5.wonderful world of endodontic working width–the - Dharmsinh ...

JOURNAL OF DENTAL SCIENCES 

Reader 

Department of Conservative Dentistry and Endodontics 

Faculty of Dental Science, Dharamsinh Desai University. 

Nadiad - 387 001. Gujarat, India 

Lecturer 

Dept of Physiology, Faculty of Dental Science, 

Dharmsinh Desai University, Nadiad - 387001. Gujarat, India 

Dr. Shashin J. Shah M.D.S., F.R.S.H. 

Dr. Jayshree S. Shah M.S. 

Volume 2 Issue 2 

WONDERFUL WORLD OF ENDODONTIC WORKING WIDTH 

–THE FORGOTTEN DIMENSION – A REVIEW 

Abstract: 

Working width- if you are familiar with this term – It was first used by Dr.Jou from the University of Pennsylvania. He 

emphasized on this as a valuable reminder that canals are three – dimensional. This means that all instrumentation 

techniques have to contend with both a working length and a working width. Incidentally, this area of the canal (coronal to 

the apical constriction) was called, and with good reason, “The Forgotten Dimension” by Carl Hawrish, an endodontist from 

Canada. 

Techniques for cleaning and shaping root canals differ in accordance with clinical observations, research discoveries and 

traditionally accepted values. 

Our goal should be to avoid both under and over preparation of the canal. Achieving this doesn’t seem to be a mystery 

anymore. Anatomical research tells us that canals come in many different diameters, from narrow to wide and from straight 

to extremely curved. 

Key words: WW [Working Width], WL [Working Length], IWW [Initial Working Width], FWW [Final Working Width], 

Instrumentation, Major Diameter, Minor Daimeter. 

Introduction : 

Root canal morphology is a critically important part of 

conventional and surgical endodontics. Many in vitro 

1,2,3,4,5 

studies have recorded the scales and average sizes of 

root canals, but there have been few clinical attempts to 

determine the working width [WW] . The initial and post 

instrumentation horizontal dimensions of the root canal 

system at WL and other levels The horizontal dimension of 

the root canal system is not only more complicated than the 

vertical dimension (root canal length or working length) but 

also more difficult to investigate because the horizontal 

dimension( root canal width or working width)varies greatly at 

each vertical level of the canal. It goes without saying that as 

professionals we should strive for the highest possible 

success rate of root canal therapy. Successful cases should 

be fully functional and pain–free. Similarly, how much time 

should elapse, until you can consider a root canal treatment 

6 

successful? Three years is a common figure. Inadequate 

and even very poorly done root canal treatment often last at 

least that long or even longer- thanks to an efficient host 

immune system. 

It is known that most true endodontic failures are caused 

by:[1] Inadequate pulpal space cleaning, 

[2] Inadequate disinfection,both are simultaneously 

interrelated.In dental schools we are taught that cleaning and 

sealing the root canals especially in the apical third, is the 

most critical part of the procedure. This basic concept has not 

changed. Anatomical criteria also plays an important role as 

root canals are curved in one or more directions. Shape also 

varies from oval, round, cylindrical, rhomboidal, double – 

pear shaped etc. 

Review of literature : 

A clinician’s primary concern is to thoroughly cleanse the root 

canal system during root canal therapy, mechanically and 

chemically removing microorganisms and their substrates 

from the canal. Without proper chemo mechanical 

instrumentation, the remaining irritants may reduce the 

success rate and cause failure of the treatment. In addition, 

canal surface irregularities require proper instrumentation for 

adequate root canal filling. Many textbooks and much 

literature focus on canal instrumentation in terms of filing, 

reaming, or other instrument motions and usage and always 

stress the importance of enlarging the canal size. Without 

solid scientific evidence, however, it is still not clear how large 

is large enough. 

There is widespread agreement among endodontists that 

cleaning & shaping of the root canal is the most important 

7,8 

phase in endodontic therapy .The aim of endodontic 

treatment is chemomechanical cleaning of the root canal and 

9 

its obturation hermatically with an inert material. Ingle et al 

have suggested that apical percolation is the main cause of 

endodontic failure. The main reasons for this failures are 

incomplete canal obturation or the presence of an untreated 

canal, for successful endodontic therapy the dentist should 

be aware of the variations in the root canal morphology. Many 

investigators have worked on the tooth morphology, 

topography, curvature, ramifications of the main root canal, 

diameters, localization and no. of foramina, and apical deltas 

10,11 

by using different methods .Since there are differences in 

Address for Correspondence: 

Dr. Shashin J. Shah M.D.S., F.R.S.H. 

