QUINTESSENCE OF DENTAL TECHNOLOGY QDT 2016

In other words, the enamel thickness at the gingival third does not permit a chamfer preparation of 0.5 mm depth.4 The long-term success and durability of ultrathin bond-ed ceramic resto

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QDT QUINTESSENCE OF

DENTAL TECHNOLOGY Sillas Duarte, DDS , MS , PhD Editor-in-Chief

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• Can help to reduce the need for bone augmentation

• One-position-only components for accurate identification of the implant position throughout the treatment process

OsseoSpeed Profile EV is an integral part of the new ASTRA TECH Implant System EV and is supported by the unique ASTRA TECH Implant System BioManagement Complex.

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QDT 2016

2

A recent study by Accenture and Oxford Economics

projected a US $1.4 trillion growth in the world

economy over the next 5 years spurred by

digi-tal technology In dentistry, the interest in digidigi-tal

technol-ogy has increased exponentially in the last few years The

heavy marketing of and interest and investment in novel

digital scanners, sensors, treatment-planning software,

and, of course, CAD/CAM technologies, created a digital

disruption in dentistry “Going digital” became synonymous

with growth and prosperity But if digital dental technology

is considered as just another IT instrument, the outcome

could be disastrous and the longevity of any program

jeop-ardized in a short period of time Organizations (schools,

clinics, corporations, private practices, and laboratories)

must be ready to embrace this technology, thus fully

ac-cepting the digital disruption and transforming operations

to soundly compete in a digital dental world

Needless to say, any new technology comes with a

price tag In dentistry this price tag can become very steep

Investments in hiring of personnel (dentists, faculty, dental

technicians, and/or staff) as well as their training,

coach-ing, and development are essential And after all that, a

program for career development must be pondered to

en-sure retention of highly committed and talented individuals

Of course, technology is perishable; it can become solete in a short period of time (Ask yourself how many times you have changed your smartphone in the last few years and have looked forward to the introduction of the next new model.) Thus, a strategy for budget allocation must be clearly established for investment, maintenance, upgrades, and improvements—all of which are highly im-portant and necessary even before adopting digital tech-nology Our experience with digital disruption has revealed

ob-it to be exceedingly posob-itive and excob-iting, since when fully planned and executed, digital technology can produce meaningful rewards in all aforementioned aspects

care-In this issue of Quintessence of Dental Technology, join

me in discovering how digital disruption, when combined with art and science, can improve predictability, increase opportunities, and expand the breadth of esthetic oral re-habilitation to heights never before imagined

Sillas Duarte, Jr, DDS, MS, PhDEditor-in-Chief

sillas.duarte@usc.edu

The Digital Disruption in Dentistry

Editorial

Kuraray America, Inc.

Exclusive distributor of Kuraray Noritake Products

www.kuraraydental.com / www.kuraraynoritake.com

1 800 496 9500www.zahndental.com

Anterior Crown Anterior Veneer Inlay / Onlay Posterior Crown

How many new shades would it take

to change your game?

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Kuraray America, Inc.

Exclusive distributor of Kuraray Noritake Products

www.kuraraydental.com / www.kuraraynoritake.com

1 800 496 9500www.zahndental.com

Anterior Crown Anterior Veneer Inlay / Onlay Posterior Crown

How many new shades would it take

to change your game?

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Victor Clavijo, DDS, MS, PhD/Neimar Sartori, DDS, MS, PhD/

Jin-Ho Phark, DMD, Dr Med Dent/Sillas Duarte, Jr, DDS, MS, PhD 4

BIOMATERIALS UPDATEBonding to Silica-Based Glass-Ceramics: A Review of Current 26Techniques and Novel Self-Etching Ceramic Primers

Jin-Ho Phark, DMD, Dr Med Dent/Neimar Sartori, DDS, MS, PhD/

Sillas Duarte, Jr, DDS, MS, PhD

Analog Protocol for Obtaining the Ideal Soft Tissue Support and 37Contour in Anterior Implant Restorations

Eric Van Dooren, DDS/Cristiano Soares, CDT/Leonardo Bocabella, CDT/

Willy Clavijo, CDT/Victor Clavijo, DDS, MS, PhD

SKYN Concept: A Digital Workfl ow for Full-Mouth Rehabilitation 47

Florin Cofar, DDS/Cyril Gaillard, DDS/Ioana Popp, CDT/Christophe Hue, CDT

Minimally Invasive Full-Mouth Rehabilitation for Dental Erosion 57

Masayuki Okawa, DDS

STATE OF THE ARTEsthetic Rehabilitation of a Patient with Severely Worn and 78Compromised Dentition

Somkiat Aimplee, DDS, MSc, FACP/Aram Torosian, MDC, CDT/

Sergio R Arias, DDS, MS/Alvaro Blasi, DDS, CDT/Sung Bin Im, MDC, CDT, BS/

Associate Professor and Chair

Division of Restorative Sciences

Herman Ostrow School of Dentistry

University of Southern California

Los Angeles, California

ASSOCIATE EDITORS

Jin-Ho Phark, DDS, Dr Med Dent

Neimar Sartori, DDS, MS, PhD

São Paulo, Brazil

EDITORIAL REVIEW BOARD

Ana Carolina Botta, DDS, MS, PhD

Stony Brook, New York

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

4350 Chandler Drive, Hanover Park, Illinois, 60133 Price per copy: $132.

MANUSCRIPT SUBMISSION

QDT publishes original articles covering dental laboratory techniques and methods For submission information, contact Lori Bateman (lbateman@quintbook.com) Copyright © 2016 by Quintessence Pub- lishing Co, Inc All rights reserved No part

of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including pho- tocopying, recording, or any information and retrieval system, without permission in writing from the publisher The publisher assumes no responsibility for unsolicited manuscripts All opinions are those of the authors Reprints of articles published in QDT can be obtained from the authors.

Permission to photocopy items solely for internal or personal use and for the internal

or personal use of specific clients is granted

by Quintessence Publishing Co, Inc, for libraries and other users registered with the Copyright Clearance Center (CCC) pro- vided the appropriate fee is paid directly to CCC (www.copyright.com)

Printed in China ISSN 1060-1341 / ISBN 978-0-86715-723-9 ERRATA

The tooth displayed on the cover of QDT 2014, fabricated by Masaaki Honda (spelled incorrectly in the issue) et al, was made in acrylic, not ceramic as stated.

The Challenging Anterior Transition Zone:Details for 111

Creating an Esthetic Result

Victor Clavijo, DDS, MS, PhD/Paulo Fernando Mesquita de Carvalho, DDS, MS/

Leonardo Bocabella, CDT

Biologic Esthetics by Gingival Framework Design: 129

Part 3 Gingival Framework Design Procedures

Yuji Tsuzuki, RDT

3D Printed Complete Dentures 141

Tae Hyung Kim, DDS/Fabiana Varjão, DDS, MS, PhD

MASTERPIECE

The Challenge of a Natural-Appearing Fixed/Removable 150

Implant-Supported Dental Prosthesis

Michael Bergler, MDT/Stephen J Chu, DMD, MSD, CDT

BIOMATERIALS UPDATE

Wear of CAD/CAM Materials 162

Nathaniel Lawson, DMD, PhD/John O Burgess, DDS

DENTSCAPETM: Tri-Axis Portrait Posing 170

Naoki Aiba, CDT, Oral Design

Implant-Supported Full-Arch Zirconia Fixed Dental Prostheses for the 179

Rehabilitation of a Patient with a Failing Dentition

Jack Goldberg, DDS, MS/Arman Torbati, DDS, FACP/Alexandre Amir Aalam, DDS/

Winston Chee, DDS, FACP

Ultrasonic Devices for Minimally Invasive Periodontal Surgery and 197

Restorative Dentistry

Ivan Contreras Molina, DDS, MSc, PhD/Gildardo Contreras Molina, DDS/

Claudia Angela Maziero Volpato, DDS, MS, PhD/Sascha A Jovanovic, DDS, MS/

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JUNE 2–4, 2017 | SAN DIEGO, CA SHERATON SAN DIEGO HOTEL & MARINA

Program Chair:

