QDT 2013: 36 [2013 ed.] 9780867155938, 0867155930

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Editorial

Passion, Innovation, ellence Throughout the years. Quintessence of Dental Technology (QDT) has transcended cultural, socioeconomic, and philosophical boundaries. This is because QDT's core values embrace our universal quest for excellence and innovation in oral rehabilitation. Recent investigations in dentistry have led to significant technical improvements related to the fabrication of restorations—a response to dentists' and patients' demands for fast, reliable, and sustainable methods to restore dental structures. These improvements have led to the introduction of a plethora of restorative strategies. Regrettably, few of them are capable of producing satisfactory, "stress-free" results, which points to the fact that dentistry is still a labor-intensive profession that requires knowledge in many different fields, along with numerous hours of training, to finally master a restorative technique. Computer-aided design and fabrication is a tool that can potentially fill the gap between technical skills and productivity. In addition, novel dental biomaterials—from ceramic-reinforced polymers to high-density polymethyl methacrylate blocks—are being developed as alternative products to expedite the time and manufacture of a given restoration. Although all this technology is exciting, esthetically acceptable results can only be achieved through human creativity. Several articles in this issue of QDT delineate new ways to push the limits of this interesting technology to obtain esthetically inspiring results. Perfectly replicating the natural dentition is the ultimate goal for all of us. Replication of the natural dentition, with all its intricacies, compels arduous discipline and dedication, which can be only translated into passion— passion for a career we have chosen, and for which we work and live. But if excellence is not attained, our efforts go unrewarded. To achieve excellence, we must remain wide open to new ideas, concepts, and methods that can elevate the quality of our skills to the next level. At the same time, defying concepts is also fundamental to the growth of our expertise. Thus, any new concept/technique needs to be tested and evaluated. Sequential learning stages, such as acquaintance, assessment, implementation, and confirmation, are needed to ratify new ideas or methods that will effectively promote innovation of knowledge. In the end, however, the only way to produce exciting outcomes is to be true to our own values. Values are the principles that we strive for, beliefs that propel us to wake up every day and to work to make a difference. Consider the three simple words that, simply combined, represent QDT's core values: Passion and Innovation with Excellence. This year, our article selection criteria have been expanded to include "cultural fit," which addresses not only the quality of the treatment and the photography presented on our pages, but more important, these core values translated through the articles you are about to read.

Sillas Duarte, Jr, DDS, MS, PhD Editor-in-Chief [email protected]

QDT 2013

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations Oswaldo Scopin de Andrade, DDS, MS, PhD' Gilberto Antonio Borges, DDS, MS, PhD' Marcelo Kyrillos, DDS 3 Marcelo Moreira, DDS 3 3 LuisCalcho,DS Lourenco Correr-Sobrinho, DDS, MS, PhD'

C

eramic laminate veneers (CLVs) offer an es-

statistical analysis. The criteria commonly used in the

thetic and functional oral rehabilitation with

literature include the United States Public Health Ser-

well-documented favorable success rates. 1-6

vice criteria, modified California Dental Association

Generally, the assessment of restorative success is

criteria, and variations thereof. 3,6,7 These systems allow

based on established clinical criteria and associated

for uniform measurements and facilitate tabulation of data for analysis. In this way, an index of success can be assigned to a given restorative treatment. These

'Director, Advanced Program in Implant and Esthetic Dentistry, Senac University, Sao Paulo, Brazil. 2 Assistant

Professor, Restorative Dentistry, Uberaba University, Uberaba, Brazil.

3 Atelie

Oral Clinic, Sao Paulo, Brazil.

4 Professor,

Department of Restorative Dentistry, Dental Materials Division, School of Dentistry, Campinas State University, Piracicaba, Sao Paulo, Brazil.

Correspondence to: Dr Oswaldo Scopin de Andrade, Rua Barao de Piracicamirim 889 #61, Piracicaba-SP, Brazil CEP 13.416-005. Email: [email protected]

evaluations are well accepted in the literature and can be used to assess the efficacy of a wide variety of treatment options. When it comes to the replacement of missing tooth structure using any type of restorative material, the question is always the same: What is the longevity of this treatment? Scientifically, there are several methods of measuring the quality of a restoration, including direct or indirect 8-1 ° and objective or subjective evaluations of a variety of different parameters.

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SCOPIN DE ANDRADE ET AL Objective parameters are the most well-accepted assessments in the dental literature." ,12 Objective parameters may include the following: • Marginal adaptation • Marginal degradation

Both marginal adaptation and cement film thickness

• Signs of leakage

play crucial roles in the long-term success of conven-

• Secondary or recurrent caries

tional crown preparations. 15-1 ' When fabricating an in-

• Color maintenance

direct restoration, every step of the process is aimed at

• Surface texture

achieving perfect marginal adaptation. 18 For example,

• Chipping or fracture

clinical guidelines for tooth preparation attempt to create the proper path of insertion to allow for minimal

In contrast, subjective parameters account for per-

cement film thickness. 19 In the laboratory, the methods

sonal feelings and opinions obtained from the patient

used to pour the molds and fabricate the restorations

and/or clinician via questionnaires and interviews: 8 ' 84 '

are likewise based on perfect marginal adaptation, ie,

Subjective parameters include patient satisfaction and

providing a minimal gap between the restoration and

patients' opinions regarding maintenance and color

tooth structure.

stability.

Traditional crown preparation often requires ex-

Today, dental restorative sciences are focused on

tensive removal of sound dental tissue. 2° Conversely,

conservative techniques, ie, the preparation of less tooth structure. Thanks to the development of new ad-

CLV treatment can be provided using minimally invasive techniques. 21-23 If properly planned and executed,

hesive materials, tooth preparation for indirect restora-

CLVs can be bonded to the tooth structure without any

tions can be restricted to enamel and superficial den-

preparation. As a result, the restoration will not have

tin. With maximum enamel preservation and carefully

a well-defined margin. 23-26 This can make it impossi-

executed adhesive procedures, problems such as sec-

ble to determine the location of the finishing line for

ondary caries and leakage do not occur as frequently

the CLV. In addition, bonding usually extends beyond

for indirect restorations luted using conventional ce-

the margins of the restoration to properly seal the

ments as for those luted using acid-based cements: 3 ' 14

surrounding dental structures. 2227 Thus, conservative

For CLVs, longitudinal studies have shown excellent

bonded restorations are dissimilar to cemented resto-

results in terms of esthetics and stability of the restora-

rations. For this reason, the authors suggest describing

tion margins. The data from these studies are generally

the junction between the bonded restoration and the

presented as success or survival rates; however, due to

tooth not as a "line of marginal adaptation" but as an

the limited number of pages and images available in a

"

area of adhesive continuity" (AAC).

published article, clinicians reading these studies may not be sure how to evaluate their own CLVs intraorally. In other words, while published studies often report the results of clinical evaluations, they rarely provide a clear understanding of how to perform clinical evaluations. Clarification of this issue would help clinicians

THE ACC: A PARADIGM SHIFT FOR INDIRECT BONDED RESTORATIONS

who are not researchers determine the quality of their

Research has shown that a marginal fit of approximate-

own treatments.

ly 100 pm is acceptable for most indirect procedures, 28

Therefore, this article aims to describe an additional method to assess the quality and longevity of CLVs us-

andivtrosuehabindmrgalftsoe than 100 pm in controlled laboratory tests. 29-31 Intra-

ing scanning electron microscopy (SEM) and esthetic

oral measurements of marginal adaptation are rare in

parameters based on digital photography.

the dental literature; indeed, it is extremely difficult to

QDT 2013

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations evaluate marginal adaptation intraorally. For example,

After the treatment plan is defined, the clinical pro-

it is challenging to directly measure around the entire

cedures must be carefully executed to preserve as

circumference of a crown and precisely determine the

much of the tooth structure as possible. Tooth prepara-

mean marginal fit. It is also impossible to evaluate all

tion should be kept mainly to enamel. Further, proper

areas of an indirect restoration. However, it is possible

impression taking and provisionalization are essential

to evaluate select areas that will provide the best avail-

from a clinical perspective. The ceramic material can

able information."

be bonded to the tooth structure using resin cement

When using a laminate veneer as an indirect resto-

or preheated composite resin.

ration, the criteria for clinical longevity must include marginal adaptation as one of the important parameters for long-term success. Because CLVs involve a conservative and additive procedure, the veneer may

Maintenance Protocol

not have a well-defined finishing line; in other words,

Every dental material undergoes thermal variation, mas-

the transition between the CLV and tooth structure

ticatory loading, and contact with abrasive substances

is totally different from the marginal adaptation of a

that may damage or alter the surface. For this reason, a

crown. For veneers without preparation and partial ve-

maintenance program must be implemented.

neers, the ceramist often leaves a slight overcontour to

As already mentioned, adhesive restorations gener-

facilitate proper insertion and positioning of the resto-

ally do not have a well-defined finishing line; rather,

ration. The overcontoured area is then removed only

they have an AAC. This area is exposed to a variety of

after final bonding using specific ceramic-polishing

harmful elements, including abrasion caused by tooth-

wheels. In this manner, the AAC is created, forming a

brushing and eating. Chemical abrasion due to the

hybrid interface of different structures that have been

consumption of acidic beverages is particularly com-

bonded together: the tooth (enamel or dentin), bond-

mon and may result in staining of the exposed resin

ing system, resin cement, and ceramic.

cement. Wear of the resin cement and consequent loss of material can lead to an unsupported ceramic margin. 32 However, if a maintenance protocol is care-

Clinical Protocol

fully followed, it is possible to prevent these problems

The clinical success of CLVs depends on four majors

defects can then be resolved via finishing and polish-

factors: enamel preservation, material selection (etch-

ing. 3,26 When only the resin cement has been stained,

or at least to detect them in their early stages. Such

able ceramic), the bonding procedure, and careful

it is possible to repair or even polish this superficial

occlusal adjustment. 21 To achieve excellence in all of

defect in areas accessible for instrumentation. Indeed,

these parameters, detailed treatment planning must

CLVs usually provide easy access because they tend to

be carried out, including the following:

be conservative restorations with supragingival margins.

1. Diagnostic digital photography protocol including

on dentin due to the presence of preexisting restora-

In some cases, the margin of a CLV may be placed both facial and intraoral views. These photographs

tions or gingival recession. Clinicians should be aware

will help to determine the extent of treatment, the

that placement of the restoration margin in this area

number of teeth to be included, and whether peri-

requires special care.

odontal plastic surgery is necessary. 2. Initial additive wax-up made on a cast obtained us-

The clinical maintenance protocol should include the following:

ing polyvinyl siloxane (PVS) impression material. The wax-up will guide all esthetic treatments. 24 3. Treatment mock-up. In this phase, the patient and

1. Careful evaluation of any preexisting restorations. Periapical radiographs may be useful in this stage.

dental team determine realistic parameters for the

2. Patient hygiene instruction and support. Bleaching

final restoration. Any alterations must be done at

toothpastes should be avoided for patients with

this stage. 24-26

CLVs. Although there is a lack of scientific data on this topic, many bleaching toothpastes appear to

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SCOPIN DE ANDRADE ET AL be extremely abrasive and may remove the surface polish of the ceramic.

evaluated under SEM and measured in vivo, a different scenario becomes evident. 33 ' 34

3. Occlusal maintenance at the end of treatment. The

SEM has been used for many years to analyze dental

canine anterior guidance must protect the anterior

structures and materials."' 36 SEM analysis can be used

segment during lateral movements. For extensive

to reveal surface details that would be almost impos-

modifications, an occlusal guard can be delivered

sible to detect using an optical microscope. In some

on the day of final cementation.

cases, a minimum magnification of x100 is necessary

4. Adjustments and repairs, as necessary. Small frac-

to correctly evaluate the outcome of an adhesive res-

tures and chipping may occur, and repair is more

toration. Of course, this may not be feasible for every

conservative than replacement. The repair protocol

clinical case. Nonetheless, the information collected

is executed as follows: (1) medium-coarse diamond

from a single image is valuable to better understand

bur with water irrigation or air abrasion with alumi-

and predict novel adhesive bonding techniques.

num oxide particles at 40 psi (PrepStart H 2 0, Dan-

For this analysis, several cases were evaluated. All

ville, San Ramon, California, USA), (2) light-curing

patients analyzed had been wearing their CLVs for

block-out resin (Ultradent, South Jordan, Utah, USA)

more than 5 years. Some patients were treated more

may be used for enamel protection, (3) 9% hydro-

than 10 years prior. The adhesive procedures were per-

fluoric acid for 20 seconds on ceramic surface to

formed under a strict bonding protocol under magnifi-

be repaired (wash, dry, and remove the LC block-

cation (x2.5). All patients were included in a controlled

out resin), (4) 35% phosphoric acid for 60 seconds

maintenance program every 6 months.

on enamel and ceramic surfaces (wash, dry, apply

Select areas from each case were subjected to SEM

a silane-coupling agent for 2 minutes, and dry), (5)

analysis to help assess the CLV margins. For the SEM

air-thinned hydrophobic adhesive (no photocuring),

evaluation, a PVS impression was taken, and a replica

(6) composite resin (applied gently with a brush), (7)

of each area of interest was created with an epoxy

photocuring followed by application of glycerin jelly

resin—based material. The restoration margins of the

and light activation again to remove the oxygen in-

epoxy resin die were sputter coated with gold (Balzers-

hibited layer, and (8) polishing with ceramic and/or

SCD 050, Oerlikon Balzers, Balzers, Liechtenstein) for

composite resin rubber wheels. If a large area is af-

180 seconds at 40 mA and analyzed under SEM (LEO

fected by fracture, a partial veneer can be placed

435 VP, LEO, Cambridge, England) at 20 kV by the

over the veneer to avoid damage to the enamel.

same operator.

The maintenance protocol should be explained to

nique with a high-content fluorapatite glass-ceramic

the patient before treatment, and an agreement form

(IPS d'Sign, Ivoclar Vivadent, Schaan, Liechtenstein).

should be signed.

For bonding, a light-curing resin cement (Variolink II,

All CLVs were made using the refractory die tech-

Ivoclar Vivadent) was used in conjunction with a hydrophobic adhesive (Heliobond, Ivoclar Vivadent) for

SEM ANALYSIS: CASE REPORTS

12

enamel or a hydrophilic adhesive (Single Bond, 3M ESPE, St Paul, Minnesota, USA) for exposed dentin.

Clinicians have generally believed that a perfect indi-

Every case analyzed followed the clinical protocol de-

rect restoration should have almost no luting or cement

scribed above. Facial, extraoral, and intraoral photo-

line; however, when long-term crowns and veneers are

graphs were taken of all patients (Fig 1).

QDT 2013

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

lc

la

ld

le

if

1h

Figs la to 1I Example of the photographic protocol used for all cases to document the preoperative situation (a, d to f), immediate posttreatment (b, g to i), and long-term follow-up (c, j to I).

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SCOPIN DE ANDRADE ET AL

CASE

Fig 2a Intraoral view of the evaluated region. Fig 2b Close - up view of the CLVs on the central incisors. Fig 2c SEM image of the cervical area of the right central incisor (magnification x18). Fig 2d SEM image showing the AAC on the right central incisor (magnification x70). RC = resin cement.

Case 1

Clinical analysis revealed a small pigmented margin in the mesial/cervical region of the right central incisor.

This case involved periodontal plastic surgery from

This was likely caused by either adhesive failure or the

maxillary first molar to first molar and placement of

presence of an air bubble inside the resin cement. In

CLVs from maxillary second premolar to second pre-

such cases, the enamel finishing line usually prevents

molar. The central incisors were selected for analysis.

tooth sensitivity.

The restorations had been in situ for 7 years (Figs 2a and 2b).

It was possible to observe the AAC using SEM analysis (Figs 2c and 2d). The resin cement appeared worn down without damage to the CLV.

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The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

CASE 2 Fig 3a CLV on the right lateral incisor. Note the visibly different texture of the restoration. Fig 3b SEM photomicrograph showing the CLV interface (arrows) as seen in the area marked on Fig 3a (magnification X42). Fig 3c SEM image showing the CLV interface (arrows) at higher magnification. Even at this magnification, it is possible to see a well-adapted AAC (magnification x165).

3a

Detector = SE1

Mag = 165X

Date 2 Mar 2012

ENT = 20.00 kV

2000

Detector = SE1 Date 2 Mar 2012

3c

Case 2

the right lateral incisor (Fig 3a). Surface irregularities at the AAC were also evident (Fig 4a).

For this case, the treatment included periodontal plas-

SEM analysis revealed a perfect and continuous mar-

tic surgery from the maxillary right second molar to the

gin (Figs 3b and 3c). One possible explanation for the

left first molar, placement of CLVs at the lateral incisors

difference between the clinical and SEM images is that

and left first and second premolars, and placement of

debonding occurred after years of function, creating

partial veneers at the right first and second premolars.

the interface separation seen clinically. At higher mag-

The CLVs at the lateral incisors were selected for analy-

nifications (Figs 4b and 4c), the restorations showed a

sis. The restorations had been in situ for 7 years.

continuous margin, despite an area of resin cement abra-

Clinical analysis revealed changes in texture and

sion (no clinical relevance). A few areas showed some

shade occurring at the midfacial surface of the CLV on

indentation marks, possibly due to finishing procedures.

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SCOPIN DE ANDRADE Er AL

Fig 4a CLV on the left lateral incisor. Minor irregularities in the AAC can be observed.

Fig 4b The irregularities in the AAC become more evident under SEM (magnification x41). Fig 4c SEM image showing the CLV interface (red arrows). Yellow arrows show the edges of the ceramic structure. The area around the resin cement shows irregularities, possibly due to abrasion. The orange arrows show a possible scratch caused by the finishing procedures (magnification x209). RC = resin cement; E = enamel.

Detector = SE1 Date 2 Mar 2012

4c

Case 3

SEM analysis revealed the presence of the AAC. A

better view of the margin was achieved by using reCLVs were placed from maxillary canine to canine and mandibular canine to canine. The CLV on the maxillary

5c). At higher magnification (Fig 5d), an area of abra-

right canine was selected for analysis. This restoration

sion was evident; however, the AAC was still clinically

received a partial veneer after fracture of the ceramic

acceptable. Figures 5e and 5f show the area where the

on the canine and lateral incisor due to an accident.

partial veneer was bonded to fix the CLV.

Clinical analysis revealed discrete marginal staining. The margin of the partial veneers was visible (Fig 5a).

16

traction cord during tissue displacement (Figs 5b and

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The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

(2 Resin cement

Mag = 750 X

111,

EMT = 20.00 NV

Detector = SEt Date 2 Mar 2012

Fig 5a CLV on the right canine. Marginal staining is evident at the AAC. Fig 5b SEM image showing the AAC. The image was obtained with the help of retraction cord placed in the sulcus (magnification x40).

Fig 5c SEM image of the area marked in Fig 5b (magnification x61). Fig 5d The AAC clearly shows no signs of deep abrasion. It is possible to see the difference between

the three structures of the AAC: enamel, resin cement (RC), and ceramic (magnification x750). Fig 5e SEM image showing the interface between the CLV and partial veneer (arrows). Scratches on the ceramic surface probably resulted from abrasion caused by toothpaste and food (magnification X40). Fig 5f SEM image showing the AAC in the repaired area (magnification x750).

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SCOPIN DE ANDRADE ET AL

CASE 4

6a

6b

6d

6c

Fig 6a CLVs on the central incisors showing an excellent AAC. Fig 6b SEM view showing the interface between the CLV and tooth structure on the central incisors. Note that the interface is easier to detect under SEM than in the clinical image (magnification x25).

Fig 6c A crack was found on the CLV at the left central incisor (magnification x25). Fig 6d Higher-magnification view of the crack (magnification x650).

Case 4

18

and right first and second premolars were selected for

This case involved periodontal plastic surgery and

analysis. Clinical analysis revealed a smooth surface at the

placement of CLVs from maxillary second premolar

AAC between the central incisors (Fig 6a). For the

to second premolar. The CLVs on the central incisors

modified CLVs at the second premolars, no damage

QDT 2013

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

7d Fig 7a Occlusal view of the modified CLV on the right second premolar. Fig 7b SEM image showing the AAC on the occlusal surface (magnification x25). RC = resin cement. Fig 7c At higher magnification, the AAC shows an area of abrasion on the enamel, with no signs of leakage (magnification x55).

Fig 7d Additional magnification reveals minor irregularities or bubbles on the ceramic surface (magnification x150). RC = resin cement.

was evident despite the location of the margin in the

SEM analysis of the second premolars helped to eluci-

occlusal area (Fig 7a).

date the behavior of the AAC when anterior canine

SEM analysis of the central incisors revealed an AAC

guidance is provided and careful occlusal adjustments

with no severe modifications (Fig 6b). A fissure was

are made (Fig 7b). An area of enamel abrasion was ob-

found in the CLV (Figs 6c and 6d), which did not cause

served (Figs 7c and 7d). The behavior of enamel and

any shade alterations. This finding is common for CLVs. 24

ceramic seems to be similar.

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SCOPIN DE ANDRADE ET AL

CASE 5

Fig 8a CLVs on the central and lateral incisors.

Fig 8b SEM view of the area marked in Fig 8a. No failures or bubbles are evident (magnification x25). Fig 8c Higher magnification of the area marked in Fig 8b. There are still no visible irregularities at the surface of the AAC (magnification x140).

Case 5

SEM analysis of the central incisor showed an ideal AAC (Figs 8b and 8c). Figures 9c to 9e show the SEM

CLVs were placed from maxillary canine to canine, and

images of the right canine. Chipping due to a fracture

partial veneers were placed at the maxillary first and

of the ceramic margin or an irregularity caused by fin-

second premolars. The canines and left central incisor

ishing procedures was observed. At the left canine,

were selected for analysis.

the margin of the CLV was visible (Figs 9f to 9h).

Clinical analysis of the left central incisor revealed staining of the margin (Fig 8a). The canines showed clinically acceptable margins (Fig 9a).

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The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

9a

Fig 9a CLV on the right canine. The AAC is visible. Fig 9b SEM image of the AAC further highlighting the smooth surface of the ceramic (magnification x25). Fig 9c SEM image of the mesial area (magnification x25). Fig 9d As seen under high magnification, it is possible for the resin cement (RC) area to be greater than 100 pm without damaging the interface (magnification x120).

SCOPIN DE ANDRADE ET AL

9f

Fig 9e SEM image showing minor chipping on the ceramic side of the AAC on the right canine (magnification X 190). Fig 9f SEM view of the left canine (magnification x25). Arrows show the area analyzed in Figs 9g and 9h. Fig 9g The arrow shows a bubble on the resin cement. Circled area is shown at higher magnification in Fig 9h. (Magnification x25). RC = resin cement. Fig 9h At high magnification, overcontouring of the resin cement (arrows) is evident (magnification X 190). Fig 9i Artistic photography of the patient. Reprinted from Arquitetura do Sorriso (Quintessence Ed, Sao Paulo, Brazil, 2012.)

IMS QDT 2013

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

9i

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SCOPIN DE ANDRADE ET Al

10a

10b

Fig 1 Oa CLV on the left lateral incisor. Fig 10b SEM image showing minor chipping at the CLV interface (arrows) (magnification x18). Fig 10c The chipped area shows irregularities at the AAC (magnification x33). Fig 10d At higher magnification, the ceramic surface reveals an irregular area likely caused by the finishing procedures (magnification x90).

Case 6 CLVs were placed on the maxillary lateral incisors and canines. The lateral incisors were selected for analysis. Clinical analysis revealed a clinically acceptable margin at both the left lateral incisor (Fig 10a) and right lateral incisor (Fig 11a).

24

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Using SEM, the ceramic surface of the left lateral incisor presented a marginal irregularity, possibly due to finishing and/or polishing procedures (Figs 10b to 10d). The right lateral incisor showed minor chipping at the CLV margin (Figs llb to 11d).

The Area of Adhesive Continuity: A New Concept for Bonded Ceramic Restorations

llb

11c

lid

Fig 11 a CLV on the right lateral incisor. Fig 11 b SEM image showing the AAC (magnification X18). Fig 11 c Clinically acceptable AAC with a measure of more than 100 pm (magnification x220). RC = resin cement. Fig 11 d SEM image showing area of minor chipping (arrows) in the ceramic side of the AAC (magnification x370).

CONCLUSIONS

ment, and ceramic. This intricate interface highlights the need for clinicians to evaluate adhesive restorations

The AAC is a new concept for the analysis of bonded

differently from conventional cemented restorations.

restorations. The AAC forms a hybrid interface of dif-

Understanding the concept of the AAC is essential to

ferent structures that have been bonded together: the

improving the longevity of bonded ceramic restorations.

tooth (enamel or dentin), bonding system, resin ce-

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SCOPIN DE ANDRADE ET AL

ACKNOWLEDGMENTS The authors would like to express their gratitude to the Atelie Oral Clinic team in S5o Paulo, Brazil. The artistic photography of the patient on page 23 was taken by Andre Schiliro for the book Arquitetura do Sorrisso, published in 2012 by Quintessence Ed, Sao Paulo, Brazil.

16. Kydd WL, Nicholls JI, Harrington G, Freeman M. Marginal leakage of cast gold crowns luted with zinc phosphate cement: In vivo study. J Prosthet Dent 1996;75:9-13. 17. Yuksel E, Zaimoglu A. Influence of marginal fit and cement types on microleakage of all-ceramic crown systems. Braz Oral Res 2012;25:261-266. 18. Massironi D, Pascetta R, Romeo G. Precision in Dental Esthetics: Clinical and Laboratory Procedures. Chicago: Quintessence, 2007. 19. Martignoni M, Shonenberger AJ. Precision Fixed Prosthodontics: Clinical and Laboratory Aspects. Chicago: Quintessence, 1990.

REFERENCES 1. Fradeani MJ. Six-year follow-up with Empress veneers. Int J Periodontics Restorative Dent 1998;18:216-225. 2. Smales RJ, Etemadi S. Long-term survival of porcelain veneers using two preparation designs: A retrospective study. Int J Prosthodont 2004;7:323-326. 3. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6 to 12 year clinical evaluation-A retrospective study. Int J Periodontics Restorative Dent 2005;25:9-17. 4. Wiedhahn K, Kerschbaum T, Fasbinder DF. Clinical long-term results with 617 Cerec veneers: A nine-year report. Int J Comput Dent 2005;8:233-246. 5. Burke FJ, Lucarotti PS. Ten-year outcome of porcelain veneers Placed within the general dental services in England and Wales. J Dent 2009;37:31-38. 6. Beier US, Kapferer I, Burtscher D, Dumfahrt H. Clinical performance of porcelain laminate veneers for up to 20 years. Int J Prosthodont 2012;25:79-85. 7. Layton DM, Clarke M, Walton TR. A systematic review and meta-analysis of the survival of feldspathic porcelain veneers over 5 and 10 years. Int J Prosthodont 2012;25:590-603. 8. Peumans M, De Munck J, Fieuws S, Lambrechts P, Vanherle G, Van Meerbeek B. A prospective ten-year clinical trial of porcelain veneers. J Adhes Dent 2004;6:65-76. 9. Petridis HP, Zekeridou A, Malliari M, Tortopidis D, Koidis P. Survival of ceramic veneers made of different materials after a minimum follow-up period of five years: A systematic review and meta-analysis. Eur J Esthet Dent 2012;7:138-152. 10. Bindl A, Mormann WH. Clinical and SEM evaluation of all-ceramic chair-side CAD/CAM-generated partial crowns. Eur J Oral Sci 2003;111:163-169. 11. Sadowsky SJ. An overview of treatment considerations for esthetic restorations: A review of the literature. J Prosthet Dent 2006;96:433-442. 12. Aykor A, Ozel E. Five-year clinical evaluation of 300 teeth restored with porcelain laminate veneers using total-etch and modified self-etch adhesive system. Oper Dent 2009;34:516523. 13. Federlin M, Schmidt S, Hiller KA, Thonemann B, Schmalz G. Partial ceramic crowns: Influence of preparation design and luting material in internal adaptation. Oper Dent 2004;29:560570. 14. Edelhoff D, Ozcan M. To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials: Cementation. Clin Oral Implants Res 2007;18(suppl 3):193-204. 15. Jacobs MS, Windeler AS. An investigation of dental luting cement solubility as a function of the marginal gap. J Prosthet Dent 1991;65:436-442.

20. Edelhoff D, Sorensen JA. Tooth structure removal associated with various preparation designs for anterior teeth. J Prost Dent 2002;87:503-509. 21. Scopin de Andrade 0, Borges G, Stefani A, Fujiy F, Battistella P. A step-by-step ultraconservative esthetic rehabilitation using lithium disilicate ceramic. Quintessence Dent Technol 2010;33: 114-131. 22. Scopin de Andrade 0, Kina S, Hirata R. Concepts for an ultraconservative approach to indirect anterior restorations. Quintessence Dent Technol 2011;34:103-119. 23. Scopin de Andrade 0, Romanini JC, Hirata R. Ultimate ceramic veneers: A laboratory-guided ultraconservative preparation concept for maximum enamel preservation. Quintessence Dent Technol 2012;34:29-43. 24. Magne P, Belser U. Bonded Porcelain Restorations in Anterior Dentition: A Biomimetic Approach. Chicago: Quintessence, 2002. 25. are' G. Predictable, precise, and repeatable tooth preparation for porcelain laminate veneers. Pract Proced Aesthet Dent 2003;15:17-24. 26. Gurel G. The Science and Art of Porcelain Laminate Veneers. Chicago: Quintessence, 2003. 27. Peumans M, Van Meerbeek B, Yoshida Y, Lambrechts P, Vanherle G. Porcelain veneers bonded to tooth structure: An ultramorphological FE-SEM examination of the adhesive interface. Dental Mater 1999;15:105-119. 28. Wolfart S, Wegner SM, AI-Halabi A, Kern M. Clinical evaluation of marginal fit of a new experimental all-ceramic system before and after cementation. Int J Prosthodont 2003;25:590-603. 29. Reich S, Gozdowski S, Trentzsch L, Frankenberger R, Lohbauer U. Marginal fit of heat-pressed vs CAD/CAM processed all-ceramic onlays using a milling unit prototype. Oper Dent 2008;33:644650. 30. Tao J, Han D. The effect of finish line curvature on marginal fit of all-ceramic CAD/CAM crowns and metal-ceramic crowns. Quintessence Int 2009;40:745-752. 31. Grenade C, Mainjot A, Vanheusden A. Fit of single tooth zirconia copings: Comparison between various manufacturing processes. J Prosthet Dent 2011;105:249-255. 32. Kramer N, Taschner M, Lohbauer U, Petschelt A, Frankenberg R. Totally bonded ceramic inlays and onlays after eight years. J Adhes Dent 2008;10:307-314. 33. Belser UC, MacEntee MI, Richter WA. Fit of three porcelainfused-to-metal marginal designs in vivo: A scanning electron microscopy study. J Prosthet Dent 1985;53:24-29. 34. Garcia-Godoy F, Kramer N, Feilzer AJ, Frankenberger R. Longterm degradation of enamel and dentin bonds: 6-years results in vitro vs. in vivo. Dent Mater 2010;26:1113-1118. 35. de Andrade OS, de Goes MF, Montes MA. Marginal adaptation and microtensile bond strength of composite indirect restorations bonded to dentin treated with adhesive and low-viscosity composite. Dent Mater 2007;23:279-287. 36. Duarte S Jr, Phark JH, Blatz M, Sadan A. Ceramic systems: An ultrastructural study. Quintessence Dent Technol 2010;33:42-60.

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QDT 2013

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The Anatomical Shell Technique:

An Approach to Improve the Esthetic Predictability of CAD/CAM Restorations Paulo Kano, DDS, MSc' Cristiano Xavier, DDS 2 Jonathan L. Ferencz, DDS 3 Eric Van Dooren, DDS 4 Nelson RFA Silva, DDS, MSc, PhD'

L

ack of predictability has been a major concern regarding the esthetic outcomes of computer-aided design/computer-assisted manufacture (CAD/CAM)

DEVELOPMENT OF THE ANATOMICAL SHELL TECHNIQUE

restorations, particularly in complex cases involving re-

construction of multiple units. Unfortunately, the litera-

One of the primary challenges in esthetic dentistry is

ture contains limited research on this topic.

achieving lifelike surface texture. 2 Surface texture di-

This article presents the anatomical shell technique,

rectly influences the value, color saturation, and zones

a method in which flowable composite resin shells are

of light reflection and absorption. An anterior restora-

used to predict the final esthetic and morphologic out-

tion that does not exhibit surface texture and luster

comes of provisional laminate veneers fabricated with

comparable to the adjacent natural teeth will imme-

CAD/CAM technology.'

diately appear out of place, especially if the natural teeth are heavily textured. A natural tooth surface is composed of horizontal and vertical concavities and

'Private Practice, Sao Paulo, Brazil. 2 Professional

Dental Photographer, Belo Horizonte, MG, Brazil.

'Clinical Professor, New York University College of Dentistry; Private Practice, New York, New York, USA. 4 Private

Practice, Antwerpen, Belgium.

'Adjunct Professor, Department of Restorative Dentistry, Federal University of Minas Gerais, Belo Horizonte, Brazil. Correspondence to: Dr Nelson RFA Silva, Alameda do Ipe Branco 520, Sao Luiz, Pampulha, Belo Horizonte, Brazil 31275-080. Email: [email protected]

convexities that vary in complexity and intensity. If these features are not precisely replicated, achieving the desired esthetic outcome is almost impossible. Generally, accurate reproduction of the natural tooth surfaces requires a highly skilled laboratory technician. However, if natural tooth surfaces could be mimicked using a milling machine, excellent outcomes could be achieved without relying on the skill of an individual technician. Thus, the authors aimed to find a novel ap-

QDT 2013

EN

KANO ET AL

Figs 1 a to I e (a) Hatjo cast. (b) Stone cast made from an impression of the Hatjo cast. (c) Frontal view of the scanned Hatjo cast. (d) Lateral view of the Hatjo cast. (e) Lateral view of the scanned Hatjo cast. Note the similar texture evident on the original and scanned images.

proach to reproduce the surface texture and luster of

Both the original Hatjo cast and replica stone cast

natural teeth using anatomical composite resin shells

were scanned (InEos Blue Scanner, Sirona, Bensheim,

in conjunction with CAD/CAM restorations.

