CAD/CAM Technology and Zirconium Oxide with Feather-edge ...

2 

CLINICAL APPLICATION 

CAD/CAM Technology and 

Zirconium Oxide with Feather-edge 

Marginal Preparation 

Stefano Patroni, MD, DDS, LMD 

University of Geneva, Switzerland 

Visiting professor, University of Parma, Italy 

Private practice, Piacenza, Italy 

Giuseppe Chiodera, DMD 

Private practice, Brescia, Italy 

Carlotta Caliceti, DMD 

Private Practice, Piacenza, Italy 

Paolo Ferrari, DMD, LMD 

University of Geneva, Switzerland 

Private Practice, Parma, Italy 

Correspondence to: Dr. Stefano Patroni 

Via S. Giovanni, 28; 29100 Piacenza, Italy 

phone: +39 0523 331852; e-mail: stefano.patroni@libero.it; www.stefanopatroni.com 

THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY 

VOLUME 5 • NUMBER 1 • SPRING 2010

Abstract 

Clinical needs and growing patient expectations 

have forced modern dentistry to focus 

on finding ever simpler protocols and 

to develop materials which offer high performance 

in their mechanical resistance 

and esthetics. 

In recent years, the scientific community 

has been venturing into the world of 

CAD/CAM, a significant technological innovation 

imported from the world of engineering. 

This innovation has made it 

possible to exploit a material which has 

long been noted for its mechanical and 

mimetic qualities: zirconium oxide. While 

CAD/CAM is revolutionizing the laboratory 

work of dental technicians, the white color 

of zirconium has opened new avenues 

PATRONI 

which may lead not only to new options 

for proper treatment planning, but also to 

new opportunities in the choice of materials 

to be used in prosthetic rehabilitation 

and variation of the types of preparations 

possible. 

The present paper will analyze the advantages 

and limitations of these methodologies, 

which are capable of simplifying 

clinical protocols and standardizing results. 

These technologies have instilled 

great enthusiasm in the profession due to 

their innovative nature, but this approach 

needs to be verified by further scientific 

evidence. 

(Eur J Esthet Dent 2010;5:XXX–XXX) 


VOLUME 5 • NUMBER 1 • SPRING 2010 

3

4 


Introduction 

CAD/CAM is a term borrowed, like the 

technology associated with it, from the 

world of engineering and has been applied 

to clinical dentistry. The end products 

in the two fields are very different as far as 

materials, forms, and dimensions are concerned, 

but the philosophy behind the 

process remains the same and involves 

the replacement of manpower with mechanized 

or robot-powered procedures. 1,2 

The procedures can be divided in two 

phases: CAD (computer-aided design), 

whereby the object is designed and created 

virtually, and CAM (computer-aided 

manufacturing) which takes the design 

from the virtual to the production of the designed 

object. 

The precision involved and the ability of 

this technology to standardize both the 

process and the finished product make its 

potential fascinating in itself; in theory it 

may even be possible to eliminate variables 

introduced by the operator in the laboratory 

phase and reduce the clinical steps 

needed to produce the final prosthesis. 3 Interest 

for CAD/CAM technology has been 

expressed by dentists the world over, as 

this technology makes it possible to work 

with different materials. Some of these include 

titanium as base metal alloys, acrylic 

resins for provisional restorations, and either 

crystalline or vitreous ceramics. The 

material with the most applications is a ceramic 

oxide stabilized with yttrium oxide 

known as zirconium dioxide (zirconia). 4 

Many questions have arisen about this 

new method from both clinicians and dental 

technicians alike; in fact, the laboratory 

will be most affected by these innovations. 

Therefore, the clinician needs to be able 

to understand how these new CAD/CAM 



technologies and intraoral optical impressions 

can be integrated with everyday clinical 

practice, what type of preparations and 

prosthetic margins will be compatible with 

these new materials, and precise information 

about how to use them. 

From a chemical point of view, zirconium 

is a grey/white hard transition metal, 

which is not found in nature as a pure mineral. 

In dentistry, zirconium is not used as a 

pure mineral but as a ceramic oxide (zirconium 

dioxide) instead. From a structural 

point of view, zirconium dioxide comes in 

three states: cubic, monocline, and tetragonal. 

5 All of these states are unstable at 

room temperature and must be combined 

with an element to hold the desired form. 