Avishai Sadan

The 25th International Symposium on Ceramics

The New Frontiers of Esthetic Excellence: Successfully Integrating the Best of Traditional and Digital Dentistry

CALL: (800) 621-0387 (toll free within US & Canada) • (630) 736-3600 (elsewhere) 1/16

FAX: (630) 736-3633 EMAIL: service@quintbook.com WEB: www.quintpub.com QUINTESSENCE PUBLISHING CO INC, 4350 Chandler Drive, Hanover Park, IL 60133

For more information, go to www.quintpub.com/isc

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Victor Clavijo, DDS, MS, PhD1Neimar Sartori, DDS, MS, PhD2Jin-Ho Phark, DMD, Dr Med Dent3Sillas Duarte, Jr, DDS, MS, PhD4

Novel Guidelines for Bonded Ceramic Veneers: Part 1

Is Tooth Preparation Truly Necessary?

1 Professor, Advanced Program in Implantology and Restorative Dentistry,

ImplantePerio Institute, São Paulo, Brazil; Visiting Scholar, Advanced

Program in Operative and Adhesive Dentistry, Herman Ostrow School of

Dentistry, University of Southern California, Los Angeles, California, USA.

2 Assistant Professor, Division of Restorative Sciences, Herman Ostrow

School of Dentistry, Assistant Director, Advanced Program in Operative

and Adhesive Dentistry, University of Southern California, Los Angeles,

California, USA.

School of Dentistry, Director of Biomaterials Laboratory, Advanced

Program in Operative and Adhesive Dentistry, University of Southern

California, Los Angeles, California, USA.

4 Associate Professor and Chair, Division of Restorative Sciences, Director,

Advanced Program in Operative and Adhesive Dentistry, Herman Ostrow

School of Dentistry, University of Southern California, Los Angeles,

California, USA.

Correspondence to: Dr Victor Clavijo, Rua Cerqueira Cesar,

1078 Indaiatuba, São Paulo, Brazil 13330-005

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CLAVIJO ET AL

QDT 2016

8

Dentists and dental laboratory technicians must

have both technical and scientific knowledge

to deliver high-quality, ultrathin bonded ceramic restorations.1,2 All esthetic treatments must be properly

indicated to provide long-lasting restorations that not just

create a beautiful smile, but also restore and maintain the

oral health and function over time

It is universally accepted that ceramic veneers

bond-ed to intraenamel tooth preparations have higher survival

rates.3 The mean thickness of enamel at the gingival third

is 410 μm (0.410 mm) on the maxillary central incisor and

367 μm (0.367 mm) on the maxillary lateral incisor (Fig

1).4 Since traditional veneers have a chamfer gingival finish

line with 0.5 mm of depth,5 dentin is exposed during the

tooth preparation In other words, the enamel thickness at

the gingival third does not permit a chamfer preparation of

0.5 mm depth.4

The long-term success and durability of ultrathin

bond-ed ceramic restorations have been achievbond-ed due to the

improvement of both ceramics and bonding systems.6

Nowadays, ultrathin bonded ceramic restorations, with

100 μm (0.1 mm) to 300 μm (0.3 mm) of thickness, can

be fabricated to partially involve one or more tooth

sur-faces (ultrathin partial veneer) (Fig 2)7–9 or completely cover

the tooth facial surface (ultrathin veneer) (Fig 3).1,2,10,11 The main advantage of ultrathin ceramic restorations is tooth preservation, since minimal or no preparation is necessary.Subgingival tooth preparation may cause gingival in-flammation over time due to injuries from the operative procedures, presence of restorative materials, marginal gaps, overhangs, and roughness of the luting agents (Fig 4).12 However, if the veneer preparation is equigingival, the natural apical migration of gingiva may expose the adhe-sive luting interface and dark tooth substrates over time (Fig 5) In a 12-year longitudinal study evaluating the gin-gival recession on subjects with good oral hygiene, the recession increased from 44% to 88% in the group of 18- to 29-year-olds, mainly at incisors and canines.13Moreover, wear of the adhesive luting interface of tra-ditional veneers over time also raises both esthetic and biologic concerns (Fig 6).14 These depressions on the in-terface act as a niche for plaque,15 which could expedite the development of secondary caries as well as gingival inflammation by retaining periodontal pathogens.16

The aim of part 1 of this article is to give the clinician step-by-step guidelines for properly selecting, planning, executing, and delivering ultrathin bonded ceramic resto-rations

Fig 1 Maxillary central incisors

showing less than 400 μm (0.4 mm)

enamel thickness at the gingival third

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Novel Guidelines for Bonded Ceramic Veneers: Part 1 Is Tooth Preparation Truly Necessary?

Figs 2a to 2c Ultrathin bonded partial ceramic veneer

restorations with areas of less than 100 μm (0.1 mm)

of thickness.

3a

3b

2c

Figs 3a and 3b Ultrathin bonded ceramic veneers

with less than 300 μm (0.3 mm) of thickness are the

ultimate goal for enamel preservation.

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CLAVIJO ET AL

QDT 2016

10

CASE SELECTION

Ultrathin bonded ceramic veneers and partial veneers

are indicated to change dental morphology, such as for

increasing the length and facial bulkiness of teeth,

clos-ing diastemas, re-anatomization of conoid teeth, restorclos-ing

teeth fractures and canine guidance, as well as for

restor-ing or increasrestor-ing the vertical dimension (Fig 7) However,

these ultrathin bonded ceramic restorations are dicated when dentin is exposed during an aggressive tooth preparation to correct tooth morphology and/or position

contrain-or to create an adequate path of insertion (Fig 8), as well

as in cases of severe tooth discoloration Figures 9 to 52 depict various cases and the restorative approach aimed at maximum preservation of human dental enamel

Fig 4 Three-year follow-up of bonded porcelain veneers with intrasulcular margins showing gingival inflammation.

Figs 5a and 5b Ten-year follow-up of bonded porcelain veneers showing the gingival bonded interfaceafter progressive gingival recession The exposure of the gingival margin leads to interface deterioration, plaque accumulation, and staining.

Figs 6a Scanning electron microscope image showing the gingival margin of a porcelain veneer bonded to a prepared tooth

(magnification ×200) C: ceramic; R: resin cement; E: enamel.

Fig 6b After artificial tooth brushing (20,000 cycles), resin cement is worn off at the gingival margin (arrow), creating a cavity prone to plaque accumulation that is extremely difficult to fix C: ceramic; R: resin cement; E: enamel.

con-Fig 6c After intense artificial tooth brushing (100,000 cycles) and exposure to coffee, the resin cement is worn off at the

gingival margin and the concavity is now filled with debris (arrow), which translates clinically to marginal staining C: ceramic; R: resin cement; E: enamel

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Figs 7a to 7d Clinical situations in which

partial ultrathin or contact lens bonded ceramic

restorations are indicated (a) restoration of

fractured tooth; (b) diastema closure; (c) tooth

re-anatomization; (d) restoration of canine

guidance.

Figs 8a and 8b Different paths of insertion

for the ultrathin bonded ceramic restorations

The (a) facial path of insertion requires less

tooth structure reduction than the (b)incisal

path of insertion.