Faculty of Dental Science, Dharmsinh Desai University. 

College Road, Nadiad - 387001. Gujarat, India 

Phone : +91 079 27471883, 27551624, +91 268 2527077 

Mobile : +91 98252 50405 

Email : smartyrushabh@gmail.com 

20


selection of material, methods used, and classification of 

canal configurations different opinions have arisen about root 

12,13 

canal morphology . 

Many studies have also demonstrated that widely accepted 

endodontic cleaning and shaping techniques are inadequate. 

1 

Haga found that mechanical preparation of root canal to two 

sizes larger than original was still not adequate. Gutierrez and 

14 

Garcia showed that often, canals are improperly cleaned. 

They attributed this inadequate instrumentation to the fact 

that root canal diameter is larger than the instrument caliber 

used in each particular case. This finding suggests that each 

canal should be calibrated independently before 

instrumentation so that proper preparation can be achieved. 

15 

Walton’s histologic study showed that canals that were 

instrumented to three sizes larger still were not thoroughly 

16 

cleaned. Recent in- vitro investigations concluded that 

stainless steel and nickel-titanium [NiTi] rotary instruments 

were not able to clean the root canals satisfactorily. 

In the absence of a study that defines what the original width 

and optimally prepared horizontal dimensions of canals are, 

clinicians are making treatment decisions without any 

support of scientific evidence. It is difficult to section all levels 

of the teeth and make the section plane exactly perpendicular 

to the canal curvature. Therefore, most morphometric studies 

cannot show the true picture of the horizontal dimensions of 

the root canal system. Until recently, most investigations 

have involved counting the number of canals and foramina 

and categorizing how the canals join or split. Current studies 

pay more attention to the shape of the canal systems and its 

clinical implications than to the actual preoperative size of the 

17,18,19 

canal . 

Routine clinical radiographs may mislead clinicians to make a 

different plan to clean the root canal system. Unfortunately, 

this area of critical importance hasn’t been investigated 

thoroughly. Some clinicians may still have the impression that 

all root canals are round in shape because of radiographs.If 

we see radiograph in Illus.1 & 2 – the actual difference of 

dimensions of root canal area (Diameter) mesio distally and 

18 

facio lingually is noticeable. Recent studies reported a high 

prevalence of oval root canals in human teeth. Crosssections 

of 90% of the mesiobuccal canals of maxillary first 

molars were found to be oval or flat. This article provides 

definitions and perspectives on the current concepts and 

techniques to handle WW (the horizontal dimension of the 

root canal system) and its clinical implications. 

Illustration 1 The mesiodistally directed radiograph 

indicates a flattened distal root canal in a mandibular first 

molar. In the same tooth, the faciolingual direction of the 

routine radiograph gives an impression of a round-shaped 

distal canal. 

22 

(TAKEN FROM JOU Y T- DENT CLIN NORTH AM ) 


Illustration 2. The faciolingual direction of the routine 

radiograph gives an impression of roundshaped canal in a 

mandibular first premolar. The mesiodistally directed 

radiograph indicates a flattened root canal in the same tooth. 

22 


Determination of the minimal and maximal final working 

width at working length: 

To what extent the canal is supposed to be prepared has been 

20 

a myth in the endodontic field. Grossman described the 

rules governing biomechanical instrumentation in his 

textbook Endodontic Practice. 

Two guidelines were considered sufficient for 

instrumentation: 

[1] Enlarge a root canal at least three sizes beyond the size 

of the first instrument that binds; 

[2] Enlarge the canal until clean, white dentinal shavings 

appear in the flutes of the instrument blade. 

Root canals should be enlarged, regardless of initial width, to 

remove irregularities of dentin and to make the walls of the 

canal smooth and tapered. 

Root canals should be widened for four reasons: 

[1] To remove microorganisms on the canal surface 

mechanically. 

[2] To remove pulp tissue ,because even when a vital pulp is 

extirpated, tags of pulp tissue and odontoblasts cling to 

the canal wall and are not removed with the body of the 

pulp; they later undergo necrosis and provide an 

environment for bacterial growth. 

[3] To increase the capacity of the root canal, to permit 

irrigating solutions to reach the apical third of the root 

canal for effective debridement. 