The tetragonal is one of the most studied 

forms in published literature 6 and is stabilized 

with yttrium. 7 This material was used 

experimentally as early as 1969 in the field 

of orthopedics. 

It is the esthetic and mechanical characteristics 

of zirconium which makes it such 

an attractive metal to work with. Indeed, not 

only is it white in color, but its resistance to 

fractures is very similar to that of titanium 

(285 N vs 305 N). 8 In addition, it is not cytotoxic, 

9 does not produce mutations of the 

cellular genome, 8,10 and it induces a modest 

inflammatory response in tissues, which 

is less than that of titanium. 11 

Another attractive characteristic of the 

material is that it has little retention of bacterial 

plaque. Scarano reported a bacterial 

covering on the surface of zirconium of 

12%, as opposed to 19% for titanium. 5 

Zirconium has multiple applications in 

dentistry. It can be used as a core for onlays/overlays, 

as a core for single crowns, 

as a framework for bridges, as abutments 

for implants (Fig 1), and as implants themselves.

Despite the material having been well 

known, the technology was not available. 

Today, thanks to CAD/CAM, this technological 

gap has been filled. 

The structures are obtained by subtraction 

milling a partially sintered zirconium 

block; this procedure is guided by dedicated 

software. 12 

An overview of zirconium 

and CAD/CAM 

It must be borne in mind that the zirconium 

structure is no longer made by a technician 

but by the milling center machine which 

grinds the zirconium block. This requires 

specific instructions and guidelines in digital 

form, which can be summarized in 

three steps: 3 

1) digitization: transforms the geometry of 

the scanned object into digital data 

2) processing: software processes the data 

and, if necessary, develops the project 

3) realization: technology (not necessarily 

a milling machine) transforms the data 

into the desired object. 

When using CAM/CAD technology, the 

classic clinical/technical itinerary (impression, 

model, waxup, casting) must interface 

with the digital pathway (Table 1). The 

transformation of analog information into 

digital information can take place at various 

points in the conventional process: 

1) The impression is developed in the laboratory. 

The laboratory forwards the 

model to the digital service who will 

digitize it, design the structure (CAD), 

realize it (CAM), and then send it back 

to the technician for ceramic stratification 

(Table 2). 

PATRONI 

Fig 1 Example of a custom implant abutment completely 

realized in zirconia. 

Table 1 

Table 2 



5

6 


Table 3a 

Table 3b 

Table 4 



2) The impression is developed in the laboratory. 

The technician digitizes the 

model with a scanner and with special 

software designs the structure (CAD) 

(Table 3a). Alternatively, the technician 

can realize a traditional waxup and scan 

it (Table 3b). In both cases, the laboratory 

will be able to issue a digital file to the 

milling center for manufacturing the 

structure (CAM). The structure is then 

sent back to the laboratory for ceramic 

stratification . 

3) The impression can take the digital route 

from its beginning (eg, using a 3M ESPE 

video camera or similar). The planning 

can take place either in the laboratory or 

in the digital service center (CAD). However, 

the manufacture of the core (CAM), 

must take place in the milling center and 

is then delivered to the laboratory along 

with a resin model for ceramic stratification 

(Table 4). 

In the authors' clinical experience, the 

method that gives the best frameworks/ 

cores for supporting ceramics is that 

which starts with a conventional waxup of 

the structure made in the laboratory which 

is then scanned. This technique allows the 

creation of an individualized structure, 

which means that the design can be customized 

with an adequate cusp and marginal 

crest. This creates, where necessary, 

a palatine framework thickening and adequate 

connection design (Fig 2a and b).

a b 

Clinical application 

For a fixed prosthesis, the base material of 

the ceramic crown which is most commonly 

used and which, according to scientific 

evidence, guarantees the highest standards 

of resistance, is a noble alloy (ceramometal 

technique). 

The greatest limitation of this technique 

is the fact that the metal restoration has limited 

translucency, which means that esthetically 

it cannot compete with the standard 

that can be achieved when integral ceramics 

are used. Integral ceramics are indicated 

in cases where excellent esthetic results 

are required as these materials best imitate 

the color and luminosity of the natural tooth 

(Fig 3). One disadvantage however, is that 

these restorations have low mechanical resistance. 

Collarless ceramics supported by a 

metal core represent a solution that, in 

theory, combines the advantages of both 

techniques, eliminating the metal in the 

marginal portions so as to reduce the umbrella 

effect. 13 Today there is also a third option, 

which cuts a middle road and which 

is increasingly being used: zirconium. 