7d 7c

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CLAVIJO ET AL

QDT 2016

12

TREATMENT PLANNING

The success of ultrathin bonded restorations depends on

an adequate treatment plan It should be done using an

appropriate dental photographic protocol as well as

diag-nostic casts and diagdiag-nostic wax-ups

Dental photographs of the patient’s face as well as

fron-tal, 45-degree, profile, and occlusal views should be taken

These are important for evaluating the dental arrangement,

smile line, gingiva position, occlusal planes, teeth color and

shape, as well as emergence profile of the teeth Moreover,

digital treatment planning can be done to facilitate

inter-disciplinary communication as well as to communicate with

the dental technician and with the patient.17

The first impression should be taken with polyvinyl

si-loxane (PVS) impression material and poured using type

IV dental stone to have the least amount of dimensional

distortion.18 Other advantages of PVS impressions are that

they can be poured multiple times within a week after the

impressions were taken Furthermore, in clinical cases that

do not require teeth impressions, the first impressions can

also be used to pour the working cast

The diagnostic wax-up should be done by the same

dental technician who will fabricate final ceramic

restora-tions, preferably without any dental reduction on the

diag-nostic cast The wax-up should be done using a wax with a

different color than the diagnostic cast to facilitate

visual-ization of the areas that will be covered by ceramic

restora-tions or reduced to achieve an adequate path of insertion

for the restorations.1 If any dental reductions are

neces-sary to achieve the correct tooth shape and position, a

reduction guide should be fabricated by the dental

techni-cian to guide the dentist to reduce the same amount of

tooth structure in the patient’s mouth before the mock-up

fabrication

SHADE MATCHING AND

MOCK-UP

The correct shade matching is key to creating

natural-looking restorations Shade matching must be done

visu-ally and also using dental photographs with the teeth

hy-drated, before the mock-up

For a correct shade matching of value, chroma, and

hue, dental photographs should be taken with different

tabs similar to the tooth shade The shade tabs should be placed at the same level on the teeth in all photographs, and the color names should be included in the frame A close-up picture with a black background can also be taken to evaluate details such as mamelons, translucence, opalescence, incisal halo, regions with higher and lower value, and presence of staining.19

Before starting any tooth preparation, it is necessary to transfer the information (representing the planned treat-ment) from the diagnostic cast to the patient’s mouth A PVS impression of the waxed diagnostic cast should be taken It should include all waxed teeth and extend at least one non-waxed tooth on each side as well as the palatal surfaces of waxed teeth After the impression materials are polymerized, the excesses are trimmed off from the gingival area (2 mm apical to the dentogingival junction) The impression should be filled with a chemical-cure bis-acryl resin with the shade selected for the final restora-tions and placed in the patient’s mouth Excesses should

be removed after resin polymerization

The mock-up allows the dentist and patient to ate whether any adjustments are necessary to achieve adequate esthetics and function In addition, it allows the patient to approve the shape and position of the proposed restorations If any intraoral correction is made, an impres-sion of the mock-up must be taken after the adjustments

evalu-to transfer those changes evalu-to the technician

ENAMEL RECONTOURING

The majority of cases restored with bonded porcelain neers do not require tooth preparation, but rather enamel recontouring Any enamel recontouring necessary should

ve-be performed only after the patient gives written consent and approves the proposed mock-up Enamel recontouring should be as least invasive as possible, because enamel preservation is the key for long-term success of any bond-

ed ceramic restorations If dentin is exposed during tooth preparation, the bonded interface becomes more suscep-tible to long-term degradation Increased tooth reduction becomes necessary to withstand the stress generated at the resin-dentin interface by the dentin flexion and com-pression

Enamel recontouring is guided by three aspects: (1) need to increase volume to the teeth’s facial surface, (2)

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color of the dental substrate, and (3) path of insertion for

the ceramic restorations The color of the dental substrate

as well as the dental technician’s skills to work with reduced

space will determine the type of tooth preparation When

the dental shade is favorable, minimal or no tooth

prepara-tion is necessary However, in cases of tooth discoloraprepara-tion,

minimalenamel preparation might be necessary to allow

the technician to mask the discolored substrate

The path of insertion of a given bonded porcelain

ve-neer is the most important aspect for ideal tooth

reshap-ing There are two possible paths of insertion for ultrathin

veneers: facial and incisal The most conservative path of

insertion for ceramic veneers is the facial path of

inser-tion (FPI), which can be done perpendicular to the long

axis of the tooth (see Fig 8a) In this situation, a minimal

and calculated enamel recontouring might be necessary

to remove undercuts or to minimize the influence of the

proximal height of contour (crest of convexity)

Indications for the incisal path of insertion (IPI), when

the veneer must be inserted parallel to the long axis of

the tooth (see Fig 8b), are: (1) development of a new

emergence profile, (2) diastemas, and (3) reshaping of the

interdental papillae In any of these cases, interproximal

enamel recontouring is necessary so that the veneer will

extend toward the lingual marginal ridge

To ensure maximum enamel preservation, enamel

re-contouring must be guided by the mock-up and reduction

guides If subgingival preparation is necessary, a shallow

gingival finish line (< 0.3 mm of depth) should be used to

avoid both dentin exposure as well as subgingival

over-contour

Before the final impression is taken, the teeth

prepara-tions should be polished to ensure maximum adaptation

of the ceramic restoration and reduce the luting film

thick-ness The polishing should be done using multiple blades,

carbide burs, and flexible disks, as well as composite and

ceramic rubber polishing points

FINAL IMPRESSION

The location of the gingival finish line of the preparation

will determine the need for retraction cords during the

final impression In cases with no gingival finish line, the

final impression must be taken without retraction cords,

maintaining the gingiva in its natural position Retraction

cords change the gingival position apically, and the dental technician has no reference as to where the restoration should be finished Restorations with overcontoured gin-gival margins disrupt the natural emergence profile of the teeth, promoting plaque accumulation, gingival inflamma-tion, and, consequently, gingival retraction over time.12

To properly replicate the tooth structure as well as the soft tissue without using retraction cords, the final impres-sion should be taken in two steps (wash technique) with hard- and light-body PVS impression material

In cases of diastema closure, the interproximal gingiva must be displaced for the final impression A dual-cord technique must be used to allow proper remodeling of the interproximal papillae In this technique, two indepen-dent unconnected retraction cords (size #0) are carefully placed interproximally The first retraction cord is used to displace the mesial papilla while reshaping it into the de-sired interproximal papillae position The same procedure

is performed for the distal papilla (see Figs 13 and 48) The location of the retraction cords should be customized to allow the technician to create the new emergence profile

of the proximal surfaces and simultaneously reshape the interdental papillae into a more attractive esthetic contour

In non-diastema cases, retraction cords must be used to displace soft tissue and expose the gingival finish line when the tooth preparation extends subgingivally (see Fig 29)

TEMPORIZATION

One advantage of ultrathin bonded ceramic restorations and ceramic fragments is that no temporization of tooth preparations is necessary in most of the cases However, when provisional restorations are necessary, they can be fabricated using the same materials used for the mock-up

To ensure that the provisional restorations stay in tion, tooth preparations should be spot etched with phos-phoric acid and an etch-and-rinse adhesive system should

posi-be applied and light-cured (Self-etch or universal sive systems should not be used for temporization.) The impression with the chemical-cure bis-acryl resin is placed

adhe-in the patient’s mouth and all excesses removed after its polymerization Even though the interproximal areas are blocked by the splinted provisional restorations, the gin-gival embrasures must still open to allow cleaning of the areas with superfloss.20

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Fig 11a After the patient approved the shape proposed for the partial veneers, defective restorations were removed using a

stainless steel #12 scalpel blade.

Fig 11b Teeth polished using aluminum oxide flexible disks.

