consistent errors in identification

in ‘X’ axis while others in ‘Y’ axis.

In general, error of landmark identification upto 0.5 mm

(in either X or Y axis) is considered acceptable.

Accurate landmark identification is the basis of correct

measurements on a cephlogram.

REFERENCES

1. Baumrind S, Frantz RC. The reliability of head films

measurements I: landmark identification. Am J Orthod Orthop

1971; 60: 111-27.

2. Baumrind S, Frantz RC. The reliability of head film

measurements. 2: conventional angular and linear

measurements. Am J Orthod 1971; 60: 505-17.

3. Houston WJ, Maher RE, McElroy D, Sherriff M. Sources of

error in measurements from cephalometric radiographs. Eu J

Orthod 1986; 8(3): 149-51.

4. Vincent AM, West VC. Cephalometric landmark identification

error. Aust Orthod J 1987; 10(2): 98-104.

5. Trpkova B, Major P, Prasad N, Nebbe B. Cephalometric

landmark identification and reproducibility: a meta-analysis.

Am J Orthod and Dentofac Orthop (ORTHO) online 1997;

112(2): 165-70. accessed on 4.9.2007.

6. Richardson A. An investigation into the reproducibility of

some points, planes, and lines used in cephalometric analysis.

Am J Orthod 1966; 52(9): 637-51.

7. Mitgard J, Bjork G, Linder-Aronson S. Reproducibility of

cephalometric landmarks and errors of measurement of

cephalometric cranial distances. Angle Orthod 1974, 44: 56-

61.

8. Gravely JF, Benzies PM. The clinical significance of tracing

error in cephalometry. Br J Orthod 1974; 1(3): 95-101.

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