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All-Ceramics
at a Glance
Introduction to indications, material selection, preparation
and insertion of all-ceramic restora...
Arbeitsgemeinschaft für Keramik in der
Zahnheilkunde e.V. (AG Keramik)
K.-H. Kunzelmann, M. Kern, P. Pospiech, A. J. Raigr...
Title:
All-ceramic materials provide esthetic and enduring treatment solutions. Photo Reichel
University Edition
This limi...
Contents
1. Foreword 4
2. All-ceramics – individual, esthetic, and metal-free 6
3. Proven clinical applications 7
4. Clini...
Foreword
4
Ceramics in dentistry –
a success story
Foreword
to the English edition
Dear Reader,
The ceramics handbook “All...
Foreword
Our thanks go to Professors Frankenberger, Kern, Kunzelmann, Mehl, Pospiech,Tinschert and
all others for their co...
2.
6
All-ceramics –
customized, esthetic
and metal-free
All-ceramics is the term for restorations consisting solely of por...
3.
Patients tend to appreciate extensive consultation
to clarify and educate on the functional and esthetic
treatment opti...
4.
8
Clinical use
Misalignment of the anterior dentition
and occlusal anomalies can be corrected
with porcelain laminate v...
5.
9
Preparation design for ceramic inlays. The isthmus
width and thickness should not be less than 1.5 mm
occlusally. At ...
5.
10
All-ceramic inlays, onlays,
and posterior partial-coverage
crowns
Residual tooth structure with extensive cavities.
...
5.
Ceramic inlays after 3 years in situ.
Photo: Mehl
11
Cuspal coverage with a conservative
partial coverage crown.
Photo:...
5.
12
A partial coverage crown digitally constructed,
with 3 reconstructed cusps, using the Cerec system.
Photo: Sirona
Al...
5.
13
Adhesive luting of the restoration requires conditioning
the enamel and/or dentin and the ceramic surface.
Photo: Fr...
5.
14
Procedure for restoring a cavity with a ceramic inlayAll-ceramic inlays, onlays,
and posterior partial-coverage
crow...
5.
Procedure for restoring a cavity with a ceramic inlay
15
Ceramic reconstruction of teeth 44 – 46.
All photos: Kunzelman...
6.
16
Porcelain laminate veneers,
anterior ceramic partial-
coverage crowns
White spots on facial surfaces of 11, 12, 21, ...
6.
17
Preparation design for all-ceramic partial-coverage
crowns, which in the anterior region corresponds
to a veneer pre...
6.
18
Porcelain laminate veneers,
anterior ceramic partial-
coverage crowns
Inadequate anterior composite-resin restoratio...
6.
19
Preparation of tooth 13 for a veneer.
Etching with phosphoric acid.
Insertion with excess of composite-resin cement....
6.
20
Porcelain laminate veneers,
anterior ceramic partial-
coverage crowns
Fig. 1: Function-correcting veneer: On the att...
6.
21
Paper-thin veneers
of alumina ceramic by Procera.
Photo: Nobel Biocare
Diastematas, incisal edge fracture,
and tooth...
6.
22
Porcelain laminate veneers,
anterior ceramic partial-
coverage crowns
Perfect veneers after insertion.
Photo: Baltze...
6.
Insertion procedures:
• Remove the provisional veneer and/or the provisional cement
• Retouch the area of the spot etch...
7.
24
Monolithic, anatomically milled complete-coverage
crown of silicate ceramic. Photo: KaVo / Ivoclar-Vivadent
Crowns, ...
7.
25
Fundamental distinctions:
Silicate ceramics fulfill high esthetic demands –
high-strength oxide ceramics are suitabl...
7.1
26
Incorrect chamfer
finish-line.
“J-lipping” or steps are
contraindicated.
Correct chamfer finish-line.
A chamfer wit...
7.1
The edges and transitions must at least match the
radius of the abrasive stones in the milling machine.
Fig.: Pospiech...
7.1
28
Anterior crowns
Horizontal grooves with depth defined by ball diamond
diameter.
A silicon key to evaluate tooth red...