Figs 12a and 12b Intraoral 45-degree views of teeth after removing the defective composite resin restorations A facial path of

insertion for the partial veneer was possible without any tooth preparation.

Fig 13 In cases of diastema closure with ultrathin partial veneers, the gingiva must be displaced using the dual-cord technique

This technique ensures correct interproximal gingival papillae displacement, allowing the technician to create a new emergence profile on the tooth proximal surface.

Figs 14a and 14b Geller model was fabricated to ensure proper adaptation and emergence profile on the proximal surfaces.

13 12b

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Fig 16 Ultrathin ceramic restorations with facial path of

inser-tion (Leonardo Bocabella, CDT).

Fig 17 Frontal view of the ultrathin partial veneers after

finishing and polishing The adequate surface texture gives the

restoration a natural-looking appearance.

Fig 18 Intraoral view of the ultrathin bonded partial veneers.

Fig 19 Extraoral view.

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facial contours of the teeth were overly bulky because no reduction was done.

Fig 22 Mock-up in the patient’s mouth for evaluating the planned treatment.

Fig 23 After the patient approved the teeth proportions proposed, crown lengthening surgery was done guided by the mock-up

(Surgery performed by Paulo Fernando de Carvalho.)

Fig 24a to 24c After soft tissue healing, a new impression was taken and another additive wax-up was performed with detailed

tooth contours and proportions.

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Fig 25 Second mock-up was fabricated based on the new diagnostic wax-up to evaluate the tooth contours and proportions.

Fig 26 After confirming that proportions and contours were correct in the mock-up, the preparation was limited only to removal of

the old restorations and enamel recontouring This step was performed over the mock-up to ensure maximum preservation of enamel, especially at the cervical third Once the mock-up was removed, enamel was polished using aluminum oxide disks, and the interproximal contacts were lightened with metallic finishing strips

Figs 27a and 27b Silicone guides, based on the diagnostic wax-up, were used to verify if there was enough space for the ceramic

restorations in the middle and incisal thirds as well as proximal surfaces Any discrepancy found would be corrected using aluminum oxide disks.

Fig 28 The gingival level of the maxillary central incisors was again recontoured with electrosurgery before the final impression was taken Fig 29 Since the previous preparations extended intrasulcularly, the gingiva was displaced for the final impression.

Figs 30a and 30b Close-up view of the gingival area of the preparation in the working cast The retraction cord properly displaced

the gingiva, exposing the intrasulcular finish line Note the absence of a traditional chamfer preparation to improve enamel bonding at the gingival margin.

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CLAVIJO ET AL

QDT 2016

18

Figs 31a to 31c Geller model fabrication All soft tissue must be kept intact to

ensure an adequate emergence profile of the ultrathin ceramic veneers.

Fig 32a Ultrathin bonded ceramic layering.

Fig 32b Finishing and polishing after sintering.

Figs 33a to 33c Ultrathin bonded ceramic veneers (Cristiano Soares, CDT)

33c

33b 33a

32b 32a

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Fig 34 Try-in of ultrathin ceramic veneers Incisal path of

insertion was selected for maximum preservation of enamel.

Fig 35 Frontal view of the ultrathin bonded ceramic veneers.

Fig 36 Profile view of the bonded restorations.

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CLAVIJO ET AL

QDT 2016

20

Fig 37 Initial intraoral frontal views showing multiple diastemas.

Fig 38a Patient exhibiting multiple diastemas must be evaluated for ideal path of insertion before deciding if a nonpreparation or a

minimal preparation approach should be used The incisal view revealed that a bonded ultrathin veneer with a facial path of insertion would result in an undercontoured lingual extension and a potential source for plaque accumulation.

Fig 38b Ultrathin bonded ceramic veneers with proximal extension toward the mesial and distal lingual marginal ridges would

provide the ideal contour for this patient An incisal path of insertion would require minimal enamel recontouring, thus preserving important enamel for bonding

followed by minor enamel polishing/flattening of the mesial height of contour.

Figs 39a and 39b Ideal tooth proportions created using the additive wax-up technique on the diagnostic cast, taking into

consider-ation the incisal path of insertion.

Fig 40 Mock-up allowed evaluation of the proposed tooth ratios and shapes.

CASE 3

39b 39a

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Fig 41 After the patient approved the proposed mock-up, it was removed and areas of undercuts and overcontours were

marked with black permanent maker pen to guide the tooth preparation.

Figs 42a to 42c Enamel was carefully recontoured proximally and facially to create an incisal path of insertion parallel to the

long axis of the teeth.

Fig 43a Observe the interproximal height of contour and constriction of the gingival enamel outline.

Fig 43b For maximum preservation of gingival enamel, no conventional finish line was performed.

Figs 44a and 44b Tooth preparations were polished and angles rounded before taking the final impression.

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CLAVIJO ET AL

QDT 2016

22

Figs 45a and 45b Proximal and incisal views before recontouring.

Fig 46a and 46b Proximal and incisal views of the same site showing minimal enamel recontouring.

Fig 47 In diastema cases, the retraction cord should be placed carefully to guide the dental technician to recreate the most

appropriate interproximal papillae design and new emergence profile Note the displacement of the gingiva for the maxillary left central incisor

Fig 48 The dual-cord technique must be used to allow proper remodeling of the interproximal papillae by the new emergence

profile of the proximal surface.

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Fig 49 Ultrathin bonded ceramic veneers were layered, finished, and polished.

Figs 50a and 50b Ultrathin bonded ceramic veneers (Leonardo Bocabello, CDT).

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Fig 51 Close-up views showing that the new emergence profile of the proximal surfaces

properly remodeled the interproximal papilla as a result of the dual-cord technique.

Fig 52 Intraoral view of the ultrathin bonded ceramic veneers.

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CONCLUSIONS

To ensure long-term success of bonded ceramic veneers,

dental enamel must be preserved in its pristine condition

Thus, ultrathin bonded ceramic veneers are the primary

choice for anterior esthetic rehabilitation If preparation is

absolutely necessary (particularly regarding path of

inser-tion), maximum preservation of gingival enamel becomes a

must The gingival margin and finish line must be prepared

to less than 0.3 mm enamel reduction, limited to reshaping

overhangs and undercuts, and a finish line created only in

cases of subgingival preparation

Today it is unacceptable to sacrifice sound enamel to

create space for artificial restorative materials Bonding

techniques associated with novel laboratory techniques

have significantly evolved to allow maximum preservation

of dental tissues Therefore, subtractive restorative

tech-niques must be reconsidered, dogmas and myths

chal-lenged, and additive restorative techniques aiming for

to-tal preservation of dento-tal tissues considered as the main

choice for esthetic rehabilitation using bonding techniques

ACKNOWLEDGMENTS

The authors are grateful for the skillful work of Leonardo Bocabello, CDT

(Cases 1 and 3) and Cristiano Soares, CDT (Case 2) in producing the

ultrathin porcelain veneers.

REFERENCES

1 Strassler HE Minimally invasive porcelain veneers: Indications for a

conservative esthetic dentistry treatment modality Gen Dent 2007;

55:686–694.

2 da Cunha LF, Gonzaga CC, Saab R, Mushashe AM, Correr GM

Reha-bilitation of the dominance of maxillary central incisors with

refrac-tory porcelain veneers requiring minimal tooth preparation

Quintes-sence Int 2015;46:837–841.

3 Gurel G, Sesma N, Calamita MA, Coachman C, Morimoto S Influence

of enamel preservation on failure rates of porcelain laminate veneers Int J Periodontics Restorative Dent 2013;33:31–39.

4 Pahlevan A, Mirzaee M, Yassine E, et al Enamel thickness after aration of tooth for porcelain laminate J Dent 2014;11:428–432.

prep-5 Magne P, Belser U Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach: Quintessence Publisher Co, Inc; 2002.