Germany) (Fig 1). The stone cast of the original Hatjo

A Hatjo cast' was duplicated in dental stone (Kro-

cast was prepared for a laminate veneer on the max-

motypo 4, Lascod, Florence, Italy). Hatjo casts corre-

illary right central incisor (Fig 2a). The prepared cast

spond to a series of epoxy casts based on the natural

was then scanned (Fig 2b). The preparation area was

smiles of male and female subjects with natural tooth

delineated using 3.88 CEREC Software (Sirona), and a

morphology and texture in the anterior region.' The

process referred to as "correlation" was performed to

benefits of the Hatjo cast will be further demonstrated

superimpose the scanned image of the original Hatjo

later in this article.

cast onto the scanned image of the prepared stone

QDT 2013

The Anatomical Shell Technique: An Approach to Improve the Esthetic Predictability of CAD/CAM Restorations

Figs 2a to 2e (a) Prepared stone cast. (b) Scanned imaged of the prepared stone cast. (c) Digital restoration after correlation. (d) Laminate veneer immediately after milling. (e) Polished laminate veneer.

cast. This allowed for the design of a laminate restora-

toration showed unclear surface texture immediately

tion that mimicked the shape and texture of the Hatjo

after milling (Fig 2d); however, a simple polishing pro-

cast (Fig 2c).

cedure using 3-pm diamond paste resolved this issue

After the restoration was created digitally, the com-

and revealed the outstanding surface texture obtained

puter file was sent to a Sirona InLab MC XL Milling

through the milling process (Fig 2e). The surface tex-

Unit. The restoration was milled using IPS Empress CAD

ture matched that of the original Hatjo cast. Therefore,

Multi Block (Ivolcar Vivadent, Schaan, Liechtenstein).

the CAD/CAM process was considered successful in

Following the milling process, the final restoration

terms of the reproduction of the surface texture.

was checked for flaws. The labial surface of the res-

QDT 2013

KANO ET AL

CASE REPORT Fig 3 Pretreatment view showing the inadequate composite resin restorations.

Figs 4a to 4d Facial views showing the patient's smile. Note that the central incisors appear too short when the patient smiles broadly.

CASE REPORT

lip. When she was 13 years old, the patient underwent orthodontic treatment that included the extraction of

The 24-year-old female patient presented with com-

the primary maxillary lateral incisors. The orthodontic

plaints regarding her existing composite resin restora-

treatment took 3 years to complete and resulted in the

tions. The patient also complained about the presence

transposition and subsequent enameloplasty of the

of gingival inflammation and severe discoloration at

canines. The result of this procedure did not please the

the composite resin margins (Fig 3).

patient; therefore, composite resin restorations were

Initial clinical and radiographic evaluations revealed

used to meet her esthetic expectations. However, the

anodontia of the maxillary lateral incisors. The canines

results of this procedure were still inadequate, and

had been moved to the lateral incisor positions and

crown lengthening was performed in another attempt

reshaped in an attempt to simulate the lateral incisor

to satisfy the patient's esthetic demands. Once again,

morphology. The patient also reported that a previous

the results were not acceptable to the patient.

accident had resulted in an unnatural smile (Fig 4).

Dental History

Treatment Plan It was decided to use porcelain laminate veneers to re-

At the age of 4, the patient had suffered a traumatic

store the patient's dentition. Considering the patient's

injury to her face that created a deep cut on her lower

high esthetic demands, the anatomical shell technique

The Anatomical Shell Technique: An Approach to Improve the Esthetic Predictability of CAD/CAM Restorations

5a

10

5 1\ 11111111111111 thillibilibioi 15

5d Figs 5a to 5d Measuring the length of the central incisors. Note the slight difference between the two teeth.

would be used to provide an accurate prediction of the final esthetic outcome.

Next, the patient and clinician analyzed several Hatjo casts to choose the optimum tooth arrangement. A

IPS Empress CAD Multi-Block (shade A2, Ivolcar

silicone index (Virtual, Ivoclar Vivadent) was obtained

Vivadent) was selected for the final restorations. No

from the labial surface of the anterior teeth of the se-

impressions or diagnostic wax-ups were used; rather,

lected Hatjo cast.

the entire esthetic treatment plan relied on an imaging

Light-cured flowable composite resin (Tetric Com-

protocol (including photographs), prefabricated Hatjo

posite Incisal, Ivolcar Vivadent) was carefully placed

casts, and digital technology (CEREC AC Bluecam,

into the index to produce very thin composite resin

version 3.88, Sirona).

shells, thus duplicating the form registered by the index (Fig 6). After polymerization, the shells were gently placed intraorally on the buccal surfaces of the teeth

Treatment Procedures

and adjusted to obtain the best possible fit. The shells were luted using the same flowable composite resin

The treatment began with physiotherapy to correct the

without acid etching and then polished (Figs 7a to 7c).

lower lip position at the patient's left side. After com-

No tooth preparation was performed at this stage.

pletion of physiotherapy, measurements of the exist-

The clinician and patient evaluated the esthetic out-

ing teeth were taken using a conventional caliper (Fig

come with the polished shells in place. Digital photo-

5). Digital smile designer was carried out to determine

graphs were taken to analyze the symmetry of the

the esthetic needs of the patient. Using existing digital

patient's teeth and face. The combination of digital

photographs of natural smiles from a computer smile

photographs and computer esthetic analyses allowed

library, the patient and dentist collaborated to select

the clinician to obtain the best esthetic result. Small

the tooth shapes that best suited her smile.

adjustments at the interproximal embrasures were per-

QDT 2013

31

KANO ET AL

6e Figs 6a to be (a to c) Hatjo cast showing the surface texture of the anterior teeth. (d) Impression of the Hatjo cast to produce the anatomical shells. (e) Note the opalescence of the shells under polarized light.

32

QDT 2013

The Anatomical Shell Technique: An Approach to Improve the Esthetic Predictability of CAD/CAM Restorations

7a

7b

7d Figs 7a to 7d (a to c) Luting and polishing of the anatomical shells. (d) Application of CEREC Optispray powder.

8a Figs 8a and 8b (a) Tooth preparation followed by (b) CEREC Optispray powder application.

formed as necessary. The patient was then asked to approve her new smile. To facilitate digital imaging, CEREC Optispray pow-

was merged and correlated with the digital image of the anatomical shells to generate the proper shape of the definitive laminate veneers (Fig 9).

der (Fig 7d) was applied intraorally to coat the teeth

The milling process was initiated using an InLab

and composite resin shells. An intraoral scanner

MC XL Milling Unit. After milling, the veneers were

(CEREC AC Bluecam) was used to create a digital

removed from the milling unit (Fig 10) and visually in-

three-dimensional model of the patient's mouth with

spected for flaws.

the temporarily cemented shells. In this way, the com-

The veneers were tried in, polished with 0.3-pm dia-

posite shells could be used to predict the final esthetic

mond paste, and cemented (Variolink Veneer Medium

outcome and guide the amount of tooth preparation.

Clear, Ivoclar Vivadent) following the manufacturer's

Tooth preparation was performed following the

instructions (Fig 11). Figure 12 demonstrates the abil-

manufacturer's guidelines (Fig 8). A digital impression was taken (CEREC AC Blue-

ity of the anatomical shell technique to deliver predictable esthetics using CAD/CAM technology.

cam), and the digital image of the tooth preparation

QDT 2013

33

KANO ET AL

9a

9b

9c

9d

9e

Figs 9a to 9e Digital impression taken after tooth preparation. The digital image was merged and correlated with the digital image of the anatomical shells to generate the proper shape of the definitive restorations. Fig 10 Laminate veneers after milling.

34

QDT 2013

The Anatomical Shell Technique: An Approach to Improve the Esthetic Predictability of CAD/CAM Restorations

11f

Figs 11a to 11 h Final result. Harmonious and lifelike surface texture was achieved. Note that the surface texture matches that of the Hatjo cast seen in Fig 6.

QDT 2013

KANO ET AL

Fig 12 The anatomical shell technique: The Hatjo cast was used to successfully predict the appearance of the definitive restorations.

CONCLUSIONS

REFERENCES

Achieving natural surface texture and predictable es-

1.

Masek R. Margin isolation for optical impressions and adhesion. Int J Comput Dent 2005;8:69-76.

2.

Kahng SL. Surface texture: Matching the single central. Dent Dialogue 2005;5:46-52.

thetic outcomes is a significant challenge when using CAD/CAM restorations. The anatomical shell technique offers a simple and innovative method to guide and accurately predict the esthetic outcome of CAD/CAMfabricated porcelain laminate veneers.

3. 4.

Coachman C, Salama M, Garber D, Calamita M, Salama H, Cabral G. Prosthetic gingival reconstruction in a fixed partial restoration. Part 1: Introduction to artificial gingiva as an alternative therapy. Int J Periodontics Restorative Dent 2009;29:471-477.

5.

Coachman C, Salama M, Garber D, Calamita M, Salama H, Cabral G. Prosthetic gingival reconstruction in the fixed partial restoration. Part 2: Diagnosis and treatment planning. Int J Periodontics Restorative Dent 2009;29:573-581.

6.

Coachman C, Salama M, Garber D, Calamita M, Salama H, Cabral G. Prosthetic gingival reconstruction in fixed partial restorations. Part 3: Laboratory procedures and maintenance. Int J Periodontics Restorative Dent 2010;30:19-29.

7.

Coachman C, Van Dooren E. An integrated cosmetic treatment plan: Soft tissue management and metal-free restoration. Pract Proced Aesthet Dent 2009;21:29-33.

8.

Fradeani M. Esthetic Rehabilitation in Fixed Prosthodontics. Vol 1: Esthetic Analysis. Chicago: Quintessence, 2004.

ACKNOWLEDGMENTS The authors are thankful to Dudu Medeiros, professional photographer in Sao Paulo, Brazil, for final production of the patient's photograph. The authors also thank Emerson Larceda Silva for the production of the final laminates.

QDT 2013

Hatjo J. A Beleza Natural dos Dentes Anteriores. Sao Paulo: Santos, 2008.

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Biomaterials Update

Achieving the Ultimate Optical Properties of Composite Resin Sillas Duarte, Jr, DDS, MS, PhD' Neimar Sartori, DDS, MS, PhD' Jin-Ho Phark, DDS, Dr Med Dent

T

he functional and esthetic properties of dental composite resins have greatly improved since their introduction over 50 years ago. Recent advances include the development of new

monomers,' -3 increased filler loading, reduced particle size, new silanation, and new particles. 4 5 The size of the filler particles incorporated into the resin matrix has

decreased significantly.€ The filler not only determines the mechanical properties of a composite resin but also allows for reduction of the amount of resin matrix and, consequently, the polymerization shrinkage.' Further, increasing the filler loading optimizes translucency and opalescence while simultaneously enhancing the esthetic and handling properties.' Light scattering and gloss retention are dependent on the filler arrangement and distribution within the resin matrix. The smaller the filler size, the more efficient the optical scattering. 8 A combination of larger and smaller fillers or filler clusters is critical to attain shades and levels of translucency similar to those of natural teeth. Thus, it is essential to understand composite resin composition as it relates to the final outcome of an esthetic restoration.

'Associate Professor and Chair, Division of Restorative Sciences, Ostrow School of Dentistry, University of Southern California; Director, Advanced Program in Operative Dentistry, University of Southern California, Los Angeles, California, USA. 'Assistant Professor of Clinical Dentistry, Division of Restorative Sciences, Ostrow School of Dentistry, University of Southern California; Assistant Director, Advanced Program in Operative Dentistry, University of Southern California, Los Angeles, California, USA. 'Assistant Professor of Clinical Dentistry, Division of Restorative Sciences, Ostrow School of Dentistry, University of Southern California; Director, Biomaterials Research Laboratory, University of Southern California, Los Angeles, California, USA. Correspondence to: Dr Sillas Duarte, Jr, Division of Restorative Sciences, Ostrow School of Dentistry, University of Southern California, DEN 4338A, 925 W 34th Street, Los Angeles, CA 90089-0641. Email: [email protected]

DUARTE ET AL Fig 1 Field-emission scanning electron microscopy image showing prepolymerized fillers of a microfilled composite resin (magnification x2,000). Fig 2 Microfilled composite resins: (a) Durafill VS silicon dioxide fillers (magnification x65,000). (b) Renamel Microfill strontium aluminum boron silicate and silicon dioxide fillers (magnification x65,000).

2a

CLASSIFICATION OF COMPOSITE RESINS Composite resins can be classified according to filler size into one of three groups: microfilled, hybrid, or nanofilled.

Microfilled Composite Resins Microfilled composite resins show adequate esthetic qualities due to their excellent polishability and capacity to retain surface gloss over time. Microfilled composite resins have an average filler size of 40 to 1,200 nm 9 and relatively low filler content of 30% to 60% by volume. Some manufacturers have included prepolymerized fillers (Fig 1) in an attempt to increase

40

QDT 2013

the overall amount of fillers without compromising the rheologic properties. However, microfilled composite resins are contraindicated for stress-bearing restorations due to their poor mechanical properties.— The large amount of inorganic content makes microfilled composite resins more susceptible to water sorption. 1 — Examples of microfilled composites include Durafill VS (Heraeus Kulzer, Hanau, Germany; Fig 2a) and Renamel Microfill (Cosmedent, Chicago, Illinois, USA; Fig 2b). Durafill VS is composed of bisphenol glycidyl methacrylate/triethylene glycol dimethacrylate and urethane dimethylacrylate with inorganic and organic fillers. The fillers comprise highly dispersed silicon dioxide (20 to 70 nm) and prepolymerized particles (up to 20,000 nm). Renamel Microfill is composed of functional acrylic resins, inorganic fillers, and prepolymerized composite resin (40 to 63,000 nm).

Achieving the Ultimate Optical Properties of Composite Resin Fig 3 Hybrid composite resin: Herculite XRV barium aluminoborosilicate glass and fumed silica fillers (magnification x65,000)

Hybrid Composite Resins

ins have multiple filler sizes and shapes, with most of the fillers showing an irregular shape (Fig 3). An irregu-

Hybrid composite resins make up a large majority of

lar shape is characterized by sharp edges that make

the composite resins available. They are composed of

proper polishing 13 and long-term gloss retention 14

polymer groups reinforced by inorganic fillers of dif-

moredifcult.Hybompsiernadct

ferent compositions and shapes, with sizes ranging

to restore both anterior and posterior teeth; however,

between 60 and 1,000 nm. 9' 11 Most hybrid composite

they are not ideal for highly esthetic areas such as the

resins present a filler ratio of 60% to 70% by volume,

facial surfaces of anterior teeth. An example of a hy-

which leads to significantly improved physical proper-

brid composite resin is Herculite XRV (Kerr Dental, Or-

ties compared to those of microfilled composite resins.

ange, California, USA).

Hybrid composite resins are formulated to restore both anterior and posterior teeth with acceptable pol-

Microhybrids

ishability and variable gloss retention. They are avail-

Enhanced milling and grinding techniques allow for

able in a wide range of colors with different degrees

the creation of composite resins with submicron par-

of opaqueness, translucency, and fluorescence. Hybrid

ticles with sizes averaging 400 to 1,000 nm. 9 The aver-

composite resins exhibit abrasion, wear, and thermal

age inorganic filler loading of microhybrid composite

expansion coefficients similar to those of natural denti-

resins is 60% by volume due to the reduced particle

tion. They also demonstrate reduced curing shrinkage

size, with a mean filler size of 400 to 600 nm. One of

and water absorption compared to microfilled com-

the major benefits of microhybrids is the incorporation

posite resins. 11 - 12

of more rounded fillers (Figs 4a and 4b) within the resin

Hybrid composite resins can be subclassified into

matrix in addition to the irregular fillers. Rounded fill-

three groups according to the filler size: (1) hybrids:

ers significantly improve polishability. 15 Thus, based on

average particle size greater than 600 nm; (2) micro-

the combination of strength and polishability, this cat-

hybrids: particle size ranging from 10 to 3,000 nm and

egory of composite resin can be classified as a univer-

mean filler size ranging from 400 to 600 nm; and (3)

sal composite. Microhybrid composite resins can be

nanohybrids: filler size ranging from 10 to 2,000 nm

effectively used to restore both anterior and posterior

and average filler size ranging from 200 to 300 nm.

teeth. 9 Examples of microhybrid composite resins include Point 4 (Kerr; Fig 4a), Filtek Z250 (3M ESPE, St

Hybrids

Paul, Minnesota, USA; Fig 4b), Esthet-X HD (Dentsply

Hybrid composite resins have an average filler size of

DeTrey, Konstanz, Germany; Fig 4c), and Vit-l-escence

600 nm and an adequate filler ratio, thus supporting

(Ultradent, South Jordan, Utah, USA; Fig 4d).

their use in stress-bearing areas. These composite res-

DDT 2013

41

DUARTE ET AL Nanohybrids

IPS Empress Direct (Ivoclar Vivadent; Fig 6), and Es-

Recently, most manufacturers have modified their com-

telite Omega (Tokuyama Dental, Tokyo, Japan; Fig 7).

posite resin formulations to include nanoparticles, pre-

IPS Empress Direct Enamel (Fig 6b), Trans, and Opal

polymer, and/or clusters of nanofillers. These compos-

(Fig 6c) shades, as well as Estelite Omega (Fig 7), of-

ite resins are classified as nanohybrids. 9

fer the lowest mean filler size and highest amount of

Nanohybrid composite resins have filler sizes rang-

rounded and/or spherical fillers. These characteris-

ing from 10 to 2,000 nm, with an average filler size of

tics improve polishability and gloss retention, both of

200 to 300 nm (Figs 5 to 7). By incorporating fillers of

which are necessary features for anterior esthetic res-

nanometric size, the amount of inorganic fillers can be

torations.

increased to 70% by volume. However, these changes do not necessarily translate into better physical properties. In reality, there is still a considerable discrepancy in terms of filler size and filler loading among

Nanofilled Composite Resins

different nanohybrids. Some composite resins with a

Nanofilled composite resins represent the most recent

mean filler size of more than 300 nm are still consid-

innovation. 9 Their inorganic fillers are composed only

ered nanohybrids. Therefore, most nanohybrids have

of nanoscale particles with a size of 100 nm and below

similar physical properties to those of rnicrohybrids. 1 €

(Figs 8 to 10). The fillers are a combination of nonag-

Different fillers, such as barium glass, amorphous sil-

glomerated/nonaggregated 20- to 75-nm silica fillers,

ica, ytterbium trifluoride, mixed oxide, silicon dioxide,

nonagglomerated/nonaggregated 4- to 11-nm zirco-

barium fluoroborosilicate glass, and zirconia, can be

nia fillers, and aggregated zirconia/silica cluster fillers

used for nanohybrid composite resins. Sharp irregular

with 20-nm silica and 4- to 11-nm zirconia particles.

fillers are mixed with rounded and/or spherical parti-

Nanoclusters are agglomerates (60 to 1,400 nm) of

cles; thus, differences in roughness and gloss retention

silica and zirconia nanoparticles fused together, thus

should be expected depending on the composite resin

creating porous structures." The dentin, enamel, and

used. These differences explain why some nanohybrids

body shades have an average cluster particle size of

show a roughness similar to that of conventional hy-

600 to 10,000 nm, while the translucent shades have

brid composite resins.

cluster particle sizes between 600 and 20,000 nm.

Examples of nanohybrid composite resins include

Nanofilled composite resins present similar mechan-

Tetric N-Ceram (IvoclarVivadent, Schaan, Liechtenstein;

ical and physical properties to those of microhybrid

Fig 5a), Clearfil Majesty Esthetic (Kuraray, Tokyo, Japan;

composite resins, with superior polishability and long-

Fig 5b), Renamel Nano (Cosmedent; Fig 5c), Miris 2

term gloss retention." Filler loading ranges from 55%

(Coltene Whaledent, Altstatten, Switzerland; Fig 5d),

to 70% by volume, which makes these composite resins suitable for anterior and posterior use.

Fig 4 Microhybrid composite resins: (a) Point 4 barium aluminoborosilicate glass and fumed silicon dioxide fillers (magnification x65,000). (b) Filtek Z250 rounded zirconia and silica fillers (magnification x65,000). (c) Esthet-X barium aluminofluoroborosilicate glass with silicon dioxide fillers (magnification: x65,000). (d) Vit-l-escence glass-strontium-boron-aluminumsilicate fillers (magnification x65,000). Fig 5 Nanohybrid composite resins: (a) Tetric N-Ceram barium glass, barioaluminum fluorosilicate glass silica, and ytterbium trifluoride fillers (magnification x65,000). (b) Clearfil Majestic Esthetic barium glass fillers (magnification x65,000). (c) Renamel Nano barium aluminum boron silicate glass and silica fume (magnification x65,000). (d) Miris 2 (Coltene Whaledent) barium glass and silanized amorphous silica (magnification: x65,000).

42

QDT 2013

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Achieving the Ultimate Optical Properties of Composite Resin

OPTICAL PROPERTIES OF COMPOSITE RESIN

Translucency Translucency plays an important role in achieving harmony between the composite resin restoration and

An appropriate composite resin color scheme must

natural teeth. Natural teeth are more translucent at the

account for the different areas of a tooth. A thought-

incisal third and at the facial and lingual enamel than

ful analysis of translucency, value, and chroma is cru-

at other segments of the tooth (Fig 13).

cial to achieve a lifelike esthetic outcome. In a natural

Composite resins are available in many translucen-

tooth, the esthetic appearance is defined by four main

cies (Fig 14). Dentin shades are the most opaque.

variations of translucency, chromaticity, and brightness

Body shades are more translucent than dentin shades

among the enamel and dentin: (1) opalescent enamel,

but less translucent than chromatic enamel shades.

(2) chromatic enamel, (3) translucent dentin, and (4)

Enamel shades are available as chromatic or achro-

opaque dentin (Fig 11). The outermost enamel layer

matic. Chromatic enamel shades are more translucent

(opalescent enamel) is opalescent, highly translucent,

than body shades but less translucent than achromatic

and high in value. As enamel approaches the den-

shades. Achromatic enamel shades are more translu-

toenamel junction, it absorbs the dentin's chromatic-

cent than enamel shades. Opalescent enamel shades

ity and becomes more chromatic, although it remains

are the most translucent of all composite resin shades.

translucent enough to allow for light transmission (chromatic enamel). Superficial dentin is less translucent than chromatic enamel and one or two points lower in chroma than the main tooth shade. Translu-

Value

cent dentin is usually high in value. The deep dentin

The value (lightness or brightness) of a color is based

(opaque dentin) is highly opaque and low in value.

on the amount of light emanating from that color. Ac-

These findings can be clearly observed in a cross sec-

cording to the Commission Internationale d'Eclairage

tion of an anterior tooth (Fig 12). The combination of

L*a*b* scale, 18 a value scale of gray from white (L* =

these optical properties is noticeable from the facial

100, absolute white) to black (L* = 0, absolute black)

aspect; thus, the color scheme must also consider the

represents the widest range of values. To better under-

translucency, chromaticity, and value of the facial thirds

stand this dimension of color, the teeth must be evalu-

(ie, the incisal, middle, and gingival third).

ated using grayscale photography. The brighter the color, the higher its value. For most composite resins, there is a negative correlation between thickness and value. By increasing the thickness of the composite resin enamel and dentin layers, decreased value will

be observed, thus increasing the grayish aspect of the final restorations.

Fig 6 Nanohybrid composite resin: IPS Empress Direct has three different arrangements of fillers according to the trans-

lucency and use. (a) Dentin shade: coarse barium glass, barium aluminum fluorosilicate glass, ytterbium trifluoride mixed oxide, silicon dioxide, and copolymer fillers. Note the presence of larger fillers. (b) Enamel shade: coarse barium glass fillers substituted by fine barium glass fillers with increased spherical mixed oxide. (c) Opal: amount of spherical particles significantly increased to improve opalescence (magnification x65,000).

Fig 7 Nanohybrid composite resin: Estelite Omega silica-zirconia spherical and rounded fillers (magnification x65,000). Fig 8 Nanofilled composite resin: Filtek Supreme XT Clear Translucent with 5- to 75-nm silica fillers and nanoclusters. Note that all fillers are spherical (magnification x65,000). Fig 9 Nanofilled composite resin: Filtek Supreme Ultra agglomerates (60 to 1400 nm) of fused nanoparticles of zirconia and silica (magnification x35,000). Fig 10 Nanofilled composite resin: (a) Filtek Supreme Ultra combination of nonagglomerated/nonaggregated 20-nm silica filler, nonagglomerated/nonaggregated 4- to 11-nm zirconia filler, and aggregated zirconia/silica cluster fillers (magnification x65,000). (b) Higher magnification (x100,000) showing the silica (20 nm) and zirconia nanofillers (4 nm).

QDT 2013

45

Opalescent enamel Chromatic enamel Translucent dentin Opaque dentin

Fig 11 The four main variations of translucency and chromaticity. Fig 12 Cross section of central incisor showing the differences in translucency, chromaticity, and brightness in enamel and dentin.

TRANSLUCENT ENAMEL

TRANSLUCENT DENTIN

CHROMATIC ENAMEL

GINGIVAL 1/3

MIDDLE 1/3

INCISAL 1/3

TRANSLUCENCY Fig 13 Schematic depiction of dental translucency.

- 80

60

-

-40

20

DENTIN

BODY

CHROMATIC ENAMEL

Fig 14 Different composite resin translucencies.

ACHROMATIC ENAMEL

OPALESCENT ENAMEL

TRANSLUCENT DENTIN

Fig 15 Schematic depiction of dental chromaticity.

Chroma

rect, Estelite Omega, Esthet-X, Durafill VS), chromatic non-VITA-based (Miris 2), or achromatic (Vit-l-escence

Chromaticity is the quality or purity of the color, inde-

or Enamel Plus HRI, Micerium, Avegno, Italy). Interest-

pendent of the value. Highly chromatic colors contain

ingly, achromatic enamel shades are not deprived of

maximum hue with few or no impurities, such as white,

hue and can show significant differences in value.

black, or gray. A color without hue is achromatic or monochromatic and will appear gray. Chroma is the amount of identifiable hue in a color. Chromaticity is often confused with saturation. Saturation, also known as intensity, is dependent on different lighting conditions. In other words, tooth saturation can change depending on the lighting available in a dental office,

ESTHETIC COMPOSITE RESIN RESTORATIONS Translucency, value, and chroma are intimately corre-

even though the color remains unchanged. Chroma is

lated in direct composite resin restorations. Any varia-

more intense at the center of the tooth (opaque and

tion during layering can positively or negatively affect

deep dentin) and at the gingival third compared to the

these optical properties. Unfortunately, the outcome

other tooth segments. Figure 15 shows a schematic

of these optical properties can only be evaluated once

example of dental chromaticity.

the restoration is finalized and polished. This fact can

Most composite resins adopt the VITA Classical

be problematic since improvement of the restoration

shade system (VITA Zahnfabrik, Bad Sackingen, Ger-

can only be achieved by removing part or all of the

many) as a color reference; however, composite resins

restoration and then reapplying the composite resin.

that use other systems are becoming more common.

Therefore, precise methods of composite resin lay-

Therefore, composite resins can also be classified as

ering are needed to ensure correct optical properties

VITA-based or non-VITA-based. Dentin shades are

that match the adjacent teeth. The translucency, value,

always chromatic whether or not they use the VITA

and chroma can be controlled by manipulation of dif-

system. Conversely, enamel shades can be chromatic

ferent thicknesses of dentin and enamel masses and

VITA-based (eg, Filtek Supreme Ultra, IPS Empress Di-

shades during layering.

QDT 2013

Fig 16 Translucency of the dentin shade decreases as the thickness increases.

84

24

A3D + A2D 18

A3D + A2D

Al D

A3D 71 -

se

1.0 mm

1.5 mm

2.0 mm

Thickness

Fig 17a Influence of the thickness of different dentin shades on chroma.

Dentin Layering

0.5mm

1.0 818. 1

1.5 mm

Thickness

Fig 17b Influence of the thickness of different dentin shades on value.

enced by the amount of fillers, filler size, scattering coefficient, and light reflectivity. Composite resins with

Dentin shades are effective in blocking the translu-

lower filler content will have a lower value than those

cency and increasing the opacity of a restoration. The

with higher filler loading due to the limited light scat-

thickness of the restorative material is crucial for a

tering. The smaller the mean filler size of a composite

natural-looking final result. 19 The translucency of the

resin, the higher its value. Clinically uncontrolled

dentin shade decreases as the thickness increases (Fig

opaque dentin layering results in a final restoration

16). This phenomenon may be desirable in large res-

with a lower value than that of the adjacent teeth.

torations.

Therefore, chromaticity must be taken into consider-

When a change in thickness occurs, three main fac-

ation when restoring missing dentin substrate.

tors are simultaneously affected: translucency, value,

To overcome such a color mismatch, the dentin

and chroma. For dentin shades, chroma remains rela-

shade layers must be applied with varying chromaticity

tively stable as the thickness increases (Fig 17a), but the

(Fig 17b). The clinical application of this technique is

value decreases drastically (Fig 17b). This decreased

shown in Figs 18 to 22. A thin layer (0.5 to 1.0 mm) of

value is a result of dispersion of luminous energy, lower reflection, and a decrease in translucency. 20—21 Value

dentin shade (Fig 20b) must be applied before the

and translucency are narrowly correlated and highly

main shade is placed. The differences in radiance and

dependent on the thickness. Value is greatly influ-

index of refraction of this underlying dentin layer assist

a dentin shade with a higher chroma than the main

ODT 2013

1

18a

118b

19a

19b

120a

12013

120c

Fig 1 8a Preoperative view of a defective composite resin restoration on the maxillary right central incisor. Fig 1 8b Grayscale image showing the value of the restoration and surrounding teeth.

Figs 19a and 19b Close-up views of the central incisors. Figs 20a to 20c (a) Using a polyvinyl siloxane template, the lingual enamel (0.5 mm) was reproduced with a highly translucent and opalescent nanofilled composite resin (Filtek Supreme Ultra Clear Translucent). (b) A thin layer (0.5 mm) of opaque dentin with a higher chroma (A3D) was used to block the lingual enamel's translucency. (c) A dentin shade with a lower chroma and high value (A2D) was applied over the deep dentin (A3D).

21b

121a 22a

22b

Fig 21 a Restoration after polishing (enamel: Filtek Supreme Ultra Al E). Fig 21 b Grayscale image showing the similar value of the restoration and neighboring tooth. Figs 22a and 22b Final outcome showing the importance of dentin shade stratification to obtain the correct (a) translucency, chroma, and (b) value.

DUARTE ET AL

23a

23b

Fig 23 Translucency variation according to thickness for (a) chromatic and (b) achromatic enamel shades.

the superficial dentin layer (Fig 20c) in sustaining its

matic and achromatic enamels, respectively, at differ-

original brightness. The use of dentin shades with dif-

ent thicknesses. The translucency of chromatic enamel

ferent chroma at different thicknesses ensures the cor-

is susceptible to variations in thickness. At 0.5 mm,

rect final dentin value.

chromatic enamel shades are highly translucent, whereas at 1.0 mm, a decrease in translucency is observed. This explains why modulation of the enamel layer

Enamel Layering

thickness is so important to obtain the correct translucency. Changes in translucency are barely perceptible

Light scattering is a result of refraction and reflection

from 0.5 to 1.0 mm for achromatic enamel. Minimal

of light at the interface between the resin matrix and

differences in translucency can be observed when

fillers. Composite resins with a smaller mean filler size

comparing chromatic and achromatic composite res-

are able to scatter more light than those with large par-

ins at 0.5 mm of thickness. However, at 1.0 mm of

ticle sizes, but the chroma is not affected either way.

thickness, it is evident that achromatic enamel is more

Conversely, the resin matrix is responsible for most op-

translucent than chromatic enamel. The translucency

tical absorption. Therefore, the chromaticity of com-

of both achromatic and chromatic enamel shades at

posite resins results from pigments added to the or-

1.5 mm is clinically unacceptable.

ganic component.

For VITA-based chromatic enamel shades, the in-

Translucency, value, and chroma are also rigorously

crease in thickness also results in a change of the main

and intimately correlated in the composite resin enam-

VITA shade (Fig 26)." This means that an Al enamel

el shade. 22 A severe discrepancy in the optical prop-

becomes A2 at 1.5 mm and A3 at 2.0 mm. Microfilled

erties of a restoration is likely to be observed when

and nanohybrid composite resins are more affected by

the thickness of the enamel shade is not properly con-

such changes in VITA shade, whereas nanofilled com-

trolled during layering.

posite resins are less susceptible to these changes. 22

The translucency of both chromatic and achromatic

Therfo,itsmpavehVITA-bsdcromati

enamel shades decreases as thickness increases (Fig 23).

enamel shades be applied at a maximum thickness of

The chroma of chromatic enamel shades increases as

1.0 mm.

thickness increases, 22 whereas chroma remains un-

Clinically, it can be extremely challenging to obtain

changed for achromatic enamel shades (Fig 24a). Con-

a 1.0-mm-thick enamel layer. The use of a layering

versely, value decreases considerably for both chro-

technique in which the clinician can control the indi-

matic and achromatic enamel shades as thickness increases (Fig 24b). 2022 These phenomena explain why

vidual thickness of each layer is vital for esthetic suc-

many clinicians find it difficult to work with direct com-

ideal enamel thickness while also ensuring correct op-

posite resin.

tical properties.

Enamel shades are used to replace natural enamel

cess. Figures 27 to 34 illustrate a technique to obtain

Enamel layering must always be initiated at the inter-

and cover exposed or artificial dentin. Figures 25a and

proximal contact. Restoring the interproximal contacts

25b show a chromatic dentin shade layered with chro-

via enamel layering ensures the appropriate interproxi-

MT 2013

Achieving the Ultimate Optical Properties of Composite Resin

Chromatic enamel

70

61

Chromatic enamel 72

76

E

E 0 36 -

Achromatic enamel Achromatic enamel

18

61

0.5 mm

0.5 mm

1.O mm

1 5 mm

1.0 mm

2 0 mm

Thickness

1 5 mm

2 0 mrn

Thickness

24b

24a

25b

0.5 mm

126a

26b

t

mm

1.0 mm

1 .0 mm

1.5 mm

1.5 mm

2.0 mm

2.0mm

Fig 24 Influence of the thickness of chromatic and achromatic enamel shades on (a) chroma and (b) value. Fig 25 Artificial dentin covered with (a) chromatic and (b) achromatic enamel shades of different thicknesses. Fig 26 (a) Chroma and (b) value variation according to thickness for chromatic enamel shades.

ODT 2013

E.

28b

29b

29c

Fig 27 Preoperative views of a defective composite resin restoration on the maxillary right central incisor.

Fig 28 Close-up views of the central incisors.

Fig 29 (a) The defective restoration was removed. (b) All sharp angles were smoothed with a coarse aluminum oxide disk. (c) Smooth finishing lines favor better optical integration with translucent composite resins.