[4] To shape the root canal to receive gutta-percha, 

because the wider the canal, the easier it is to fill it. 

Definition of working width 

21 

Working width is defined as: 

“The initial and post instrumentation horizontal dimensions of 

the root canal system at WL and other levels”. 

• Minimum initial working width (Min IWW) corresponds to 

the initial apical file size that binds at the WL. 

• The maximum final working width (Max FWW) 

corresponds to master apical file size that is generally 

three ISO sizes larger than the Min IWW. 

21


Working 

Width 

MinlWW MaxFWW 

The factors affecting the determination of Min IWW are: 

• Canal shape 

• Canal length 

• Canal taper 

• Canal curvature 

• Canal contents 

• Canal wall irregularity 

• Type of instruments used to determine the initial WL 

In a round canal, it is easy to determine the working width, but 

in canals that are oval, long oval, flattened ribbon like or 

irregular, discrepancy arises leading to incomplete cleaning 

and produces a “key hole” or a“dumb bell” preparation of the 

root canal. 

Illustration 3. Cross-section of a Mandibular first premolar, 

indicating a long-oval and irregular rootcanal. In the same 

tooth, the faciolingual direction of the routine radiograph may 

be mistakenly recognized as a round-shaped canal because 

a mesiodistally directed radiograph is rarely available 

clinically. 

22 


Current descriptions of the horizontal dimensions (crosssections) 

of the root canal. 

1. Round (circular) : MaxIWW equals MinIWW 

2. Oval : MaxIWW is greater than MinIWW (upto two 

times more) 

3. Long Oval : MaxIWW is two or more times greater than 

MinIWW (upto four times more) 

4. Flattened (flat, ribbon) : MaxIWW is four or more times 

greater than MinIWW. 

5. Irregular : cannot be defined by 1-4. 

22 


21 

Significance of working width 

• To obtain an apical stop which is as round as possible so 

as to get an impermeable seal 

• So that the dentinal tubules at the apical 1 mm is devoid 

of any micro organism. 


• Apical preparation width with large working width 

removes more bacteria than small apical preparation. It 

also permits irrigation solutions to be placed closer to 

WL with easier exchange of irrigants. 

The initial and post instrumentation horizontal dimensions of 

the root canal system at working length and other levels are 

different at different levels in a relatively round canal, the 

lesser and the greater initial horizontal dimensions are 

approximately the same. In an oval, long oval or flat canal (as 

shown in Box), the maximal initial horizontal dimension 

(MaxIWW) may be several times larger than the minimal 

initial dimension (MinIWW) at different levels of the canal. For 

22 

example, in a maxillary cuspid , MinIWW at working length 

(MinIWW0) may be the same as MaXIWW at working length 

(MaxIWW0). But 12 mm short of working length, its 

MaxIWW12 is probably three to four times larger than 

MinIWW12. This is because at that level, the cross section of 

a cuspid very often is a long oval or flat canal shape. 

Determination of initial working width at working length 

(initial apical file determination estimation of initial canal 

diameter) 

In the course of cleaning and shaping the root canal system, 

the clinician must determine three critical parameters. These 

are the length of the canal, the taper of preparation, and the 

horizontal dimension of the preparation at its most apical 

extent, also referred to as the initial apical file size. 

Factors affecting the determination of minimal initial 

working width at working length 

Several factors may affect the accuracy of determining the 

MinIWW0. The canal shape, length, taper, curvature, 

content, and wall irregularities and the instrument used may 

all influence the result because each can affect the clinician’s 

tactile sense. The combination of those factors makes correct 

determination of IWW very difficult, if not impossible. 

Understanding these factors can minimize the 

underestimation of the IWW. 

Canal shape 

The variation of canal shape as stated earlier, the round canal 

can be measured more easily because the MinIWW and 

MaxIWW are the same. Other factors, however, make 

determination of IWW difficult, even in straight canals. The 

proper instrument and tactile sensation may determine the 

MinIWW of the oval, long oval, and flat canals. The 

determination of MaxIWW, however, cannot easily be 

realized with current methods. 