PATRONI 

Fig 2a and b Examples of zirconia copings with a well-represented margin to guarantee the mechanical 

strength. 

Fig 3 The best material for prosthetic reconstructions, 

in terms of esthetics, is the material able to mimic 

the translucency of natural teeth. 



7

8 


a b 

Fig 4a Discolored natural tooth; the use of a high 

translucency crown would end in a unsatisfactory result. 

a b c 

a b 

Fig 6a and b A clinical case: the smile before and after treatment. 



Fig 4b The ceramic crown supported by a zirconia 

core once cemented. The unfavorable tooth value is 

partially masked, increasing the core thickness. In spite 

of that, however, a discolored abutment appears 

through the marginal tissues anyway. 

Fig 5a to c Manufacturers 

advise a round 

shoulder or a chamfer 

preparation for a zirconia 

ceramic crown.

a b 

PATRONI 

Fig 7a and b The initial intraoral situation (a). Final result (b): the four incisors with zirconia crowns cemented. 

The mandible was rehabilitated with an implant-supported fixed prosthesis. 

a b 

c d 

Fig 8a to d Maxillary anterior teeth before treatment (a). Four incisors prepared with a marginal chamfer (b). 

Four zirconia ceramic crowns on the master model (c). The end of treatment; the four upper incisors were reconstructed 

with zirconia ceramic crowns, the two cusps were restored by ceramic veneering (d). 



9

10 


a b 

Fig 9a and b Some details of the crown margins and their tissue integration. 

a 

c 



b 

Fig 10a to c In the case of a feather-edge preparation, 

it is necessary to finish with a metallic margin. 

When using a zirconia core, the margin should also be 

well represented, but the white color simplifies the esthetic 

result.

Zirconium has excellent mechanical and 

esthetic characteristics. Mechanically, this 

is observed if the material is used in thickness 

of 0.5 mm or more. This thickness 

guarantees excellent mechanical resistance 

but partially diminishes the esthetic 

result. In some cases however, the thickness 

of the structure makes it possible to 

mask highly discolored prepared teeth, optimizing 

the esthetic results (Fig 4a and b). 

In order to obtain the very best esthetic 

results, it is necessary to use a thickness of 

0.3 mm, as this gives a high degree of luminosity 

and translucency. 14 It should be 

noted however, that these characteristics 

are inferior to those that can be obtained 

from integral ceramics (light transmission 

through 0.6 mm thick flat specimens of 

densely sintered alumina is 72% versus 

48% for densely sintered zirconia). 15 

For restorations with a zirconium oxide 

core, the producers recommend round 

shouldered or chamfered preparations as 

these are considered to be best for precision, 

resistance, and esthetic outcome 

(Figs 5 to 9). 

The presence of a margin means that 

excellent definition is required in the 

preparation phase and then adequate 

transferral of that information to the laboratory. 

These problems are easier to solve 

with a feather-edge preparation where the 

finishing line is no longer represented by 

a line but rather by an area (Table 5). 

The advantage of a butt preparation 

(shoulder or chamfer) is that it allows, from 

the margin, an adequate thickness of 

restoration materials (metal-opaque ceramics), 

reducing as much as possible 

the unsightliness of a metal border. 

However, it is necessary with a featheredge 

preparation to have a well-represented 

and clinically evident metallic margin 

Table 5 

PATRONI 

(Fig 10). This may be considered an esthetic 

compromise and is usually indicated for 

complex perio-prosthetic rehabilitations. 

This limitation can be overcome by using 

a material such as zirconium, which makes 

it possible to create a white margin. While 

being clinically acceptable, this integrates 

well esthetically with the periodontal tissues 

without needing to “invade” the dentogingival 

sulcus, which would complicate 

the prosthetic procedures and risk damage 

to the periodontal attachment. 

This led to the idea of combining zirconium 

oxide with the feather-edge preparation, 

a solution which, while not advised, is 

allowed by the producers on the condition 

that certain fundamental clinical and technical 

considerations are taken into account. 

Why feather-edge 

marginal preparation? 