32a

32b

Fig 30 (a) Artificial dentin was placed and extended over the enamel to conceal the finishing margins. (b) Opalescent composite resin was applied along the mamelons to improve light transmission at the incisal edge.

Fig 31 Enamel layering was initiated by restoring the interproximal contacts. The interproximal transitional line angles must be clearly defined and have a 1.0-mm maximum thickness.

Fig 32a Final outcome after polishing. Note the differences in translucency obtained by modulating the thickness of the enamel layer. Fig 32b Grayscale image showing the adequate value of the restoration compared to the natural dentition.

Achieving the Ultimate Optical Properties of Composite Resin mal translucency and provides the clinician with visual evidence regarding the remaining facial thickness of the enamel layers. After the interproximal contacts are restored, the interproximal transitional line angles will be clearly visible (Fig 31). The artificial interproximal transitional line angles must have a maximum thickness of 1.0 mm (Fig 31). The clinician can then measure the line angle thickness and fill in the space between the two line angles with the proper amount of enamel layering. This technique allows for determination of the correct thickness of the overall enamel layer and offers ideal translucency, value, and chroma. In addition, this technique can be used for multiple anterior restorations when the tooth shape needs to be adjusted.

5. Ruddell DE, Maloney MM, Thompson JY. Effect of novel filler particles on the mechanical and wear properties of dental composites. Dent Mater 2002;18:72-80. 6. Ferracane JL. Current trends in dental composites. Crit Rev Oral Biol Med 1995;6:302-318. 7. Ilie N, Nickel R. Resin composite restorative materials. Aust Dent J 2011;56(suppl 1):59-66. 8. Campbell PM, Johnston WM, O'Brien WJ. Light scattering and gloss of an experimental quartz-filled composite. J Dent Res 1986;65:892-894. 9. Ferracane JL. Resin composite-State of the art. Dent Mater 2011;27:29-38. 10. Dietschi D, Campanile G, Holz J, Meyer JM. Comparison of the color stability of ten new-generation composites: An in vitro study. Dent Mater 1994;10:353-362. 11. Hervas-Garcia A, Martinez-Lozano MA, Cabanes-Vila J, BarjauEscribano A, Fos-Galve P. Composite resins. A review of the materials and clinical indications. Med Oral Patol Oral Cir Bucal 2006;11:E215-E220. 12. Braga RR, Ballester RY, Ferracane JL. Factors involved in the development of polymerization shrinkage stress in resincomposites: A systematic review. Dent Mater 2005;21:962-970.

CONCLUSIONS

13. Stoddard JW, Johnson GH. An evaluation of polishing agents for composite resins. J Prosthet Dent 1991;65:491-495.

Composite resins are highly sensitive to translucency,

14. Furuse AY, Gordon K, Rodrigues FP, Silikas N, Watts DC. Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging. J Dent 2008;36:945-

value, and chroma. Composite resins containing adequate amounts of nanoscale filler as well as increased filler loading are ideal for anterior esthetic restorations. Controlling the thickness of the dentin and enamel layers is essential to obtain a lifelike restoration.

952. 15. Botta AC, Duarte S, Jr., Paulin Filho PI, Gheno SM, Powers JM. Surface roughness of enamel and four resin composites. Am J Dent 2009;22:252-254. 16. Ilie N, Nickel R. Investigations on mechanical behaviour of dental composites. Clin Oral Investig 2009;13:427-438. 17. Mitra SB, Wu D, Holmes BN. An application of nanotechnology in advanced dental materials. J Am Dent Assoc 2003;134:13821390.

REFERENCES

18. Colorimetry: Official Recommendations of the International Commission on Illumination. Vienna, Austria: Commission Internationale d'Eclairage, 1971.

1. Chung CM, Kim JG, Kim MS, Kim KM, Kim KN. Development of a new photocurable composite resin with reduced curing shrinkage. Dent Mater 2002;18:174-178.

19. Duarte S Jr, Perdigao J, Lopes M. Composite resin restorationsNatural aesthetic and dynamics of light. Pract Proced Aesthet

2. Atai M, Nekoomanesh M, Hashemi SA, Amani S. Physical and mechanical properties of an experimental dental composite based on a new monomer. Dent Mater 2004;20:663-668.

20. Schmeling M, Meyer-Filho A, de Andrada MA, Baratieri LN. Chromatic influence of value resin composites. Oper Dent 2010; 35:44-449.

3. Lu H, Stansbury JW, Nie J, Berchtold KA, Bowman CN. Development of highly reactive mono-(meth)acrylates as reactive diluents for dimethacrylate-based dental resin systems. Biomaterials 2005;26:1329-1336.

21. Lee YK. Influence of scattering/absorption characteristics on the color of resin composites. Dent Mater 2007;23:124-131.

4. Ikejima I, Nomoto R, McCabe JF. Shear punch strength and flexural strength of model composites with varying filler volume fraction, particle size and silanation. Dent Mater 2003;19:206-

Dent 2003;15:657-664.

22. Duarte S Jr, Oliveira ALBM, Phark J. Influence of enamel layering thickness on chroma, value, and VITA shade for esthetic composite resin restorations. Am J Esthet Dent 2011;1:158168.

211.

Fig 33 Opalescence of the final restoration. Fig 34 Close-up views showing the (a) natural translucency and chroma due to the use of layering modulation and (b) importance of the use of proper thicknesses during enamel layering.

DDT 2013

57

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Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

Leonardo Bacherini, DDS' Myra Brennan, DMD 2 Leonardo Bocabel a, CDT 3 4 PaolVign,CDT

M

inimally invasive treatment of a severely dis-

ficial tooth and discolored abutment will directly influ-

colored dentition using ceramic restorations

ence the extent of the tooth preparation and the selec-

is a complex process that should begin with

tion of the ceramic/ingot material. Achieving an optimal

fabrication of a cast to design the precise contours of

esthetic result using conservative techniques requires a

the future restorations. The relationship between the art-

comprehensive esthetic and functional analysis. 1-4 Fradeani and Bacherinis recently described the minimally invasive prosthetic procedures (MIPP) to conser-

'Private Practice, Sieci-Pontassieve-Firenze, Italy. 2 Private

Practice, Hingham, Massachusetts, USA.

vatively restore worn dentition. The principles of the MIPP treatment modality can also be applied to the

'Dental Technician and Ceramist, Sao Paulo, Brazil.

esthetic rehabilitation of severely discolored dentition.

—Dental Technician and Ceramist, Florence, Italy.

This article presents the step-by-step treatment of a

Correspondence to: Dr Leonardo Bacherini, Studio Odontoiatrico, P.zza Aldo Moro, 7, Sieci-Pontassieve (FI), 50065 Italy. Email: [email protected]; www.dentsign.it

patient with severely discolored teeth using monolithic lithium disilicate ceramic restorations and following MIPP principles.

QDT 2013

BACHERINI ET Al

MIPP PRINCIPLES

collect, organize, and synthesize the clinical findings. The laboratory checklist 14 was then used to convey

The principles of the MIPP modality can be described

the proposed restoration morphology, develop a di-

as follows:

agnostic wax-up, and fabricate an overlay cast of the restorations.

1

Increased vertical dimension of occlusion (VDO). By increasing the VDO, the extent of occlusal tooth preparation can be minimized; likewise, the remain-

Step 1: Esthetic and Functional Analysis

ing enamel can be conserved for adhesive bonding.

(Figs 1 to 6)

2. Reduced tooth preparation. By using high-strength monolithic lithium disilicate ceramic (IPS e.max

Following completion of the comprehensive examina-

Press, Ivoclar Vivadent, Schaan, Liechtenstein), the

tion and photographic analysis of the patient, an algi-

overall thickness of the ceramic restoration can be

nate impression of both arches, facebow record, and

reduced, thus minimizing the amount of tooth prep-

centric relation (CR) bite registration were taken to ar-

aration.

ticulate the study casts on a semi-adjustable articula-

3. Monolithic lithium disilicate posterior restorations.

tor. Based on the laboratory checklist, a 3-mm increase

Even with reduced thicknesses (0.8 to 1.0 mm),

in VDO in the anterior segment was deemed neces-

monolithic materials used in occlusion with a full-

sary prior to fabricating the diagnostic wax-up.

contour design are capable of providing sufficient strength in the posterior areas.

The key features revealed by the pretreatment analyses were as follows:

4. Adhesive bonding. Glass-ceramic restorations, which offer improved fatigue resistance in the oral environment, show increased bond strength when used in conjunction with resin-based luting cements. 6-13

— Severe tetracycline staining, requiring selection of an ingot capable of masking heavy discoloration. — Generalized occlusal wear, indicating the potential to increase the VDO. — No to minimal tooth display of the maxillary incisors at the rest position.

CASE REPORT

— Worn mandibular incisal edges visible during smil-

The 43-year-old male patient presented with a severe-

— Visible and acceptable maxillary gingival tissue pro-

ly discolored dentition due to tetracycline staining and generalized enamel wear due to parafunctional activity. He requested prosthetic treatment to improve the appearance of his smile. The esthetic and functional analysis checklist described by Fradeani 14 was used to

ing. file during smiling. — Acceptable interocclusal rest space and no signs/ symptoms of temporomandibular disorder. — Insufficient anterior guidance and posterior disocclusion.

Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

CASE REPORT

1

2a

2b

3a

3b

3c

Fig 1 Initial presentation. Note the severe tooth discoloration. Figs 2a and 2b No to minimal tooth display at the rest position. Figs 3a to 3d Progression of the smile.

3d

QDT 2013

61

BACHERINI ET AL

4a

4b

4c

5c

Figs 4a to 4c Tetracycline staining was very visible from the central incisors to first molars. Figs 5a to 5c Generalized incisal/occlusal wear and inadequate preexisting restorations were evident. Figs 6a to 6e Evaluation of the occlusion and occlusal views of the arches further emphasized the worn dentition.

6d

6e

62

QDT 2013

Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

19a

Figs 7a and 7b Diagnostic wax-up. Figs 8a and 8b Direct mock-up using a transparent matrix with flowable composite resin.

Figs 9a to 9c Esthetic evaluation of the smile with the direct mock-up. Note the tooth display in the rest position resulting from the increased incisal length. Fig 10 The increased VDO created additional posterior interocclusal rest space.

Step 2: Composite Resin Direct Mock-up of Anterior Teeth (Figs 7 to 10)

Key Elements: — The pin on the articulator was increased by 3 mm,

A diagnostic wax-up of the maxillary and mandibular

which in turn created approximately 3 mm of addi-

anterior teeth was completed, followed by fabrication

tional interocclusal space between the anterior teeth

of a silicone index. An intraoral mock-up of the pro-

and 1 mm of additional interocclusal space between

posed anterior restorations was made using flowable

the posterior teeth.

composite resin, and modifications were performed as necessary to improve the esthetics. A new facebow record and CR registration were taken with the anterior

— The maxillary incisal edges were increased in length to improve the esthetics and phonetics. 15 — The mandibular incisal edges were increased in height,

mock-up in place to serve as a jig, thus maintaining the

and the maxillary palatal surfaces were increased in

proposed VDO.

thickness. These changes promoted occlusion and esthetic visibility of the mandibular teeth.

QDT 2013

63

Figs 11 a to 11 c Fabrication of the acrylic resin overlay templates.

II

1

Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

12a

12b

13a

13c

Figs 12a and 12b Tooth preparation of the maxillary anterior teeth. Note the thickness of the provisionals after relining. Figs 13a to 13c Functional evaluation of the provisionals and anterior guidance.

Step 3: Acrylic Resin Overlay Template of Anterior and Posterior Teeth (Figs 11 to 15)

Key Elements: — Opening the VDO created additional 1 mm posterior

The original study casts were remounted with the ante-

interocclusal space for the restoration before tooth

rior mock-up and new CR record prior to finalizing the

structure was removed (0.5 mm in each arch).

diagnostic wax-up of the posterior teeth. An overlay template of the anterior and posterior teeth was fab-

— Selection of a monolithic lithium disilicate ceramic minimized the ceramic thickness to 0.8 mm.

ricated using acrylic resin to create the desired tooth

— Provisional overlay restorations bonded to unpre-

form and evaluate the new occlusal scheme and VDO. The anterior and posterior overlays were bonded to

pared teeth were used to evaluate the increased VDO.

the unprepared teeth and then adjusted. The new

— Patient and occlusion were evaluated at 1 month

VDO and CR position were reevaluated after 1 month.

prior to tooth preparation for final restorations.

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BACHERINI ET AL

14a

15a Figs 14a and 14b The new VDO in the CR position. Note the increased space in the anterior region. Figs 15a and 15b Provisional restorations showing canine guidance and adequate posterior disocclusion.

Step 4: Tooth Preparation and Pro visionalization (Figs 16 to 18) The 0.8-mm tooth preparation was performed through the acrylic resin posterior overlays. At the buccal aspect, the preparation extended to the cementoenamel junction (CEJ); however, at the lingual/palatal aspect, the preparation extended only halfway to the CEJ.

Key Elements: © The increased VDO provided 0.5 mm of additional space in each arch before tooth preparation. © Minimal occlusal reduction of 0.3 mm was performed, while preserving as much enamel as possible. © Partial-coverage restorations were planned to restore the cusps for function and buccal surfaces for esthetics.

66

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Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

17b

18a

0.8 mm occlusal reduction (0.5 mm mock-up + 0.3 mm enamel)

Lithium disilicate 0.8 mm of Monolithic ceramic

118b

Figs 16a and 16b Preparation of the posterior teeth. Figs 17a and 17b Lateral view of the posterior teeth after preparation. Figs 18a and 18b Schematic representation of the MIPP philosophy for posterior teeth.

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67

BACHERINI ET AL

1111111111 1 1 1 19a

JAN

Figs 19a to 19e Laboratory fabrication of the posterior partial-coverage ceramic restorations.

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Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

Figs 20a to 20c Final posterior restorations. Only the maxillary premolars were layered with enamel porcelain to blend in with the adjacent anterior crowns. Note the minimal thickness of the restorations.

Step 5: Monolithic Lithium Disilicate Posterior Restorations (Figs 19 to 25) The final impression for the posterior tooth prepara-

Key Elements: — Monolithic lithium disilicate restoration thickness: 0.8 mm.

tions was taken with the anterior provisionals in situ.

— When possible, a supragingival finish line was used

The monolithic partial-coverage ceramic restorations

to remain in enamel and facilitate adhesive cemen-

were fabricated, and a strict cementation protocol was

tation.

followed. 15

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23a

Fig 21 Posterior provisionals in situ prior to cementation of the definitive restorations. Figs 22a to 22d Preparation of the maxillary posterior teeth. Figs 23a to 23d Preparation of the mandibular posterior teeth. Note the amount of preserved enamel.

QDT 2013

Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

24d

Figs 24a to 24d Maxillary posterior restorations after cementation. Figs 25a to 25d Mandibular posterior restorations after cementation.

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BACHERINI ET Al

Figs 26a and 26b Definitive preparation of the anterior teeth using minimally invasive procedures. Note the amount of enamel at the palatal surface resulting from the increased VDO. Figs 27 and 28 Fabrication and try-in of different ceramic ingots. Note the differences in opacity. The two ingots selected for try-in were Low Translucency BL3 and Medium Opacity 1; the final choice was Low Translucency BL3 (IPS e.max Press).

Step 6: Bilayered Lithium Disilicate Anterior Restorations (Figs 26 to 31)

Key Elements: © Multiple ingots were tried in to identify the ingot

The final impression for the anterior tooth preparations

with sufficient opacity to mask the severe discolor-

was taken with the definitive posterior restorations in

ation and recreate the optical appearance of a natu-

situ. Maxillary bilayered crowns and mandibular bilayered veneers were fabricated from lithium disilicate

ral tooth. © Careful communication with the laboratory and ex-

and cemented following a three-step adhesive bond-

pert technical skills of the ceramist are necessary to

ing protocol. 15

create beautiful anterior restorations with minimal thickness.

113 QDT 2013

Esthetic Rehab

ation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

0.6 Ingot LT BL3

0.5 Feldspathic ceramic

Figs 29a and 29b Layering process for the anterior restorations (veneers in the mandible and minimally invasive crown in the maxilla). Note the surface texture and the opalescence at the marginal area. Fig 29c Schematic representation of the MIPP philosphy for anterior teeth. Figs 30a and 30b Intraoral views of the abutments at the day of cementation. Figs 31a and 31b Definitive anterior restorations after cementation.

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BACHERINI ET Al

Figs 32a to 32j Intraoral views of the definitive restorations. Note the esthetic, functional, and biologic integration of the restorations. The close-up of the anterior restorations at high contrast (Fig 32j) allows better appreciation of the work of the technician (Leonardo Bocabella).

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Esthetic Rehabilitation of a Severely Discolored Dentition with Minimally Invasive Prosthetic Procedures (MIPP)

33b

Figs 33a and 33b Final tooth display at rest.

Figs 34a to 34c Progression of the final smile.

Figs 35a and 35b Final appearance of the patient with his new smile.

Step 7: Functional and Esthetic Integration (Figs 32 to 35) The occlusion was checked for simultaneous contact in the maximal intercuspal position as well as for anterior guidance and posterior disocclusion. The ceramic restorations masked the discoloration of the underlying teeth and integrated naturally with the patient's face.

Key

Elements:

— Comprehensive functional and esthetic analysis prior to treatment. — Clear laboratory communication and transfer of information. — Technical expertise and collaboration between the dentist and technician.

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BACHERINI ET AL

CONCLUSIONS It is a significant challenge to provide esthetic and lifelike ceramic restorations using conservative techniques; however, high-strength ceramic materials with excellent optical properties, such as lithium disilicate, have made this goal possible. Lithium disilicate restorations can be fabricated with minimal thicknesses to allow for limited tooth reduction. Further, this type of ceramic can be adhesively bonded to the preserved enamel. The MIPP approach aims to conserve enamel structure while providing excellent esthetic results and maintaining the strength of the ceramic restorations. If the clinical and laboratory protocols are carefully followed, esthetic, functional, and long-lasting restorations can be achieved.

REFERENCES 1. Van Noort R. Introduction to Dental Materials, ed 2. St Louis: Elsevier, 2007. 2. McLean JW, Hubbard JR, Kedge MI. Science and Art of Dental Ceramics. Chicago: Quintessence, 1979. 3. Chaiiyabutr Y, Kois J, LeBeau D, Nunokawa G. Effect of abutment tooth color, cement color, and ceramic thickness on the resulting optical color of a CAD/CAM glass-ceramic lithium disilicate-reinforced crown. J Prosthet Dent 2011;105:83-90.

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QDT 2013

4. Fradeani M. Esthetic Rehabilitation in Fixed Prosthodontics: Esthetic Analysis. Chicago: Quintessence, 2004. 5. Fradeani M, Bacherini L, Brennan M. Esthetic rehabilitation of a severely worn dentition with minimally invasive prosthetic procedures (MIPP). Int J Periodontics Restorative Dent 2012;32:135-137. 6. Stappert CF, Chitmongkolsuk S, Silva NR, Att W, Strub JR. Effect of mouth-motion fatigue and thermal cycling on the marginal accuracy of partial coverage restorations made of various dental materials. Dent Mater 2008;24:1248-1257. 7. Rosenblum MA, Schulman A. A review of all-ceramic restorations. J Am Dent Assoc 1997;128:297-307. 8. Kramer N, Frankenberger R. Clinical performance of bonded leucite-reinforced glass ceramic inlays and onlays after eight years. Dent Mater 2005;21:262-271. 9. El-Mowafy 0, Brochu JF. Longevity and clinical performance of IPS-Empress ceramic restorations-A literature review. J Can Dent Assoc 2002;68:233-237. 10. Pallesen U, van Dijken JW. An 8-year evaluation of sintered ceramic and glass ceramic inlays processed by the Cerec CAD/ CAM system. Eur J Oral Sci 2000;108:239-246. 11. Della Bona A, Anusavice KJ, Shen C. Microtensile strength of composite bonded to hot-pressed ceramics. J Adhes Dent 2000;2:305-313. 12. Sindel J, Frankenberger R, Kramer N, Petschelt A. Crack formation of all-ceramic crowns dependent on different core build-up and luting materials. J Dent 1999;27:175-181. 13. Li ZC, White SN. Mechanical properties of dental luting cements. J Prosthet Dent 1999;81:597-609. 14. Fradeani M. Esthetic Rehabilitation in Fixed Prosthodontics: Prosthetic Treatment. Chicago: Quintessence, 2008. 15. Bacherini L, Brennan M. Esthetic rehabilitation of compromised anterior teeth: Prosthetic treatment of an orthodontic case. Quintessence Dent Technol 2012;32:7-28.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge? $0,

Galip GOrel, DDS, MS' Adriano Shayder, CDT2 3 BraulioPc,DS ichacho, DMD 4

t

sthetic dentistry is a delicate combination of sci-

dental team must then incorporate their own personal

entific principles and artistic abilities. Mathemati-

artistic abilities and their subjective feelings into cre-

cal parameters used by the dentist and the lab-

ating a smile. The creativity of the procedure makes

oratory technician combine to produce an attractive

each treatment unique and the dentist's job pleasingly

esthetic appearance. However, these geometric laws

varied and rewarding.

must not be used mechanically but rather should act

As

the popularity of esthetic dentistry increases,

as guidelines for each individual clinical restoration. 1-3

growing numbers of patients are seeking treatment

Because general esthetic rules are not entirely ob-

for the improvement of unesthetic anterior dentition.

jective, the dentist must also consider the subjective

Whereas patients previously focused on the mere res-

concerns of the character and the inner being of the in-

toration of traumatized, periodontally involved, or cari-

dividual patient when designing the new natural smile.

ous teeth, today the focus has shifted to treatment for

Taking these criteria into account, the dentist and the

enhancement of the esthetic appearance of existing healthy teeth as well. In addition, the professional approach to dentistry has changed dramatically. Acceleration in the development of dental ceramic systems,

'Private Practice, Istanbul, Turkey; Visiting Professor, New York University, New York, USA. 2 Dental 3 Private

Technician, Sao Paulo, Brazil. Practice, Barbacena, Brazil.

'Professor, Department of Oral Rehabilitation, Faculty of Dental Medicine, Hebrew University, Jerusalem; Private Practice, Tel Aviv, Israel. Correspondence to: Dr Galip Gurel, Te€vikiye Cad Bayer Apt no. 143 Kat:6, Nisantasi 34365, Istanbul, Turkey. Email: [email protected]

bonding materials, and CAD-CAM (computer-aided design, and computer-assisted manufacturing) technologies has made conservative tooth preparation and restorative procedures controllable in a way never before imaginable. Digital dentistry has also been changing the profession. Diagnosis, treatment planning, dental procedures, and the laboratory technical phases are all being reshaped by the many aspects of digital CAD/CAM

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OPEL ET AL

Fig 1 The patient's short maxillary anterior teeth cannot be seen with lips at rest position.

dentistry as more and more dentists adopt this meth-

of artistic visual language with disciplines such as psy-

odology. Advances in the milling of block materials

chology, neurobiology, anthropology, and sociology.

have significantly increased clinical reliability, efficien-

Visagism makes it possible to determine which emo-

cy, economy, and esthetic results in both the clinical

tions and personality traits patients wish to express

and laboratory applications of CAD/CAM. These new

through their appearance and, specific to dentistry,

techniques enable the clinician to achieve esthetic im-

through their smiles. The aim is to create a smile design

provements and more predictable, esthetically pleas-

that expresses the patient's personality and lifestyle,

ing results. Some of the more progressive dental

ensuring harmony between the restorations and the patient's physical appearance, values, and attitudes. 56

schools have been implementing CAD/CAM in their curriculum, and most probably these young dentists will not even know how to treat a patient without having these technologies as an adjunctive tool.

A mock-up is a method for creating the length, position, volume, and shape (as well as the surface texture in specific indications) of the teeth to be restored or the Esthetic procedures have the ability to alter the entire

new smile design in three dimensions (3D) directly in

appearance of the patient by providing them with an

the patient's mouth.' In today's esthetic dental world,

attractive smile. Patients gain not only an improved

it is almost impossible to assess the final structural and

appearance but also a potential morale boost that acts

esthetic result without a mock-up, especially from the

positively on their mental health and self-esteem. Any

patient's point of view. This procedure requires precise

high-end esthetic restoration must take into account

knowledge of the tooth anatomy along with intuition,

the personality of the patient and interpret and inte-

sensitivity, and a good perception of the patient's indi-

grate it into the procedure. 4 The importance of psy-

vidual personality (Figs 1 to 3).

chological factors that may enhance or detract from

A mock-up assumes even greater importance when

the esthetic appearance should never be underesti-

porcelain laminate veneers (PLVs) are being designed

mated.

because of their relative thinness and the need for a

In dentistry, visagism is a novel concept that ap-

conservative preparation approach, since the tooth

plies the principles of visual art to the composition of

preparation will be determined directly by the position

a customized smile. Visagism involves the creation of a

and volume of the definitive restoration.' Also, during

customized personal image that expresses a person's

the buildup of the mock-up, the more additive the ap-

sense of identity. The method used to apply this con-

proach, the more minimally invasive it will be.

cept is derived from the association of the principles

78

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Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge?

2b

2c

3a

3c

Fig 2a to 2c The patient's short lateral and central incisors (and diastema that did not please him). Together with the incisal attrition, the teeth went through passive eruption over the years, shifting the gingival level coronally. Fig 3a Incisal attrition extends to the palatal surface, which also needs to be covered with the definitive restorations. Fig 3b Due to ongoing eruption of the teeth and full contacts, space needs to be created for the restorations to partially cover the affected palatal surfaces of the teeth. Fig 3c Orthodontic treatment was initiated to intrude the maxillary anterior dentition to open space between the maxillary and mandibular incisors as well as align the soft tissues. Fig 3d After orthodontic treatment there is adequate space between the incisors. The smile was re-evaluated, and PLV restorative treatment was chosen to improve the proportions and optical properties of the six maxillary anterior teeth.

QDT 2013

GORE' ET Al Fig 4 Direct mock-up placed on the teeth after orthodontic treatment defines the new incisal edge position and the facial contours. Figs 5a and 5b Full-face smile photos before and after mock-up.

80

Starting Point: Incisal Edge Position

Tooth Morphology and Surface Texture

The position of the incisal edge acts as the parameter

The challenge to emulate nature and establish oral

upon which the rest of the design is built. Elongation

harmony is an extraordinarily complex issue, particu-

of the incisal edge is often indicated to correct incisal

larly in anterior restorations. Knowledge of the inter-

wear, inadequate tooth display, or a displeasing tooth

play of shape, function, and surface texture is the basis

or crown proportion. Once it is set, the incisal edge

for esthetically appealing restorations and will have an

serves to determine the proper tooth proportion and gingival level, making it especially important. Several

immediate effect on the integration with the surrounding gingiva. 4,10-14

teeth should serve as the reference line for the cor-

Surface texture interrelates with the size, shape, and

rect incisal edge position of the treated teeth. How-

position of the teeth. In esthetic restorations, the sur-

ever, the incisal edge of the maxillary central incisor is

face texture of the anterior teeth and their enamel,

the first determinant in the creation of the new smile

which becomes abraded over time, are important fac-

design.

tors to consider.

Determining the incisal edge position is critical be-

Once the incisal edge position is defined, the tooth

cause it will affect the whole design and proportion

morphology and surface texture should be built up

of the mock-up in three dimensions, and therefore it

with an additive approach. This will not only be a great

must be verified both vertically and horizontally. For

tool for dentist-patient communication but also will

example, the horizontal (buccolingual) component of

help the ceramist tremendously either for the wax-

the mock-up will directly affect the facial contouring of

up or subsequently in the porcelain buildup. The pa-

the new teeth design (Figs 4 and 5). 9

tient will have a better understanding of the potential

QDT 2013

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge?

Fig 6 The wax-up is created based on the mock-up data.

shape, form, texture, and alignment of the final design

This concept was introduced as the aesthetic pre-

as well the new lip posture. 15,16 And if both the patient

evaluative temporaries (APT) technique,' and it has

and the dentist are happy with this outcome, the teeth

proved to be extremely beneficial for addressing the

can be prepared through this mock-up.

key factors even before treatment has been initiated and, most importantly, for ensuring minimally invasive tooth preparation.

WAX-UP

Step 1: Evaluation of the APT The first step is to use the silicone index (duplicated

Once agreement about the general dimensions of the

from the wax-up) over the patient's teeth before the

design has been reached by the dentist (technically,

case is started. No tooth preparations have been done

ie, form, function, and esthetics) and the patient (es-

yet. Because the patient is not anesthetized, this cre-

thetics), this information is sent to the ceramist in the

ates a good opportunity for the dentist, patient, and

form of conventional alginate, elastomeric, or digital

ceramist to evaluate the esthetic, phonetic, and func-

impressions accompanied by clinical photographs and

tional outcome, which will be identical to the planned

videos if necessary. One of the major considerations of

definitive restorations. 17-19

a ceramist should be to turn this mock-up into a wax-

If any alterations or changes are needed, they are

up following the exact guidelines that were provided

done at this stage to make sure the patient is com-

(Fig 6).

pletely satisfied with the final outcome. Even if no

In the past, a precise silicone index would be fabri-

changes are needed, it may even be very helpful not

cated from this wax-up, which in turn would be used

to start the treatment until the patient accepts this out-

for the fabrication of the provisional restorations (ie,

come instead of hoping the ceramist can create mira-

veneers, crowns, or acrylic shells). The provisionals

cles in the lab on a design the patient disliked from the

would allow the patient to "test drive" the esthet-

beginning (Figs 7 and 8).

ics, phonetics, and function of the new design. The problem is that occasionally the patient will be dis-

Step 2: Tooth preparations through the APT

pleased with one or more factors (esthetic, phonetic,

Because it ensures and mimics the planned final out-

or functional) after the dentist has completed the tooth

come and represents the planned final contours of the

preparation (mostly guesswork) and the impression

actual restorations, the major advantage of using the

making. To avoid this problem, the authors conceived

APT is that the dentist can prepare the teeth directly

the idea of using these provisionals in two additional

and very precisely through it. 2• The facial thickness

clinical steps, not only for the provisionals to be made

of the APT and the use of depth cutters (the depth

but even before the treatment planning is completed.

of which will depend on the color changes that are

QDT 2013

GO

GORE ET AL Figs 7a and 7b A silicone index is fabricated from the wax-up, and the inside is filled with flowable self-cure composite resin (DMG Luxatemp Star, Hamburg, Germany), to be placed in the mouth as an APT.

7a

8b

1 8c

18d

Fig 8a The thin shell and the APT in the patient's mouth before polymerization. Note that as yet there have been no injections or tooth preparations carried out. Fig 8b If necessary, the APT can easily be removed from the mouth since it has not been bonded to the teeth. The additive design in this case means that preparations will be less invasive. Figs 8c and 8d The patient with the new APT. Since no anesthesia was used, it is easy to evaluate the esthetic integration of the new smile design and the patient's facial features.

planned) will dictate the amount of facial reduction

ing the ultimate esthetic dental approach should never

that is needed. With this technique, the dentist will

forget that a critical factor concerning the nature of ce-

avoid any unnecessary loss of enamel and dentin as-

ramic restorations is that they cannot be thinned down

sociated with excessive tooth preparation and be able

or shortened without impacting the outer surface, in-

to perform the ideal preparation depth and volume

cisal edge, or general esthetics of the restoration (Figs

for the intended restoration production. Those seek-

9 to 11).

QDT 2013

Figs 9a to 9h Preparation of the teeth through the APT.

9a

9b

9c

90

1 9e

9h Fig 9a APT over the untouched tooth surfaces. Fig 9b The depth cutter is used through the APT. Fig 9c The thickness of the depth cutter is indicated by the color markings, which will be directly related to the thickness of the planned PLVs. Fig 9d Vertical incisal edge depths are created for the butt joint incisal design. The horizontal depths were marked with a pencil to orient the exact depth for the final facial preparation after the APT is removed. Fig 9e Partially removed APT from the left side of the incisors demonstrates the minimally invasive approach. Note that even though a 2-mm depth was created vertically through the APT's incisal edges, there are no preparation marks on the teeth. Fig 9f When the entire APT is removed, the areas that need further preparation are easily detected. The pencil markings will guide the dentist in the minimally invasive facial preparation. Fig 9g Facial tooth reduction should be continued only until the pencil marks disappear, indicating that the depth needed for the porcelain thickness has been reached. Fig 9h Facial and incisal preparation are roughly completed.

GUREL ET AL

10b

11a

11c

11d

Figs 10a and 10b Due to the incisopalatal attrition, the preparation borders need to be extended just beyond these areas. Figs 11 a and 11 b Invested and pressed e.max (Ivoclar Vivadent, Schaan, Liechtenstein) cores for the monolithic

application.

Fig 1 1 c Finished pressed monolithic veneers (e.max LT Al). Note the supragingival margin location, making margins almost invisible from a speaking distance even with lips retracted. Figs 11d to 1 1 f Integration with the lips.

QDT 2013

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge?

11g

11h

Fig 11g Close-up view. Ceramist: Hilal Kuday, Istanbul, Turkey. Fig 11 h Postoperative smiling patient.

ENTERING THE DIGITAL ERA We can all take advantage of today's high-tech tools in

a conventional impression, this mock-up is then sent to the laboratory via digital scanning together with the

our daily esthetic treatments. Digital impression mak-

original digital impression of the patient's preoperative situation.

ing (in place of conventional elastomeric impressions)

On the other side of the computer®whether that

and CAM techniques are now widely available. Yet we

means next door or in another city or even continent®

still need to create our smile design in the patient's

the ceramist receives the virtual data in a matter of

mouth via mock-ups, laboratory wax-ups, and the APT

minutes via the Internet. This eliminates all the prob-

for an exacting final outcome and tooth preparation

lems of transporting the silicone impressions, stone

guide. With the restoration of six teeth, we can com-

casts, and facebow transfers, which under normal cir-

pletely plan and create a new smile design (Figs '12 to 17). 21

cumstances would take at least a day if not more.

High-Tech Digital Dentistry

Three-Dimensional Printing In today's high-tech world, we are not only able to

Following basic esthetic principles, we start designing

email 3D images, we also have access to 3D printing

the case in the patient's mouth with the mock-up, which

of the virtual images that we have emailed. Thus, the

already creates a very positive change in the patient's

digital impressions of the patient's existing teeth and

facial appearance. One of the most challenging tasks

the mock-up can be printed in 3D in the ceramist's vi-

in esthetic rehabilitation is establishing a harmonious distribution of tooth shapes, sizes, and proportions.

cinity, as if the actual stone casts are sent to or poured by him.