One of the most common method to evaluate canal shape is 

sectioning of the root. Cross sections at different level in a 

root allows direct viewing of canal shape & position relative to 

23,24 

the borders of the root surface 

Canal length 

When using an instrument to gauge working length, the 

longer the canal, the greater the frictional resistance. In a very 

long canal (>25 mm), the frictional resistance may increase to 

affect the clinician’s tactile sense for determining the IWW 

correctly. In addition, if the coronal flare is too conservative or 

limited to the coronal third of the canal, then the shaft of the 

22


instrument may engage the canal wall and cause a 

false/premature conclusion as to WW. 

Canal taper 

Any tapering discrepancy between the gauging instrument 

and canal may lead to an early instrument engagement of the 

canal wall, causing a false sensation of apical binding. Early 

coronal flare can increase the taper of the canal and reduce 

the tapering discrepancy between the gauging instrument 

and canal wall. The last 3 to 5 mm of the canal can have 

parallel walls, making correct determination of IWW difficult. 

Canal curvature 

Curved canals can cause deflection of the gauging 

instrument and increase the frictional resistance. The 

curvature of the root canal can be categorized into twodimensional, 

three-dimensional, small radius, large radius, 

and double curvature (S-shaped, bayonet-shaped) and with 

different degrees of severity. Each of these curvatures has a 

different effect on a clinician’s tactile sense. The combination 

of these curvatures makes correct determination of IWW 

extremely difficult, if not impossible. In curved mandibular 

25 

premolars, the study by Wu et al indicated that the first K file 

and the first Light speed instrument that bound at the working 

length failed to accurately reflect the diameter of the apical 

canal. Careful canal Preparation is an important part of 

Successful root canal therapy. The ability to enlarge a canal 

without deviation from the original canal curvature is a 

9,26,27 

primary objective in endodontic instrumentation . It has 

been stated that “The final Preparation should be an exact 

replica of the original canal Configuration in shape, taper and 

28 

flow, only larger” . After studying the effects of several 

26 

instrumentation techniques, Weince et al noted that every 

file,whether precurved or straight , tended to straighten within 

the canal. They reported that the largest amount of apical 

canal preparation occurred at the outer portion of the 

curvature, away from the furcation. An attempt to solve this 

problems has led to the development of various 

instrumentation technique like step back, crown down, 

balanced force, anti curvature filling etc in addition several 

instruments like k flex, flex arc, flex-o, protaper, race files, 

light speed, hero shaper-hands and rotary files have been 

designed. This instruments aim at alleviating procedural 

difficulties at coronal, middle, apical regions of root canal. 

The Schneider method is the primary technique used to 

28 

measure canal angulation . 

Canal content 

The content of the root canal may be fibrous in nature. 

Calcified material (calcific metamorphosis) may also be part 

of the canal content. During determination of IWW, the mixed 

canal contents can create different degrees of frictional 

resistance against the gauging instrument. It can eventually 

affect the clinician’s tactile sense. This factor makes correct 

determination of IWW somewhat more difficult. 

Canal wall irregularities 

Attached pulp stones, denticles, and reparative dentin canal 

create convexities on the canal wall surface. Resorption can 

produce concavities on the canal wall surface. These 

phenomena can serve as an impacting factor that induces a 


false estimation of the true canal dimension at working length 

and other levels. 

22 


Instrument for determining initial working width 

The rigidity, flexibility, and tapering of the instrument used for 

determining IWW can affect accuracy. As mentioned 

previously, any tapering discrepancy between the gauging 

instrument and canal may lead to an early instrument 

engagement of the canal wall, altering the tactile sensation. In 

addition, the rigid instrument in a curved canal also can lead 

to a false tactility. During IWW determination, the combination 

of those affecting factors can have a great impact on the 

accuracy. Understanding these factors can minimize the 

underestimation of the IWW and maximize its accuracy. 

Eliminating or minimizing the influence of affecting 

factors: 

Being aware of the existence of the affecting factors in IWW 

determination is the primary step in maximizing the accuracy 

of the technique. Without knowing these factors, clinicians 

can repeatedly make the same mistakes in underestimating 

IWW, which will lead to incomplete cleaning and shaping of 

the root canal system as shown in Illustration 4-6. (TAKEN 

22 

FROM JOU Y T- DENT CLIN NORTH AM ) 

Illustration 5. A cross-section of prepared and filled canals 

indicates an incomplete instrumentation and may result in a 

failed root canal treatment. The ‘‘dumbbell’’ effects are typical 

pictures that demonstrate the unprepared parts of the root 

canal. This misadventure can come from underestimation of 

the IWW and the lack of understanding of endodontic 

WWconcepts 

23


Illustration 6 A cross-section of incompletely prepared and 

filled canals demonstrates the complicated situation of 

endodontic WW. Understanding the concepts and the 

techniques of endodontic WW can minimize misadventures 

of incomplete instrumentation & a failed root canal treatment. 