6 D’Arcangelo C, De Angelis F, Vadini M, D’Amario M Clinical evaluation

on porcelain laminate veneers bonded with light-cured composite: Results up to 7 years Clin Oral Investig 2012;16:1071–1079.

7 Miranda ME, Olivieri KA, Rigolin FJ, Basting RT Ceramic fragments and metal-free full crowns: A conservative esthetic option for closing diastemas and rehabilitating smiles Oper Dent 2013;38:567–571.

8 Gresnigt M, Ozcan M Esthetic rehabilitation of anterior teeth with porcelain laminates and sectional veneers J Can Dent Assoc 2011;77:b143.

9 Horvath S, Schulz CP Minimally invasive restoration of a maxillary central incisor with a partial veneer Eur J Esthet Dent 2012;7:6–16.

10 Friedman M Multiple potential of etched porcelain laminate veneers

J Am Dent Assoc 1987;115:83E–87E.

11 Materdomini D, Friedman MJ The contact lens effect: Enhancing porcelain veneer esthetics J Esthet Dent 1995;7:99–103.

12 Ferencz JL Maintaining and enhancing gingival architecture in fixed prosthodontics J Prosthet Dent 1991;65:650–657.

13 Serino G, Wennström JL, Lindhe J, Eneroth L The prevalence and distribution of gingival recession in subjects with a high standard of oral hygiene J Clin Periodontol 1994;21:57–63.

14 Belli R, Pelka M, Petschelt A, Lohbauer U In vitro wear gap formation

of self-adhesive resin cements: A CLSM evaluation J Dent 2009;37:984–993.

15 Silness J Periodontal conditions in patients treated with dental

bridg-es 3 The relationship between the location of the crown margin and the periodontal condition J Periodontal Res 1970;5:225–229.

16 Silness J Fixed prosthodontics and periodontal health Dent Clin North Am 1980;24:317–329.

17 Coachman C, Calamita M Digital smile design: A tool for treatment planning and communication in esthetic dentistry Quintessence Dent Technol 2012;35:103–111.

18 Anusavice KJ, Shen C, Rawls HR Phillips’ Science of Dental als 12 ed Elsevier/Saunders; 2013.

Materi-19 Soares C, Soares LM, Duarte GF, Sartori N Maintaining the esthetics

of anterior teeth with a flapless single-tooth immediate implant placement Quintessence Dent Technol 2015;38:113–125.

20 Vailati F, Belser UC Full-mouth adhesive rehabilitation of a severely eroded dentition: The three-step technique Part 2 Eur J Esthet Dent 2008;3:128–146.

Trang 28

QDT 2016

In recent years, as a result of the rapidly progressing

CAD/CAM technology, a large number of new ceramic and hybrid materials have been introduced While additional choices will benefi t the patient due to the expanded indications, they make it increasingly diffi cult for clinicians and technicians to keep informed in terms

all-of proper material selection and, more important, correct surface treatment and bonding protocols This article will review the surface treatment application techniques for bonding of silica-based ceramic materials

Tooth-colored all-ceramic and hybrid materials can be divided into three categories based on their composition:

(1) glass-matrix ceramics, which consist of nonmetallic

inorganic ceramics with a glass phase; (2) polycrystalline

ceramics, which consist of nonmetallic inorganic

ceram-ics without any glass phase; and (3) resin-matrix ceramceram-ics,

which consist of polymer matrices that contain inorganic refractory components, such as porcelains, glasses, ce-ramics, and glass-ceramics.1

Due to their optical properties and despite their tions in terms of strength, the glass-matrix ceramics, which are also termed silica-based ceramics,2 are one of the most commonly used materials for all-ceramic restorations Silica-based ceramic materials are listed in Table 1 The

School of Dentistry, Director of Biomaterials Laboratory, Advanced

Program in Operative and Adhesive Dentistry, University of Southern

California, Los Angeles, California, USA.

School of Dentistry, Assistant Director, Advanced Program in Operative

and Adhesive Dentistry, University of Southern California, Los Angeles,

California, USA.

3 Associate Professor and Chair, Division of Restorative Sciences,

Director, Advanced Program in Operative and Adhesive Dentistry,

Herman Ostrow School of Dentistry, University of Southern California,

Los Angeles, California, USA.

Correspondence to: Dr Jin-Ho Phark, Division of Restorative

Sciences, Herman Ostrow School of Dentistry, University of Southern

California, 925 W 34th Street, Los Angeles, CA 90089-0641, USA

Email: phark@usc.edu

Bonding to Silica-Based Glass-Ceramics:

A Review of Current Techniques and

Novel Self-Etching Ceramic Primers

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QDT 2016

28

PHARK ET AL

glass matrix consists of mainly silicon dioxide (also called

silica or quartz) with various amounts of alumina The silica

content allows these materials to be etched with

hydro-fl uoric acid prior to bonding, whereas the polycrystalline

ceramics, such as alumina and zirconia, cannot be etched

due to the lack of the glass phase

While the purely glass-based ceramic systems are very

esthetic due to their high translucency, they have low

me-chanical properties To increase the strength of the glass

matrix, natural or synthetic crystals can be dispersed in it

This process is called dispersion strengthening, as it is more diffi cult for the dispersed crystals to be penetrated

by cracks so that crack propagation in the matrix can be stopped or slowed down.3 Natural leucite crystals derived from potassium feldspar can be found in several materi-als, such as IPS Empress Esthetic, IPS Empress CAD, IPS Classic (Ivoclar Vivadent), Vitadur, Vita VMK 68, and Vitablocs (VITA Zahnfabrik) Synthetic crystals consist of other leucite-based crystals, eg, IPS d.SIGN (Ivoclar Viva-dent), VM7, VM9, VM13 (VITA Zahnfabrik), Noritake EX-3,

Table 1 Silica-Based Ceramic Materials

Type Products Indications

Flexural strength Composition (%)

Etching time (with HF acid)

Leucite Pressable:

IPS Empress Esthetic (Ivoclar Vivadent) Machinable:

IPS Empress CAD (Ivoclar Vivadent)

Inlays, onlays, crowns, veneers

160 MPa SiO2 (60.0–65.0)

Al2O3 (16.0–20.0)

K2O (10.0–14.0)

Na2O (3.5–6.5) Other oxides (0.5–7.0) Pigments (0.2–1.0)

60 s

VITABLOCKS Mark II (VITA Zahnfabrik) Inlays, onlays, crowns 130 MPa 60 sLithium disilicate Pressable:

IPS e.max Press (Ivoclar Vivadent) Machinable:

IPS e.max CAD (Ivoclar Vivadent)

Inlays, onlays, crowns, FPDs, veneers, implant crowns/abutment

Al2O3 (0.0–5.0) MgO (0.0–5.0) Pigments (0.0–8.0)

20 s

Zirconia-reinforced

lithium silicate VITA Suprinity (VITA Zahnfabrik)

Celtra Duo (DENTSPLY Caulk)

Inlays, onlays, crowns, implant crowns, veneers

420 MPa

210–370 MPa

Inlays, onlays, crowns, implant crowns

160 MPa Ceramic part:

(86 wt%/75 vol%) SiO2 (58–63)

Al2O3 (20–23)

Na2O (9–11)

K2O (4–6)

B2O3 (0.5–2) ZrO2 < 1 CaO < 1 Polymer part:

(14 wt%/25 vol%) Urethane dimethacrylate (UDMA) Triethylene glycol dimethacrylate

Trang 30

Bonding to Silica-Based Glass-Ceramics: A Review of Current Techniques and Novel Self-Etching Ceramic Primers