In the last 10 years, the prosthetic treatment 

plan has changed due to the introduction 

of implants. Indeed, it is because of implants 

that it is possible to treat individual 

or multiple edentulous areas (Fig 11), without 

resorting to the preparation of healthy 

11 



12 

a 


c d 

Fig 11a to d In the last decade, the vast majority of clinicians prefer, in the case of partially edentulous areas 

between two healthy teeth, to place an implant instead of conventional prosthesis. 

teeth and sacrificing sound tissue to accommodate 

bridges. In the same way, 

many seriously compromised teeth, which 

until recently would have been treated in a 

prosthetic manner with complete crowns, 

can today be rehabilitated with indirect adhesive 

restorations. 

The indications for a fixed prosthesis 

have changed, and it is much less frequent 

that a healthy tooth is rehabilitated 

with a fixed prosthesis. It is even rarer that 

the clinician performs endodontic treatment 

for prosthetic reasons as vital teeth 

can be treated with restorative therapy. 

Therefore, prosthetic dentistry almost always 

follows the endodontic treatment 



b 

needed to recover teeth which have been 

destroyed by decay. 

The carious lesion, moreover, does not 

only extend horizontally towards the pulp 

chamber but follows the line of the dental 

tubules and often extends apically and involves 

the periodontal attachment. For this 

reason, the majority of cases require a 

crown-lengthening procedure before the 

prosthetic phase in order to make the 

residual healthy tissue accessible and to 

re-establish a correct relationship with 

these without damaging the periodontal 

attachment (Figs 12 and 13). 

In the same surgical time, it is possible 

to carry out a feather-edge preparation of

a 

Fig 12a to c Surgical crown lengthening is frequently 

necessary to properly rehabilitate a seriously 

decayed tooth. During the surgery, the tooth is prepared 

up to the bony crest, and after suturing the temporary 

is relined. With a feather-edge preparation it is easy to 

obtain, 4 months after surgery, healthy tissues around 

the prepared tooth. 

a b 

PATRONI 

Fig 13 The tissues maturing around natural abutments 4 months after periodontal surgery (a). The teeth were 

prepared once the flap was raised and the final impression was obtained without any further marginal preparation. 

The zirconia crowns once cemented (b). 

b 

c 

13 



14 


a b 

Fig 14a and b A clinical case: the initial smile (a) and the final smile (b). 

a b 

Fig 15a and b The tooth wear, the lost anterior occlusal relationships, and unpleasant esthetic (a). The final 

result (b). 

the abutments once the flap is raised 16-18 

while, at the same time, optimizing all 

other parameters that render the longterm 

results more predictable. 

These parameters involve: 

■ re-establishing biological dimensions 

■ lengthening short abutments 

■ recovering the ferrule effect 

■ correcting root proximities 

■ eliminating residual concavities following 

furcation barreling 



■ bone surgery to eliminate the shallow 

infra-osseous pockets 

■ surgery to correct esthetic problems 

such as a gummy smile or to harmonize 

unsightly gingival trajectory arcs. 

The present approach involves, once the 

flap has been rised, a feather-edge preparation 

of the teeth as far as the osseous 

crest.

a b 

c d 

e f 

In order to be able to benefit from all of the 

advantages offered by a feather-edge 

preparation, it is important to not modify 

this preparation once the surgical phase is 

over, unless to carry out small adjustments 

which do not involve the marginal area. Indeed, 

once the abutment is re-prepared in 

the impression stage, this may create a reference 

margin in the marginal finish area 

which is binding for the final restoration 

(Figs 14 to 20). When the tissues have ma- 

PATRONI 

Fig 16a to f Abutments immediately before surgery (a). Once the flap was raised during periodontal surgery, 

the teeth were prepared until the osseous crest (b). The flap sutured at the osseous crest (c). The abutments with 

the first retraction cord inserted 10 months after surgery (d). The abutments with the second retraction cord inserted 

immediately before the final impression (e). The final cemented restorations (f). 

tured completely it will be possible to take 

a definitive impression and finalize the 

prosthetic restoration (Fig 21). 

There is a published technique which 

makes it possible to exploit the advantages 

of the feather-edge preparation carried 

out “blind,” that is, without surgical access. 

19,20 Naturally, each preparation type 

has advantages and disadvantages. The 

choice of one rather than another is often 

guided by the different degrees of difficul- 

15 



16 

a 


Fig 17a to c The palatal view showing the healthy tissues around the crowns. 