Maxillary anterior teeth are considered the key ele-

The associated sharing of stereolithography (STL)

ments in a pleasant smile. Some studies have shown

files creates an instant collaboration between the den-

differences in the widths, lengths, and width-length

tist and laboratory. STL is an interchange file format

ratios of maxillary anterior teeth. 21 Instead of making

used for rapid prototyping technology to produce

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11 3

12

115

14

16

Figs 12 and 13 The patient exhibits short maxillary incisors and crowded dentition in both arches.

Fig 14 Orthodontic treatment was carried out for 9 months to align the teeth and move them to their ideal position. Fig 15 After orthodontic treatment, the situation is re-evaluated for the PLV restorations.

Fig 16 Before the mock-up, the intended outcome is double-checked with the digital smile design concept. Fig 17 The mock-up in the patient's mouth, defining the final length and facial contours of the intended PLVs. 17

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Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge?

118c Fig 18a The mock-up design is transferred to the laboratory as virtual data in a matter of minutes via the Internet. The ceramist can print this in a 3D printer to obtain the same mock-up model in real sizes®important especially if a cutback/layering technique is to be used. Figs 18b and 18c The wax-up is more refined by using the dimensions of the mock-up as a reference.

3D parts. It allows CAD software to communicate to

die assembly, margin trimming, and articulation. How-

the additive manufacturing systems, much like a PDF

ever, the disadvantage of these 3D printers, for now, is

does in 2D printing. These systems allow the user to

their price tag, which can range from $10,000 to more

transmit the data file via email in an STL format for

than $100,000.

fabrication of accurate, articulated CNC 5-axis milled

Once the 3D printing is completed, the ceramist

or stereolithographic (SLA) plastic polymer models for

can easily start to build the wax-up using conventional

fabrication of dental restorations.

techniques (Figs 18a to 18c), paying close attention to

The advantages of 3D printing are obvious: no need

all the details such as tooth morphology and texture,

for mixing and pouring of dental stone into the impres-

and then either ship or email it (through 3D printing)

sions, and no bubbles or inaccuracies in the stone cast.

to the dentist.

Also, savings are realized by the reduced amount of

The wax-up needs to be transferred to the mouth

packaging needed and its associated shipping costs.

so that the APT can be verified by the dentist and the

The dentist is relieved of the tasks of model base and

patient. Because this wax-up is so similar to the first

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120

Fig 19 APT, which is an exact copy of the wax-up, is produced and placed over the unprepared teeth before the patient is anesthetized. This is the best time to evaluate all aspects of the smile.

Fig 20 Patient smile prior to preparation of the teeth: pretreatment, mock-up, after wax-up and APT. Fig 21 Final preparations through the APT. Note the minimal invasiveness of the prepared incisors, where only the finishing configuration is more pronounced. The canines were kept prep-less.

mock-up previously verified by the patient, esthetic

will be aware of the subtle changes in 3D. A major

problems rarely arise. However, if the patient or the

advantage of using the APT is to ensure that the final

dentist is not happy with this outcome, simple altera-

outcome is accepted by both the dentist and the pa-

tions can be made until both are satisfied with the

tient (Figs 19 and 20).

result. This will require rescanning so that the ceramist

88

ODT 2013

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge? Fig 22 Digital impression is made of the prepared teeth from second premolar to second premolar with the new Omnicam camera.

Tooth preparations through the APT

sions, and for clinicians it eliminates one of the most

The teeth can be prepared very precisely through the

tedious and error-prone experiences of the dental

APT since it represents the final contours of the actual

visit. Digital scanning results in lower overall expens-

restorations. The exact facial thickness can be verified

es for the dentist due to a more efficient workflow,

with the help of a silicone index. The facial thickness

elimination of the need for remakes, and less material

of the APT and the use of depth cutters through it

usage. With intraoral digital impressions, there is no

will dictate the necessary facial reduction. In this way,

need for an impression tray, tray adhesives, alginate,

the dentist will avoid the unnecessary loss of enamel

elastomeric impression materials, impression material

and even dentin associated with uncontrolled exces-

disinfection, or occlusal registration material. 27 They

sive tooth preparation and will be able to produce the

also eliminate the need for a staff member to secure

ideal preparation depth and volume for the restora-

the tray in position, time lost in waiting for materials to

tion production. The use of the APT is not limited to

set, and the additional lab and clinical steps required

preserving and exacting the final facial volume; it is

when sectional impressions are being used to register

also used to determine the exact incisal length and

a full arch. Digital impressions do not require the clini-

the amount of reduction that is necesarry at the incisal

cian to wait for an impression cast in dental stone to

edge. Reduction during the preparation should be car-

set; instead, an instant 3D replica is available as soon

ried out through the APT to ensure the exact prepared

as the recording is completed.

incisal edge position (Fig 21).

Currently there are several proven systems on the

After the teeth are prepared and the surrounding

market offering intraoral digital impression capabilities,

gingiva is stable and healthy, the impression can be

in which the virtual and actual worlds are being com-

made either by traditional means or digitally. The digi-

bined (see Fig 1): Lava Chairside Oral Scanner COS (3M

tal impression technologies currently available to the

ESPE, St Paul, Minnesota, USA), iTero digital scanner

dentist are satisfactory provided the exact conditions

(Align Technology, formerly Cadent, San Jose, California,

needed for traditional elastomeric impression making

USA), CEREC (Sirona, Bensheim, Germany), and E4D

are provided (ie, healthy nonbleeding supporting tis-

Dentist (D4D Technologies, Richardson, Texas, USA).

sues, moisture control, retraction cords if necessary,

The CEREC system, with its Omnicam, for instance,

etc). Under these ideal circumstances, the digital im-

offers the dentist digital scanning of the anterior seg-

pression making captures the visible tooth and tissue

ment from second premolar to second premolar in less

in detail, matching or even surpassing the capabilities

than 30 seconds, in full color and with no need to use

of elastomeric impression materials. 22-26

a powder. The same procedure and timing can be applied to the opposing arch as well, and then the occlusion is registered digitally (Fig 22).

Advantages of Digital Impression Making

A virtual impression of the prepared teeth is emailed

to the lab. Meanwhile, the ceramist scans the wax-up

For patients, digital impression making avoids what of-

model (already approved by the patient in the form

ten turns into the taking of multiple unpleasant impres-

of an APT) and superimposes the two on top of each

DDT 2013

GORR. ET AL.

123b Fig 23a The image is immediately sent via the Internet to the laboratory, no matter where in the world it is located. Fig 23b The wax-up, which is the foundation of the APT, is also digitally scanned either chairside or in the laboratory so every detail related to the final esthetic design is copied. Fig 23c The two images®the prepared teeth and the APT (wax-up)®are superimposed with special software. This will define the exact CAM procedure for the PLVs made out of e.max CAD ingots. Fig 24a The same procedure is animated by the Keynote software. Fig 24b Bonded CAD/CAM PLVs in the patient's mouth. Note the minimal cutback on the central incisor veneers, which are layered with feldspathic porcelain; monolithic CAD PLVs on the lateral incisors and on the prep-less canines. Fig 25a Close-up intraoral and full-face views of definitive restorations. Ceramist: Adriano Shayder, Sao Paulo, Brazil. Fig 25b Pre- and postoperative smiles.

other. As simple as that, the restorations are ready to

High-strength ceramics feature substantial flexural

be digitally milled from one of several choices of ma-

strength and fracture toughness compared to the old

terials (Fig 23).

esthetic ceramic materials. IPS e.max CAD (Ivoclar Vivadent, Schaan, Liechtenstein) was introduced in 2006

CAM procedure

as a lithium-disilicate CAD/CAM material with flexural

The materials to choose from include esthetic and

strength (360 MPa) two to three times that of feld-

high-strength ceramics, composite resins for both pro-

spathic ceramic materials, which is etched and adhe-

visional and definitive restorations, and nanoceramics

sively bonded to the tooth (Figs 24 and 25). 28-3•

(Lava Ultimate, 3M ESPE) that offer ease of handling and a glossy surface finish.

Lithium disilicate for use as a monolithic restoration in chairside CAD/CAM systems or as a core under feldspathic porcelain is available in block form in nine A®D shades, two translucencies, and four bleach shades.

QDT 2013

OPEL ET Al

EXPECTATIONS FOR THE NEAR FUTURE

The software is excellent for inlays, onlays, and full crowns in the posterior zone (premolar or molar site). Although it offers advantages in the anterior zone,

When attempting to deliver monolithic crowns or ve-

use of the Biogeneric software is limited to designing

neers specifically in the anterior zone, the challenge

a single central or lateral incisor in situations where the

to emulate nature and establish oral harmony is highly

contralateral tooth is intact. Its design capabilities are

complex, particularly if a new smile design is being es-

inadequate in situations where a contralateral tooth is

tablished. Knowledge of the interplay of shape, func-

missing or unesthetic, especially if the aim is the chair-

tion, and surface texture is the basis for esthetically

side fabrication of the monolithic crowns or veneers.

appealing restorations. Surface texture affects the size perception, shape, and position of the teeth, and yet with the current digital CAD/CAM technologies, each of these factors still depends on the clinician's and ce-

Anterior Single Tooth Restorations

ramist's expertise and in-depth knowledge of shape,

The CAD-CAM systems can be easily modified with

function, and surface texture of the teeth.

a library of different tooth morphologies, shapes, and

Although nearly all CAD software programs have

especially surface textures, including different vertical

integrated case management/tracking and design

and horizontal axes, that can be designed and config-

systems, unfortunately they are not yet equipped to

ured in their 3D forms. These new software programs,

create new smile designs and tooth shapes for the es-

with their very user-friendly and simple-to-deliver de-

thetic zone that look real. The options for the dentist/

signs, enable the dentist or ceramist to simply copy

ceramist are either to copy the adjacent teeth (which

and paste a 3D tooth design (changing their length-

may be adequate for single tooth replacements) or to

width ratio and sagittal positioning as necessary) over

possess the knowledge and skills necessary to design

the digitally scanned, nonprepared teeth to be re-

the restorations yourself.

stored for use as an actual esthetic test drive such as

For now, the high quality of the final esthetic results of CAD/CAM machining alone for the anterior maxilla

an APT, or on the prepared tooth for the final monolithic CAM procedures.

is not quite high enough, especially when milling and finishing of the monolithic restoration is completed chairside, because of the limitations of the existing software programs. Anterior teeth that are initially ma-

Multiple Anterior Tooth Restorations

chined, either with a chairside or laboratory CAD/CAM

Creating the new smile design in the anterior region

system, greatly benefit from the attention of skilled

with multiple restorations is one of the most challeng-

laboratory ceramists who can perform an additional

ing tasks in esthetic dentistry, whether it is performed

layering step. The monolithic veneers or crowns require

manually in the patient's mouth (ie, mock-up, wax-up,

either the dentist's or ceramist's artistic and esthetic

and APT) or digitally on a computer. Recently, two ma-

touches.

jor concepts were introduced to the world of esthetic

One of the advanced features available to dentists today is CEREC Biogeneric software (Sirona), which

dentistry: the digital smile design (DSD) conceptm" and visagism. 3334

takes the patient's intact tooth structure into account

The DSD concept is based on enhanced visual com-

and identifies the exact morphology of the missing

munication in daily treatment planning, better integra-

tooth structure using algorithms based on natural hu-

tion of the interdisciplinary team, and improved inter-

man tooth morphologies. The program collects exten-

action with the patient.

sive optic measurements of the preparation site and

Photographic and video facial esthetic analyses of

adjacent teeth, analyzing the patient's natural denti-

the patient are performed to understand the relation-

tion to create a crown proposal customized for the

ship of the teeth, gums, lips, and face in motion. With

individual patient. Measurements include mesial and

the use of a simple software program designed for

distal neighboring teeth as well as the opposing arch

slide presentations (Keynote for Mac or Powerpoint

dentition for the proper form, function, and occlusion.

for PC), these images are then manipulated to create

QDT 2013

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge? the digital smile design.The DSD is an attractive pre-

with the strength and surface finish of ceramics. Two

sentation of the treatment plan that can be shared with

types of composite resin blocks are available. One

other specialists through the Internet and shown to the

brand is designed for final restorations with higher fill-

patient. When combined with the APT, the DSD can

er ratios employing new filler strategies" and for per-

be transformed into something that can be tested and

manent indirect composite veneers. Lava Ultimate Re-

approved by the patient before the treatment itself begins. 31," Dedicated imaging software was recently

storative is a nanoceramic material available in eight

introduced (Dental Magic; dentalmaster.net ) that fur-

both CEREC AC and E4D chairside CAD/CAM system s."-43

ther facilitates the simulation/imaging of a new enhanced smile design.

shades in both low- and high-translucency forms for

The other marketed composite resin blocks (Vita

With the visagism concept, clinicians can design a

CAD-Temp, Vident; Telio CAD, Ivoclar Vivadent; Para-

smile that even further blends the patient's physical

digm MZ100, 3M ESPE), which are designed for long-

appearance, personality, and desires and translates

term provisional restorations, 44,45 also have the advan-

them into natural tooth shapes in psychodentofacial

tage of being able to be rapidly fabricated, adjusted,

harmony. When observing maxillary anterior teeth, a

and polished chairside. Within the parameters of the

number of reference lines should be considered, such

visagism concept, these composite resin blocks can

as those that unite the gingival zeniths, incisal embra-

easily be milled chairside in advance (based on a se-

sures, gingival papillae, and incisal plane. These lines

lection from a 3D digital library), tried in the patient's

are archetypal symbols, which means specific varia-

mouth, and positioned correctly in 3D. Upon accep-

tions in their composition will arouse different emo-

tance by the patient, the new design is digitally re-

tions in the observer. 5,33-36

corded and then the teeth are prepared through the

Clinicians must understand the emotional message

new APTs. Next, the prepared teeth are digitally re-

behind any smile design they create and should dis-

corded, and a virtual model of the prepared teeth is

cuss this aspect with the patient before treatment. Ver-

created. Superimposed over this virtual model will be

tical, horizontal, inclined, straight, and curved lines in-

the CAM design used to mill the earlier composites.

teract in infinite ways to create the diversity of natural

Monolithic PLVs or crowns can then be milled out of a

tooth shapes. These lines contain their own power of

wide array of porcelain blocks.

expression and emotional significance. If this concept were applied to the new upgraded software programs, which could automatically add the 3D value to the new smile design, it would be a significant improvement.

Advantages of Monolithic PLVs or Crowns

The dentist could then easily select the tooth forms,

Monolithic restorations created using a chairside

or even a combination of different tooth shapes," from

CAD/CAM system are fabricated from a single homo-

a 3D digital library and place them over the digital im-

geneous material rather than a bilayered restoration

pression of the existing dentition as an APT. In this way,

consisting of a coping base and a veneer layer. The

he or she could avoid the learning curve of reshap-

industrial material fabrication process provides a ho-

ing the tooth form and changing the texture using the

mogeneous, dense material without porosity or voids,

complex digital tools to lengthen, smooth, or add vol-

which maximizes the material's physical properties. 4',"

ume, as proposed by the existing software programs.

If, in the anterior esthetic zone, the tooth morphology, shape, and especially surface texture can be selected using the anticipated new upgraded softwares,

Nanoceramics: Composites

monolithic esthetic restorations can then be produced chairside by dentists of varying skill levels in a single

Manufacturers have recently introduced composite res-

appointment requiring only a single injection to anes-

in blocks made of nanoceramic materials for milling

thesize the patient both for the tooth preparation and

crowns and veneers. These materials offer the benefits

the bonding of the veneers or crowns.

of easy handling similar to composite resins combined

DDT 2013

93

GUREL ET AL

Need for Replacement of the Feldspathic Porcelain Restorations that would satisfy the requirements for areas that need minimal- to zero-preparation veneers (or mini or sectional veneers) would continue to pose a challenge for dental CAM processes because of the paper-thin nature typically required of the restorations that replace, for example, an incisal corner, until further improvements are made on the material side of the technology.

CONCLUSION The CAM machines are now precise enough to mill every detail within micrometers, such as line angles and characteristics of form (and texture to a certain extent). Upgrades to the new software programs will allow clinicians to become involved in analyzing data and programming the machines about what to do, and chairside to create monolithic veneers or crown designs without the need for extensive lab work. It appears that the dental CAD/CAM technologies are undergoing promising improvements limited only by the visions and imaginations of the dentists, ceramists, dental community, and the technical breakthroughs of the engineers in charge. Innovations will continue to explode endlessly into the future. Nevertheless, databases will never completely replace the human factor. Machines can perform very delicate tasks and make proposals based on information, but a skilled person is ultimately needed in the decisionmaking procedures and to perform final touchups to the CAD/CAM-produced restorations.

5. Paolucci B, Calamita M, Coachman C, Gurel G, Shayder A, Hallawell P. Visagism: The art of dental composition. Quintessence Dent Technol 2012;35:187-200. 6. Paolucci B. Gurel G, Coachman C, et al. Visagismo: A Arte de Personalizar o Desenho do Sorriso. S J. o Paulo: Vm Cultural, 2011. 7. Magne P, Perroud R, Hotges JS, Belser UC. Clinical performance of novel-design porcelain veneers for the recovery of coronal volume and length. Int J Periodontics Restorative Dent 2000;20:440-457. 8. Gurel G, Morimoto S, Calamita MA, Coachman C, Sesma N. Clinical performance of porcelain laminate veneers: Outcomes of the aesthetic pre-evaluative temporary (APT) technique. Int J Periodontics Restorative Dent 2012;32:625-635. 9. Chu SJ. Range and mean distribution frequency of individual tooth width of maxillary anterior dentition. Pract Proced Aesthet Dent 2007;19:209-215. 10. Bichacho N. Papilla regeneration by noninvasive prosthodontic treatment: Segmental proximal restorations. Pract Periodontics Aesthet Dent 1998;10:75,77-78. 11. Hatj6 J. A Beleza Natural dos Dentes Anteriores. S5o Paulo: Santos, 2008. 12. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1996. 13. Fradeani M. Esthetic Rehabilitation in Fixed Prosthodontics. Vol 1: Esthetic Analysis: A Systematic Approach to Prosthetic Treatment. Chicago: Quintessence, 2004. 14. Ahmad I. Geometric considerations in anterior dental esthetics: Restorative principles. Pract Periodontics Aesthet Dent 1998; 10:813-822. 15. Wolfart S, Thormann H, Freitag S, Kern M. Assessment of dental appearance following changes in incisor proportions. Eur J Oral Sci 2005;113:159-165. 16. Magne P, Gallucci GO, Belser UC. Anatomic crown width/ length ratios of unworn and worn maxillary teeth in white subjects. J Prosthet Dent 2003;89:453-461. 17. Gurel G, Bichacho N. Permanent diagnostic provisional restorations for predictable results when redesigning the smile. Pract Proced Aesthet Dent 200;18:281-286; quiz 288, 316-317. 18. Reshad M, Cascione D, Kim T. Anterior provisional restorations used to determine form, function, and esthetics for complex restorative situations, using all-ceramic restorative systems. J Esthet Restorative Dent; 2010;22:7-16. 19. Mizrahi B. Visualization before finalization: A predictable procedure for porcelain laminate veneers. Pract Proced Aesthet Dent 2005;17:513-518; quiz 520, 566. 20. Gurel G. The Science and Art of Porcelain Laminate Veneers. London: Quintessence, 2003: Chapter 7. 21. Duarte S Jr, Schnider P, Lorezon AP. The importance of width/ length ratios of maxillary anterior permanent teeth in esthetic rehabilitation. Eur J Esthet Dent 2008;3:224-234.

REFERENCES 1. Rufenacht CR. Fundamentals of Esthetics. Chicago: Quintessence, 1990. 2. Frush JP, Fisher RD. Introduction to dentogenic restorations. J Prosthet Dent 1955;5:586-595. 3. Goldstein RE, Lancaster JS. Survey of patient attitudes toward current esthetic procedures. J Prosthet Dent 1984;52:775-780. 4. Rufenacht CR. Principles of Esthetic Integration. Chicago: Quintessence, 2000:169-240.

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22. Jacobsen B. Taking the headache out of dental impressions. Dent Today 2007;26(9):74,76. 23. Henkel G. A comparison of fixed prostheses generated from conventional vs digitally scanned dental impressions. Compend Contin Educ Dent 2007;28:422-431. 24. Ender A, Mehl A. Full arch scans: Conventional versus digital impressions-An in-vitro study. Int J Comput Dent 2011;14:1121 25. Farah J, Reed C, Wojtowicz D. 3M ESPE Lava Chairside Oral Scanner COS. Dent Advisor 2009;10:1-3.

Anterior Esthetics with APT: Are CAD-CAM Systems Ready for the High-End Anterior Esthetics Challenge? 26. Touchstone A, Nieting T, Ulmer N. Digital transition: The collaboration between dentists and laboratory technicians on CAD/ CAM restorations. J Am Dent Assoc 2010;141(Suppl 2):15S19S. 27. Garg AK. Cadent iTero's digital system for dental impressions: The end of trays and putty? Dent Implantol Update 2008;19(1): 1-4. 28. Hill TJ, McCabe P, Tysowsky G. Bonding and thickness effect on fracture load of CAD/CAM crowns [abstract]. J Dent Res 2008;87(spec iss A):Abstract 2321. 29. Bindl A, Luthy H, Mormann WH. Thin-wall ceramic CAD/CAM crown copings: Strength and fracture pattern. J Oral Rehabil 2006;33:520-528. 30. Tysowsky GW. The science behind lithium disilicate: A metalfree alternative. Dent Today 2009;28:93-97. 31. Coachman C, Calamita M. Digital smile design: A tool for treatment planning and communication in esthetic dentistry. Quintessence Dent Technol 2012;35:103-112. 32. Coachman C, Van Dooren E, Gurel G, Landsberg C, Calamita M, Bichacho N. Smile design: From digital treatment planning to clinical reality. In: Cohen M (ed). Interdisciplinary Treatment Planning, vol 2. Chicago: Quintessence, 2012. 33. Hallawell P. Visagismo: Harmonia e Estetica. Sao Paulo: Senac, 2003. 34. Paolucci B. Visagismo e odontologia. In: Hallawell P (ed). Visagismo Integrado: Identidade, Estilo, Beleza. Sao Paulo: Senac, 2009:243-250. 35. Jung CG. Man and His Symbols. New York: Dell, 1968.

37. Alex G. Preparing porcelain surfaces for optimal bonding. Functional Esthetics Restorative Dent 2008;2(1):38-49. 38. Levine N. To the sky and beyond. Dent Prod Report 2009:116. 39. Fasbinder DJ. Materials for chairside CAD/CAM restorations. Compend Contin Educ Dent 2010;31:702-709. 40. Fasbinder DJ. Clinical performance of chairside CAD/CAM restorations. J Am Dent Assoc 2006;137(suppl):22S-31S. 41. Otto T, Schneider D. Long-term clinical results of chairside Cerec CAD/CAM inlays and onlays: A case series. Int J Prosthodont 2008;21:53-59. 42. Charlton DG, Roberts HW, Tiba A. Measurement of select physical and mechanical properties of 3 machinable ceramic materials. Quintessence Int 2008;39:573-579. 43. Fasbinder DJ, Neiva G, Dennison JB, Heys D. Clinical evaluation of CAD/CAM generated ceramic onlays [abstract]. J Dent Res 2011;90(spec iss A):Abstract 0378. 44. Guth JF, Almeida E Silva JS, Ramberger M, Beuer F, Edelhoff D. Treatment concept with CAD/CAM-fabricated high-density polymer temporary restorations. J Esthet Restor Dent 2012;24: 310-318. 45. Fasbinder DJ. Commentary: Treatment concept with CAD/ CAM-fabricated high-density polymer temporary restorations. J Esthet Restor Dent 2012;24:319-320. 46. Klim J. Clinical applications of chairside CAD/CAM dentistry. Compend Contin Educ Dent 2007;28(Suppl 2):19-26. 47. McLaren E. CAD/CAM All-Ceramic Restorations Achieving Ultimate Esthetics: Clinical & Laboratory Perspective. ACDNA Presentation, June 2006.

36. LeDoux J. The Emotional Brain: The Mysterious Underpinnings of Emotional Life. New York: Simon and Schuster, 1998.

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Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Vincenzo Musella, MDT'

C -

onventional fabrication of a composite resin

reverse approach: the inverse layering technique. This

restoration involves the use of a direct additive

technique is based on the use of a precise wax-up to

technique. This article presents an alternative

carefully design the anatomical tooth shapes.

method in which the restoration is fabricated using a

When the author developed this technique approximately 15 years ago, the poor consistency of the available older-generation flowable composite materials often led to problems in terms of stability and esthetics. Therefore, the author now recommends a

'Montale, Rangone, Italy. Correspondence to: Vincenzo Musella, Via S. Lucia 4, 41051 Montale Rangon (MO), Italy. Email: [email protected] www.vincenzomusella.com

new generation of nanofilled flowable composite material (crea.lign, Bredent, Senden, Germany), which combines all of the material properties necessary for a long-lasting esthetic result.

MUSELLA

Fig 1 Preoperative view.

Fig 2 Application of polyurethane resin to the blocked-out impressions.

The Inverse Layering Technique: Step-by-Step Procedures

ers

Fig 3 Master cast with removable dies.

can then be applied using the reverse approach.

First, the dies and plaster base must be isolated (Fig 12). A base layer of dentin can then be applied, with colored dentin masses spread directly over it (Fig 13).

Figure 1 shows the preoperative situation of a sample

Polymerization is carried out for 3 to 4 seconds (Fig 14),

case. The teeth were prepared for bonded inlays and

thus finalizing the bottom of the restoration (Fig 15).

onlays. To prepare the master cast, impressions must

The inverse layering then proceeds inside the silicone

be blocked out before pouring of the low-viscosity

key using BL3 dentin to mimic the incisal ridges. The

polyurethane resin (Exakto-Form, Bredent) (Fig 2). The

BL3 dentin should be alternated with the transparent

resin dies are then separated from the impression and

silicone to intensify the contrast, and pre-curing should

prepared individually. Next, the dies are repositioned

be carried out for 3 to 4 seconds to prevent mixing of

onto the impression, and the impression is filled with

the different dentin masses (Figs 16 to 19).

class IV gypsum. The resulting master cast allows for

Next, an E3 incisal layer is applied (Figs 20 to 22).

maintenance of the emergence profile and easy re-

A blue incisal layer is applied to the mesial and distal

moval of the dies (Fig 3). Next, the waxed-up removable dies (Fig 4) are trans-

areas, followed again by pre-curing (Figs 23 to 25). A thin layer of dentin with a high value (A1) is then ap-

ferred to a plaster base (Fig 5). The plaster base should

plied around the perimeter to serve as a transition be-

be notched (Figs 6 and 7) to facilitate fabrication of a

tween the enamel and dentin, which will have a final

silicone key. Transparent silicone (shore hardness: 60;

color of A3 (Figs 26 to 28). This layer is followed by

visio.sil, Bredent) (Fig 8) is then injected. A clear, rigid

application of A2 dentin close to the perimeter and A3

plastic sheet is used to help reproduce the exact de-

dentin at the center of the restoration (Figs 29 to 33).

tails of the cast during injection (Fig 9). The silicone

For final characterization, brown and orange coloring

key is then compacted in a pressure cooker at 4 atm.

can be applied (Figs 34 and 35).

The silicone key must accurately reproduce the wax-up,

Final polymerization is carried out for 6 minutes us-

which contains crucial information regarding the nec-

ing the bre.Lux Power Unit (Bredent) (Fig 36). Finishing

essary thickness of the composite resin layers. Further,

and polishing procedures can then be applied (Fig 37)

it is important to select a silicone material that is not too

until a lifelike appearance has been achieved (Figs 38

rigid; otherwise, fractures may occur during removal.

and 39). Finally, adhesive cementation of the definitive

Before initiating the inverse layering technique, a

restorations is performed (Figs 40 and 41). The inverse

small amount of wax should be removed from the

layering technique is suitable not only for partial resto-

edges of the dies (Fig 10) to create run-off channels for

rations such as inlays, onlays, or overlays, but also for

the composite resin (Fig 11). The composite resin lay-

more complex cases (Figs 42 to 47).

QDT 2013

The inverse Layering Technique

Fig 4 The waxed-up dies on the cast. Fig 5 Transfer of the dies to the plaster base. Figs 6 and 7 Notches placed in the plaster base to facilitate the silicone key. Fig 8 Injection of transparent silicone. Fig 9 Rigid plastic sheet used during silicone injection.

CIDT 2013

10

15

14

13

Figs 10 and 11 Removal of wax from the edge of the dies to create run-off channels. Fig 12 Isolation of the dies and plaster base. Figs 13 to 15 Application and curing of colored dentin masses on the base of the restorations.

18

Figs 16 to 19 Application and curing of the BL3 dentin layer.

19

rinT

LLJ

Figs 20 to 22 Application and curing of the E3 incisal layer.

Figs 23 to 25 Application and curing of the blue incisal layer.

Figs 26 to 28 Application and curing of the Al dentin layer around the perimeter of the restoration.

QDT 2013

MUSELLA

29

31

30

Figs 29 to 33 Application and curing of A2 and A3 dentin.

Figs 34 and 35 Final characterization. Fig 36 Final polymerization.

32

34

36

QDT 2013

35

se

Liyer,

fr

37a

37b

37c

d

Figs 37a to 37f Finishing and polishing procedures. Fig 38 Definitive restorations on the cast.

QDT 2013

Fig 39 Definitive restorations on the cast. Fig 40 Adhesive cementation. Fig 41 Final result.

Figs 42 to 47 Inverse layering technique applied to a complex case involving a full-mouth rehabilitation.

QDT 2013

The Inverse Layering Technique

MUSELLA riety of substructure materials. The combination of the opalescent ceramic and oligomeric matrix allows for When performing the inverse layering technique, use

the fabrication of restorations that are both esthetically

of the silicone key is crucial to control the distribu-

pleasing and crack resistant.

tion of composite resin. Once the pressed silicone is

Research (from the University of Jena, Germany)

removed, the differences in glossiness between the

shows that the mean surface roughness of this material

waxed areas and the rest of the tooth will form a well-

(0.03 pm) offers color stability and bonding properties

defined line showing where to apply the composite

equal to those of a veneering ceramic. The mechanical

resin without the risk of overmodeling. Alternatively,

properties of this composite resin far exceed those of

pencil marks can be made to delineate the area before

traditional hybrid composites, especially in terms of

casting of the silicone so that this line will be visible

polymerization shrinkage.

after removal of the key.

An important but often neglected factor is the light

The most important factor is selection of the appro-

source used for polymerization. The power unit em-

priate composite resin for layering. The material used

ployed by the author uses a new generation of light-

should meet the following criteria:

emitting diode lamps to provide curing devoid of heat, thus reducing stress and polymerization shrinkage.

— Low surface roughness after polishing to prevent plaque accumulation and discoloration — High density to improve the mechanical characteristics and facilitate polishing — Hypoallergenic and biocompatible characteristics — Good modulus of elasticity and excellent resistance to abrasion to avoid fractures

CONCLUSIONS The inverse layering technique produces long-lasting restorations with excellent esthetic results. This technique is relatively easy to perform and can be used for

The light-cured composite resin used by the author

both simple and complex cases.

comprises 50% opalescent ceramic particles and an oligomeric matrix. The material is purely nanofilled, thus preventing agglomeration. Further, the particle size of 40 nm ensures a compact and uniform surface, with a unique gel-like consistency and homogeneity. This composite resin is suitable for use with a wide va-

ACKNOWLEDGMENT The author thanks Dr Luca Cantoni for his clinical collaboration.

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Pink Ceramic: Combining Esthetics, and Longevity

Jungo Endo, MDT' Anas Aloum, BDS, FACP 2

R

egenerating hard and soft tissue contours has

A number of materials can be used to achieve es-

always been a clinical challenge (Fig 1). The sur-

thetic outcomes. Acrylic resin, composite resin, and

gical procedures available to reestablish three-

pink ceramic are among the most popular materials

dimensional tissue architecture are still unpredictable

used to reconstruct missing tissues (Figs 2 to 7). Each

and may result in compromised esthetic outcomes.

material has its own advantages and disadvantages.

In response to these drawbacks, prosthetic treatment

Both acrylic and composite resin offer good color

methods have continued to evolve. Dental implants

matching since they can be applied intraorally. How-

and a variety of fixed and removable restorations are

ever, the longevity of these restorations is question-

now available to reconstruct soft and hard tissue de-

able because resin materials degrade over time. Ad-

fects. Nonetheless, providing an acceptable color match

ditionally, maintenance of resin restorations can be

between the restored pink elements and the existing

cumbersome for the patient.

ones remains a significant challenge.

The use of pink ceramic is technique and operator sensitive. Since most laboratory technicians do not use pink ceramic on a daily basis, the procedures can be frustrating and the outcomes disappointing. Obtain-

'Private Laboratory, Santa Monica, California, USA.

ing a good color match requires careful attention to

'Private Practice, Abu Dhabi, United Arab Emirates.

detail, starting with the framework design and ending with meticulous mechanical polishing.

Correspondence to: Jungo Endo and Anas Aloum. Jungo Endo Dental Studio, 1460 7th Street, Suite 204, Santa Monica, CA 90401. Email: [email protected]; [email protected] .

In this article, a step-by-step approach is described to achieve natural-looking pink ceramic restorations on metal frameworks.

QDT 2013

ENDWALOUM Fig 1 Vertical and horizontal hard and soft tissue loss.

Figs 2a to 2c Heat-processed acrylic resin restoration on a titanium framework.

Fig 3 Acrylic resin restoration in situ.

Figs 4a and 4b Four-unit implant-supported restoration. Pink ceramic was added to replace the missing soft tissue. Note the color mismatch between the natural mucosa and prosthesis.

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Pink Ceramic: Combining Esthetics and Longevity

Figs 5a to 5c Full-mouth reconstruction using an implant-supported porcelain-fused-to-metal restoration with pink ceramic.

Figs 6a and 6b Screw-retained prosthesis

Figs 7a to 7c Maxillary implant-tooth€supported porcelain-fused-to-metal prosthesis with pink ceramic. The mandibular prosthesis had been in situ for over 5 years; note the color degradation of the acrylic resin.

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ENDUi ALUUIVI

Figs 8a to 8c Three different results using the same pink porcelain shade but different opaque pastes: (a) White, (b) A1, (c) Pink. Fig 9 Anterior metal-ceramic restoration with White opaque paste. Fig 10 Anterior metal-ceramic restoration with Pink opaque paste.