Cerabien, Cerabien ZR (Kuraray Noritake); lithium disilicate

(IPS e.max Press or CAD, Ivoclar Vivadent) or lithium silicate

(VITA Suprinity [VITA Zahnfabrik], Celtra Duo, [Dentsply])

crystals; and fl uorapatite-based crystals (IPS e.max

Zir-Press, Ivoclar Vivadent).1

A new class of materials containing glass-ceramic with

an interpenetrating resin matrix, also often referred to as

hybrid ceramic, has been introduced to the market fairly

re-cently Currently, the only hybrid ceramic material available is

VITA Enamic (VITA Zahnfabrik) It is composed of a dual

net-work with a feldspathic ceramic part (86% by weight/75%

by volume) and a polymer part (14% by weight/25% by

vol-ume) consisting of urethane dimeth acrylate (UDMA) and

triethylene glycol dimethacrylate (TEGDMA).4

BONDING MECHANISMS

The inherent mechanical properties of some of the

silica-based materials require adhesive cementation of the

res-torations, which increases their strength.5 To allow optimal and stable long-term bonding to the intaglio surface of the restoration, micromechanical retention and chemical treat-ment are required.2

Micromechanical Retention

Micromechanical retention can be achieved by altering the surface texture using either mechanical or chemical means, resulting in an enlarged surface area and microscopically small undercuts within the altered surface The applied cements or adhesives can fl ow into these undercuts and, when hardened, interlock to provide stable retention.6

Chemical Etching with HF Acid

One of the most common techniques to alter the surface is

by chemical treatment For this purpose, highly corrosive agents (Table 2), such as hydrofl uoric (HF) acid, are used

Table 2 Ceramic Etching Gels

Product Company Effective acid Other components

Etching time for spathic glass ceramic

Color: yellow

90 s, extra- and intraoral Porcelain etch Premier Dental HF 9.6% N/A

Color: yellow Ceramics etch VITA Zahnfabrik HF 2.5% to < 5% Sulphuric acid 5% to < 10%

Ethanol 2.5% to < 10%

Color: red

Only extraoral

IPS ceramic etching

gel Ivoclar Vivadent HF 3% to < 7% N/AColor: red 60 s

Monobond Etch &

Prime

Ivoclar Vivadent Tetrabutylammonium

dihydrogen trifl uoride < 10%

Butanol 20% to 25%

Bis(triethoxysilyl)ethane (< 1%) Methacrylated phosphoric acid ester (3% to 5%) Color: green

40 s (apply for 20 s, wait for 20 s), extra- and intraoral

Porcelain etch 9.5% Bisco HF 9.5%

Polyacrylamidomethylpro-pane sulfonic acid 50% to 75%

Color: yellow

90 s, extra- and intraoral

Porcelain etch 4% Bisco HF 4%

Polyacrylamidomethylpro-pane sulfonic acid 50% to 75%

Color: orange

5–6 min

Porcelain etch gel Pulpdent HF 9.6% N/A

Color: yellow 60 s, extra- and intraoral

Information according to manufacturers.

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PHARK ET AL

QDT 2016

30

HF acid is used industrially for etching and polishing

glass-es, ceramics, and metals In addition to cleaning processglass-es,

it is also used for etching semiconductors.7 HF acid is an

aqueous solution of hydrogen fluoride Even though it is

considered a weak acid, it is still hazardous and very

cor-rosive Personal protective equipment must be worn during

handling, and the patient must be protected using rubber

dam Some countries prohibit the intraoral application of

HF acid Exposure of skin or other soft tissue to HF acid

will result in severe burns that penetrate quickly into

deeper layers and healing is very slow.7 Enamel and dentin

treated with HF acid have been shown to exhibit lower

bond strength values to composites.8,9

HF acid can selectively etch the glassy matrix of

silica-based ceramics Due to the higher affinity of fluoride to

silicon than to oxygen, HF acid and silica form

tetrafluo-rosilane: 4HF (aq) + SiO2 (s)➝SiF4 (g) + 2H2O (l) The

tet-rafluorosilane further reacts with HF and forms the soluble

hydrofluorosilicic acid: 4SiF4 (g) + 3H2O (l) + 2HF (aq)

➝ 3H2SiF6 (aq) + H2SiO3 (aq) Thus, the glassy matrix is

dissolved and can be rinsed away, leaving the surface

to-pography and roughness altered and allowing

microme-chanical retention.10,11 Surface roughness has been shown

to increase along with increasing concentrations of HF

acid.12,13 While the strength of silica-based ceramic with

leucite filler particles was shown to be reduced by

etch-ing compared to non-etched specimens, there was no

cor-relation between reduction in strength and concentration

among the etched groups.12,13 However, the strength

re-duction might not be of concern clinically, since adhesive bonding has been shown to result in the restoration of and

an even further increase of the strength values.5 For lithium disilicate– or fluorapatite-reinforced silica-based ceramics,

no decrease in strength has been shown regardless of HF acid application.5,14

For glass-ceramics containing leucite, an etching time

of 2 minutes with either 5% or 9.6% HF acid has

result-ed in the highest bond strength values (Fig 1).15,16 While the manufacturer-recommended etching time with 5%

HF acid is 20 seconds for optimal bonding to lithium silicate ceramic (Fig 2), some studies found higher bond strengths after 120 seconds of etching.17,18 Differences

di-in acid concentration also have been found; etchdi-ing with 4.9% HF acid resulted in lower bond strength compared to the same etching time with 9.5% HF acid.19 Etching of the hybrid ceramic material (VITA Enamic) for 60 seconds with 5% HF acid resulted in stabile long-term bond strength.20

Chemical Treatment with Novel Self-Etching Ceramic Primer

Due to the toxicity of HF acid, alternative etching mediums have been used, such as titanium tetrafluoride,21,22 acidu-lated phosphate fluoride gel,23,24 and ammonium hydrogen bifluoride.25,26 These materials showed results that were more or less comparable to HF acid application but require the separate application of a silane A recently introduced

Fig 1 Microstructure of a leucite-reinforced glass-ceramic

(IPS Empress CAD) etched with hydrofluoric acid for 90

seconds (magnification × 10,000).

Fig 2 Microstructure of a lithium disilicate–reinforced

glass-ceramic (e.max CAD) etched with hydrofluoric acid for 20 seconds (magnification × 10,000).

Trang 32

approach in chemical surface treatment of silica-based

ceramics is the self-priming etchant (Monobond Etch &

Prime [MBEP], Ivoclar Vivadent), which reduces one step

in the technique-sensitive ceramic bonding protocol by

combining etching and silane application It consists of a

butanol-based mixture of tetrabutylammonium

dihydro-gen trifluoride as an etching medium and an organosilane

(bis-triethoxysilyl-ethane) that are applied to the ceramic

surface at the same time for a total of 40 seconds After

this step, the gel is rinsed off with water and after drying

the treated surface is ready for cementation An additional silane application step, as usually required for the conven-tional protocol with HF acid etching and coupling agent,

is not necessary with this novel material Because it is much milder and less toxic than HF acid, it might be a suit-able alternative to HF acid for intraoral repair of ceramic restorations However, it also does not create as deep an etching pattern as HF (Figs 3 to 7) Nonetheless, findings from the authors’ biomaterials laboratory revealed that bond strengths to leucite-reinforced glass-ceramic (IPS

Fig 3a Microstructure of a feldspathic ceramic veneer (Creation CC) after the application of a self-etching ceramic primer

(Monobond Etch & Prime, MBEP) following the manufacturer’s recommendation (magnification × 1,000) Note the difference

between the intact nonetched area adjacent to the one treated with MBEP.