Fig 18 The buccal emergence profile respecting the 

tissue health. 



b c 

a 

b 

c 

Fig 19a to c Six months after the surgery, when 

teeth were prepared up to the osseous crest, the abutments 

were ready for the final prosthetic phase: occlusal 

(a) and buccal view (b). Cemented zirconium 

oxide prostheses (c).

a b 

c d 

e f 

g h 

Fig 20 The old restorations (a). The abutments once 

the previous prosthesis was removed (b). The periodontal 

intervention with the open flap abutment preparation 

(c). The final abutments 10 months after surgery (d). The 

red line on the master model represents where the technician 

placed the apical limit of the restoration after ditching; 

the black line represents the gingival level (e). The 

zirconia copings try-in (f). The tracing of the gingival scallop 

on the zirconia copings (g). Zirconia copings removed 

after try-in and tracing (the amount of the coping 

margin positioned into the sulcus is evident) (h). Oneyear 

follow-up, the good tissue integration is evident (i). 

i 

PATRONI 

17 



18 


a b 

Fig 21a and b The impression is easily obtained in 

cases of feather-edge preparation; the intra-crevicular 

part of the prepared tooth appears as a rising margin. 

ty and operative management. The feather-edge 

preparation may be the solution 

for several clinical problems and simplifies 

the procedure beginning with the 

preparation itself and including the relining 

of the provisional, the final impression, 

and all further laboratory phases. 

Advantages of featheredge 

marginal preparation 

■ Saves dental tissue: it is therefore indicated 

for teeth which have suffered serious 

periodontal damage as a consequence 

of periodontitis. 

■ Simplifies the final impression as there 

is no longer a finishing line but rather a 

finishing area. 

■ Relining the provisional is easier and 

faster. Even in cases where the border of 

a temporary crown is slightly shortened, 

no marginal precision is lost as would 

happen in the case of a “short” provisional 

margin with a shoulder or chamfer 

preparation. In fact, the finishing tar- 



get is represented by an area and not a 

line. However, the management of the 

esthetic zone is more delicate as a short 

margin would make it impossible to 

condition the gingival tissues and shape 

the prosthetic emergence profiles at an 

interproximal level. 

■ In cases of shoulder or chamfer preparations, 

the finish line is well defined and 

is the line that the technician must refer 

to without any doubt. The margin of the 

restoration must be unequivocally positioned 

at this level. On the other hand, 

with a feather-edge preparation, the 

prosthetic margin can be positioned at 

any level in an apico-coronal direction, 

as long as it respects the periodontal attachment. 

Once the structure has been 

realized, it could invade too deeply into 

the gingival sulcus. In this case, it can be 

shortened during the trial. In healthy 

conditions, the interproximal probing 

depth is approximately 3 mm and it is 

possible to receive a structure from the 

laboratory which finishes at this depth. 

From a clinical point of view, it is often 

unnecessary to position the prosthetic 

margin at this level interproximally, as in 

this zone there are no important esthetic 

requirements but only the need for tissue 

conditioning to recreate an adequate 

emergence profile. This profile is 

obtainable when the margin is positioned 

at 1 mm inside the sulcus. Therefore, 

any invasion by the restoration is 

unnecessary and could damage the 

periodontal attachment and make it difficult 

to remove any cement excess. Furthermore, 

adjusting the margin and 

shortening it does not lead to any loss 

of precision nor will it compromise the 

esthetic result.

Disadvantages of the 

feather-edge marginal 

preparation 

The disadvantages of a feather-edge 

preparation are emphasized in the case 

of a prosthetic rehabilitation using the 

ceramo-metal technique: 

■ The presence of a visible metal collar is 

necessary to guarantee precision and 

resistance at the margin. This border, 

when not hidden in the gingival sulcus, 

is particularly unattractive and certainly 

unacceptable in the esthetic zone. 

■ If a metallic border is not properly 

formed there is a risk that a horizontal 

overhang will be created. 21 

This is potentially damaging for the periodontal 

tissues as it can retain bacteria 

and plaque. 22-25 The zirconia margin is 

mandatory in this area especially during 

cementing and while chewing; in fact, in 

these conditions there is a high concentration 

of stress on the margins which could 

cause ceramic chipping. 26,27 

In order to create enough space for the 

restoration material, there is risk of creating 

an over-tapered preparation. This does not 

guarantee a retentive and stable form for 

the restoration unless one resorts to additional 

retentions. 28 

All of the above is particularly disadvantageous 

in cases of: 