THE OPAQUE LAYER: THE KEY TO COLOR MATCHING

the authors suggest using a custom shade guide with

Controlling the opaque layer is of major importance

a standardized metal framework was fabricated and

to enhance the color match. Different opaque pastes

three opaque layers (White, Al, and Pink) were ap-

will produce different results even with the same ce-

plied. Two different thicknesses of pink porcelain (0.3

negatively affect the operator's judgment. Therefore, a metal backing for each tab (Figs 11 to 19). To demonstrate the importance of the opaque layer,

ramic layering. Figs 8 to 10 show the influence of three

and 1.5 mm; shade G3, Creation CC) were baked on

opaque pastes (Creation CC White, A1, and Pink, Jen-

top of the three pastes. As seen in Fig 20, the results

sen Dental, North Haven, Connecticut, USA) on the

varied significantly in terms of value, chroma, and hue.

value, chroma, and hue of dental restorations. A shade

For technicians, it is critical to know the thickness of

guide can be used to choose the correct opaque

the final pink layer and which opaque color to use for

color; however, the major drawback of stock shade

each case, because this will influence the results dra-

guides is that no metal backing is provided This can

matically.

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Pink Ceramic: Combining Esthetics and Longevity

12

Figs 11 and 12 Custom shade tab with a metal backing. Fig 13 Stock shade guide. Note the light transmission due to the lack of a metal backing.

Fig 14 The three shades of opaque paste baked on the metal backing of the custom shade guide. Fig 15 Pink ceramic samples on the custom shade guides. Fig 16 Stock shade guide used for shade taking. Fig 17 Pink ceramic layered on the metal backing.

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ENDO/ALOUM

Fig 18 Against a black background, the custom shade guide highlights the differences between different pink ceramic samples. From left: White, Al, and Pink opaque with G2 pink porcelain (Creation CC); White, Al, and Pink opaque with G3 pink porcelain (Creation CC).

Fig 19 Custom shade guide used for shade taking.

AI

Pink

Opaque

G3 Porcelain thickness

Fig 20 Pink ceramic layers with different thicknesses (0.3 and 1.5 mm) baked on the three opaque pastes (A1, White, and Pink). Note the wide range of color outcomes.

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Pink Ceramic: Combining Esthetics and Longevity

21

22

24

Fig 21 Preoperative view showing the two implants and removable partial denture. Fig 22 Try-in of the metal substructure.

Fig 23 Shade taking using the custom shade tabs.

Fig 24 Substructure design with artificial gingiva. Fig 25 Opaque layer (shade Al) on the metal framework. 25

CASE REPORTS Case 1

supported fixed prosthesis was fabricated using two new implants (Osseotite external hex, Biomet 3i, Palm Beach Gardens, Florida, USA). The custom substructure and suprastructure were cemented (Fig 22). Custom shade tabs were used for shade taking (Fig 23).

The male patient presented with two implants support-

Figures 24 to 27 show the ceramic layering proce-

ing an unsatisfactory removable prosthesis (Fig 21). Due

dures, which were carried out based on the wax-up.

to the unfavorable implant angulations, an implant-

The final results can be seen in Figs 28 and 29.

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El

ENDO/ALOUM

26a

26b

Figs 26a to 26c Ceramic layering (Creation CC). Fig 27 Final ceramic layering before firing. Figs 28 and 29 Final result.

114

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Pink Ceramic: Combining Esthetics and Longevity

CASE 2

30

33

Fig 30 Preoperative view showing the seven implants in the anterior region. Fig 31 Removable prosthesis. Fig 32 Try-in of the new denture teeth. Fig 33 Fixed provisional restoration.

Case 2

an acrylic resin fixed provisional restoration (Figs 32

The male patient had lost a number of his anterior

therefore, custom metal abutments (Jensen Security

teeth due to trauma. Three implants were placed in

Alloy, Jensen Dental) were made using a Neo Super

the maxilla and four implants (Astra Tech, Dentsply,

Cascom Casting Machine (KDF, Torrance, California,

and 33). The implants were placed in a labial direction;

York, Pennsylvania, USA) were placed in the mandible

USA) (Figs 34 to 36). A custom shade tab was used to

(Fig 30). An unesthetic removable partial prosthesis

measure the shade of the adjacent pink tissues (Fig

(Fig 31) was causing speech problems due to air leaks.

37). Figures 38 to 40 demonstrate the same treatment

A full-contour wax-up was tried in, customized to

steps applied in the previous case. Figures 41 and 42

the patient's smile and phonetics, and transferred to

show the final results.

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115

ENDO/ALOUM

35

36

Fig 34 Implants placed with a facial angulation. Fig 35 Custom abutments. Fig 36 Metal framework on the abutments. Fig 37 Shade taking using the custom shade tabs. Note Al opaque underneath. Fig 38 Opaque layering.

38

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Pink Ceramic: Combining Esthetics and Longevity

40

39

41

42 Figs 39 and 40 Ceramic layering (Creation CC). Figs 41 and 42 Final result.

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lag

ENDO/ALOUM

CASE 3

44

45

Figs 43 and 44 Intraoral views after implant placement. Fig 45 Full-contour wax-up on the final implant cast.

Figs 46 and 47 The metal framework. Four implants were screw retained, while one was retained on a custom abutment due to its labial angulation.

118

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Pink Ceramic: Combining Esthetics and Longevity

49

48

Fig 48 Shade taking using custom shade tab.

Fig 49 Shade taking using stock shade tab. Fig 50 Opaque layering. Fig 51 Ceramic layering (Creation CC).

Case 3

51

prosthesis using UCLA abutments was fabricated. One implant at the maxillary left central incisor site received a custom abutment due to its labial angulation (Figs

The female patient presented with a localized defect

45 to 47).

due to a car accident. It was decided to restore the

Figures 48 to 51 demonstrate the same treatment

defect with a fixed implant-supported porcelain-fused-

steps applied in the previous cases. In localized de-

to-metal prosthesis with pink ceramic. Five implants

fects, obtaining an excellent color match is challeng-

were placed (Replace Select, Nobel Biocare, Gote-

ing but critical for natural-looking integration with the

borg, Sweden) (Figs 43 and 44), and a screw-retained

surrounding tissues (Fig 52).

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ENDO/ALOUM

Fig 52 Final result.

CONCLUSION Pink ceramic offers excellent color matching with the surrounding soft tissues. Proper handling of the opaque layer is essential to success. The use of custom shade guides is recommended to enhance the final results.

QDT 2013

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Noninvasive Provisional Restorations Using High-Density Polymers

Josef Schweiger, CDT' Daniel Edelhoff, CDT Dr Med Dent, PhD'

N

ew manufacturing technologies have enabled

This case report describes the complex oral reha-

the use of industrially prefabricated acrylic

bilitation of a young ice hockey player with hard tissue

or composite resin materials known as high-

damage caused by a combination of traumatic injury

density polymers. These materials offer superior quali-

and erosive and abrasive processes. The patient under-

ties to those of direct provisional restorative materials.€ 2

went a pretreatment phase featuring adhesively ceTheig-dnstypolmera izduneral

conditions to form a highly homogeneous structure.

mented provisional restorations made of polymethyl methacrylate (PM MA)-based high-density polymer.

As a result, they provide several advantages, including

CAD/CAM-fabricated restorations (Telio CAD, Ivoclar

increased long-term stability, improved biocompatibil-

Vivadent, Schaan, Liechtenstein) were used to provide

ity, and reduced wear. 3,4 Further, they offer more favor-

an extended evaluation phase, during which the new

able computer-aided design/computer-assisted man-

vertical dimension of occlusion (VDO) and planned re-

ufacture (CAD/CAM) processing characteristics and

habilitation were assessed. 9-13

can be used at reduced thicknesses compared to ceramic materials. 5-8

CASE REPORT Preoperative Situation 'Dental Technician, Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Munich, Germany. 'Professor, Department of Prosthodontics, Dental School, LudwigMaximilians-University Munich, Munich, Germany. Correspondence to: Josef Schweiger, Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestr. 70, D-80336 Munich, Germany. Email: josef.schweiger@ med.uni-muenchen.de

122

QDT 2013

The 29-year-old ice hockey player requested restoration of his extensive tooth defects and related changes in VDO. He reported increasing sensitivity to chemical and thermal stimuli and complained about the considerable esthetic impairments of his teeth (Fig 1). After a review of the patient's medical history and an

Noninvasive Provisional Restorations Using High Density Polymers -

CASE REPORT

Figs 1 and 2 Preoperative view showing the abrasive and erosive defects and the traumatic injury of the maxillary anterior teeth. These defects negatively affected both esthetics and function, including the loss of anterior canine guidance.

evaluation of the clinical findings, abrasive and erosive

aged dentition with minimally invasive provisional ve-

processes were identified as the primary causative fac-

neers and onlays made of high-density PMMA mate-

tors for the generalized loss of tooth structure. These

rial (shade A2, Telio CAD). The provisionals would be

processes were associated with tooth grinding during

adhesively bonded to the damaged tooth structure.

extreme sports activities and frequent consumption of

The objective of this step was to immediately improve

acidic beverages. Additionally, sports-related traumat-

the patient's intraoral situation while sacrificing as little

ic incidents contributed to the extensive defects in the

tooth structure as possible. This provisional stage would

maxillary anterior dentition. As a result of these dental

proceed as follows:

injuries, the proportions of the maxillary anterior teeth had been severely affected (Fig 2). This complex rehabilitation presented several significant challenges: reconstructing the VDO, establishing appropriate oral function and esthetics, and satisfying the patient's request for an immediate improvement of the oral situation.

1. Fabrication of a wax-up to establish the esthetic and functional morphology of the teeth. 2. Intraoral evaluation of the esthetics using a diagnostic template based on the wax-up. 3. Replacement of the existing fillings followed by adhesive dentin sealing of the maxillary anterior teeth. 4. Transfer of the newly established VDO to an occlusal splint for a 12-week evaluation phase.

Treatment Planning The treatment goal was to establish appropriate mor-

6. Precision impression-taking of the maxilla and mandible and registration of the maxillomandibular relationship with a sectioned occlusal splint.

phology of the teeth with anterior/canine-guided dy-

7. Digitization of the wax-up and CAD/CAM fabrica-

namic occlusion and to adjust the VDO accordingly.

tion of form-identical veneer-shaped provisionals

Portrait and intraoral photographs were taken to pro-

using high-density polymer.

vide the dental technician with an initial view of the pretreatment situation. Alginate impressions of the max-

8. Trial period (12 months) with the provisionals in place, with modifications made as necessary.

illa and mandible were taken to create diagnostic casts

9. Segment-by-segment transfer of the provisional res-

in the laboratory. In addition, a centric bite record and

torations into lithium disilicate ceramic restorations

arbitrary facebow registration were taken.

(IPS e.max Press or CAD, Ivoclar Vivadent). If neces-

After the clinical findings had been evaluated and

sary, sections of the adhesively cemented provision-

the alternative treatment options had been discussed,

als could be used as buildups in the subsequent

the patient and dental team settled on the treatment

preparation for the final restorations.

plan. First, it was decided to restore the severely dam-

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123

SCHWEIGER/EDELHOFF

Figs 3a and 3b (a) Preoperative frontal view. (b) Esthetic evaluation of the analytic wax-up. A diagnostic template based on the wax-up was fabricated, filled with provisional restorative material, and placed on the teeth.

Fig 4 Exposed maxillary anterior dentin surfaces were sealed using multistep dentin adhesive and low-viscosity composite resin. Fig 5 An occlusal splint was used for functional evaluation of the VDO established in the wax-up.

Pretreatment and Preparation

facebow transfer and centric relation record were tak-

The analytic wax-up was evaluated (Figs 3a and 3b)

splint allowed the VDO established on the wax-up to

on the patient using a diagnostic template filled with

be accurately transferred to the patient's mouth (Fig 5).

direct provisional restorative material (Telio C&B). Af-

No complications occurred in the 12-week functional

ter the patient approved this initial "blueprint" of the

evaluation phase. Following completion of this phase,

restoration, the existing fillings were replaced, and

precision impressions of the maxilla and mandible

the dentin areas of the maxillary anterior teeth were

were taken, and the occlusal splint was sectioned in

adhesively sealed (Fig 4). The enamel areas of the

half to ensure accurate transfer of the reconstructed

maxillary incisors were slightly beveled with a flame-

maxillomandibular relationship.

shaped preparation diamond bur to remove under-

en, and an occlusal splint was prepared. The occlusal

On the basis of the high-precision polyether impres-

cuts and increase the surface available for bonding.

sions, casts with detachable segments (Figs 6 to 8) as

The dentin-sealing treatment eliminated most of the

well as uncut casts were prepared. The occlusal splint,

patient's sensitivity to chemical and thermal stimuli.

which had been worn and modified without any com-

After another set of alginate impressions was taken, a

plications during the evaluation phase, was sectioned

QDT 2013

Noninvasive Provisional Restorations Using High-Density Polymers

6

8

7

9a

9b

Figs 6 to 8 High-precision impressions were used to fabricate casts with detachable segments. Figs 9a and 9b The occlusal splint was sectioned, and a bite record of each half was taken. Fig 10 Vertical space available after mounting of the cast on the semiadjustable articulator. 10

at the incisal area, and a record of each half was taken

sal pin was adjusted accordingly. This adjustment re-

using bisphenol glycidyl methacrylate (bis-GMA) ma-

sulted in a 2.5-mm increase in the vertical space in

terial (Luxatemp Automix Solar, DMG, Hamburg, Ger-

each arch (as measured on the incisal pin) (Fig 11).

many) (Fig 9). At the end of this session, the splint

Consequently, the amount of space available was

was replaced in the oral cavity and reconnected using

measured to be 4.6 mm (2.3 mm per arch) in the ante-

PMMA-based cold-curing resin (PalaDur Transparent,

rior region and 3 mm (1.5 mm per arch) in the poste-

Heraeus Kulzer, Hanau, Germany). The patient was ad-

rior region (Fig 12). 14

vised to continue wearing the splint until the provisional restorations could be placed. Subsequently, the cast was mounted on a semi-adjustable articulator in

Computer-Aided Design

relation to the skull, and the opposing arch was articulated and fixed in place with plaster using the bis-GMA

The master casts were digitized with an inEos labora-

records as a reference (Fig 10). A 5-mm increase in the VDO was established with

tory scanner (Sirona, Bensheim, Germany). This scan-

the aid of the bite record, and the position of the inci-

of triangulation (Fig 13). Either a squash bite record

ner uses strip-light projection based on the principle

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125

SCHWEIGER/EDELHOFF

11

13

12

114

115

Fig 11 A 5-mm increase in VDO was established, and the incisal pin of the articulator was set accordingly. Fig 12 The 5-mm increase at the incisal pin resulted in an increased vertical height of 4.6 mm in the anterior region and 3 mm in the posterior region (modified according to Bumann and Lotzmann 14). VL = vertical space available at the incisal pin; V 1 = vertical space available in the area of the teeth; L = distance between the condyle axis and incisal pin; IA = distance between the condyle axis and anterior tooth; I, = distance between the condyle axis and posterior tooth. Fig 13 Three-dimensional digitization of the master cast. Figs 14 and 15 The posterior teeth were designed according to biogenerically calculated occlusal surfaces based on the analytical wax-up.

126

made of a scannable registration material or a plas-

the basis of biogenerically calculated occlusal surfaces

ter cast of the opposing arch can be used to produce

(Figs 14 and 15). The anterior teeth were constructed

a digitized model of the desired arch. A squash bite

in the CAD system's correlation mode using the ana-

was used for this case (Metal-Bite, R-Dental, Hamburg, Germany).

lytic wax-up as the correlate. Both the cast representing the current oral situation (master cast) and the cast

Since it is not yet possible to design the maxilla and

representing the target situation (plaster cast of the

mandible simultaneously in the CEREC system (Sirona),

wax-up) (Figs 16 and 17) were scanned, and a correla-

the design the CAD/CAM restorations was divided into

tion between selected areas was created (Fig 18). This

two stages. To achieve an accurate occlusal plane and

method allowed for easy and quick translation of the

create appropriate curves of Spee and Wilson, the de-

wax-up into a CAD data set, which contained informa-

sign of the mandibular restorations was first performed

tion regarding both the external surface of the restora-

on the basis of the existing wax-up. The incisal pin was

tion (wax-up) and the actual situation of the inner sur-

set at 2.5 mm. The posterior teeth were designed on

face of the crown (Fig 19).

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Noninvasive Provisional Restorations Using High Density Polymers -

18 Figs 16 and 17 The anterior teeth were designed using the software's correlation mode based on the analytic wax-up.

Fig 18 The copy line (green) established by the technician determines the area that is electronically transferred from the wax-up to the master cast. Fig 19 Design of the maxillary anterior teeth. The exterior surface of the restoration reflects the wax-up, and the inner surface of the crown is designed according to the master cast.

For the maxilla, the incisal pin was set to 5 mm, and

€ Flexural strength: 130 ® 10 MPa

a squash bite of the mandibular cast was used as the

€ Modulus of elasticity: 3,200 ® 300 MPa

opposing dentition. The occlusal surfaces of this cast

€ Water absorption: < 28 pg/cm 2

had already been finished with high-density polymer.

€ Water solubility: < 0.6 pg/cm 2 € Ball indentation hardness: 180 ® 5 MPa

Computer-Assisted Manufacture

The restorations can be milled using the CEREC or inLab systems. Alternatively, the restorations can be

After the milling paths had been calculated—a process

outsourced and fabricated in a milling center (Nobel

that the inLab system performs automatically—the oc-

Procera, Nobel Biocare, Cologne, Germany).

clusal surfaces (ie, the incisal veneers) were milled from a high-density polymer block (Fig 20) under water

The indications for the CAD/CAM restorations are as follows:

cooling in the inLab MCXL milling unit (block size B40; shade A2). The industrially manufactured high-density polymer blocks are characterized by excellent material

€ Anterior and posterior provisional crowns with a maximum wear period of 12 months.

properties, including high homogeneity without irreg-

€ Anterior and posterior provisional fixed dental pros-

ularities, outstanding polishing ability, and reduced

theses with up to two pontics and a maximum wear

affinity for plaque. 15 The main properties of the CAD/CAM restorations are as follows 15 :

period of 12 months. € Implant provisionals with a maximum wear period of 12 months.

E

20

SCHWEIGER/EDEIHOFF

Fig 20 High-density polymer block.

Fig 21 The restorations were manufactured in splinted quadrants.

€ Therapeutic restorations used to correct temporo-

conditioned with methyl methacrylate—based liquid

mandibular joint problems and allow for occlusal

(Telio Activator) (Fig 22). The liquid was brushed onto

adjustments.

the entire inner surface of the restoration for at least 30 seconds using an applicator brush to ensure even

To improve the time- and cost-effectiveness of the

distribution and quick penetration. The surface condi-

restorations, they were manufactured in splinted quad-

tioner was allowed to react for another 30 to 60 sec-

rants (Fig 21) and separated manually. After milling,

onds (total reaction time: 1 to 2 minutes). Light-curing

the lug was cut off using a fine crosscut tungsten car-

microfilled composite resin bonding paste (SR Com-

bide bur or a diamond-coated separating disk.

posiv) was then applied to promote a reliable bond between the restoration and relining material (Fig 23). The bonding paste was cured with a light-curing unit.

Relining

The low-viscosity relining material was then applied (Fig 24), and the restoration was placed onto a die

The restorations were fabricated in a subtractive man-

coated with separator liquid (Vectris Model Separator,

ufacturing process in which the rotating milling instru-

Ivoclar Vivadent) using gentle finger pressure (Fig 25).

ment cuts material away from the block. If any interfer-

Excess material was evened out with a brush (Fig 26).

ences are present around the sharp edges and angles

Final polymerization was performed with a high-per-

inside the restoration, the accuracy of fit can be nega-

formance curing light (> 1,000 mW/cm 2 ; Bluephase,

tively affected. To identify such interferences, a dupli-

lvoclar Vivadent) for 15 seconds at each segment. If a

cate die was painted red with a water-soluble felt-tip

standard curing light (> 500 mW/cm 2) is used, the ex-

pen. The restorations were placed on the painted die

posure time for each segment should be doubled to

to make any interferences visible on the inner surfaces.

30 seconds.

The interferences were then removed with a round tungsten carbide bur under a stereomicroscope. To eliminate small inaccuracies of fit, the restorations can be relined with light-curing flowable composite

Finishing and Polishing

resin (Telio Add-On Flow). This is especially recom-

The authors' experience has shown that it is best to

mended if the nonprepared occlusal surfaces exhibit

wait until after the relining material has been applied,

sharp angles and edges, which the rotating milling in-

if necessary, before finishing the restoration and ad-

struments will not be able to reproduce on the inner

justing the static and dynamic occlusal contacts. After

restoration surfaces. Prior to application of the relining

polymerization, the relined restorations were briefly

material, the inner aspects of the occlusal composite

warmed with a steam jet to soften the wax-based

resin surfaces were air abraded with aluminum oxide

separator liquid. Once the separator had softened,

(50 pm, 1 bar, 29 psi). Next, the abraded surfaces were

the restorations could be easily removed from the dies

QDT 2013

Noninvasive Provisional Restorations Using High-Density Polymers

Fig 22 The surface-conditioning agent. Fig 23 The relining material and bonding paste. 22

2 Fig 24 Application of the relining material. Figs 25 and 26 The restorations were placed on dies coated with separator liquid, and excess material was removed with a fine brush.

using two fingers (Fig 27). The CAD/CAM restorations

Placement of the Provisional Restorations

were finished and adjusted with fine crosscut tungsten carbide burs (Fig 28). Gray lens- and flame-shaped

The restorations were tried in using try-in paste (shade

silicone polishing burs, which allow for controlled re-

High Value +1, Variolink Professional Set Veneer, Ivo-

moval of acrylic resin material, were used to rework the

clar Vivadent) (Figs 33 and 34). Final cementation was

thinly tapered edges of the restoration. Acrypol pol-

performed with a matching light-curing luting mate-

ishing paste (Bredent, Senden, Germany) was used for

rial. Before placement, the inner surfaces of the res-

prepolishing, followed by application of Abraso Star

torations were silicoated (30-pm aluminum oxide; dis-

Glaze (Bredent) for high-luster polishing (Fig 29).

tance to nozzle: 10 mm; reduced blast pressure: 1 bar,

The completed restorations demonstrated excellent

15 psi; blast time per unit: 10 seconds; Rocatec Soft,

esthetic characteristics, including outstanding light-

3M ESPE, St Paul, Minnesota, USA) and covered with

optical properties (Fig 30) and impeccable surface lus-

a bonding agent (Monobond Plus, Ivoclar Vivadent).

ter (Figs 31 and 32).

The natural tooth structure was conditioned with a

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129

SCHWEIGER/EDELHOFF

27a

29

Figs 27a to 27c To remove the restorations from the plaster dies, they were briefly warmed with a steam jet and then pulled off. Fig 28 The restorations were finished with fine crosscut tungsten carbide burs. Fig 29 High-luster polishing was achieved using polishing paste. Fig 30 The CAD/CAM-fabricated provisionals showing the excellent light-optical properties.

30

Figs 31 and 32 The maxillary anterior restorations on the uncut cast showing the surface luster.

32

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Noninvasive Provisional Restorations Using High-Density Polymers

35b Figs 33a and 33b Maxillary anterior provisional veneers during try-in. Figs 34a and 34b Mandibular anterior provisional veneers during try-in. Figs 35a and 35b Occlusal views of the maxilla (a) before and (b) after adhesive cementation.

multistep dentin adhesive (Syntac, Ivoclar Vivadent)

accurate prediction of the final restorative outcome.

using the total-etch technique. Final polymerization

Additionally, the immediate provisionalization quickly

was carried out with a high-performance curing light

satisfied the esthetic and functional needs of the pa-

(Bluephase G2) (Figs 35 and 36).

tient using a virtually noninvasive technique. The pa-

The extended provisional phase allowed for long-

tient was highly satisfied with the results (Fig 37).

term evaluation of the new VDO and provided an

QDT 2013

Ma

SCHWEIGER/EDELHOFF

Fig 36 Intraoral view of the maxillary restorations after cementation. Figs 37a and 37b Final result.

CONCLUSIONS High-quality provisional restorations represent a key stage in the treatment planning of complex cases. An extended provisional phase allows the dental team and patient to agree on a final treatment objective. Occlusal conditions and material thickness are essential criteria when selecting the restorative materials to be used for each case. This approach results in excellent predictability of the final result.

5. Edelhoff D, Schweiger J. Im Sinne des Patienten. J Con Dent Educ 2011;14:420-423. 6. Edelhoff D, Beuer F, Schweiger J, Brix 0, Stimmelmayr M, Guth JF. CAD/CAM-generated high-density polymer restorations for the pretreatment of complex cases. Quintessence Int 2012;6:457-467. 7. Edelhoff D, Brix 0, Schweiger J, Beuer F. Rehabilitation eines Patienten mit Dentinogenesis imperfecta. ZM 2010;100:38-42. 8. Edelhoff D, Schweiger J. Im Sinne des Patienten. Reflect 2010; (3):18-20. 9. Edelhoff D, Schweiger J, Brix 0, Guth JF, Beuer F. CAD/CAMgenerierte Restaurationen aus Hochleistungspolymer zur Vorbehandlung komplexer Falle. Quintessenz 2011;62:625-635. 10. Edelhoff D, Brix 0, Schweiger J. Wieder lacheln konnen. Reflect 2010;(1)13-14.

REFERENCES 1. Beuer F, Schweiger J, Edelhoff D. Digital dentistry: An overview of recent developments for CAD/CAM generated restorations. Br Dent J 2008;204:505-511. 2. Beuer F, Schweiger J, Stimmelmayr M, Edelhoff D. CAD/CAMbearbeitete Hochleistungspolymere als Langzeitprovisorien in der Implantologie. Implantologie 2010;18:397-404. 3. Edelhoff D, Guth JF, Schweiger J, Maier B, Beuer F. Vorbehandlung komplexer FaIle in der festsitzenden Prothetik. Neue Materialien und Konzepte. Wissen Kompakt 2010;4:3-16. 4. Schweiger J, Beuer F. Hochleistungskunststoffe fur die CAD/ CAM-Fertigung. Dig Dent News 2008;2:12-19.

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11. Huth K-Ch, Edelhoff D, Schweiger J. Dentinogenesis imperfectaVon der Rehabilitation im Milchgebiss bis zur non-invasiven Restauration mit Hochleistungspolymeren im jugendlichen bleibenden Gebiss. Deutscher Zahnarzte Kalender 2011;70:23-35. 12. Schweiger J, Stumbaum M, Richter J, Beuer F. Digital dentistry—Die Rehabilitation der vertikalen Kieferrelation mittels CAD/ CAM-Technik. J Cont Dent Educ 2011;14:158-171. 13. Stumbaum M, Konec D, Schweiger J, Gernet W. Reconstruction of the vertical jaw relation using CAD/CAM. Int J Comput Dent 2010;13:9-25. 14. Bumann A, Lotzmann U. Funktionsdiagnost k und Therapieprinzipien. Stuttgart: Georg Thieme, 2000. 15. EU Sicherheitsdatenblatt Telio CAD. Schaan, Liechtenstein: Ivoclar Vivadent, 2009.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Naoki Hayashi, RDT Ultimate Styles Dental Laboratory 12 Mauchly Unit M Irvine, CA 92618 email: [email protected]

N AO K I H AYAS H I

Dental works & Photography

-From within-

ow

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Es

Actu a l p rep a ra t ion in p a t ien t's mou t h

HAYASHI

Diag nost ic wax-up o n the dup lica te d p rep arat ion g u i de cast

Energy Flow—From within

>Preparation guide

lv Wax-up Actual preparation la, Communication is key

Preparation guide cast of maxilla and mandible

HAYASHI

14. Internal stain—custom charactenzation

L4_

110

1 13

136

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11 2

Energy Flow

©

From within

Porcelain Buildup Steps 1. After degassing of refractory cast 2. Working of dark core area on the refractory cast

9. LT natural 10. Incisal dentin

3. Complementary color effect on left central incisor

11. Silky E2

4. Masking porcelain on left and right central incisors

12. T-Blue

5. Opacious dentin

13. After baking of internal structures

6. Dentin

14. Internal stain—custom characterization

7. Dentin

15. Cervical translucent, Silky E2, and T-Blue

8. Mamelon

16. Luster and halo

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137

Combination, porcelain jacket crown, porcelain laminate veneer, zirconia crown, and porcelain inlay / Noritake KATANA, CZR, and EX-3

Invisible Beauty

This clinical case is a professional collaboration with Jon Y. Yoshimura, DDS. I deeply thank Dr Yoshimura for both his insatiable desire for excellence in his dental practice and his understanding of my hard work and effort.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Dario Adolfi, DDS, CDT' Oswaldo Scopin de Andrade, DDS, MS, PhD 2 GustavoJierVnz,DS 3 Mauricio Contar Adolfi, DDS 4

T

he achievements seen in the fields of esthetics

must be followed to optimize the treatment. Thus, suc-

and implant dentistry have attracted the atten-

cessful outcomes depend on meticulous treatment

tion of clinicians as well as dental technicians,

planning and careful execution of the clinical and labo-

but oftentimes innovations are implemented without

ratory procedures planned for each individual case. 1,2

making a global assessment of the patient's restorative

Sevralfctosinu emtplanig,cud

needs. In the case of full-mouth rehabilitation, a suitable

patient health status, patient motivation, treatment

restorative protocol is crucial, and a logical sequence

time, expected costs over treatment phases, professional skills of the operators for each phase, and expected long-term results.'

'Director of Spazio Education, Sao Paulo, Brazil. 'Director of the Advanced Program in Implant and Esthetic Dentistry, Senac University, Sao Paulo, Brazil. 'Director of the Oral Rehabilitation Program, Postgraduate School of the Argentinian Dental Academy (A.O.A.), Buenos Aires, Argentina. 'Director of the Periodontal and Oral Implantology Department, Spazio Education, Sao Paulo, Brazil. Correspondence to: Dr Dario Adolfi, Av. Juscelino Kubitschek, 1726, 21st floor, Sao Paulo, SP, Brazil, CEP 04543-000. Email: [email protected]

The objective of this article is to describe all clinical and laboratory steps for a functional and esthetic protocol for full-mouth rehabilitation that promotes patient understanding and dental team cooperation to achieve predictable outcomes. Patients needing oral rehabilitation require a thorough initial assessment to determine the options for treatment as well as the patient's willingness to accept recommendations proposed in the treatment planning. Thus, caution must be exercised in the first clini-

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ADOLFI/SCOPIN

Fig 1 The four reconstructive steps of a functional and esthetic full-mouth oral rehabilitation protocol: maxillary anterior segment (blue), mandibular anterior segment (red), mandibular posterior segment (orange), and maxillary posterior segment (magenta).

Fig 2 Reconstruction starts on the maxillary segment from right to left premolars. The premolars may be included in this step to achieve better esthetic diagnoses.

cal examination. The practitioner should explain the

FUNCTIONAL AND ESTHETIC PROTOCOL FOR ORAL REHABILITATION

options in a simple and straightforward way to encourage patient understanding. The final treatment plan is detailed in the second appointment. 4 The success of an esthetic rehabilitation depends on the dental team's knowledge of the biologic con-

The functional and esthetic protocol for oral rehabilita-

siderations related to teeth and implants as well as the

tion can be divided into four steps (Fig 1):

communication maintained between the prosthodontist, oral surgeon, and dental technician.'

1. Reconstruction of the maxillary anterior segment

When several changes are planned, a diagnostic

(from the right second to the left second premolars).

wax-up is fabricated on the study casts to facilitate

2. Reconstruction of the mandibular anterior segment

visualization of the shape, position, and proportions

(from canine to canine).

of the planned restorations and to provide the most

3. Reconstruction of the mandibular posterior segment.

functional and esthetic conditions possible. Diagnos-

4. Reconstruction of the maxillary posterior segment.

tic wax-ups can facilitate patient assessment of the proposed treatment as well as allow technicians and dentists to predict potential problems that could arise during treatment. 67 Use of wax-ups facilitates the development of prop-

140

Phase 1: Reconstruction of the Maxillary Anterior Segment

er contours for provisional restorations and provides

This is one of the most important phases, because it

a detailed and accurate guide throughout the restor-

defines the patient's overall esthetic appearance (Fig 2).

ative process that can inform other intraoral tools, such

When the buccal corridor needs to be realigned, the

as a silicone index for crown lengthening or surgical

premolars are included with the anterior segment so

stents used for implant placement.' The creation of a

that their overall aspect can be harmonized with the

diagnostic wax-up must follow the functional and es-

anterior teeth. Otherwise, premolars are only included

thetic protocol for oral rehabilitation.

in phase 4. Phase 1 provides the dental team with a

CID

Functional and Esthetic Protocol for Oral Rehabilitation

Esthetic Checklist 1. Midline, symmetry axis, and tooth axis

1.1nterincisal angle 8. Incisal edge position 9. Lip line

3. Zenith of gingival contours

4. Morphology, proportic and basic shape of natuiteeth

10. Insical edge configuration 11. 3D implant position

12. Color 13. Surface textures and

6. Interproximal contacts

superficial gloss

Fig 3 The esthetic checklist.

complete overview of the restorative case and addresses the patient's esthetic expectations. 9

for function during excursive mandibular movements. This should be achieved in accordance with phase 1

When study casts are used in combination with in-

to establish adequate anterior guidance that favors

traoral mock-ups to plan the restorations, clinicians

the esthetics of the anterior teeth. It is important to

can work with greater predictability and fewer errors,

keep the mandibular canine longer than the incisors

even in complex cases that require multiple adjust-

for efficient disocclusion patterns (Fig 4). On eccen-

ments. Depending on the clinical scenario and the

tric mandibular excursions, freedom of movement and

clinician's skills and knowledge, the intraoral mock-up

less muscle energy are essential and are favored by

can be made using composite resin on specific areas

the anterior guidance on protrusive and lateral man-

to promote the predictability of the functional and es-

dibular paths.

thetic outcomes. The diagnostic wax-up in phase 1 must include:

The following characteristics must be assessed while the mandibular anterior teeth are in occlusion with the maxillary teeth (Fig 5):

€ Development of the tooth size, shape, and arrangement € Fabrication of a mock-up for esthetic and phonetic evaluation € Adherence to the esthetic checklist concepts (Fig 3)

€ Tooth size and form € Vertical dimension of occlusion € Centric relation € Phonetics € Quantity and quality of disocclusion € Disocclusion patterns (eg, canine guidance and par-

Phase 2: Reconstruction of the Mandibular Anterior Segment

tial and total group function)

In this phase, the size and position (individual and overall) of the mandibular anterior teeth must be evaluated

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ADOLFUSCOPIN

Fig 4 Reconstruction of the mandibular canines.

Fig 5 Reconstruction of maxillary and mandibular teeth in phases 1 and 2.