Fig 3b Higher magnification of the same specimen showing the microstructure of a feldspathic ceramic veneer (Creation CC)

after the application of a self-etching ceramic primer (Monobond Etch & Prime) following the manufacturer’s recommendation

(magnification × 10,000).

Fig 4 Microstructure of a leucite-reinforced glass-ceramic (IPS Empress CAD Multi) after the application of a self-etching

ceramic primer (Monobond Etch & Prime) following the manufacturer’s recommendation (magnification × 10,000)

Fig 5 Microstructure of a lithium disilicate–reinforced glass-ceramic (e.max CAD) after the application of a self-etching

ce-ramic primer (Monobond Etch & Prime) following the manufacturer’s recommendation (magnification × 10,000)

Trang 33

PHARK ET AL

QDT 2016

32

Empress CAD) with self-etching ceramic primer (MBEP)

were comparable to that of using HF acid etching in

com-bination with silane However, bonding to lithium disilicate–

reinforced glass-ceramics still seems to be a challenge for

this novel product.27

Mechanical Treatment

For surface treatment, bur grinding or airborne particle

abrasion using aluminum-oxide particles of various sizes

has been employed as well It is routinely used on non–

silica-based high-strength ceramics, such as zirconia and

alumina, due to their inertness and inability to be etched

with HF acid On glass-based ceramics, this treatment

has been shown to have a significant effect on surface

roughness and it also had a detrimental effect on flexural

strength when compared to HF acid.14,25,28,29 Regarding

bond strength, bur grinding and airborne particle abrasion

of lithium disilicate–reinforced glass-ceramic have been

shown to result in lower bond strengths compared to HF

acid etching.19,30,31 Therefore, silica-based ceramics should

not be treated with bur grinding or airborne particle

abra-sion, but only with HF acid

CHEMICAL BONDING

While micromechanical retention does have an important role, it is not the only factor leading to successful long-term bonding to silica-based ceramic materials.25,32 Chem-ical treatment further enhances bonding by applying coupling agents (Table 3), which are bifunctional mole-cules that allow a chemical reaction between the inor-ganic ceramic and the organic resin cement The most commonly used coupling agents are organosilanes, such

as γ-methacryloxypropyl trimethoxysilane Their methoxy group (-OCH3) is hydrolyzed in the presence of water to a silanol group (-Si-OH), which subsequently can bond with the hydroxyl groups on the surface of the ceramic, forming

a siloxane bond (-Si-O-Si-) The other functional group, a methacrylate group, is able to polymerize with the organic resin by forming a covalent bond.3,11 The silane also in-creases the hydrophobicity and wettability of the treated surface,33 thus enhancing its interaction with the hydro-phobic resin cements

Silanes are sold in two different forms They are either prehydrolyzed or unhydrolyzed The prehydrolyzed silanes are applied as one-bottle systems in a solvent that con-tains ethanol and water Unfortunately, this form has a

Fig 6 Microstructure of a zirconia-reinforced lithium silicate

glass-ceramic (VITA Suprinity) after the application of a

self-etching ceramic primer (Monobond Etch & Prime)

fol-lowing the manufacturer’s recommendation (magnification ×

10,000)

Fig 7 Microstructure of a zirconia-reinforced lithium silicate

glass-ceramic (Celtra Duo) after the application of a etching ceramic primer (Monobond Etch & Prime) following the manufacturer’s recommendation (magnification × 10,000)

Trang 34

monomer Other components Purpose, substrate

Monobond Plus Ivoclar

Etch & Prime

Ivoclar Vivadent

1 Bis(triethoxysilyl)ethane (< 1%)

Methacrylated phosphoric acid ester 3% to 5%

Butanol 20% to 25%

Tetrabutylammonium dihydrogen trifluoride

< 10%

Ceramics (silica based)

RelyX ceramic

primer 3M ESPE 1 Methacryloxypropyl-trimethoxysilane < 2% Ethyl alcohol 70% to 80%

Water 20% to 30%

Ceramics (silica based), composites

BIS-Silane Bisco 2

3-(trimethoxysilyl)propyl-2-methyl-2-propenoic acid 5% to 10%

Ethanol 50% to 75% Ceramics (silica

based)

Porcelain primer Bisco 1

3-(trimethoxysilyl)propyl-2-methyl-2-propenoic acid 1% to 5%

Acetone 30% to 50% Ceramics (silica

based)

Ceramic bond Voco 1 Silane Acetone 50% to 100% Ceramics (silica and

non-silica based), composites, metals Silane Ultradent 1 Methacryloxypropyl

trimethoxysilane < 10% Isopropyl alcohol < 95% Ceramics (silica based) Silane primer Kerr 1 3-trimethoxysilylpropyl

methacrylate 1% to 5%

Ethanol 60% to 100%

Bisphenol A ethoxylate dimethacrylate 1% to 5%

TEGDMA 1% to 5%

Porcelain silane Premier

Ethanol > 80% Ceramics (silica and

non-silica based), composites, non-noble metals Clearfil porcelain

bond activator Kuraray 1 3-trimethoxysilylpropyl methacrylate < 5% Hydrophobic aromatic dimethacrylate 40% to

60%

resin cement silane

coupling agent

Dentsply Caulk 1 Silane Ethyl alcohol 92.6% Acetone 7.4% Ceramics (silica based), composites

Zahnfabrik

1 3-trimethoxysilylpropyl methacrylate < 2.5%

Ethanol 25% to 50%

Phosphoric acid < 5%

Distilled water Activator Catalyst

Information according to manufacturers

Trang 35

QDT 2016

34

PHARK ET AL

limited shelf life, because the hydrolized molecules may

autocondensate, especially in the presence of

atmospher-ic moisture Once the solution has changed to a cloudy or

milky appearance, the silane cannot be used.34 Two-bottle

systems, on the other hand, have increased shelf life,

be-cause they consist of a separate unhydrolyzed silane that

is mixed with an aqueous acetic acid solution at the time

of the procedure Upon mixing of the two components, the

hydrolysis is initiated.10,11

To improve the silanization process even further, the

use of heat has been advocated It is suggested that by

either placing the restoration into a furnace or blowing hot

air on it, both at 100°C, water, alcohol, and other products

would be removed and the covalent bond formation

be-tween silane and silica would be promoted.33,35 However,

recent studies did not support the benefi cial effect of heat

treatment in combination with silane application Moreover,

they stress the synergistic effect of HF acid and silane

application.36,37

It is important to remember that organosilanes achieve

optimal bonding to silica-based ceramic materials;

how-ever, they do not chemically bond to non–silica-based

ce-ramics, such as alumina and zirconia For these materials,

special monomers containing functional groups based on

phosphate ester or phosphonic acid are more suited.2,38

ADHESIVE/RESIN CEMENT

INTERACTION AND

SILANE-CONTAINING ADHESIVES

The additional application of bonding agent to the etched

and silanated ceramic surface prior to cement application

has been shown to be unbenefi cial39 or even detrimental

to bond strength.40 Self-etching adhesives showed lower

bond strengths than regular adhesives.16 Even the

incorpo-ration of silanes into the bonding agent, such as in the more

recently introduced universal bonding agents (Scotchbond

Universal, 3M ESPE, or All-Bond Universal, Bisco), was not

able to overcome this problem The application of

univer-sal bonding agents to silica-based ceramics without prior

HF acid etching and silane application is not

recommend-ed.41–43 While the combination of a universal bonding agent

with a self-adhesive cement resulted in a signifi cant drop

of bond strength after artifi cial aging,43 the combination

of the same bonding agent with a regular dual-cure resin cement did not.42 Besides the silane component, universal bonding agents also might contain special monomers on phosphate ester bases, such as 10-MDP, that chemically bond to zirconia but not to silica-based ceramics