■ patients with a thin gingival biotype in 

whom the metal borders, even if intracrevicularly 

positioned, could show 

through the gingival margins, resulting 

in an esthetically unsatisfactory rehabilitation 

■ short abutments with a high risk of 

crown debonding. The vertical preparation 

is considered to be unsightly as the 

PATRONI 

elimination of less dental material gives 

the technician less space for ceramic 

stratification and, especially in the anterior 

teeth, in cases of even minimal gingival 

recession the metallic margin of 

the prosthesis is visible. With regard to 

precision, a vertical preparation (feather 

edge or bevel) may ensure a better seal 

than a horizontal one (shoulder or 

chamfer) before luting. In contrast, after 

the cementing it provides worse seating. 

This is due to the difficult defluxion of the 

cement at the prosthetic margin. 29,30 The 

final result therefore, in terms of precision, 

can be considered totally superimposable 

and, in any case, clinically acceptable 

for both types of preparation 

(vertical and horizontal). 29,31 

Zirconium oxide and 

feather-edge preparation 

The marginal design recommended by 

the producers of zirconium oxide is a 

chamfer or round shouldered margin 

combined with a preparation that has a 

slightly increased taper compared to the 

conventional ones: 4 degrees per side 

compared to the vertical as opposed to 2 

to 3 degrees per side (Fig 22). 15,26,32 The authors' 

clinical experience suggests that zirconium 

oxide could also be used in vertical 

preparations, thereby combining a 

much simpler and much faster preparation 

with a material which is at least as mechanically 

resistant as gold, yet more esthetically 

pleasing. 

The design of the zirconium core must 

not differ from a core for a ceramo-metal 

restoration in the case of the feather-edge 

preparation. The emergence profile must 

respect the periodontium and be easy to 

19 



20 


a b 

Fig 22a and b The ideal taper recommended in prosthetic dentistry is 2 degrees on each side (a). The recommended 

taper in the case of zirconia crowns is 4 degrees on each side (b). 

Fig 23 Chipping of the marginal crests: the two zirconia cores were designed in a standard way without considering 

the necessity of ceramic support in relation to the occlusal contact points. 



a b 

c d 

clean, simulating the horizontal natural 

contour of the cementoenamel junction. 

It is possible to realize the edge of the 

restoration in zirconium with a form and 

thickness similar to that of gold. The zirconium 

edge however, integrates better 

than a metal one. This is more noticeable 

in the molar region as it does not necessarily 

require intra-crevicular positioning 

to achieve satisfying esthetic results. 33 The 

zirconium oxide edge must be 0.5 to 0.7 

mm wide in order to guarantee resistance 

to chipping during insertion and luting 

phases. 

PATRONI 

Fig 24a to d False root realized, creating a forced pathway for the interproximal brush to clean the distal tooth 

surface. 

The main condition to be respected in order 

to minimize the chipping risk and obtain 

a successful long-term result, is that 

the ceramic has to be adequately supported 

by the underlying structure so that 

it will work during compression (Figs 23 

and 24). 34 

In extended structures, planning the 

connections is of the utmost importance 

and should be orientated appropriately: in 

the molar region the corono-apical sections 

should be most represented, while in 

the esthetic zone the vestibular-palatal 

thickness should be greater. 

21 



22 

a 


c d e 

f g 

Fig 25a to g A clinical case: frontal view of the abutments (a) and occlusal view (b). Details of healthy marginal 

tissues once the temporaries were removed: in the case of feather-edge preparation it is easier to guarantee 

the periodontal health around the prosthesis (c to e). Zirconia crowns on the master model (f). Frontal view 

of the final result (g). 

It is important to plan for a ceramic thickness 

that guarantees a good esthetic result 

without the connections needing to be adjusted 

after the structure is finished, as any 

adjustments at that point cause the structure 

to be seriously weakened (Fig 25). 



b 

Conclusions 

Although the combination of zirconium 

and feather-edge preparation requires further 

randomized clinical studies in the 

medium and long term, it would seem to

offer an extremely interesting solution from 

a clinical point of view. 

Indeed, the zirconium confers to the 

restoration excellent esthetic and mechanical 

characteristics, as long as the plan 

allows for a rigorously personalized support 

structure for the overlaying ceramic. 

Feather-edge marginal preparation adapts 

well to the increasingly frequent requirement 

of pre-prosthetic periodontal surgical 

interventions. Moreover, the possibility of 

performing the final tooth preparation once 

the flap is raised reduces the number of interventions 

and the risk of invading the sulcus 

and damaging the supra-crestal fibers. 