Before the IWW determination, it is suggested to widen the 

orifices, to do early coronal flaring and additional canal flaring 

(crown down, double flaring ) to ensure effective irrigation, 

and minimize any interferences with tactile sensation. 

Carefully selecting the adequate instrument of maximal 

flexibility and minimal taper such as Light Speed may avoid 

interference and help to achieve better results. 

Ideally, root canal preparation should follow the exact outline 

of the horizontal dimensions of the root canal at every level of 

the canal. In this ideal condition, especially for long oval and 

flattened root canals, they can be cleaned and shaped 

properly with minimal mishaps of weakening, stripping, or 

perforating the canal walls as shown in Illustration 4D. 

Circumferential preparation or instrumentation may have to 

be considered for these cases to minimize incomplete 

cleaning of the root canal system. Most of the NiTi rotary 

instruments provide a continuous reaming action that makes 

the canal relatively circular in shape. Indiscriminate use of 

NiTi rotary instruments alone for root canal cleaning and 

shaping may result in incomplete cleaning of the root canal 

system and lead to failure of the endodontic therapy. Recent 

3 0 , 1 6 , 3 1 , 3 2 , 3 3 

studies have indicated that no current 

instrumentation technique was able to completely clean 

dentin walls of the oval, long oval and flattened root canals. 

The manual crown down instrumentation technique, 

however, was more efficient and effective in cleaning root 

canals than rotary instrumentation. 

Canal anatomy 

Computer tomography has made visualizing canal systems a 

much simpler task. We’ve learned that nearly every canal is 

curved. What may appear as a straight canal in a twodimensional 

X-ray almost always has some degree of 

curvature in an unseen plane. 

Illusration 7: Anatomical variations in canals of posterior 

33 

teeth 

Maxillary Apical Sizes(Working Widths) 

Central & Lateral 

Canine 

Premolar 

Molar MB 

DB 

P 

JOE 10/99 

Compendium 

1991 

80 

80 

45-80 

45 

45 

60 

MB:40-65 

MandibularApicalSizes(Working Widths) 

Incisors 

Canine 

Premolar 

Molar MB 

ML 

D 

6 

Illustration 8 

Compendium 

1991 

60 

80 

45-80 

45 

40 

50 

Light Speed 

1997 

60-70 

60 

50-60 

45 

40 

50 

DB:40-55 

Light Speed 

1997 

60 

55 

55 

45 

35 

50 


Dental CT , called dentascan is dedicated post processing 

and image evaluation software for the teeth and the jaw which 

creates panoramic and paraxial views of maxilla and 

mandible. Dentascan can play in assessment of variation of 

root canal morphology and thus helpful in prediction the 

prognosis of a complex case. CT or dentascan are primarily 

utilized for pre-evaluation of implant sites, buccolingual 

34,35,36 

extend of cysts, tumors, periapical lesions .Furthermore, 

the cross-sectional shape of most canals is not round but oval 

(mimicking the oval shape of most roots). Lastly, few canals 

have a constant taper; instead, they exhibit nearly parallel 

walls in multiple segments throughout the length of the canal. 

Most canals are curved in one or more directions. The more 

severe a curve, the more difficult the treatment. Most canals 

6 

are oval in cross-section . Oval canals have two diameters, a 

minor (smaller) and a major (larger) diameter.The quality of 

cleaning is dependent on instrumenting to the larger 

diameter; it’s Working Width Working Width (WW) is best 

understood by studying cross-sections of apical canals. If the 

greater diameter of the original canal is measured, the correct 

WW is an instrument size slightly larger than that dimension. 

The apical constriction is the narrowest point of the canal with 

an average diameter of just under 0.50mm.However—and 

this is important—just coronal to the apical constriction canal 

diameters increase significantly; ranging from 0.55 to 1.00 

2,3,4 

mm and higher . 