Fig 6 The curve of Spee is provided by the mandibular posterior teeth.

Phase 3: Reconstruction of the Mandibular Posterior Segment

Fig 7 Phase 4 showing reconstruction of the maxillary posterior teeth.

The occlusal contacts determine the occlusal equilibrium and thus the functional relationships that conserve tooth integrity and individual positions as well

This phase determines the anteroposterior curvature

as provide axial loads at stability at the correct vertical

of the occlusal plane (curve of Spee) achieved through

dimension of occlusion (Fig 7).

the positions of the mandibular posterior teeth. The

After designing the rehabilitation protocol through

curve of Spee is an imaginary line extending from the

development of a diagnostic wax-up, the provisional

tip of the mandibular canine, touching the buccal cusp

restorations are fabricated according to the wax-up.

tips of all the mandibular posterior teeth, and continu-

The provisionals must protect the teeth and reestab-

ing to the anterior border of the ramus (Fig 6).

lish the desired function and esthetics. They must be a perfect copy of the diagnostic wax-up and are fabricated with the indirect approach, ie, at the dental

Phase 4: Reconstruction of the Maxillary Posterior Segment In this phase, the maxillary posterior teeth are recon-

142

laboratory by the dental technician. First, the diagnostic wax-up casts are duplicated and new stone casts are poured and related in a semiadjustable articulator. The provisionals are then made

structed and the occlusal relationships in the posterior

using the double-pressing technique for each tooth

quadrants are established. The three occlusal relation-

segment to allow better control of occlusal contact

ships are cusp to fossa, cusp to marginal mesial ridge,

points as well as of the acrylic resin expansion setting

and cusp to marginal distal ridge.

properties.

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Functional and Esthetic Protocol for Oral Rehabilitation

CASE REPORT

Fig 8 Initial clinical situation showing an Angle Class II, division 2 malocclusion and an accentuated overbite. Figs 9 and 10 Occlusal views showing porcelain fused to metal crowns and large restorations. -

-

Fig 11 The mandibular anterior teeth are extruded, but the gingival levels were adequate.

CASE PRESENTATION

large restorations, tooth rotations, and some gingival

A 64-year-old Caucasian woman with an Angle Class II,

were extruded because of the lack of occlusal contact

division 2 malocclusion and accentuated overbite pre-

with the maxillary anterior teeth (Fig 11). No issues with

sented for treatment (Fig 8). The first clinical examina-

the vertical dimension of occlusion or temporoman-

tion revealed several porcelain-fused-to-metal crowns,

dibular disorders were observed.

recession (Figs 9 and 10). Also, the mandibular incisors

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143

ADOLFI/SCOPIN

Treatment Objectives

maxillary central incisors were facially inclined, and the

Because the patient was an adult and presented an

palatal aspect. On the study casts, the central incisors

adequate facial profile, it was decided to maintain

would be moved toward the palatal and the lateral in-

molar-to-molar Class II relationships and to correct the

cisors would be slightly inclined to the facial aspects.

lateral incisors and canines were inclined more to the

exaggerated overjet and overbite of the maxillary cen-

Tooth widths were reduced to generate a new anterior

tral incisors. The aim for the mandibular arch was to

arch relationship. At phase 2, the canines were reposi-

reestablish the anteroposterior curve (curve of Spee)

tioned along with the mandibular anterior teeth.

as well as to level the anterior segment and provide

During the fabrication of the provisionals, the clini-

light occlusal contacts on the maxillary anterior teeth

cal crowns were removed from the working cast, leav-

to avoid continued mandibular tooth eruption. In ad-

ing just the cervical lines as a guide for fabricating the

dition, adequate overbite and overjet along with ad-

provisionals from artificial teeth (Premium, Heraeus

equate canine guidance were planned to create an

Kulzer, Hanau, Germany) (Fig 12).

esthetic smile.

At the same time, indices made from silicone material (Zetalabor, Zhermack Badia, Polesine, Italy) were prepared over the provisionals to ensure correct intra-

Treatment Planning

oral transfer (Figs 13 and 14). The index was used to transfer the correct central incisor position and to re-

Initial impressions of the maxilla and mandible were

cord the correct overjet, overbite, midline, and tooth

taken with irreversible hydrocolloid material (alginate)

axis.

and poured in orthodontic plaster. It is important that

The maxillary right central incisor served as a refer-

accurate casts be kept as part of the patient's records.

ence key for placement of all of the provisionals. The

Also, silicone impressions were created for study casts

provisional for the right central incisor was positioned

and were related in a semi-adjustable articulator with

on the silicone index and secured with cyanoacrylate

the aid of a facebow. The provisional restorations for the maxillary inci-

glue to assure stability for the intraoral try-in (Fig 15). The maxillary right central incisor was prepared for a

sors were fabricated on the study casts using artificial

crown restoration, and the silicone index was posi-

acrylic teeth to correct the accentuated overjet.

tioned without interfering with the adjacent teeth. A

The patient received a complete outline of the treat-

small amount of autopolymerizing acrylic resin (Unifast

ment plan with indications for root canal therapy for

Trad powder Ivory, GC America, Alsip, Illinois, USA)

maxillary and mandibular incisors and fiber-reinforced

was placed on the palatal aspect of the right central

post and core restorations. Tooth preparation would

incisor using the Nealon or brush-dip technique to sta-

be made for all anterior maxillary teeth, and the maxil-

bilize the provisional crown (Figs 16 and 17). At this

lary teeth would receive laboratory-made provisionals

point, it was possible to verify that the midline and the

based on the diagnostic wax-up.

tooth axis were correctly positioned (Figs 18 and 19). The maxillary left central incisor as well as the maxillary lateral incisors were then prepared to receive provi-

Functional and Esthetic Protocol

sionals.

Phase 1: Reconstruction of the maxillary segment

build-up to help guide the positioning of fiber posts

It is important to bear in mind that any modifications

to the root (Fig 20). The fiber posts must remain within

of tooth arrangement not achieved by orthodontic

the reconstruction material (Luxacore, DMG, Hamburg,

All provisional crowns were placed prior to coronal

movement must preserve the correct cervical tooth

Germany) to strengthen the coronal build-ups after

levels for proper planning of new tooth positions. The

tooth preparation (Fig 21).

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Functional and Esthetic Protocol for Oral Rehabilitation

CASE REPORT Fig 12 Provisional restorations made on the working cast. The cervical lines were maintained. Fig 13 Silicone indices over the provisional restorations on the working cast. 12

13

Fig 14 The silicone index is trimmed to accommodate the position of the central incisor. Fig 15 The provisional acrylic esthetic veneer for the maxillary right central incisor is positioned on the silicone key and secured with cyanoacrylate. 15

Figs 16 and 17 The silicone index with the esthetic veneer in position.

17

Figs 18 and 19 The esthetic acrylic veneer is in position over maxillary right central incisor. The median line and axial inclinations are now correct.

19

Fig 20 Provisional restorations positioned before reconstruction with fiber posts. Fig 21 Fiber posts placed within the coronal reconstructions.

21

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ADOLFI/SCOPIN

22

23

24

25

Fig 22 The mandibular anterior teeth had overerupted due to the lack of occlusal contact with their maxillary antagonists. However, adequate gingival levels can be seen. Figs 23 to 25 Acrylic resin veneers were secured with cyanoacrylate glue and flowable resin composite over tooth preparations to simulate the position of provisional restorations.

Fig 26 The palatal morphology of anterior teeth and their occlusal contact relationships are defined by correct positioning of acrylic resin veneers.

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Functional and Esthetic Protocol for Oral Rehabilitation

27

28

Fig 27 Frontal aspect of the diagnostic wax-up. Fig 28 Correct development of occlusal contacts and anterior guidance pathways.

Phase 2: Reconstruction of the mandibular anterior segment

canines and mandibular anterior teeth, impressions

The mandibular anterior teeth, from right canine to

were taken with polyvinyl siloxane material to gener-

After the provisionals were placed on the maxillary

left canine, had continued to erupt due to the lack of

ate the working casts, which were mounted on a semi-

occlusal contact (Fig 22). The treatment aims were to

adjustable articulator with the aid of a facebow.

perform root canal therapy and adequate incisal reduction as well as to correct the size and arrangement

Diagnostic wax up

of the teeth. Because no changes were needed in the

The wax-up of the maxillary posterior teeth and the

gingival levels and the anatomic crowns presented no

mandibular dentition completed the planning of the

-

wear, they were used as references to create the de-

restorative work and the fabrication of the remaining

finitive clinical crowns.

provisionals (Figs 27 and 28).

After incisal reduction was completed on the mandibular anterior teeth, Premium acrylic resin teeth,

Provisional restorations

similar to laminate veneers, were shaped and secured

The diagnostic wax-up casts were duplicated and re-

over the anterior teeth with cyanoacrylate glue and

lated on a semi-adjustable articulator with the provi-

flowable composite resin to guide the preparation of

sional restorations fabricated using the double-pressing

the maxillary canines and the placement of provision-

technique. The provisional crowns must be very close

als (Figs 23 to 25). The correct positioning of the acrylic

to the diagnostic wax-up to provide a general idea of

laminate veneers on the mandibular incisors was help-

the finished case (Figs 29 to 31).

ful in achieving adequate palatal morphology of the maxillary teeth in the wax-up (Fig 26).

The mandibular anterior teeth were prepared to receive fiber posts prior to placement of the provisional crowns (Fig 32).

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ADOLFI/SCOPIN

Figs 29 and 30 Occlusal aspect of the provisional crowns. Fig 31 Perfect occlusal relationships were developed on the provisionals. Fig 32 Placement of provisional crowns from the mandibular left canine to the mandibular right lateral incisor. Because the mandibular right canine would be restored with minimal tooth preparation and a ceramic laminate veneer, it is not necessary to perform this specific step in this phase. Fig 33 Reconstruction of the mandibular posterior teeth with the correct anteroposterior occlusal plane.

QDT 2013

Functional and Esthetic Protocol for Oral Rehabilitation

34

Fig 34 All the provisional restorations are in position according to the functional and esthetic protocol. Figs 35 and 36 The new occlusal contacts would provide balance to the masticatory system, stability to the tooth positions, and the correct vertical dimension of occlusion.

Phase 4: Reconstruction of the maxillary

Phase 3: Reconstruction of the mandibular posterior segment

posterior segment

The overall position of the mandibular posterior teeth

The maxillary left first premolar was prepared for a

had been altered, particularly on the left side, with dia-

provisional in good occlusal contact with its mandibu-

stema and rotation between the canine and first pre-

lar antagonist. It is very important to make individual

molar (see Fig 10). After necessary corrections, it was

crown adjustments at this time, because it is still pos-

possible to improve the anteroposterior curve (curve

sible to make minor modifications on the mandibular

of Spee). The left canine and first premolar were pre-

provisional restorations for the anteroposterior curve

pared for complete crowns and received provisional res-

or at the buccal corridor. If repositioning of a man-

torations. Any interference with the antagonist arch on

dibular provisional crown was deemed necessary, a

mandibular closure must be adjusted on the maxillary

new relining was made before preparing the remain-

teeth while maintaining an adequate vertical dimension

ing maxillary posterior teeth. The planned objectives

of occlusion. It is important to avoid altering the position

were achieved over several clinical appointments (Figs

and morphology of the mandibular provisional crowns

34 to 36).

and thus the anteroposterior curve that had been established on the diagnostic wax-up (Fig 33).

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ADOLFI/SCOPIN

Fig 37 A screw-retained provisional with adequate cervical contours following 6 months of healing. The provisional crown restores the implant placed in the position of the mandibular left first molar. Figs 38 and 39 Lateral views of the gingival levels after crown lengthening.

37

Implant placement

bovine bone matrix (Bio-Oss, Geistlich, Princeton, New

nificant distal coronal destruction and up to 4 mm of

Jersey, USA) to preserve the alveolar process. 1 • Be-

subgingival involvement that compromised the entire

cause of high initial implant stability, the provisional

structure. Conventional methods of treatment would

crown was placed at the time of surgery." -13 A pre-

include crown lengthening and extensive osteotomy

fabricated abutment (Easy Abutment, Nobel Biocare,

along with root canal treatment and post insertion to

Zurich, Switzerland), originally designed for cemented

rebuild the lost coronal structure. Thus, it was decided

crowns, was selected to fabricate a screw-retained,

to extract the tooth and replace it with an implant to

implant-supported restoration. All contacts during cen-

preserve bone structure and encourage a more favor-

tric and eccentric mandibular positions were removed to avoid excessive loading during healing. 14-16 The

able prognosis.

A minimally traumatic tooth extraction was per-

provisional crown was maintained throughout the heal-

formed to avoid compromising soft and hard tissue

ing period while the soft and hard tissues matured 1718

architecture, and a 5.0 mm x 8.0 mm implant (No-

belReplace, Nobel Biocare) was placed through the

150

The extraction alveoli were filled with demineralized

The mandibular left first molar presented with sig-

37). Flapless crown lengthening 19 was performed on the

root septum to assure that adequate anatomy was

maxillary central incisors to improve the gingival levels

preserved after tooth extraction.

(Figs 38 and 39).

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(Fig

Functional and Esthetic Protocol for Oral Rehabilitation

Figs 40 and 41 The maxillary and mandibular teeth prepared to receive all-ceramic crowns.

40

41

Fig 42 The working casts on a semiadjustable articulator. Fig 43 The stone casts made from the provisional restorations to be related with the working casts.

Fig 44 Silicone index obtained from the provisional restorations Fig 45 The silicone index is used on the working casts to control overbite and overjet relationships.

Impression procedures

to-zirconia technique, with the exception of the man-

After achieving adequate balance among the provi-

dibular right canine that was prepared for a partial ce-

sional restorations during the oral rehabilitation pro-

ramic restoration (Figs 40 and 41).

cess, it was possible to provide definitive ceramic res-

Thus, new impressions were taken with addition sili-

torations in phases. It is recommended to start in the

cone material (Flexitime, Heraeus Kulzer) to generate

anterior maxilla and mandible to verify the functional

the definitive working casts related on a semi-adjust-

and esthetic checklists (see Fig 3) that determine si-

able articulator (Fig 42). The stone casts obtained from

multaneous and bilateral contacts, centric relation oc-

the maxillary and mandibular provisional restorations

clusion, adequate phonetics, vertical dimension of oc-

must be related with the working casts to provide in-

clusion, and anterior guidance pathways.

formation for the definitive ceramic crowns with the

The maxillary and the mandibular anterior teeth

aid of the silicone indices (Figs 43 to 45).

were restored with all-ceramic crowns using the press-

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ADOLFI/SCOPIN

Figs 46 and 47 The zirconium dioxide copings on the working casts.

Press-to-zirconia technology

phases 1 and 2 (Figs 48 to 50). The high translucency

With the incorporation of computer-aided design and

ingot (IPS e.max ZirPress, Ivoclar-Vivadent) in value Al

computer-assisted manufacture (CAD/CAM) technol-

was selected to provide excellent optical characteris-

ogy to fabricate zirconium dioxide frameworks, the

tics including fluorescence. All restorations were ad-

demand for metal-free restorations, primarily in the

justed on the working cast before the intraoral try-in

esthetic zone, has increased considerably by both pa-

(Figs 51 to 53).

tients and practitioners. The benefits of zirconia frame-

After the provisional restorations were removed, the

works include biocompatibility, esthetics, excellent

tooth preparations were cleaned with pumice paste to

marginal fit, and strength. Also, it is possible to benefit

remove any remnant of provisional cement and to as-

from an injection molding procedure to "press" the

sure perfect crown fit. Ceramic crowns were adjusted

esthetic veneering over the zirconia framework. This

by checking the interproximal contacts of the maxillary

technique not only provides stable and predictable

and mandibular teeth on each side and then by adjust-

quality but also excellent development of anatomical

ing occlusal contacts, tooth by tooth, with the antago-

and morphologic features at the occlusal surface with

nists. This procedure was done with care to maintain

correct contact points.

the vertical dimension of occlusion.

Lava zirconia (3M ESPE, St Paul, Minnesota, USA) in

The vertical dimension of occlusion was achieved

shade no. 2 was used for the frameworks for the maxil-

through bilateral contact of the maxillary and mandib-

lary and mandibular teeth (Figs 46 and 47). The man-

ular dentition, including the canines, using articulating

dibular right canine received a lithium disilicate lami-

paper (Bausch, Nashua, New Hampshire, USA) with

nate core with ceramic veneering material (IPS e.max,

progressive thickness of 200 pm to 12 pm.

Ivoclar-Vivadent, Schaan, Liechtenstein). Before the

The aim of these functional adjustments was to de-

esthetic wax-up of the maxillary and mandibular an-

termine the occlusal patterns established by the pro-

terior teeth, a liner material (IPS e.max Ceram ZirLiner,

visional restorations with canine guidance and partial

Ivoclar-Vivadent) was applied over the zirconia copings

and/or total anterior group function. In this clinical sit-

to improve bond strength at the interface of the ce-

uation, canine guidance and disocclusion of the poste-

ramic veneer and zirconia core.

rior teeth were created (Figs 54 to 56).

The completed waxed-up restorations must follow

After all functional, esthetic, and morphologic ad-

the functional and esthetic requirements set out in

justments were performed, the maxillary incisors were

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Functional and Esthetic Protocol for Oral Rehabilitation

52

Figs 48 and 49 Full-contour wax-ups over the zirconia copings.

Fig 50 The completed wax-ups for the definitive ceramic restorations in full occlusion. Figs 51 and 52 Definitive maxillary and mandibular crowns made using the injection molding and press technology.

Fig 53 The adjustment of occlusal contacts and anterior guidance is completed on the semiadjustable articulator.

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ADOLFI/SCOPIN

Fig 54 Adjustment of the definitive maxillary and mandibular anterior restorations in the mouth. Figs 55 and 56 The canine guidance and disocclusion patterns of posterior teeth are visible.

Figs 57 and 58 The definitive maxillary anterior restorations after bonding. Fig 59 The definitive mandibular anterior restorations after bonding.

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Functional and Esthetic Protocol for Oral Rehabilitation

Figs 60 and 61 The working casts with the zirconia copings related in the semi-adjustable articulator. The maxillary right first molar would receive an inlay ceramic restoration with lithium disilicate framework.

reduced using the cut-back technique. Incisal and

The all-ceramic restorations were luted with univer-

transparent IPS e.max material is built up for adequate

sal resin cement Panavia F 2.0 (Kuraray, Tokyo, Japan).

translucence and opalescence. The cut-back was not

At this point, the esthetics, vertical dimension of oc-

necessary for the mandibular incisors, which received

clusion, central relation, and anterior guidance€de-

only one layer of shade material no.1 for the final shade Al and were baked at 720—C under vacuum.

scribed in phases 1 and 2€had already been defined

The bluish shades, cracks, halo effects, and interproxi-

for this functional and esthetic reconstruction. To rehabilitate the posterior teeth, complete impres-

mal stains were painted with IPS e.max Ceram Essence

sions of the maxillary and mandibular arches were taken

(Ivoclar -Vivadent) to create a multilayered effect and

with Flexitime silicone material, and zirconia copings

obtain optical differentiation between dentin and in-

were fabricated. A pick-up transfer was performed to

cisal features. Finally, restorations were glazed twice

generate the working casts related in a semi-adjust-

and fired at 770—C under vacuum to preserve all characterizations.

61). A complete esthetic wax-up with the correct oc-

able articulator with the aid of a facebow (Figs 60 and

The all-ceramic restorations were then polished

clusal morphology was developed over the zirconia

with felt wheels and pumice powder to establish the

frameworks, according to the principles already de-

superficial gloss. Superficial gloss is one of the most

scribed (Figs 62 to 66).

important factors in the natural integration of restorations (Figs 57 to 59).

The implant-supported provisional restorations on the mandibular first molars were used to transfer the

QDT 2013

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ADOLFI/SCOPIN

64

Fig 62 Frontal view of all wax-ups in position on the semi-adjustable articulator. Figs 63 and 64 Lateral views showing the high functional and morphologic quality of the posterior wax-ups. Figs 65 and 66 Occlusal views of posterior wax-ups over the zirconia copings.

156

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Functional and Esthetic Protocol for Oral Rehabilitation

Figs 67 and 68 The framework wax-up of the dental implant for the mandibular left first molar is made with adequate size for ceramic support before scanning of the prosthetic component.

necessary information to fabricate customized zirco-

because of excellent biocompatibility. Soft tissue re-

nia abutments with the correct emergence profile and

sponse to zirconium dioxide is better than soft tissue

cervical contours. The temporary implant restoration

response to metals, and less plaque accumulation is

served as a transfer coping.

observed; consequently, minimal or no tissue reaction can be expected. 2122

All-ceramic abutments have started to play a significant role in achieving esthetically successful results,

All waxed-up restorations were injected and pressed

but the material itself is not the exclusive determinant

as described and were adjusted in the articulator be-

of esthetic success. It is the use of appropriate design,

fore try-in (Figs 69 to 73). The previous verification of

proper handling of the materials, as well as the zirconia

the occlusal contacts allowed for only minor adjust-

abutment that enables the clinician to achieve esthetic

ments in the oral cavity. At clinical try-in, adjustment

outcomes that were not possible with traditional metal

started with the proximal contacts of maxillary and

alloys. 20 Zirconia frameworks must have adequate di-

mandibular posterior teeth in the same quadrant. The

mensions, be designed to support ceramic veneering

occlusal contacts were developed on a tooth-to-tooth

material, and avoid fracture and/or delamination (chip-

basis, maintaining the vertical dimension of occlusion

ping) (Figs 67 and 68).

provided by bilateral contact points on the maxillary

The subgingiva I portions of all-ceramic zirconia abut-

and mandibular canines; progressive articulating pa-

ments were not veneered; they are designed to be in

per foils (Bausch) were used from 200 pm to 12 pm

direct contact with the soft tissue emergence profile

(Figs 74 to 76).

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E.

ADOLFI/SCOPIN

rP\1". 7191€ 70

71

72

73

Fig 69 Injected ceramic crowns on the working cast.

Figs 70 and 71 Lateral views of injected ceramic crowns after occlusal adjustments. Figs 72 and 73 Occlusal views of injection-molded, press-to-zirconia restorations.

ODT 2013

Functional and Esthetic Protocol for Oral Rehabilitation

Fig 74 The maxillary and mandibular posterior restorations after the minor occlusal adjustment. Fig 75 The mandibular posterior restorations tried in before characterization and glazing. Fig 76 The maxillary posterior restorations tried in before characterization and glazing.

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ADOLFI/SCOPIN

77

Fig 77 Frontal view of the completed case. Fig 78 The maxillary arch with ceramic bonded restorations in position. Fig 79 Correct development of the mandibular occlusal plane.

Fig 80 The definitive maxillary and mandibular restorations achieved light occlusal contacts. Fig 81 Occlusal aspect of the definitive maxillary resto-

rations. A lithium dissilicate restoration is bonded to the maxillary right first molar.

80

Fig 82 Occlusal aspect of the definitive mandibular restorations.

81

QDT 2013

Functional and Esthetic Protocol for Oral Rehabilitation When it is necessary to improve the occlusal morphology after all the adjustments, the dental technician can use the non-edge technique" for natural reconstruction of occlusal anatomy and easy reestablishment of proper function. All posterior ceramic restorations were characterized and glazed as described for the anterior restorations and were then luted with a universal resin cement (Panavia F 2.0) (Figs 77 to 82).

CONCLUSION A functional and esthetic protocol for full-mouth rehabilitation must have a well-defined diagnosis, prognosis, and treatment plan. This article presented a protocol with four phases to treat complex cases with the use of diagnostic wax-ups and provisional crowns, which provides benefits to patients and practitioners. The association between CAD/CAM technologies for zirconia frameworks and injection/press techniques for veneering esthetic materials guarantees highly functional and esthetic definitive all-ceramic restorations.

6. Denehy GE. A direct approach to restore anterior teeth. Am J Dent 2000;13(special issue):55D-59D. 7. Vanini L, Mangani F, Klimovskaia 0 (eds). Conservative Restoration of Anterior Teeth. Viterbo, Italy: ACME, 2005. 8. Ferencz J, Fanetti P. Enhanced communication. Inside Dent Technol 2011;2. http://www.dentalaegis.com/idt/2011/01/enhancedcommunication . Accessed 17 Dec 2012. 9. Vailati F, Belser UC. Full-mouth adhesive rehabilitation of severely eroded dentition: The three-step technique. Part 1. Eur J Esthet Dent 2008;3:30-44. 10. Araujo MG, Lindhe J. Ridge preservation with the use of BioOss collagen: A 6-month study in the dog. Clin Oral Implants Res 2009;20:433-440. 11. Szmukler-Moncler S, Salama H, Reingerwirtz Y, Dubruille JH. Timing of loading and effect of micromotion on bone-dental implant interface: Review of experimental literature. J Biomed Mater Res 1998;43:192-203. 12. Gapski R, Wang HL, Mascarenhas P, Lang NP. Critical review of immediate implant loading. Clin Oral Impl Res 2003;15:787794. 13. Ganeles J, Wismeijer D. Early and immediately restored and loaded dental implants for single-tooth and partial-arch applications. Int J Oral Maxillofac Implants 2004;19(suppl):92-102. 14. Kupeyan HK, May KB. Implant and provisional crown placement: A one-stage protocol. Implant Dent 1998;7:213-219. 15. Wohrle PS. Single-tooth replacement in the aesthetic zone with immediate provisionalization: Fourteen consecutive case reports. Pract Periodontics Aesthet Dent 1998;10:1107-1114. 16. Wang HL, Ormianier Z, Palti A, Perel ML, Trisi P, Sammartino G. Consensus conference on immediate loading: The single tooth and partial edentulous areas. Implant Dent 2006;15:324-333. 17. Tupac RG. When is an implant ready for a tooth? J Calif Dent Assoc 2003;31:911-915.

REFERENCES 1. Stevens FW. The generalist as the coordinator of the dental team. Am J Orthod 1969;56:107-113. 2. Douglass GD. Making a comprehensive diagnosis in a comprehensive care curriculum. J Dent Educ 2002;66:414-420. 3. Poi WR, Panzarini SR, Pedrini D, Manfrini TM, Zina LG, Hamanaka EF. Plano de tratamento em odontologia: Analise dos pianos propostos por alunos de graduacao. Pesq Bras Odontoped Clin Integr 2007;7:297-301. 4. Hook CR, Comer RW, Trombly RM, Guinn JW, Shrout MK. Treatment planning processes in dental schools. J Dent Educ 2002; 66:68-74.

18. Morton D, Jaffin R, Weber HR Immediate restoration and loading of dental implants: Clinical considerations and protocols. Int J Oral Maxilofac Implants 2004;19(suppl):103-108. 19. Joly JC, Carvalho PFM, da Silva RC. In: Reconstrucao Tecidual Estetica: Procedimentos Plasticos e Regenerativos Periodontais e Periimplantares. Brazil: Artes Medicas, 2010,253-309. 20. Blatz MB, Bergler M, Hoist S, Block MS. Zirconia abutments for single-tooth implants-Rationale and clinical guidelines. J Oral Maxillofac Surg 2009;67(11 suppl):74-81. 21. Rimondini L, Cerroni L, Carrassi A, Torricelli R Bacterial colonization of zirconia ceramic surfaces: An in vitro and in vivo study. Int J Oral Maxillofac Implants 2002;17:793-798. 22. Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on commercially pure titanium and zirconium oxidedisks: An in vivo human study. J Periodontol 2004;75:292-296. 23. Adolfi D. Natural Esthetics. Chicago: Quintessence, 2003.

5. Adolfi D. Functional, esthetic, and morphologic adjustment of anterior teeth. Quintessence Dental Technol 2009;32:153-168.

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Porcelain-Fused-to-Metal and All-Ceramic Crowns for Posterior Teeth: Material Science and Laboratory Procedures

Masayuki Saito, RDT' Kimiyo Sawyer, RDT 2

ver the last decade, laboratory procedures

trast, porcelain-fused-to-metal (PFM), pressed lithium

have changed dramatically due to the intro-

disilicate (LD), and porcelain-fused-to-zirconia (PFZ)

duction of computer-aided design/computer-

crowns remain popular among smaller laboratories.

assisted manufacture (CAD/CAM) technology. This

This article compares these four restoration types based

evolution began with the use of zirconia as a base

on their material science and laboratory procedures.

material for dental restorations. Recently, the use of CAD/CAM-fabricated full-contour zirconia (FCZ) crowns for posterior teeth has become a popular restoration option among large commercial laboratories. In con-

Material Science 'Master Ceramist, Cusp Dental Laboratory, Malden, Massachusetts, USA. 'President, Cusp Dental Laboratory, Malden, Massachusetts, USA. Correspondence to: Kimiyo Sawyer, Cusp Dental Laboratory, 381 Pearl Street, Maiden, MA 02148. Email: [email protected]

QDT 2013

Properly constructed and seated PFM crowns provide optimal strength and longevity. An anatomical framework design is crucial to provide proper support and maintain the appropriate thickness for the veneering porcelain.1-3

Porcelain Fused to Metal and All Ceramic Crowns for Posterior Teeth -

The following criteria are critical to proper fabrica-

-

-

-

CAM systems are now equipped with the printing ca-

tion":

pability to create an acrylic resin pattern for PFM cop-

® The coefficients of thermal expansion of the porce-

is particularly appealing because it is inexpensive and

ings and full cast restorations. Cobalt-chromium alloy lain and alloy must be closely matched to achieve a strong bond; otherwise, adhesive failure (eg, delamination or fracture) may occur.

highly biocompatible. The laboratory is responsible for scanning the dies, designing the virtual frameworks, and electronically

® Proper casting temperature and timing are needed

transferring the digital information to a printing facility.

to prevent overheating or miscasting. Excess gas in

The acrylic resin pattern provides a consistent thick-

the alloy can cause small surface pits and bubbles in

ness and sufficient support for the porcelain. However;

the veneering porcelain.

these CAD/CAM systems do have limitations; it is of-

® A smooth metal surface must be achieved via finish-

ten necessary to manually perform touch-ups and fin-

ing procedures to strengthen the bond with the ve-

ish the margins with a wax-up to achieve an optimal

neering porcelain. ® It is important to avoid sharp angles or pits on the veneering surface, which can lead to cracking due to internal stress.

marginal seal before investing and casting. Despite these imperfections, CAD/CAM technology is rapidly progressing. There are three basic layering porcelain powders:

® Heat treatment is necessary for degassing and to

dentin (body), enamel, and incisal (translucent). Dentin

create an oxide layer; which promotes a chemical

and enamel layers control the color; while the incisal

bond between the alloy and porcelain.

layer provides translucency. When restoring anterior

® The use of an opaque layer as the first porcelain

teeth, all three powders must be used to achieve ac-

coat is crucial for three reasons: (1) to ensure a strong

ceptable esthetics. However; newly developed enamel

bond at the interface of the opaque porcelain and alloy, (2) to mask the metal color, and (3) to provide

porcelains (eg, EX-3 Speed Enamel, Kuraray Noritake, Tokyo, Japan) offer higher translucency than conven-

a base color for the targeted shade. 2®3 When a satis-

tional enamel porcelain while remaining less translu-

factory opaque layer has been baked, the dentin

cent than incisial porcelain. For posterior crowns, these

(body), enamel, and incisal (translucent) porcelain

new enamel porcelains can be used in conjunction with

layers can be applied to achieve the desired ap-

dentin porcelain to provide acceptable color and

pearance.

translucency in only two layers. This two-layer technique offers esthetic outcomes similar to those of the

The fabrication of PFM crowns involves many steps;

more time-consuming three-layer technique (Fig 1).

therefore, errors may occur. Nevertheless, more than 50

The two-layer technique is also more suitable for en-

years of research, development, and clinical experiences

try-level ceramists due to its simplicity.

show that PFM crowns in the posterior region main-

The opaque layer must be baked twice; the first thin

tain a high survival rate (95%) 4,5 with well-established strength and reliability.

layer of wash bake ensures the bond strength between the porcelain and metal, while the second layer covers the entire metal surface to mask the dark color. 2'3 One of the most challenging aspects of fabricating

Laboratory Procedures

PFM crowns is the high light reflection at the marginal

Laboratory procedures have changed dramatically since

through the metal. Therefore, controlling light reflec-

areas, which is caused by the lack of light transmission the inception of CAD/CAM technology. Many large laboratories now rely on high-end CAD/CAM systems.

tion during layering is important for a successful es-

thetic outcome. 2,3 An internal stain (EX-3 Internal Stain,

In the beginning, CAD/CAM milling materials included

Kuraray Noritake) can be applied over the opaque

only all-ceramic options such as zircon ia or glass blocks.

layer to control the light reflection. Internal staining

As the technology progressed, however, the milling

does not increase the thickness of the crown and is

capabilities expanded to include wax, composite res-

ideal for use at the margins (Fig 2). When using the

in, and cobalt-chromium alloy; further; some CAD/

two-layer approach, the amount of body porcelain

QDT 2013

SAITO/SAWYER

lb

la

Figs 1a and lb Two-layer PFM crowns (left) and three-layer PFM crowns (right). Note the similar esthetic outcomes.

Fig 2 Application of internal stain over the opaque layer to control light reflection. Fig 3 Two-layer build-up technique.

2 Speed Enamel (translucent + enamel powders)

Translucent powder

Three-layer method

Cutback line for two-layer method

Two-layer method

3

should be decreased with a cutback method, while the

as chemical and dimensional stability due to its

amount of enamel porcelain should be increased to

transformation-toughening characteristics. 6 The differ-

enhance translucency (Fig 3).

ent brands of Y-TZP available on the market show a similar coefficient of thermal expansion (CTE) and other physical properties. Therefore, veneering porcelain from one system can be applied to copings from other

PFZ CROWNS Material Science

manufacturers listed in Table 1. However, two or more different brands of porcelain powders should not be mixed during application, as each brand's CTE is not exactly the same.

Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP)

One of the unique features of Y TZP is that its sur-

ceramic is commonly used in dentistry. This material

face structure transforms from a tetragonal to monoclinic phase at low temperatures with moisture. 5 Flinn

offers high flexural strength and toughness as well

DDT 2013

-

Porcelain-Fused-to-Metal and All-Ceramic Crowns for Posterior Teeth

Table 1

Coefficient of Thermal Expansion (CTE) of Different Ceramic Systems

Brand

CTE*

Cercon (Dentsply, York, Pennsylvania, USA)

10.5

CEREC YZ (Sirona, Long Island City, New York, USA)

10.5

KATANA (Kuraray Noritake, Tokyo, Japan)

10.5

Lava (3M ESPE, St Paul, Minnesota, USA)

10.0

Prettau (Zirkonzahn, Gais, Switzerland)

10.6

Procera ZR (Nobel Biocare, Zurich, Switzerland)

10.4

*As specified by the manufacturers.

et a1 7 found that this surface transformation triggered a statistically significant decrease in the flexural strength

Laboratory Procedures

of thin bars of Y-TZP. Flexural strength differs among

Just as in PFM crowns, PFZ crowns consist of two dif-

various brands. Regardless, Y-TZP core materials have

ferent materials: the core zirconia and the veneering

not been problematic in clinical use. 8 The bond be-

porcelain. Also as in PFM crowns, the veneering mate-

tween the zirconia core material and veneering porce-

rial is composed of feldspathic porcelain; however, the

lain differs from that of PFM crowns because zirconia

coefficient of thermal expansion (CTE) is approximate-

does not require creation of an oxide layer for bonding.

ly 9 ppm for PFZ crowns as opposed to 14 to 15 ppm

This is due to the fact oxide already exists in the compo-

for PFM crowns.'

nents currently available on the market€approximately

The PFZ framework procedure is simpler than that

95% zirconium oxide and 5% yttrium oxide. One study

of PFM because it is produced by CAD/CAM and

found that PFZ restorations show better bond strength

does not require additional procedures to increase the

between the core and veneering material than PFM

bond strength. A chamfer preparation should be used

restorations.— This indicates that the bond strength may

at the margin, without a bevel or knife-edge finish line,

not be the primary determinant of veneer failure for

to support the ceramic structure (Fig 4). 12 Fine details

all-ceramic zirconia restorations. Chipping of the por-

of the framework cannot be confirmed until milling

celain layer has been frequently reported as a cause of

and sintering; therefore, certain adjustments using a

failure (13% to 25% of failures)."

dental handpiece will be required. Additional buildup

Blatz et all— reported the outcomes of 2,635 posteri-

is not possible. The milling unit has limited burs, which

or crowns fabricated by the present authors' laboratory

means the inside of the coping usually needs further

for a variety of private practitioners (14 prosthodon-

grinding to achieve optimal fit to the die. When grind-

tists and 8 general dentists). This survey concluded

ing zirconia with a diamond bur and high-speed tur-

that the survival times and probabilities of PFZ crowns

bine, cooling water supply is necessary because excess

(veneering layer: Cerabien ZR, Kuraray Noritake) were

heat can lead to microcracks at the coping surface and

statistically similar to those of PFM crowns. 1 — Another

eventually to fracture. The thermal conductivity of zir-

study evaluated the remake ratios of 24,392 zirconia-

conia is lower than that of metal alloy, which means

based porcelain crowns (23,787 Cerabien ZR crowns;

PFZ crowns must be heated up and cooled down

605 Lava Ceram crowns, 3M ESPE, St Paul, Minnesota,

slowly. It is important to follow the manufacturer's bak-

USA) fabricated in a private laboratory. The overall re-

ing instructions (Table 2); otherwise, cracks or fractures

make ratio was less than 1%. 11 The results showed that

may occur.—

the quality of the veneering porcelain greatly contributed to the success of the restoration.

The translucency of the zirconia core decreases light reflection at the cervical area; thus, PFZ crowns

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165

SAITO/SAWYER Fig 4 Ideal preparation for PFZ posterior crowns.

4

Table 2

Baking Instructions for PFM and PFZ Crowns*

Material

Dry-out time Low (min) temperature (©C/©F)

Heat rate (©C/©F)

High temperature (©C/©F)

Hold time (min)

Cooling time (min)

PFM (EX-3)

600/1,112

7

45/81

930/1,706

0

0

PFZ (Cerabien ZR)

600/1,112

7

45/81

930/1,706

1

4

*To be used as a guideline only. Baking temperatures can vary by case and furnace.

offer a more natural appearance compared to PFM

to 930—C depending on the size and opacity. The ve-

crowns. Unlike glass-ceramic, zirconia also offers a cer-

neering porcelain must be baked at a temperature

tain level of masking ability. Depending on the target-

well below the core ingot melting range. In contrast,

ed shade, the color of an abutment tooth and the light

the veneering porcelain for PFM crowns has a much

reflection at the cervical area can be controlled using

higher baking temperature (910—C to 950—C). In gen-

appropriate internal stains. PFZ crowns can be fabri-

eral, high-fusing porcelains are stronger than low-fusing

cated using the same two-layer technique used for the

porcelains.'

PFM crowns.

When veneering porcelain is applied over LD, a thin layer should be used to avoid possible chipping 13 ; further, the thickness of the core material must also be reduced. Thus, the fracture strength of the bilayer LD is affected by both the total specimen thickness and core

Material Science

thickness. 14 Pressed LD crowns require resin bonding cementation to ensure sufficient strength and longevity.

Pressed LD has the highest flexural strength (400 MPa) among the glass-ceramics used in prosthetic dentistry. Clinical studies have shown excellent short-term results.' Monolithic LD seems to be particularly well suited for posterior crowns.

Laboratory Procedures In the authors' commercial laboratory, trial tests were

The baking temperature of the feldspathic veneer-

performed before the actual procedures of the clinical

ing porcelain is lower than that of many other types.

cases of pressed LD crowns. The results showed that

The high baking temperature of the dentin and incisal

LD crowns (IPS e.max Press, Ivoclar Vivadent, Schaan,

porcelain is 750—C. In terms of the core material, the

Liechtenstein) were twice as strong as Leucite-reinforced

press temperature of an LD ingot ranges from 910—C

glass-ceramic crowns (IPS Empress, Ivoclar Vivadent)

QDT 2013

Porcelain-Fused-to-Metal and All-Ceramic Crowns for Posterior Teeth Table 3

Mean Flexural Strength of Ceramic Restorations

Material

Flexural strength (MPa)

Pressed LD (IPS e.max Press)

400

LD CAD block (IPS e.max CAD)

360

Leucite-reinforced glass-ceramic (IPS Empress)

150

Glass-ceramic (VITABLOCKS Mark II)

120

15a

Figs 5a and 5b The translucency and color of an LD crown can be influenced by the underlying tooth color, especially the margin area. Fig 6 Custom die fabricated using tooth-colored resin or wax.

and three times stronger than standard glass-ceramic

Pressed LD crowns can be ideal for a simple-tone

crowns (VITABLOCKS Mark II, VITA Zahnfabrik, Bad

tooth color as a shade guide, especially in the cervical

Sackingen, Germany) (Table 3). As a result of these

area. However, the high translucency of the final shade

findings, LD material replaced the earlier generations

will be affected by the underlying tooth (Fig 5). For

of glass-ceramic materials.

anterior restorations, it is important to create an extra

The laboratory procedures for pressed crowns are

die using tooth-colored resin or wax to mimic the

the same as for lithium disilicate or Leucite-reinforced

stump shade. The final color of the LD crown can then

glass-ceramic as long as the crown is fabricated prop-

be properly assessed (Fig 6). For posterior restora-

erly using the lost-wax technique. The fit and final

tions, these extra steps are rarely necessary, and PFM

anatomy are easy to manage. The acrylic resin pattern

or PFZ restorations should be used instead.

created by the CAD/CAM system should be finished

When fabricating LD crowns, selecting an ingot with

manually by a technician to promote optimal fit and

the appropriate value and chroma is important. When

marginal sealing. Due to the high flexural strength of

the final shade is incorporated into the final appear-

LD crowns, many clinicians who use chairside CAD/

ance of a pressed LD crown, a low-translucency (LT)

CAM systems also use lithium disilicate blocks despite

ingot should be used. The color of an LT ingot is simi-

the extra time required for sintering (Table 3).

lar to that of the dentin porcelain. The incisal area

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167

SAITO/SAWYER Fig 7 Transformation of zirconia from a tetragonal to a

SEM

monoclinic crystal structure. Hydrothermal condition: 180 C, 1 MPa x 5 h

Tetragonal

xsoo sown

Zr0 2 coping surface Monoclinic crystal structure (20 € 30 pm)

Weakened strength

7

Table 4

The Effect of Accelerated Aging on Flexural Strength of Y-TZP 7 ' 17 Flexural strength, MPa (SD)

Brand

Tetragonal

Monoclinic

Lava (3M ESPE)

1,158.0 (88)

829.5 (71)

Prettau (Zirconzahn)

1,406.0 (243)

882.7 (91)

Zirprime (Kuraray Noritake)

1,126.0 (92)

976.0 (37)

needs to be lighter in shade than the cervical area;

crowns reported reduced wear rates compared to

therefore, an ingot with a lighter shade than the target

those of regular feldspathic porcelain. 16 However, stud-

shade should be used for monolithic crowns. If the tar-

ies regarding the long-term durability of FCZ crowns

get shade is A2, a lighter-shade Al ingot is usually ap-

are still needed.

propriate.

Low-temperature degradation may be an issue over time. In clinical practice, the occlusal contact areas and marginal areas tend to be thinner than the manufacturers' recommended range of 0.5 to 1.0 mm. As discussed earlier, Y-TZP surface transformation can lead to lower flexural strength; however, this effect varies

168

Material Science

among different brands of materials. Therefore, the

FCZ crowns, which are typically composed of 3-mol%

should be selected for cases requiring a thin area (Fig

Y-TZP, are the fastest-growing restoration in terms of

7). In one study, hydrothermal aging of Y-TZP caused a

popularity due to their slightly increased translucency

statistically significant decrease in flexural strength fol-

brand that showed the least change in flexural strength

than the core material, efficiency, and affordability. A

lowing the transformation from a tetragonal to a

previous clinical study showed that FCZ crowns on

monoclinic crystal structure.'— Table 4 shows the effect

molar teeth performed well after 1 year in service, with

of accelerated aging on several brands of Y-TZP mate-

no evidence of cracks, chips, or fractures. 15 Another

rials. Additional clinical studies are needed to more

clinical study of the wear of dentition opposing FCZ

fully understand this effect over the long term.''''

QDT 2013

Porcelain-Fused-to-Metal and All-Ceramic Crowns for Posterior Teeth Fig 8a Milled crown soaked in liquid dye to achieve the targeted shade for monochromatic coloring. Fig 8b Multicolor dyeing before sintering.

Fig 8c Monochromatic (left) and multicolor (right) crowns after sintering.

Laboratory Procedures

Adequate occlusal reduction is necessary because occlusal and marginal areas may experience excessive

In recent years, the majority of FCZ procedures have

stress and loading post-insertion. Tight occlusal con-

been performed using a CAD/CAM system. However, manual adjustment of the intaglio surfaces is often

tact involves a preparation with at least 0.5 mm of occlusal space. For PFM this is not as crucial, as with

necessary.

less than 0.5 mm an undersirable spot of metal will

Crown shading is usually performed before sinter-

show due to lack of space for layering porcelain. Con-

ing. Two shading methods are available for FCZ crowns:

sidering the long-term function of a crown and the

monochromatic shading or multicolor shading using

limitations of CAD/CAM systems, it may be prudent to

the Lava Ceram system.

maintain at least 0.5 mm of space at all aspects of the

For monochromatic shading, a milled crown is soaked

restoration to avoid fractures. 17

in liquid dye to achieve a target shade of monochromatic color. After sintering, the crown is treated with an external stain (Fig 8). For multicolor shading, two or three different liquid dyes are applied with a brush at specific areas of the milled crown before sintering. The

CASE REPORT

crowns are again completed with an external stain.

This case report involves the fabrication a single crown

The color of an as-milled crown is solid, chalky white.

for a mandibular right first molar adjacent to two

The dye is absorbed from the crown, and the color only

healthy teeth. The case was received from a private

appears after sintering. Thus, establishing both the mix-

practitioner.

ing ratio of the liquid dye and the number of applica-

A chamfer margin preparation and appropriate oc-

tions is crucial to achieve an optimal final color. The

clusal reduction had been carried out. Four crowns

external stain will have only a small effect on the color.

were fabricated with four different materials for comparison in the patient's mouth:

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CASE REPORT

Fig 9a Comparison of translucency between ceramic crowns in monochromatic image. (left to right) PFM, FCZ, PFZ, and pressed LD. Fig 9b Comparisons of translucency in the margin area. (left to right) Pressed LD, PFZ, and FCZ crowns. Fig 10 First molar crowns fabricated using (left to right) PFM, PFZ, pressed LD, and FCZ on the casts.

1. PFM: Ceradelta 2 (silver-palladium alloy; Cendres+

were tried in, each shade was confirmed as A2 using

Metaux, Bern, Switzerland) and EX-3 (Kuraray Nori-

a dental spectrophotometer (Crystaleye, Olympus,

take)

Tokyo, Japan).

2. PFZ: Noritake KATANA coping and Noritake Cerabien ZR

Figures 10 and 11 show the differences between the crowns on the casts and in the patient's mouth.

3. LD: IPS e.max Press (LT Al ingot)

The cervical area of the pressed LD crown appears to

4. FCZ: Lava Plus

provide the best color match. The PFM crown shows high brightness due to light reflection. The PFZ and

A shade of A2 was instructed by the dentist based

FCZ crowns show better esthetics compared to the

on the VITA Lumin shade guide (VITA Zahnfabrik). Shade

PFM crown. The incisal areas of the feldspathic porce-

photographs, which are often sent to technicians for

lain in the PFM and PFZ crowns show superior color

anterior crowns, are not provided in posterior cases.

than those of the LD and FCZ crowns, which have

The crowns were fabricated following the manufactur-

monolithic material characteristics. The value of a mono-

ers' instructions (Figs 9 and 10). Before the crowns

lithic crown is the same over the entire crown surface;

Porcelain-Fused-to-Metal and All-Ceramic Crowns for Posterior Teeth

Fig 11 Occlusal (top), monochromatic (middle), and buccal (bottom) views of the (left to right) PFM, PFZ, pressed LD, and FCZ crowns. Fig 12 Confirming the selected shade at the final try-in stage.

therefore, the incisal areas of the LD and FCZ crowns

The occlusal area of FCZ crowns can be improved es-

have a higher value than would be ideal (Fig 11).

thetically by increasing the chroma before sintering.

In the patient's mouth, overall the PFM and PFZ crowns show better shade matching than the two monolithic crowns. Even though the A2 shade appeared acceptable on the casts, the occlusal aspects of the LD and FCZ crowns in the patient's mouth appear to have a higher

CONCLUSIONS Understanding the material science and laboratory

value than the adjacent teeth. For mandibular molar

procedures of porcelain-fused-to-metal, porcelain-

crowns, the occlusal surfaces are more visible than the

fused-to-zirconia, lithium disilicate, and full-contour

buccal surfaces, which makes occlusal shade matching

zirconia crowns is a primary factor for successful restor-

especially important (Fig 12). The use of shade Al for

ative treatment. Considering the range of options avail-

pressed LD crowns would result in excessive value at

able on the market, dental technicians are challenged

the occlusal surface since the material is solid in tone.

to master the techniques and technology necessary to

Shade A2 should be used for optimal color matching.

achieve long-term clinical success.

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ACKNOWLEDGMENTS The authors extend special thanks to Drs Kimberly S. Weiss and Miguel Vidal for their collaboration; Mr Yoshihisa Yamada and Mr Toshio Sakakibara, Kuraray Noritake Dental, for their technical advice and material support; and Dr Mark Wang for his material support.

REFERENCES 1. Rosenstiel SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics, ed 4. St Louis: Mosby, 2006. 2. Yamamoto M. Metal-Ceramics: Principle and Methods of Makoto Yamamoto. Chicago: Quintessence, 1985. 3. Ban K. Q&A: Ceramometal science. In: Dental Technology Library, ed 1. Tokyo: Ishiyaku, 1989:2-20. 4. Gungor MA, Artunc C, Dundar M. Seven-year clinical follow-up study of Probond ceramic crowns. Quintessence Int 2007;38:456-463. 5. Vigolo P, Mutinelli S. Evaluation of zirconium-oxide-based ceramic single-unit posterior fixed dental prostheses (FDPs) generated with two CAD/CAM systems compared to porcelainfused-to-metal single-unit posterior FDPs: A 5-year clinical prospective study. J Prosthodont 2012;21:265-269. 6. Blatz MB, Bergler M, Ozer F, Hoist S, Phark HJ, Chiche GJ. Bond strength of different veneering ceramics to zirconia and their susceptibility to thermocycling. Am J Dent 2010;23:213-216. 7. Flinn BD, Roberts BR, Mancl LA, Raigrodski AJ. The effect of accelerated aging on strength of thin Y-TZP. Presented at the 88th General Session and Exhibition of the International Association for Dental Research, Barcelona, 17 July 2010. 8. Christensen RP, Ploeger BJ. A clinical comparison of zirconia, metal and alumina fixed-prosthesis frameworks veneered with layered or pressed ceramic: A three-year report. J Am Dent Assoc 2010;141:1317-1329.

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9. Raigrodski AJ, Chiche GJ, Potiket N, et al. The efficacy of posterior three-unit zirconium-oxide-based ceramic fixed partial dental prostheses: A prospective clinical pilot study. J Prosthet Dent 2006;96:237-244. 10. Blatz MB, Mante F, Chiche GJ, et al. Clinical survival of posterior zirconia crowns in private practice. Presented at the 88th General Session and Exhibition of the International Association for Dental Research, Barcelona, 16 July 2010. 11. Raigrodski AJ, Dogan S, Englund G. 4-8 year retrospective dental laboratory survey of zirconia-based restorations. Presented at the 41st Annual Meeting and Exhibition of the American Academy of Dental Research, Tampa, Florida, 22 Mar 2012. 12. Kunzelmann KH, Kern M, Pospiech P, et al. All-Ceramics at a Glance, ed 1. Ettingen, Switzerland: Society for Dental Ceramics, 1997. 13. Guess PC, Zavanelli RA, Silva NR, Bonfante EA, Coelho PG, Thompson VP. Monolithic CAD/CAM lithium disilicate versus veneered Y-TZP crowns: Comparison of failure modes and reliability after fatigue. Int J Prosthodont 2010;23:434-442. 14. Baladhandayutham B, Beck P, Litaker MS, Cakir D, Burgess J. Fracture strength of all-ceramic restorations after fatigue loading. Presented at the 41st Annual Meeting and Exhibition of the American Academy of Dental Research, Tampa, Florida, 21 Mar 2012. 15. Christensen GJ. BruxZir and Milled IPS e.max CAD: Very promising 1-year results. Clinicians Report 2012;5(6). 16. Sorensen JA, Sultan EA, Sorensen PN. Three-body wear of enamel against full crown ceramics. Presented at the 89th General Session and Exhibition of the International Association for Dental Research, San Diego, 18 Mar 2011. 17. Mochales C, Maerten A, Rack A, et al. Monoclinic phase transformations of zirconia-based dental prostheses, induced by clinically practised surface manipulations. Acta Biomater 2011;7: 2994-3002.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

RP

VAS

Monolithic CAD/CAM Porcelain Laminate Veneers with External Staining Galip Gurel, DDS, MS' Birgul Metin Yerusalmi, DDS 2 Adrian()Shye,CDT 3

The patient exhibits a gummy smile and proportionally short teeth. The soft tissue is healthy. The plan is to apically lengthen the teeth and create a better smile design with CAD/CAM monolithic veneers.

'Private Practice, Istanbul, Turkey; Visiting Professor, New York University, USA. 2 Private

Practice, Istanbul, Turkey.

'Dental Technician, Sao Paulo, Brazil.

Correspondence to: Dr Galip Gurel, Tesvikiye Cad. Bayer Apt No. 63 Kat:6, Nisantasi 34365, Istanbul, Turkey. Email: [email protected]

Teeth are apically crown lengthened with a hard tissue laser.

Relatively better proportions are achieved.

The mock-up starts with the two central incisors, making sure that the incisal edges are positioned correctly, followed by the lateral incisors and canines. Additive mock-up is best for minimally invasive tooth preparation.

A wax-up that mimics the dimensions of the mock-up is made with ideal morphology and surface texture.

Note the prep-less veneer design on the mesial of the canines.

The surface texture and 3D morphology play an important role in this case, as the monolithic veneers will be milled out of this design.

DIGITAL DESIGN

A digital impression of the wax-up is made.

The digital impression of the wax-up is superimposed on a digital impression of the patient's teeth after apical crown lengthening.

CAD/CAM APT

Copying the same morphology and surface texture of the wax-up, the aesthetic pre-evaluative temporary (APT) is made of plastic ingots.

PREPARATION THROUGH APT

The depths that are created with the depth cutter are marked with a pencil for extremely precise tooth preparation, and 'nasal depths are created with a 1.5-mm-thick fissure diamond bur.

After the APT is removed, one can easily see the remaining parts of the teeth to be prepared (by following the pencil drawings done through the APT).

LIZ G THE TOOTH PREPARATION

A round-ended extrafine fissure diamond bur is used, followed by the white Arkansas stone and sandpaper disk.

OVISIONAL RESTORATIONS

Second digital impression is made after the tooth preparation.

The previously scanned wax-up, superimposed over the patient's prepared teeth digital impression, is used for milling the composite veneers to be used as provisionals as well as for milling the final monolithic porcelain laminate veneers.

Milling the composite ingots to be used as provisional veneers.

The teeth are spot etched and the whole surface is treated with adhesive.

The provisional veneers are partially bonded over the prepared teeth.

INGOT MILLING AND SINTERING

Milling the e.max CAD HT bleach 4 ingots for the final monolithic porcelain laminate veneers.

Monolithic e.max CAD HT ingots on the cast after being milled and before sintering.

Note how the exact surface texture and tooth form is copied from the wax-up.

Monolithic e.max CAD HT ingots on the cast after sintering.

Monlithic e.max CAD HT ingots on the dies ready for external staining.

EXTERNAL STAINING

The first layer is stained with blue and its different shades to create the translucency effects.

The second layer is stained with white and its different shades to soften the translucency effects.

The third layer is stained with orange and its different shades to create the opalescence effects.

High-illumination light transmission is used for observing the translucency after the monolithic veneers are externally stained.

Light reflection after monolithic veneers are externally stained.

DEFINITIVE RESTORATIONS

Externally stained veneers on the cast.

Externally stained veneers in the mouth 1 week after cementation.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

Jin-Ho Phark, DDS, Dr Med Dent' Giuseppe Romeo, MDT2

E

sthetic dental rehabilitation is an undoubtedly

This article presents a new system that will enable

complex process. Numerous factors must be

dental professionals to go beyond the usual creative

evaluated when designing a dental restoration,

standards in esthetic rehabilitation. First, the principal

including tooth alignment, clinical crown dimensions,

tooth forms and their characteristics will be analyzed.

and occlusion. Complete understanding of all anatom-

This discussion will lay the groundwork for the intro-

ical parameters is essential to create an esthetic and

duction of a new tooth-form classification: Dental Ana-

harmonious restoration. 1-5

tomical Combinations. By sectioning the three principal tooth forms and recombining their individual characteristics, new tooth forms can be created. Finally, the application of this new system will be demonstrated via a clinical case report.

'Assistant Professor of Clinical Dentistry, Division of Restorative Sciences, Ostrow School of Dentistry; Director, Biomaterials Research Laboratory, University of Southern California, Los Angeles, California, USA. 'Oral Design Center, Torino, Italy; Burbank Dental Laboratory, Burbank, California, USA; Clinical Assistant Professor, Division of Restorative Sciences, Ostrow School of Dentistry, University of Southern California, Los Angeles, California, USA; Director, Ceramic Esthetics Department, Center of Dental Technology, Los Angeles, California, USA. Correspondence to: Dr Jin-Ho Phark, Ostrow School of Dentistry of USC, 925 W 34th Street, DEN 4112, Los Angeles, CA 900890641. Email: [email protected]

TOOTH ANATOMY The Three Basic Tooth Forms Various facial and dental forms exist in nature, and some researchers have proposed that these types should be the starting point for the rehabilitation of patients requiring a fixed or removable restoration. 6-8

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PHARK/ROMEO

Fig 3 Triangular tooth form.

Fig 2 Ovoid tooth form.

Fig 1 Square tooth form.

Many older studies examined the correlation between

• Triangular: The distal ridge is not parallel to the me-

dental form and other factors, including sex,' face

sial ridge but rather markedly inclined, defining a

form, 1011 shape of the maxillary arch," constitutional

very narrow V-shaped cervical zone with a convexity

type, 12 or personality. 9' 13 Even though these concepts have now been disproven ;0,14-16 some professionals

at the center of the crown. The incisal edge is wide

still consider these theories applicable to anterior res-

convexity at the center. The incisal angles are slight-

torations. However, it seems unlikely that such mathe-

ly acute (Fig 3).

mesiodistally and may have either a slight curve or

matical rules can provide a predictable outcome because they tend to detract from the creativity needed for a successful final result: 7 ' 18 The literature shows that there are three basic tooth forms in nature: the square (type A), the ovoid (type B), and the triangular (type

C)1 0,19,20:

Tooth Outlines During the design stage, all tooth forms must be evaluated from an incisal, cervical, and frontal view with a right-lateral and left-lateral projection (Fig 4). This

• Square: The mesial and distal proximal surfaces are

evaluation will provide an overall sense of the tooth

parallel and perpendicular to the incisal edge and present a wide U-shaped cervical area. The vestib-

organization as well as the relationship between the anatomical parts (Figs 5 and 6). 21,22

ulodistal transitional ridge may be slightly curved,

The three principal tooth forms comprise numerous

while the incisal edge is straight or slightly curved.

variations that include both the shape and form of the

The incisal edge is longer in the mesiodistal direc-

teeth. 23 In this context, the term "form" indicates all

tion than that of the ovoid form and almost the same

macrocharacteristics, such as the outline of the tooth,

length as that of the triangular form (Fig 1).

development of the ridge, depth of the grooves, and

• Ovoid: The incisal edge has a central protuberance;

difference between the mesial and distal incisal an-

its length mesiodistally is the shortest of the three

gles. 24 ' 25 Microcharacteristics, ie, surface texture, also

forms. The mesial and distal transition line angles

play an important role in the anatomical qualities of

are rounded and converge at the incisal and cervical

the tooth (Fig 4).

areas. The U-shaped cervical line is more oval than in the square type (Fig 2).

184

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The physical form of a tooth is determined by its outline, comprising the incisal border, proximal ridges,

Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

L

4111N 6

7

Fig 4 Outline of the tooth structure showing the position of the (left) vertical and (right) horizontal grooves and ridges. Fig 5 Cervical views of the tooth form. Fig 6 Tooth form viewed from the incisal area toward the cervical area. Fig 7 Joining the transition lines through the tooth lobes. These lines define all characteristics of the tooth that will make it appear as a single body. Fig 8 Surface torsion allows for individualization of the vestibulodistal lobes.

and cervical line. These lines dictate the path of the

8

the operator should begin work on each transition line

ridges and the shape of the lobes. Thus, the outline

starting from the lingual surface. In all natural teeth,

of the tooth should be evaluated before analyzing the

the ridges and grooves begin at the lingual surface

tooth three-dimensionally.

and then connect to the proximal and vestibular surfaces (Fig 7).

Transition Lines The characteristics of tooth form are not separate enti-

Surface Torsion

ties; rather, they combine to create a single feature. In

Surface torsion is another important factor in the de-

other words, a tooth is crossed by grooves that deter-

sign of an artificial tooth. From an incisal view, distal

mine the three-dimensional anatomical areas. A fron-

protrusion becomes evident at the level of the cervix

tal view alone does not provide sufficient information

(Fig 8). Failure to consider this surface torsion may re-

to reproduce the area around a transition line. Thus,

sult in artificial incisors that appear flat or distally pro-

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185

PHARK/ROMEO Fig 9 Segmentation of the tooth.

truded. 21 The line of rotation starts from the vestibular

If necessary, these full segments can be further divided

aspect and continues lingually.

in half, resulting in six half segments: mesial cervical,

Torsion is common to all teeth, although to varying

mesial body, mesial incisal, distal cervical, distal body,

degrees of intensity. Surface torsion is gentler in the in-

and distal incisal (Fig 9). To create the final tooth form,

cisors and more pronounced in the canines; however,

the full or half segments can be recombined, creating

the technician may define the extent of torsion based

complementary classes (Table 1). The class numbering

on the desired tooth form. In more facially positioned

system (1:3, 1:2, 1/2:3, or 1/2:2) indicates which segment

teeth, surface torsion becomes more evident.

was used (number before the colon = full [1] or half [1/2] segment) and with how many basic tooth forms for recombination (number after the colon = 2 or 3 basic tooth forms). The first complementary class, 1:3, uses one full segment of each of the three principal tooth forms, resulting in 6 different shape combinations (Fig 10).The sec-

Based on the anatomical concepts discussed above,

ond complementary class, 1:2, uses one full segment

the authors now introduce a new tooth-form classifi-

combined with two principal tooth forms. This results

cation system: Dental Anatomical Combinations. This

in 18 different tooth shapes (Figs 11 to 13). The third

simple concept aims to help dental professionals pro-

(Fig 14) and fourth (Figs 15 to 17) complementary

duce different tooth anatomies that extend beyond

classes, 1/2:3 and 1/2:2, involve half segments combined

the standard tooth shapes.

with 3 or 2 principal tooth shapes, respectively. By di-

The basic principle of this system is the segmenta-

viding the tooth vertically or obliquely into two parts,

tion and recombination of two or even all three of the

the segments are always in contrast with the final

basic tooth forms. 26 First, the perimeter of each tooth

shape, giving the tooth a more dynamic appearance.

form is sectioned into smaller segments; for example,

Although many anatomical combinations are pos-

by sectioning the tooth into three different segments,

sible mathematically, only a selection of them is shown

a mesial, distal, and incisal segment can be obtained.

here. In total, this article presents 48 anatomical tooth

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

Table 1 Segments

Dental Anatomical Combinations Principal

Complementary

shapes

class 1:3

1

2

1:2

3

1/2:3

1/2

2

1/2:2

10a

10b Figs 10a and 10b Complementary class 1:3. Full tooth segments of all three basic tooth forms are combined with each other.

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PHARK/ROMFO

11a

11b

12a

188

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

13b

Figs 11 a and 11 b Complementary class 1:2 ovoid-square combinations. Figs 1 2a and 1 2b Complementary class 1:2 square-triangular combinations. Figs 1 3a and 1 3b Complementary class 1:2 ovoid-triangular combinations.

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PHARK/ROMEO

1 4a

1 4b

triangular

15a

190

combinations. These combinations demonstrate new

a concrete visual message rather than an abstract one,

ways for clinicians and technicians to give artificial

thus allowing for better communication between the

teeth a more dynamic appearance. Segmentation is a

clinician and technician and enhanced production of

means of composition. In the laboratory, it represents

the desired tooth forms.

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

1:16a

16b

Figs 14a and 14b Complementary class 1/2:3. Half segments of all three basic tooth forms are combined with each other. Many more combinations are possible than shown here.

Figs 15a and 15b Complementary class 1/2:2 triangular-ovoid combinations. Figs 16a and 16b Complementary class 1/2:2 ovoid-square combinations.

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PHARIVROME0

17b Figs 17a and 17b Complementary class 1/2:2 square-triangular combinations.

CASE REPORT

ing lateral incisors. However, the spaces between the anterior teeth were closed completely at that time;

A 46-year-old male patient presented with concerns

further, other than minimal enameloplasty, the trans-

regarding the esthetics of his maxillary anterior denti-

formation of the canines into lateral incisors remained

tion. His chief complaint was the diastemata between

unfinished. The patient did not undergo additional

the central incisors and between the right central in-

orthodontic treatment. He requested an esthetic but

cisor and canine (Fig 18). Both maxillary lateral inci-

minimally invasive treatment to preserve as much in-

sors were congenitally missing. At a young age, the

tact tooth structure as possible. The treatment plan

patient underwent orthodontic treatment to transpose

comprised six veneers to restore the maxillary central

his canines and premolars to substitute for the miss-

incisors, canines, and first premolars.

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

CASE REPORT

Figs 18a to 18f Preoperative situation. Note the diastemata and the incomplete transformation of the canines used to replace the congenitally missing lateral incisors.

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PHARK/ROMEO

19a

Figs 19a to 19g Fabrication of the diagnostic wax-up. (a) Initial situation. (b) Positioning of the ridges. (c) Waxing of the central ridge and incisal cones. (d to g) Reevaluation of the wax-up from a variety of angles.

Diagnostic Wax-up

every stage of the process, the wax-up must be care-

fully evaluated from all dimensional aspects (Figs 19d

Prior to formulation of the treatment plan, impressions

to 19g). Once the facial surface was completed, sur-

were taken to fabricate diagnostic casts and a diagnos-

face characterization was carried out (Fig 20). Figures

tic wax-up." The diagnostic cast showed a triangular-

21a to 21h show the finalized wax-up with successful

ovoid tooth configuration of the maxillary incisors. 26 A

transformation of the canines into lateral incisors and

1/2:3 complementary class, combining all three princi-

of the first premolars into canines. Figure 21i shows

pal tooth forms, was chosen for the wax-up to close

the central incisors with a 1/2:3 complementary class.

the diastemata and redistribute the interproximal spac-

To transform the canines into lateral incisors, the dif-

es more effectively. Beginning at the marginal ridges,

ferences between them in terms of overall shape, size,

the incisal cones and central ridge were waxed up, fol-

and anatomical features (eg, mesiodistal and orofacial

lowed by the facial surface (Figs 19a to.19c)." During

width) should be considered. Therefore, measurements

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

20a

20b

20c

21a

21c

21f Figs 20a to 20c Surface characterization.

Figs 21a to 21i (a to h) Completed wax-up with transformation of the canines into lateral incisors and first premolars into canines. A squaretriangular shape was chosen. (i) Complementary class 1/2:3 applied to the wax-up.

square

ovoid

ovoid

............... ...............

triangular

ovoid

ovoid .....

triangular

square

square ——.

quare

......

triangular

triangular . '

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PHARK/ROMEO

22a

22b Figs 22a to 22c Measurement of the mesiodistal and orofacial width of the canine in the cervical area.

Fig 23 To achieve an optimal cervical emergence profile, the canine had to be reduced to the size of a lateral incisor.

23

of the canines were taken at the cervical areas. The

toured final restoration. At the same time, excessive

canines had a mesiodistal and orofacial width of 7 mm

preparation would conflict with the patient's desire for

(Fig 22), whereas a lateral incisor has a mean mesiodistal and orofacial width of approximately 5 mm. 1,21,28

minimally invasive treatment and, more importantly, compromise optimal bonding of the veneers by ex-

Thus, to create a cervical emergence profile that

posing the dentin.

matches that of a lateral incisor, the canine had to be

Considering these parameters, tooth preparation

reduced in width to 5 mm (Fig 23). At the facial sur-

was simulated in the laboratory (Fig 24). Such a simu-

face, the reduced convexity of a lateral incisor com-

lation aids communication between the technician and

pared to a canine should also be taken into account.

dentist. Based on the simulation, silicone keys were

Insufficient preparation of the canine may result in ei-

fabricated (Fig 25) and delivered to the dentist as a

ther inadequate thickness of the ceramic or, if minimal

preparation guide. 27 Further, the preparation simula-

thickness of the ceramic is maintained, in an overcon-

tion allowed for the fabrication of a provisional shell.