This type of preparation, with its white 

zirconium borders, does not require that 

the margins be positioned deeply into the 

References 

1. Massironi D, Pascetta R, Ferraris 

F. Sistema CAD/CAM 

Lava: l’importanza del fattore 

umano nella ricerca dell’ottimale 

precisione e adattamento 

marginale. Quintessenza Internazionale 

2004;2:39-50. 

2. Liu PR, Essig ME. Panorama of 

dental CAD/CAM restorative 

systems. Compend Contin 

Educ Dent 

2008;29:482,484,486-488. 

3. Beuer F, Schweiger J, Edelhoff 

D. Digital dentistry: an 

overview of recent developments 

for CAD/CAM generated 

restorations. Br Dent J 

2008;10;204:505-511. 

4. Vagkopoulou T, Koutayas SO, 

Koidis P, Strub JR. Zirconia in 

dentistry: Part 1. Discovering 

the nature of an upcoming 

bioceramic. Eur J Esthet Dent 

2009;4:130-151. 

5. Denry I, Kelly JR. State of the 

art of zirconia for dental applications. 

Dent Mater 

2008;24:299-307. 

6. Manicone PF, Rossi Iommetti 

P, Raffaelli L. An overview of 

zirconia ceramics: basic properties 

and clinical applications. 

J Dent 2007;35:819-826. 

7. Cehreli MC, Kökat AM, Akça K. 

CAD/CAM Zirconia vs. slipcast 

glass-infiltrated 

Alumina/Zirconia all-ceramic 

crowns: 2-year results of a randomized 

controlled clinical 

trial. J Appl Oral Sci 

2009;17:49-55. 

8. Dion I, Rouais F, Baquey C, 

Lahaye M, Salmon R, Trut L et 

al. Physico-chemistry and cytotoxicity 

of ceramics: part I: 

characterization of ceramic 

powders. J Mater Sci Mater 

Med 1997;8:325-332. 

PATRONI 

sulcus, as the metal borders do not need 

to be hidden. 

It is therefore possible with this combination 

to reduce and simplify the clinical 

steps needed for the final prosthesis, while 

at the same time guaranteeing greater stability 

and health of the tissues over time. 

This is a simple and time saving technique 

that could be used on a daily basis 

by those clinicians striving to obtain an optimal 

clinical result. 

Acknowledgment 

The authors would like to thank Antonello Di Felice, 

CDT, Private practice, Rome, Italy for the great lab work 

for this study. 

9. Silva VV, Lameiras FS, Lobato 

ZI. Biological reactivity of zirconia-hydroxyapatite 

composites. 

J Biomed Mater Res 

2002;63:583-590. 

10. Covacci V, Bruzzese N, Maccauro 

G, Andreassi C, Ricci 

GA, Piconi C et al. In vitro evaluation 

of the mutagenic and 

carcinogenic power of high 

purity zirconia ceramic. Biomaterials 

1999;20:371-376. 

11. Warashina H, Sakano S, Kitamura 

S, Yamauchi KI, Yamaguchi 

J, Ishiguro N, 

Hasegawa Y. Reaction to alumina, 

zirconia, titanium and 

polyethylene particles implanted 

onto murine calvaria. Biomaterials 

2003;24:3655-3661. 

12. Miyazaki T, Hotta Y, Kunii J, 

Kuriyama S, Tamaki Y. A 

review of dental CAD/CAM: 

current status and future perspectives 

from 20 years of 

experience. Dent Mater J 

2009;28:44-56. 

23 



24 


13. Magne P, Magne M, Belser U. 

The esthetic width in fixed 

prosthodontics. J Prosthodont 

1999;8:106-118. 

14. Baldissara P, Llukacej A, 

Valandro LF, Bottino MA, Scotti 

R. Traslucency of ZrO 2 copings 

for all-ceramic FPDs. 

Academy of Dental Materials, 

23-25 Oct 2006, Sao Paulo, 

Brazil. 

15. Sadan A, Blatz M, Lang B. 

Clinical consideration for 

densely sintered alumina and 

zirconia restoration. Int J Periodontics 

Restorative Dent 

2005;25:213-219. 