CONTAMINATION

Throughout the bonding process, there can be several ways that contamination could interfere with the adhesive interaction between the ceramic surface and cement Dur-ing etching with HF acid, insoluble silica-fl uoride salts as byproducts precipitate on the surface.44 They might inhibit proper adaptation of the silane and cement, thus leading to

a reduction in bond strength These salts can be removed

by cleaning the restoration in an ultrasonic bath or by ing and rubbing the surface with phosphoric acid for 1 minute before application of the silane.44–46 While the phosphoric acid did have the ability to clean the surface, it does not increase the surface roughness and does not increase bond strength.31,44 In instances that the contami-nation with saliva, blood, or silicone try-in paste of a presi-lanized restoration has occurred during the try-in procedure, the bond strength of the cement to the ceramic will be compromised To remove the organic contaminants, air-borne particle abrasion and re-etching with HF acid have been proposed.47 However, these techniques might weak-

etch-en the ceramic material.13,21,28,31 Instead, the surface can be etched with phosphoric acid for 60 seconds.48 The applica-tion of 0.5% sodium hypochlorite solution for 20 seconds, followed by rinsing with water, has shown to be effective for cleaning leucite-reinforced but not lithium disilicate–reinforced glass-ceramic.49 Rinsing thoroughly with water,

or using alcohol, air polishing with sodium bicarbonate, or even using a special cleaning paste (Ivoclean, Ivoclar Viva-dent) did not clean the bonding surface of silica-based ce-ramics as well as etching with phosphoric acid.47,49 All cleaning approaches have to be followed by a reapplica-tion of fresh silane A more ideal situation would be to have the etching and silane application occur after the try-in procedure and then have the surface kept free from any contaminants until the execution of the bonding steps.45

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35

QDT 2016

NEUTRALIZATION, DISPOSAL,

AND EMERGENCY MEASURES

With insuffi cient rinsing of the HF acid, continuous etching

as well as the overall acidic environment can negatively

infl uence the polymerization of resinous cements

Neutral-ization of the acid with agents such as sodium carbonate

powder (IPS Neutralizing Powder, Ivoclar Vivadent) has

been suggested.50,51 The neutralizing agent can remove

the precipitant that is formed during etching by forming

sodium fl uoride and the unstable carbonic acid.51 However,

studies have shown that such approaches did not enhance

bond strength and even led to increased contact-angle

measurements by leaving behind the agent’s own

pre-cipitates and thus negatively affecting bond strength.50–52

Thus, acid neutralization appears to be unnecessary, since

similar neutralizing effects could easily be achieved by

thorough rinsing of the etched surface with an air-water

spray for 30 seconds.50,51

While neutralization of HF acid does not appear to be

important in terms of bonding, it is crucial during

emergen-cy management and for disposal of HF acid Due to the

corrosiveness of HF acid, compatible containers (no glass

or metal containers) in accordance with local hazardous

waste management regulations must be used

Addition-ally, HF acid can be neutralized, eg, with sodium carbonate

powder, or diluted with water before disposal.7 When

han-dling HF acid, proper personal protective equipment must

be used

If accidental exposure of any tissue should occur,

in-tensive rinsing with water followed by application of

ap-propriate neutralizing agents is advised Calcium gluconate

in various forms—gel for skin exposure, eye drops for eye

injury, and nebulized spray after inhalation—and

benzalko-nium chloride for nail injury are indicated as fi rst aid

mea-sures after HF acid exposure.7 In any case, a doctor must

be consulted

CONCLUSION

While novel systems have been recently introduced to

sim-plify the bonding protocol to etchable glass-ceramics,

treat-ment with HF acid followed by silane application can still

be considered as the gold standard to ensure long-term

successful adhesive effectiveness to ceramic restorations

REFERENCES

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2 Blatz MB, Sadan A, Kern M Resin-ceramic bonding: A review of the literature J Prosthet Dent 2003;89:268–274.

3 Anusavice K, Shen C, Rawls H Phillips’ Science of Dental Materials

St Louis: Elsevier, 2013.

4 Duarte S, Sartori N, Cascione D, Phark JH Ceramic-reinforced mers: Overview of CAD/CAM hybrid restorative materials Quintes- sence Dent Technol 2014;27:32–48.

poly-5 Posritong S, Borges AL, Chu TM, et al The impact of hydrofl uoric acid etching followed by unfi lled resin on the biaxial strength of a glass-ceramic Dent Mater 2013;29:e281–e290.

6 Duarte S, Phark JH, Blaltz MB, Sadan A Ceramic systems: An structural study Quintessence Dent Technol 2010;33:42–60.

ultra-7 Ozcan M, Allahbeickaraghi A, Dündar M Possible hazardous effects

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on the bond strength of a composite resin to a machinable porcelain

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QDT 2016

Analog Protocol for Obtaining the Ideal

Soft Tissue Support and Contour in

Anterior Implant Restorations

The restoration of a single anterior tooth with an

implant-supported prosthesis can be an esthetic challenge The final results are influenced by three main parameters: bone level and thickness, soft tissue contour and stability, and the clinical crown appearance

Many articles describe different techniques for ing the ideal emergence profile of the implant restoration, mainly defining the ideal soft tissue contour by the provi-sional restoration Still it is sometimes difficult to quantify and determine the ideal soft tissue support and emer-gence profile in some cases

develop-This case presentation demonstrates a technique that will allow the clinician and the dental technician to deter-mine the ideal soft tissue support for challenging anterior implant restorations It describes step by step the analog treatment modalities for copying the ideal, natural root form

1 Private Practice limited to prosthodontics, implants, and periodontal

plastic surgery, Antwerpen, Belgium.

2 Dental Technician, Campinas, Brazil.

3 Dental Technician, Curitaba, Brazil

4 Professor, Advanced Program in Implantology and Restorative Dentistry,

ImplantePerio Institute, São Paulo, Brazil; Visiting Scholar, Advanced

Program in Operative and Adhesive Dentistry, Herman Ostrow School

of Dentistry, University of Southern California, Los Angeles, California,

USA.

Correspondence to: Dr Eric Van Dooren, Tavérnierkaai 2,

2000 Antwerpen, Belgium Email: vandoorendent@skynet.be

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CASE PRESENTATION

Diagnosis and Treatment Planning

A 32-year-old woman presented with a fractured right

central incisor (Fig 1) The tooth was splinted with a

com-posite retainer to the adjacent teeth Radiographic

evalu-ation showed a satisfactory endodontic treatment (Fig 2)

Probing depth did not exceed 4 mm in any of the

exam-ined areas Moderate gingival inflammation was present,

especially on the distal aspect of the tooth A cone beam

computed tomography (CBCT) scan confirmed light bone

loss on the buccal aspect and adequate apical bone

re-The extracted tooth will be used to determine the gingival contour for the provisional crown/abutment as well as for the final crown Since the natural root dimen-sions will be copied, the soft tissue support and design should be ideal (Figs 8 to 11)

CASE PRESENTATION

Fig 1 Initial intraoral view.

Figs 2a and 2b Maxillary central incisor radiographs.

Fig 3 CBCT scan confirming the presence of the buccal

bone walls Note the loss of interdental bone on the distal aspect of the right central incisor This will influence the final result and height of the distal papilla

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Analog Protocol for Obtaining the Ideal Soft Tissue Support and Contour in Anterior Implant Restorations

Figs 6a and 6b Extracted right central incisor Palatal (P),

mesial (M), distal (D), and buccal (B) views.

Fig 7 After repositioning the tooth in the impression, a soft

tissue mask (Gingifast Rigid, Zhermack) will be injected

around the tooth in order to have an exact copy of the root

contour in the model

Figs 4a and 4b Initial preparation before

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