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

24a

24b

124c

24d

Figs 24a and 24b Preoperative preparation simulation. Figs 24c and 24d Silicone keys based on the diagnostic wax-up.

Fig 25 Silicone preparation guides.

Tooth Preparation

imal preparation including only the facial surface was

The silicone guides were first used to verify the original

aspects of the first premolars remained untouched.

dimensions of the teeth in relation to the projected

For the canines, tooth preparation was performed as

needed at the first premolars. The occlusal and lingual

tooth shape as outlined in the wax-up (Fig 26a). No

projected in the simulation. The incisal edge was re-

preparation was necessary for the central incisors. Min-

duced by 1 mm using diamond burs (Komet, Lemgo,

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PHARK/ROMEO

26c

126d Fig 26a Intraoral verification of the difference between the wax-up and preoperative situation. Fig 26b Interproximal reduction with a diamond bur. Fig 26c Diamond wheel used for interproximal reduction. A gingival protector (not pictured) was used to protect the soft tissues. Fig 26d Verification of the cervical width. Fig 26e Final tooth preparation.

26e

Germany), followed by a 1-mm reduction of the facial

Prior to impression taking, retraction cords without

surface with a light chamfer at the cervical margin. The

any hemostatic agent were placed (Fig 26e). A poly-

mesial and distal surfaces were each reduced by 1 mm

vinyl siloxane impression material (Extrude EXTRA and

using diamond burs, and diamond-coated disks (Kom-

WASH, Kerr, Orange, California, USA) was used in con-

et) were used in the interproximal region to shape the

junction with the double-mix technique to capture the

cervical area to the desired width of 5 mm (Figs 26b

preparations. The prepared teeth were then provision-

to 26d). A gingival protector (Zekrya, DMG America,

alized with the previously made provisional shell after

Englewood, New Jersey, USA) was used to retract and

relining.

protect the soft tissues.

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Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

27c

27b

27f Fig 27a Soft tissue cast from the alveolar cast. Fig 27b Alveolar cast with segmented dies. Fig 27c Refractory dies on the alveolar cast. Fig 27d Layering of feldspathic ceramic onto the refractory dies to build up the incisal wall and proximal aspect. Fig 27e Completed ceramic layering.

27g

Fig 27f Optimal adaptation of the intaglio surface to the master die. Fig 27g Alveolar cast with the final restorations.

Fabrication of the Ceramic Veneers

followed by the first bake. The entire labial shape was then layered using 20 ceramic masses (Fig 27e).

To fabricate the ceramic veneers, an alveolar cast con-

After the next bake, the ceramic was ground with

sisting of an intact soft tissue cast and interchangeable

diamond burs to create the desired anatomical shape

dies was created (Figs 27a and 27b). 29 The presence

and texture. Glazing was performed to provide har-

of the soft tissues is crucial because they are central in

mony between the restorations and adjacent natural

the positioning of the transition lines and because they

teeth, and all veneers were manually polished.

allow for better control over the tooth shape. 17,18

The veneers were removed from the refractory dies

Feldspathic ceramic (Creation, Jensen, North Ha-

via sandblasting with glass beads at low pressure. The

ven, Connecticut, USA) was layered to fabricate the

veneers were then adapted to the master dies using

veneers. The first step of the layering process was to

a stereomicroscope at x12 and x20 magnification.

apply two layers of connector material on the refrac-

For optimal adaption of the intaglio surfaces of the

tory dies with two different firings (Fig 27c). Next, vari-

veneers, adjustments were initially performed at the

ous enamel and translucent masses were applied to

finish line and peripheral areas, followed by the cen-

build up the incisal wall (Fig 27d). Modifiers and stains

tral areas (Fig 270. Once adaptation was complete, the

were also added to obtain incisal effects; the mesial

contact points were checked on the solid cast, and the

and distal aspects were built up in the same manner,

veneers were ready for delivery (Figs 27g and 28).

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PHARK/ROMEO

I 28b Fig 28a Definitive ceramic veneers. Figs 28b to 28d Optimal marginal fit of the ceramic veneers on the master dies.

Try-in and Cementation

Silane, Premier Dental, Plymouth Meeting, Pennsylvania, USA) was applied for 2 minutes.

The provisional restorations were removed, and the

A light-cured nanofilled composite resin material

teeth were cleaned using pumice. The definitive resto-

(shade CT, Filtek Supreme Ultra, 3M ESPE, St Paul,

rations were tried in to verify the fit, shape, and shade.

Minnesota, USA) was used for cementation. In the oral

The intaglio surfaces of the feldspathic veneers

cavity, the cement at the margins will be subjected to

were etched with 4.5% hydrochloric acid (IPS Ceramic

water sorption, subsurface degradation, wear, and dis-

Etching Gel, Ivoclar Vivadent, Schaan, Liechtenstein)

coloration. 32 In comparison to methacrylate- or phos-

for 1 minute (Fig 29a) to promote micromechanical

phate-based resin cements, preheated composite res-

retention by removing the glass matrix. This etching

ins used as luting agents have been shown to exhibit

process produces crystalline precipitates that are in-

reduced deterioration by wear. 32 Cements with smaller

soluble in water (Fig 29b). The precipitates can be

filler particle size and higher filler load also showed

removed by either ultrasonic cleaning for 5 minutes

less wear. 33,34 Further, unlike self- or dual-curing ce-

or etching with 35% phosphoric acid (Ultraetch, Ultra-

ments, light-cured cements allow unlimited time for

dent, South Jordan, Utah, USA) for 1 minute (Fig 29c).

placement of the restoration and removal of excess

Failure to remove such residues may result in reduced

cement.

bond strength to the ceramic intaglio surface. 3" 1 After

For better handling during cementation, the highly

rinsing and drying, a silane coupling agent (Porcelain

viscous composite resin should be preheated. Heating

QDT 2013

Dental Anatomical Combinations: A Guide to Ultimate Dental Esthetics

91111,9, I 29b

1_21c Fig 29a Hydrofluoric acid etching of the intaglio surfaces. Fig 29b Formation of precipitates on the intaglio surfaces after etching. Fig 29c Removal of the precipitates by additional etching with phosphoric acid.

the composite resin reduces viscosity, improves flowability, and decreases film thickness. 32 However, once removed from the heating unit, the composite resin cools down quickly during handling and may cool even more rapidly if applied to a much colder restoration at room temperature, thus voiding the advantages of the preheating. Therefore, the restoration must be pre-

heated as well. To avoid rapid temperature loss, the veneers were filled with a thin layer of the preheated composite resin (Fig 30a) and then placed into the heating unit until needed (Fig 30b). The veneers were bonded one after another, beginning with the central incisors and proceeding to the canines and premolars. While the veneers were being

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Eli

PHARK/ROMEO

Fig 30a Thin layer of preheated composite resin applied to the intaglio surface of the veneer. Fig 30b Placement of the composite resin-loaded veneers into the heater. Fig 30c Light polymerization through a layer of glycerin gel.

preheated, a total-etch adhesive system (Optibond FL, Kerr) was applied to each tooth but initially left un-

CONCLUSIONS

cured. After placement of the restoration on the des-

By creating different anatomical combinations of basic

ignated tooth and removal of excess luting agent, light

tooth forms, dental professionals can design a wide

curing was performed for 40 seconds through a layer

range of esthetic restorations that are individually tai-

of glycerin gel to avoid the oxygen inhibited layer (Fig

lored to each patient's needs. The proposed classifica-

30c). A scalpel and scaler were used to remove excess

tion system€Dental Anatomical Combinations€will

adhesive and luting cement. Interproximal areas were

aid clinicians and technicians in the fabrication of har-

finished with polishing strips (Sof-Lex Finishing Strips,

monious and dynamic artificial teeth. Detailed treat-

3M ESPE), and occlusion was checked and adjusted.

ment planning and careful communication between

To complete the rehabilitation, the insufficient Class V

the dentist and laboratory are essential for a successful

restorations on the second premolars and first molars

final result.

were replaced with nanohybrid composite resin restorations (ENA HRi, Synca, Le Gardeur, Quebec, Canada). Figure 31 shows the final result 2 months after delivery.

ACKNOWLEDGMENTS The authors would like to thank Ms Juree Lee, MDC, for her technical support.

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PHARK/ROMEO

REFERENCES 1. Beaudreau DE. Tooth form and contour. J Am Soc Prey Dent 1973:36-47. 2. Butler PM, Joysey KA. Development, Function and Evolution of Teeth. London: Academic Press, 1978. 3. Eissmann HF, Radke RA, Noble WH. Physiologic design criteria for fixed dental restorations. Dent Clin North Am 1971;15:543568.

19. Williams JL. A New Classification of Human Tooth Forms with Special Reference to a New System of Artificial Teeth. New York: Dentists' Supply, 1914. 20. Nishimura Y. Dental crown shape for ceramic restorations. Quintessenz Zahntech 1992;18:647-669. 21. Black GV. Descriptive Anatomy of the Human Teeth. Philadelphia: S.S. White, 1897.

4. FarerJW, Isaacson D. Biologic contours. J Prey Dent 1974;1:4-7.

22. Perard VS. Anatomy and Drawing. New York: Dover, 2004.

5. Yuodelis RA, Weaver JD, Sapkos S. Facial and lingual contours of artificial complete crown restorations and their effects on the periodontium. J Prosthet Dent 1973;29:61-66.

23. Shaw DM. Form and function of teeth: A theory of "Maximum Shear." J Anat 1917;52:97-106.

6. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994. 7. Goldstein RE, Belinfante L, Nahai F. Change Your Smile. Chicago: Quintessence, 1997.

24. Arnheim R. Art and Visual Perception: A Psychology of the Creative Eye. Berkeley: University of California Press, 1974. 25. Morris ML. Artificial crown contours and gingival health. J Prosthet Dent 1962;12:1146-1156.

8. Rufenacht CR. Fundamentals of Esthetics. Chicago: Quintessence, 1990.

26. Romeo G. Reconstruction of tooth form in various anatomical tooth combinations. Quintessence Dent Technol 2006;29:446456.

9. Frush J, Fisher R. Introduction to dentogenic restorations. J Prosthet Dent 1955;11:586-595.

27. Massironi D, Pascetta R, Romeo G. Precision in Dental Esthetics: Clinical Procedures. Chicago: Quintessence, 2007.

10. Williams JL. The temperamental selection of artificial teeth, a fallacy. Dent Digest 1914;20:63-75.

28. Nelson SJ. Wheeler's Dental Anatomy, Physiology and Occlusion, ed 9. Philadelphia: Saunders, 2009.

11. Nelson A. The esthetic triangle in the arrangement of teeth: Face form, tooth form and alignment form, harmonious or grotesque. National Dent Assoc J 1922;9:392-401.

29. Magne M, Bazos P, Magne P. The alveolar cast. Quintessence Dent Technol 2009;32:39-46.

12. Horauf K. Anterior tooth forms and constitutional types [in German]. Dtsch Zahnarztl Z 1958;13:512-523. 13. White J, Flagg E. Temperament in relation to the teeth. Dent Cosmos 1884;26:113-119. 14. Berksun S, Hasanreisoglu U, Gokdeniz B. Computer-based evaluation of gender identification and morphologic classification of tooth face and arch forms. J Prosthet Dent 2002;88:578-584. 15. McCord JF, Burke T, Roberts C, Deakin M. Perceptions of denture aesthetics: A two-centre study of denture wearers and denture providers. Aust Dent J 1994;39:365-367. 16. Sellen PN, Jagger DC, Harrison A. Computer-generated study of the correlation between tooth, face, arch forms, and palatal contour. J Prosthet Dent 1998;84:163-168. 17. Kataoka S, Nishimura Y, Sadan A. Nature's Morphology: An Atlas of Tooth Shape and Form. Chicago: Quintessence, 2002.

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18. Yamamoto M, Miyoshi Y, Kataoka S. Fundamentals of esthetics: Contouring techniques for metal ceramic restorations. Quintessence Dent Technol 1990/1991;14:14-81.

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30. Duarte S, Phark J-H, Blatz M, Sadan A. Ceramic systems: An ultrastructural study. Quintessence Dent Technol 2010;33:42-60. 31. Magne P, Cascione D. Influence of post-etching cleaning and connecting porcelain on the microtensile bond strength of composite resin to feldspathic porcelain. J Prosthet Dent 2006;96: 354-361. 32. Duarte S, Sartori N, Sadan A, Phark J-H. Adhesive resin cements for bonding esthetic restorations: A review. Quintessence Dent Technol 2011;34:40-66. 33. Shinkai K, Suzuki S, Katoh Y. Effect of filler size on wear resistance of resin cement. Odontology 2001;89:41-44. 34. Condon JR, Ferracane JL. In vitro wear of composite with varied cure, filler level, and filler treatment. J Dent Res 1997;76:14051411.

Copyright of Quintessence of Dental Technology (QDT) is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

MagnificationEnhanced CAD/CAM Restorations

T

hanks to the introduction and development of

during abutment tooth preparation and from misun-

high-strength core ceramics such as alumina

derstandings regarding CAD/CAM ceramic crowns.

and zirconia, the use of all-ceramic restorations

Therefore, this article discusses the fabrication of well-

has rapidly increased in esthetic dentistry. However,

fitting CAD/CAM crowns based on magnification-en-

as opposed to porcelain-fused-metal (PFM) restora-

hanced abutment tooth preparation.

tions, all-ceramic frameworks can be difficult to fabricate in the dental laboratory and thus require computer-aided design/computer-assisted manufacture (CAD/ CAM) processing. Further, although all-ceramic restorations offer excellent esthetic results, they often show inferior fit compared to manually fabricated PFM or gold crowns. In other words, there is a discrepancy between the expected precision of CAD/CAM restora-

CAD/CAM CERAMIC CROWNS: ABUTMENT TOOTH PREPARATION CAD Considerations

tions and the actual clinical results. The author sug-

The fabrication of CAD/CAM all-ceramic restorations

gests that this discrepancy results from human error

begins with measurement of the abutment teeth using a contact-type scanner (eg, a touch probe) or a noncontact-type scanner that captures laser reflection with a charge-coupled device. The framework will be designed based on these measurements. The scanner type must be taken into consideration

'Private Practice, Osaka, Japan. Correspondence to: Dr Masahiro Minami, Minami Dental Office, Dojima Building 1st floor, 2-6-8 Nishitenma, Kita-ku, Osaka City, Osaka, Japan. Email: [email protected]

during tooth preparation (Fig 1). With contact-type scanners (eg, Procera All Ceramic, Nobel Biocare, Yorba Linda, California, USA), it can be difficult to measure details that are smaller than the diameter of

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Fig 1 The scanned images differ between scanner types, even when the same abutment tooth is used. CCD = charge-coupled device.

Fig 2 When an abutment tooth has an unclear finish line, it is difficult to determine the proper location for the margin.

the probe. For this reason, the finish line should be

are cut using a milling bur with a tip diameter of 0.8 to

designed as an accentuated chamfer rather than as a

1 mm, shapes that are smaller than this diameter are

shoulder, with a smooth continuous margin.' When us-

impossible to reproduce. Therefore, if there is a sharp

ing a noncontact-type scanner, precise measurement

line angle at the abutment tooth, it can be difficult

is possible regardless of the shape of the finish line;

to perform appropriate cutting inside the block, thus

however, a smooth continuous margin and clear finish

leading to overcutting (Fig 3). Special care should be

line are indispensable for either type of scanner. Since

taken to round the line angles of the marginal ridge,

CAD will be carried out on a large monitor 20 inch-

cusp, incisal margin, etc.

es), the finish line can be greatly magnified (Fig 2). An

A smooth finish line is essential. The margin of a

unclear or interrupted finish line, such as a knife edge,

zirconia framework is usually produced with extra

must be avoided to prevent errors in the setting of the

thickness to prevent chipping and other defects dur-

crown margin.

ing cutting. 2 After sintering, manual finishing is carried

A taper of 6 degrees is recommended, creating a to-

out using a bur or disk. If the finish line offers suffi-

tal occlusal convergence (TOC)€ie, the angle formed

cient thickness€such as in an accentuated chamfer

by the two axial planes€of approximately 12 degrees.

or rounded shoulder€there will be minimal need for

The crown thickness should be approximately 0.8 to

excess thickness and finishing can be performed eas-

1.2 mm at the margin, 1 to 1.5 mm at the center of

ily. However, if a thin design such as a knife-edge fin-

the crown, and 1.5 to 2.0 mm at the incisal edge and

ish line is used, manual adjustment of the thickness

occlusal surface.

requires considerable caution (Fig 4). For this reason, tooth preparation with a clear shape at the margin is also desirable.

CAM Considerations Zirconia frameworks are typically fabricated by mill-

Although abutment tooth preparation for CAD/CAM restorations follows the same basic principles as used for conventional fixed partial dentures, consideration

ing semi-sintered or pre-sintered zirconia blocks with

of the factors discussed above will help to ensure ex-

a milling bur, followed by sintering. Since the blocks

tremely well-fitting CAD/CAM ceramic crowns (Fig 5).

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Magnification-Enhanced CAD/CAM Restorations

Fig 3 When the finish line shows sharp line angles or uneven areas that are smaller than the diameter of the milling burs, the space between the abutment tooth and coping will increase.

Fig 4 The use of a knife-edge design makes it difficult to adjust the areas of marginal reinforcement.

Figs 5a to 5e Abutment preparation for a CAD/CAM restoration. The finish line should be clear, smooth, and continuous, with adequately rounded line angles. The amount of reduction should ensure adequate thickness of the veneering porcelain. The TOC should be approximately 12 degrees.

THE FINISH LINE: MICROSCOPEENHANCED RESULTS When viewing a prepared abutment tooth on a CAD monitor, the clinician's first response may be to think,

eye coordination are hindered by the limitations of the naked eye; therefore, the author suggests the use of a magnifying device such as a microscope for the preparation of an abutment tooth and adjustment of the finish line.

"What an irregular finish line!" This is similar to the

While microscope-enhanced treatments have gained

usual response when a clinician first observes an abut-

recognition in dentistry, many clinicians are still hesi-

ment tooth under a microscope. In both cases, the

tant to incorporate such techniques. The author often

abutment tooth is observed at high magnification.

encounters questions such as, "Is the microscope re-

An image of an abutment tooth on a CAD monitor is

ally necessary?" and "How long will it take to get used

magnified x10 to x20 (Fig 6). The clinician's efforts

to the microscope?" To answer these questions, an

to prepare a smooth finish line using delicate hand-

experiment was carried out to confirm the benefit of

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MINAMI

Fig 6 An abutment tooth magnified on the CAD monitor.

Fig 7a After preparation with the naked eye, the thickness of the finish line was not uniform. Using a microscope, the finish line was uniform and smooth.

Fig 7b After preparation with the naked eye, the margin size was double. Using a microscope, an almost ideal accentuated chamfer was achieved.

the microscope during tooth preparation and to deter-

the chamfer width, (2) continuity of the finish line, and

mine how much time is needed to master microscopic

(3) morphology of the areas near the finish line.

preparation of abutment teeth.

Materials and Methods

Results The results are shown in Tables 1 to 3.

The axial surfaces of 30 extracted human teeth were

For the dentist accustomed to microscopic treatment

prepared by three dentists with varying levels of ex-

(dentist 1; Fig 8), the preparations carried out with the

perience with the microscope. The microscope was

naked eye were often rated as normal, sometimes as

used on one side of each crown but not on the oth-

poor, and never as excellent. Under the microscope,

er (Fig 7). The three dentists had 12 years, 1 month,

however, the results were mostly excellent and never

or no experience with microscopic dental treatment,

poor or very poor. Therefore, use of the microscope

respectively. The dentist with no experience was pro-

led to a marked improvement in the quality of the

vided with basic training in the use of the microscope

tooth preparations.

for approximately 1 hour before the experiment. The

For the dentist who had used the microscope for

surfaces were finished with a regular-grit and a fine-grit

approximately 1 month (dentist 2; Fig 9), the prepara-

diamond finishing bur using an accentuated chamfer

tions carried out with the naked eye were most often

and a 1:5 speed increasing contra-angle. The results

rated as normal, and the distribution of the results re-

were microscopically evaluated (magnification x20) by

sembled that of dentist 1. When the microscope was

two dental technicians. The following three categories

used, the results were rarely rated as poor or very poor

were evaluated using a 5-point scale: (1) uniformity of

and mostly rated as normal, good, or excellent. This

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Magnification-Enhanced CAD/CAM Restorations

Table 1

Tooth Preparation Scores (No. of Specimens) for Dentist 1 (12 Years Experience with Microscope) Score

Criterion Uniformity of chamfer*

Continuity of finish line*

Very poor

Poor

Normal

Good

Excellent

With microscope

0

0

2

12

6

Without microscope

0

6

6

8

0

With microscope Without microscope

Morphology of finishing area*

Total*

0

0

3

7

10

10

4

6

0

0

0

0

1

8

11

With microscope Without microscope

2

7

7

4

0

With microscope

0

0

6

27

27

12

17

19

12

0

Without microscope

*P < .01 between results with and without the microscope (Mann-Whitney U test).

Table 2

Tooth Preparation Scores (No. of Specimens) for Dentist 2 (1 Month Experience with Microscope) Score

Criterion

Very poor

Poor

Normal

Good

Excellent

With microscope

0

0

4

9

7

Without microscope

0

5

10

4

1

Continuity of finish line**

With microscope

2

1

8

8

1

Without microscope

3

9

5

2

1

Morphology of finishing area**

With microscope

0

0

4

6

10

Without microscope

0

0

8

9

3

With microscope

2

1

16

23

18

Without microscope

3

14

23

15

5

Uniformity of chamfer*

Total***

*P < .01, **P < .001, and ***P < .0001 between results with and without the microscope (Mann-Whitney U test).

Table 3

Tooth Preparation Scores (No. of Specimens) for Dentist 3 (No Experience with Microscope) Score

Criterion Uniformity of chamfer Continuity of finish line*

Very poor

Poor

With microscope

0

Without microscope

2

With microscope

3

Without microscope Morphology of finishing area*

Total**

Normal

Good

Excellent

6

8

6

0

3

11

4

0

3

10

4

0

10

5

5

0

0

With microscope

0

2

10

8

0

Without microscope

0

5

15

0

0

3

11

28

18

0

12

13

31

4

0

With microscope Without microscope

< .01 and ""P < .001 between results with and without the microscope (Mann-Whitney U test). No signif cant difference was found regarding uniformity of

the chamfer.

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Fig 8 Results of the experiment for dentist 1 (12 years of experience using a microscope).

Fig 9 Results of the experiment for dentist 2 (1 month of experience using a microscope).

Fig 10 Results of the experiment for dentist 3 (no experience using a microscope).

suggests that 1 month of experience is sufficient to

Ultrasonic Instrumentation

benefit from use of the microscope. With further experience, the results of dentist 2 would be expected to

In the experiment described above, the bur occasion-

increase in excellence.

ally slipped during preparation and caused discontinu-

Finally, for the dentist who had no previous experi-

ity of the finish line. Ripping (ie, a so-called J-margin)

ence with the microscope (dentist 3; Fig 10), the prep-

was also observed in some cases. These phenomena

arations carried out with the naked eye showed similar

are likely to occur when a rotary instrument is used.

results to those of dentists 1 and 2. When the micro-

When the finish line is established below the gingi-

scope was used, very poor results were rare, while

val level, the bur must be kept away from the marginal

good results were markedly increased. This suggests

gingiva to avoid damaging the soft tissue. Most den-

that only 1 hour of training led to a clear benefit when

tists use retraction cord to protect marginal gingiva;

using a microscope for tooth preparation. Based on these results, abutment tooth preparation

nonetheless, damage may still extend to the inner gingival epithelium.

should be performed using a microscope at a magni-

For these reasons, the results are often limited when

fication of approximately x10 to obtain a high-quality

finishing is carried out with a bur alone. The use of

finish line. Short-term training is considered sufficient

other instruments with or without a bur should be con-

for dentists to acquire a reasonable level of skill to per-

sidered. In addition to a fine-grit bur, the instruments

form microscope-enhanced tooth preparation.

available for finishing an abutment tooth include hand

QDT 2013

Magnification-Enhanced CAD/CAM Restorations Fig 11 Comparison of surfaces pre-

pared using a fine-grit diamond bur (left) or 30-pm-grit ultrasonic instrument (right). Similar smooth surfaces can be observed, but evidence of bur slippage is present at the surface prepared using the rotary instrument.

Fig 12 Comparison of surfaces prepared using a 30-pmgrit ultrasonic instrument at different power levels. As the power decreases, the surface becomes finer.

Fig 13 Confocal scanning laser micrographs showing similar roughness between the surfaces prepared using an ultrasonic instrument at low power and a fine-grit finishing bur.

instruments such as chisels and acoustic or ultrasonic

to recent improvements, ultrasonic tips with a power

instruments (Fig 11).

controller are now available. Previously, touching a

The results produced by hand instruments are gen-

finger to a high-power tip for only 2 seconds would

erally considered to be satisfactory; however, there is a

cause severe pain. Now, one can touch the tip without

risk of damaging the marginal gingiva due to slippage

pain at a low power level. Moreover, tips with very fine diamond particles have been introduced. Sous et a1 4

of the instrument. Hand instrumentation must be per-

repotdhavysmourfceanbp d

formed carefully to achieve consistent results. Regarding ultrasonic scalers, some studies have re-

by controlling the fineness of the diamond particles

ported that these instruments produce rough and unsatisfactory surfaces. In 1996, Laufer et a1 3 compared

and the power of the ultrasonic instrument. The cur-

the roughness of surfaces prepared with rotary instru-

(Fig 12) and confocal laser scanning microscopy (Fig

rent author's observations using electron microscopy

ments, manual instruments, and ultrasonic tips. The

13) also suggest that the roughness of surfaces pre-

results showed that surfaces prepared with ultrasonic

pared with a low-power ultrasonic tip (grit size: 30 pm)

tips were clearly rougher than those prepared with

is comparable to that of surfaces prepared with a fine-

other instruments. However, it should be noted that

grit finishing bur (Fig 14).

only high-power ultrasonic generators were available

Further, ultrasonic tips (piezoelectric generation) pose

in those days; further, ultrasonic tips are believed to

a minimal threat to the soft tissues. Thus, subgingival

have been coarser in the past than they are today. Due

preparation can be performed without damaging the

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MINAMI

Fig 14 Abutment teeth prepared by dentists 2 and 3 using an ultrasonic instrument at low power under a microscope. A uniform and continuous chamfer was prepared irrespective of the operator.

Fig 15 The semispherical tip facilitates preparation even in close contact with the adjacent teeth (Ieft).The cylindershaped tip (right) requires no special training because it can be handled like a diamond bur. There is a mark on the instrument 1 mm from the tip end. This marking assists in the evaluation of the subgingival preparation depth.

gingival epithelium. Regarding the shape, cylindrical or

fore, simpler and more precise methods of evaluation

semispherical tips are easy to handle.' Using semi-

will now be described.

spherical tips, the surfaces can be easily prepared even when the abutment tooth is in close contact with the neighboring tooth (Fig 15).

CAD Monitor One method to enhance the accuracy of evaluations is to project the image of a scanned abutment tooth on

EVALUATING THE TOOTH PREPARATION

thickness of the abutment using the CAD software.

If there is an undercut on the tooth or if the line angle

because it is complex, time consuming, and can only

is not appropriate, excessive grinding will occur at the

be performed after fabrication of a plaster cast.

a CAD monitor to check the morphology, width, and However, this method remains clinically impractical

inner surface during fabrication of the coping. This will result in insufficient tooth preparation, even if the axial wall, stump, and occlusal surface of the abutment tooth have been appropriately prepared. To avoid

212

Intraoral Scanner

such a situation, a silicone index taken from a diagnos-

Recent improvements in intraoral optic impression

tic wax-up can be used to verify the amount of tooth

scanners and their associated software have made

reduction. Further, the morphology of the abutment

these devices well suited for clinical use. In addition

tooth can be evaluated from multiple angles using a

to scanning of the abutment teeth and opposing den-

plaster cast after taking preliminary impressions. How-

tition, intraoral scanners can predict and design the

ever, these methods do not allow for precise evalua-

morphology of the final restorations based on the

tion of small details. Further, fabrication and evaluation

surrounding teeth using the latest computer software

of a plaster cast is a time-consuming process. There-

(CEREC Biogeneric, Sirona, Bensheim, Germany).

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Magnification-Enhanced CAD/CAM Restorations

Fig 16a After immediate chairside scanning of the prepared tooth, the crown can be designed using CAD software. Note the presence of TOC and an undercut.

Fig 1613 Incisal edge preparation. The edge is round, and the area immediately below it shows an adequate thickness (1.2 mm).

Fig 16c Evaluation of the labial thickness and lingual clearance of the final restoration. The three-plane preparation on the labial surface can also be confirmed by observing cross sections.

Fig 16d Measurement of the position of the subgingival finish line.

Fig 16e Completed all-ceramic crown. The material thickness on the labial side (1.5 mm), as designed using CAD software, is reflected in the final restoration.

These devices were originally designed for the chair-

tween the morphology of the final restoration and abut-

side fabrication of restorations, but they are also ideal

ment tooth. In addition to providing data about the

for precise evaluation of abutment preparations. The

abutment, the device can also guide users in the prop-

scanning process is fast and simple; likewise, a custom-

er adjustment of abutment preparation by showing the

ized crown can be quickly and easily designed using

thickness necessary for proper restoration morphology

the CEREC software. This clarifies the relationship be-

and clearance against the opposing teeth (Fig 16).

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Fig 17 For finishing, a microscope is used at high magnification (x10), and a fine-grit finishing bur is used at low speed with a 1:5 increasing contra-angle.

PREPARATION PROCEDURES

CONCLUSIONS AND CASE REPORT

Abutment teeth should be prepared at low magnifica-

Satisfactory CAD/CAM ceramic crowns can only be

tion (approximately x3) using a 1:5 speed increasing

fabricated in conjunction with appropriate preparation

contra-angle. If a crown abutment is accessed with a

of the abutment teeth. In other words, the success of

bur from multiple angles by direct observation under

CAD/CAM restorations depends on controlling human

the microscope alone, the microscope may need to

error. Magnification of the treatment site is highly ef-

be frequently repositioned. This detracts from the time

fective in the detection of any mistakes made during

efficiency of the procedure. Therefore, a magnifier is

tooth preparation, and the use of an ultrasonic tip fa-

often used in conjunction with the microscope. The

cilitates the correction of such errors.

shape of an abutment tooth and/or the parallelism be-

Many of the devices discussed in this paper are ex-

tween abutment teeth should be adjusted by careful

pensive, and some clinicians may argue that they are

evaluation from multiple angles at low magnification,

too complicated and time consuming for wide clinical

thus further recommending the use of a magnifier.

use. This article proposed a method to easily and ef-

The tooth preparation is finalized under the micro-

fectively perform microscope-enhanced tooth prepa-

scope at high magnification (approximately x10) to

ration to achieve high-quality CAD/CAM restorations.

obtain a satisfactory finish line (Fig 17). In provisionally

This method can be learned in a relatively short period

prepared abutment teeth, direct observation is possi-

of time without the need for significant training.

ble near the palatal/lingual angle beyond the proximal

Figure 18 shows the treatment of a clinical case in-

surface (eg, when preparing a maxillary incisor). There-

volving microscope-enhanced CAD/CAM restorations

fore, the bur can be handled under direct observation

in the maxillary esthetic zone.

without frequently changing the position of the microscope. In such cases, even dentists with minimal experience using the microscope can control the bur easily. Next, scanning is performed using an intraoral scanner. The crown is designed, the morphology of the abutment tooth and amount of tooth reduction are verified on the CAD monitor, and any need for modifications is determined. If a provisional crown is fabricated, an acrylic resin block may be milled at this point. Final adjustment of the finish line must be performed using an ultrasonic tip at low power (eg, power level 5 or 6 in perio mode, Suprasson, Satelec, Merignac, France), particularly for subgingival preparations. The final adjustment should be carried out while evaluating the smoothness of the finish line under magnification x10.

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REFERENCES 1. Hidaka T. Enhancing marginal fit through magnification. Int J Microdent 2010;2:42-47. 2. Miyazaki T, Miura H, Kimura K (eds). Zirconia Restorations: Design, Handling, and Practice [in Japanesel.Tokyo: Ishiyaku, 2011. 3. Laufer B, Pilo R, Cardash H. Surface roughness of tooth shoulder preparations created by rotary instrumentation, hand planing, and ultrasonic oscillation. J Prosthet Dent 1996;75:4-8. 4. Sous M, Lepetitcorps Y, Lasserre JF, Six N. Ultrasonic sulcus penetration: A new approach for full crown preparations. Int J Periodontics Restorative Dent 2009;29:277-287. 5. Massironi D, Pascetta R, Romeo G. Precision in Dental Esthetics: Clinical and Laboratory Procedures. Chicago: Quintessence, 2006.

Magnification Enhanced CAD/CAM Restorations -

CASE REPORT

18b

Fig 1 8a Preoperative view of a clinical case. The 30-year-old female patient requested replacement of the existing crowns on the maxillary right central incisor and left lateral incisor. Note the discoloration of the exposed root. Fig 1 8b After rough preparation using dental loupes, subgingival preparation was performed under a microscope. Fig 18c Immediately after abutment preparation, the oral cavity was scanned chairside, and the shape of the abutment tooth and its relationship with the final restoration were determined. Figs 18d Evaluation of the prepared tooth on the CAD monitor. The areas requiring correction were adjusted under the microscope.

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MINAMI

Fig 18e During adjusting and finishing of the abutment tooth, an acrylic resin block was milled to fabricate a provisional crown. The color of the provisional crown immediately after milling was influenced by the stained root, and the cutting edge was less transparent than the edges of the adjacent teeth. Therefore, the incisal area was cut back, and transparent resin was applied. The cervical area was characterized using opaque resin. The margin was adjusted.

Fig 18f The margin was finished using an ultrasonic instrument under the microscope (magnification x10).

Fig 18g Comparison of the abutment tooth after the final preparation and its projection on the monitor after scanning. A smooth accentuated chamfer with a uniform width was confirmed. The preparation surface was smooth, and the line and corner angles were round. The taper was appropriate. Fig 18h Final results.

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