OOO 

200 

50-60 

60 

40-65 

35-50 

35 

40 

P-55-80 

OOO 

200 

55 

45 

40 

35-50 

40-60 

50-80 

J Endodon 

1997 

60-90 

50-70 

35-90 

35-60 

40-60 

80-100 

TAKEN FROM ENDO TRIBUNE-MARCH 2008 E STEVE SENIA (6) 

J Endodon 

1997 

45-70 

50-70 

50-70 

35-60 

24


Discussion: 

Proper access cavity preparation and obturation form the 

keystone for successful root canal therapy.nearly 60% of the 

failures are apparently caused by incomplete obliteration of 

the radicular space.Root canal variation predispose to 

inadequate root canal preparation and should be 

34 

recongnized before or during treatment . 

Studies have suggested that root canals have not been 

thoroughly cleaned even after being enlarged three sizes 

greater than their original diameters. The enlarging of root 

canals is one of the most challenging & decisive steps during 

37 26 

endodontic therapy . Weine et al described the problems 

concerning the preparation of curved root canals. 

Undesirable shaping effects such as zips and elbows can 

readily occur when appropriate shaping precautions are not 

38-45 

taken. Several authors have reported on the effects 

produced by different enlarging techniques & /or instruments 

.Ideally the root canal path should be followed during root 

canal preparations without substantial deviation from it’s 

26,46,7 

originally position 

The concepts and techniques of WW may play an important 

role in this finding. Any investigation of the effectiveness of 

cleaning the root canal system without carefully estimating 

the MinIWW and MaxIWW in the oval, long oval, and flattened 

root canals may result in misleading data, especially if the 

horizontal canal morphology was not carefully assessed. In 

an oval, long oval or flat canal, circumferential 

instrumentation seems to be the only reasonable way to 

properly clean and shape the canal. Especially in the infected 

canals, the infected dentin has to be removed to ensure a 

successful treatment. Ideally, during root canal preparation, 

the instruments and techniques used should always confirm 

to and retain the original shape of the canal to maximize the 

cleaning effectiveness and minimize unnecessary 

weakening of tooth structure to achieve the optimal result. It is 

very challenging to aggressively clean and shape the infected 

canal without weakening the tooth structure. Clinically, the 

heavily infected cervical part of the canal has often been 

enlarged with Gates-Glidden burs or canal wideners to a 

round shape instead of following the original oval, long oval or 

flat shape. Although the strength of the tooth structure is 

47 

evidently reduced , the FWW in the cervical area has been 

determined by the clinician’s preference instead of scientific 

1,2,3,4,13,14,19 

evidence. 

Literature reveals a periodic renewal of interest in the root 

canal morphology of teeth in order to learn more about them 

or to search for different ways in which to improve endodontic 

48,49 

techniques and, ultimately success . 

CONCLUSION 

21 

Most of the research for the root canal instrumentation has 

not addressed the importance of the horizontal dimensions or 

WW of the root canal system. In preparing, the long oval or flat 

canals, the WW concept plays a more critical role that alerts 

the operator to the possibilities of incomplete root canal 

preparation. There has been minimal development of 

concepts, techniques, and technology to measure IWW and 

to determine FWW accurately or properly. Understanding the 

current concepts and techniques of WW can help to solidify 

the concepts & improve techniques of cleaning and shaping 

of the root canal system. Carefully maintaining the aseptic 


chain, using adequate irrigating solutions to enhance efficacy 

and cautiously applying current concepts and techniques of 

WW may provide a better quality of endodontic therapy for the 

patient. 

In vitro studies found that manual circumferential filing had 

statistically significant better effectiveness than rotary 

15 

instrumentation for cleaning flattened root canals . The 

concepts of the WW indicate that different approaches and 

techniques are needed to improve root canal preparation and 

promote better quality of root canal treatment. 

Since we cannot see deep into curved canals, we rely on an 

instrument’s tactile feedback to give us clues about canal 

anatomy.Canal statistics are handy, but because canals differ 

widely we are working blindly without feedback. Let’s stop 

thinking canals are basically the same size and shape , 

because they are not. The solution is to stop guessing and 

begin using instruments that provide accurate feedback . We 

should customize every one of our canal preparations. As 

50 

Spanberg so aptly stated, treating canals similarly is like 

forcing everyone to wear the same size shoe- one size 

doesn’t fit all! 

Respect the canal morphology diameter variability as the 

fingerprint of a person, which is never similar. 

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preparations following instrumentation. J Br Endod Soc 

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2) Kerekes K, Tronstad L. Morphometric observations on 

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rd 

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11 

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t h 

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26

5.wonderful world of endodontic working width–the - Dharmsinh ...

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