7.1
29
The wall thickness of zirconia (Lava)
anterior crown copings can be reduced
down to 0.5 mm. This conserves tooth st...
7.1
30
Anterior crowns
Preoperative condition for anterior crowns.
Photo: Hirschfeld
Anterior crowns with ZrO2 framework,
...
7.1
The choice of luting materials for definitive insertion depends on the ceramic material selected.
In general:
• Silica...
7.2
32
Molar crowns of In-Ceram
Alumina veneered.
Photo: VITA Zahnfabrik, Huiss
Posterior crowns
Ceramic
Material properti...
7.2
33
Framework made of zirconia ceramic
can be colored like dentin.
Photo: VITA Zahnfabrik
Posterior crowns with framewo...
7.2
Posterior crowns
34
Fig. 2: Minimum preparation depth for crowns of
oxide ceramic (Al2O3, ZrO2) copings
Preparation de...
7.2
35
Fig. 5: Basic principles of framework design
for crown copings
The framework of Al2O3 or ZrO2 ceramic must support ...
7.3
36
Frameworks for a 3- and 4-unit
anterior fixed partial denture. Even on tooth 23
with the pronounced recession, the ...
7.3.1
37
Anterior fixed partial denture of lithium-disilicate
(Empress 2) and ovate pontics.
A lithium-disilicate fixed pa...
7.3.1
38
Anterior fixed partial dentures
Pre-oprative: Restoration with a zirconia based fixed
partial denture and a zirco...
7.3.2
39
The zirconia coping for the mandibular first molar
crown. Note the excellent marginal fit.
Occlusal view of the f...
7.3.2
40
Posterior fixed partial dentures
Veneer
min. 0.7mm
max. 2.0mm
Fig. 2: Wall and layer thicknesses for crown coping...
7.3.2
41
4-unit fixed partial denture with ZrO2
framework (Lava), in situ for 4 years.
Photos: Groten
4-unit fixed partial...
7.3.2
Posterior fixed partial dentures
42
Fixed partial denture units
require sufficient connector
surfaces in vertical, o...
7.4
43
Primary copings of zirconia ceramic
combined with galvanically
fabricated secondary coping. Cold welding
as for met...
7.4
44
All-ceramics for telescopic crowns
Cerec-manufactured primary copings
of ZrO2 and the completed overlay prosthesis
...
45
7.4 / 7.5
Customizing the gingival aspect of a ZrO2 abutment.
The white material prevents the titanium from shining
thr...
ZrO2 abutment (Lava) with metal insert and
matching crown.
All-ceramic implant abutments,
and implant-supported crowns and...
47
7.5
ZrO2 abutments screw into endosteal implant to
support a multi-unit fixed partial denture.
Fig.: Nobel Biocare
Supe...
8.
48
Indications for
ceramic materials
Crown Crown Fixed Fixed Telescopic Implant- Abut- Inlay Partial- Veneer Inlay Resi...
9.
49
VITA 3D-Master
shading system.
Fig.: VITA Zahnfabrik
Shade selectionShade selection for all-ceramic restorations
An ...
9.
50
Shade selection
Digitale shade scanner. Fig.: VITA Zahnfabrik
Conditions for patient:
• No lipstick, highly-colored ...