16. Carnevale G, Freni Sterrantino 

S, Di Febo G. Soft and hard 

tissue wound healing following 

tooth preparation to the alveolar 

crest. Int J Periodontics 

Restorative Dent 1983;3:36-53. 

17. Carnevale G, Di Febo G, Biscaro 

L, Freni Sterrantino SF, 

Fuzzi M. An in vivo study of 

teeth reprepared during periodontal 

surgery. Int J Periodontics 

Restorative Dent 

1990;10:40-55. 

18. Carnevale G, Di Febo G, Fuzzi 

M. A retrospective analysis of 

the perio-prosthetic aspect of 

teeth reprepared during periodontal 

surgery. J Clin Periodontol 

1990;17:313-316. 

19. Loi I, Scutella‘ F, Galli F. Tecnica 

di preparazione orientata 

biologicamente (B.O.P.T) un 

nuovo approccio nella 

preparazione protesica in 

odontostomatologia. Quintessenza 

Internazionale 

2008;24:69-74. 



20. Loi I, Scutella‘ F, Galli F, Di 

Felice A. Il contorno coronale 

protesico con la tecnica di 

preparazione B.O.P.T. (Biologically 

Oriented Preparation Tecnique): 

Considerazioni tecniche. 

Quintessenza 

Internazionale 2009;25:19-30. 

21. Martignoni M, Schonenberger 

A. Precision fixed prosthodontics: 

clinical and laboratory 

aspects. Chicago: Quintessence, 

1990:52-57. 

22.Orkin DA, Reddy J, Bradshaw 

D. The relationship of the position 

of crown margins to gingival 

health. J Prosthet Dent 

1987;57:421-424 

23.Flores-de-Jacoby L, Zafiropoulos 

GG, Ciancio S. The effect 

of crown margin location on 

plaque and periodontal health. 

Int J Periodontics Restorative 

Dent 1989;9:197-205. 

24. Valderhaug J, Birkeland JM. 

Periodontal conditions in 

patients 5 years following 

insertion of fixed prostheses. 

Pocket depth and loss of 

attachment. J Oral Rehabil 

1976;3:237-243. 

25.Valderhaug J, Birkeland JM. 

Periodontal conditions and 

carious lesions following the 

insertion of fixed protheses. A 

10-year follow-up study. Int 

Dent J 1981;30:296. 

26.Hoard RJ, Caputo AA, Contino 

RM, Koenig ME. Intracoronal 

pressure during crown cementation. 

J Prosthet Dent 

1978;40:520-525. 

27. Wilson PR, Goodkind RJ, 

Delong R, Sakaguchi R. Deformation 

of crowns during 

cementation. J Prosthet Dent 

1990;4:601-609. 

28.Schillingburg HT, Hobo S, 

Whitsett LD, Jacobi R, Brackett 

SE. Fundamentals of fixed 

prosthodontics, ed 3. Chicago: 

Quintessence Publishing, 

1997:119-169. 

29. Hunter AJ, Hunter AR. Gingival 

margins for crowns: A review 

and discussion. Part 2: Discrepancies 

and configurations. 

J Prosthet Dent 1990;64: 

636-642. 

30. Gavelis JR, Morency JD, Riley 

ED, Sozio RB. The effect of 

various finish line preparations 

on the marginal seal and 

occlusal seat of full crown 

preparations. J Prosthet Dent 

1981;45:138-145. 

31 Fradeani M, Barducci G. 

Esthetic Rehabilitation in Fixed 

Prosthodontics, Volume 2— 

Prosthetic Treatment: A Systematic 

Approach to Esthetic, 

Biologic, and Functional Integration. 

London: Quintessence 

Publishing, 2008:330-351. 

32.El Ebrashi MK, Craig RG, Peyton 

FA. Experimental stress 

analysis of dental restorations. 

Part III. The concept of the 

geometry of proximal margins. 

J Prosthet Dent 1969;22:333. 

33.Scotti R, Kantorski KZ, Monaco 

C, Valandro LF, Ciocca L, Bottino 

MA. SEM evaluation of in 

situ early bacterial colonization 

on a Y-TZP ceramic: a pilot 

study. Int J Prosthodont 

2007;20:419-422. 

34.Sailer I, Gauckler LJ, Hammerle 

CHF. Five-year clinical 

results of zirconia frameworks 

for posterior fixed partial dentures. 

Int J Prosthodont 

2007;20:383-388.

CAD/CAM Technology and Zirconium Oxide with Feather-edge ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?