2008 all ceramics at a glance
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2008 all ceramics at a glance

  1. 1. All-Ceramics at a Glance Introduction to indications, material selection, preparation and insertion of all-ceramic restorations Arbeitsgemeinschaft für Keramik in der Zahnheilkunde e.V. (AG Keramik) Society for Dental Ceramics (SDC) K.-H. Kunzelmann, M. Kern, P. Pospiech, A. J. Raigrodski, H. E. Strassler, A. Mehl, R. Frankenberger, B. Reiss, K. Wiedhahn ISBN 978-3-00-021677-0 1st English Edition
  2. 2. Arbeitsgemeinschaft für Keramik in der Zahnheilkunde e.V. (AG Keramik) K.-H. Kunzelmann, M. Kern, P. Pospiech, A. J. Raigrodski, H. E. Strassler, A. Mehl, R. Frankenberger, B. Reiss, K. Wiedhahn Society for Dental Ceramics (SDC) All-Ceramics at a Glance Introduction to indications, material selection, preparation and insertion of all-ceramic restorations 1st English Edition
  3. 3. Title: All-ceramic materials provide esthetic and enduring treatment solutions. Photo Reichel University Edition This limited edition has been published for universities, professors, lecturers and students of dentistry. With this special edition, the authors, editors, and publisher? hahelped make available, free of charge to teaching and research, both tried-and-true and new knowledge about all-ceramic restorations gained from clinical and private practice. The authors hereby give the recipient of this edition the right to make print-outs exclusively for the purposes of the university or college and distribute them as study material at the university or college. However, we request that no electronic copies be made or distributed. We thank you for your cooperation. The initiators of this University Edition strongly hope for a lively exchange of ideas with professors and students, to ensure a broad clinical basis for all-ceramics as a progressive treatment procedure. Authors, Committee, and Board of the Society for Dental Ceramics September 2008 Society for Dental Cermics Arbeitsgemeinschaft für Keramik in der Zahnheilkunde e.V. P.O.B. 100 117, D-76255 Ettlingen, Germany Tel. ++49 721 945 2929 eMail info@ag-keramik.de www.ag-keramik.de © Copyright 2007
  4. 4. Contents 1. Foreword 4 2. All-ceramics – individual, esthetic, and metal-free 6 3. Proven clinical applications 7 4. Clinical use 8 5. All-ceramic inlays, onlays, and posterior partial-coverage crowns 9 6. Porcelain laminate veneers, anterior ceramic partial-coverage crowns 16 7. Crowns, fixed partial dentures, telescopic crowns, implant-supported restoration 24 7.1 Anterior crowns 26 7.2 Posterior crowns 32 7.3 All-ceramic fixed partial dentures 36 7.3.1 Anterior fixed partial dentures 36 7.3.2 Posterior fixed partial dentures 39 7.4 All-ceramics for telescopic crowns 43 7.5 Implant abutments, and implant-supported crowns and fixed partial dentures 45 8. Indications for ceramic materials 48 9. Shade selection 49 10. Luting techniques 51 10.1 Adhesive bonding of feldspathic porcelain 52 10.2 Step-by-step procedure for intimate adaptation 56 10.3 Conventional luting procedures 62 11. Try-in, adjustment, and polishing procedures 64 12. Removing all-ceramic restorations 66 13. Intra-oral ceramic repair 67 14. Rationale for all-ceramic restorations 68 15. Clinical results 70 16. Ceramic and CAD/CAM systems 73 17. Literature on all-ceramics 84 18. Society for Dental Ceramics: Purpose and intent 90 19. From the practice for the practice 91 20. Overview of dental ceramics – ceramic systems (fold-out page) 3 1. Foreword 4 2. All-ceramics – individual, esthetic, and metal-free 6 3. Proven clinical applications 7 4. Clinical use 8 5. All-ceramic inlays, onlays, and posterior partial-coverage crowns 9 6. Porcelain laminate veneers, anterior ceramic partial-coverage crowns 16 7. Crowns, fixed partial dentures, telescopic crowns, implant-supported restoration 24 7.1 Anterior crowns 26 7.2 Posterior crowns 32 7.3 All-ceramic fixed partial dentures 36 7.3.1 Anterior fixed partial dentures 36 7.3.2 Posterior fixed partial dentures 39 7.4 All-ceramics for telescopic crowns 43 7.5 Implant abutments, and implant-supported crowns and fixed partial dentures 45 8. Indications for ceramic materials 48 9. Shade selection 49 10. Luting techniques 51 10.1 Adhesive bonding of feldspathic porcelain 52 10.2 Step-by-step procedure for intimate adaptation 56 10.3 Conventional luting procedures 62 11. Try-in, adjustment, and polishing procedures 64 12. Removing all-ceramic restorations 66 13. Intra-oral ceramic repair 67 14. Rationale for all-ceramic restorations 68 15. Clinical results 70 16. Ceramic and CAD/CAM systems 73 17. Literature on all-ceramics 84 18. Society for Dental Ceramics: Purpose and intent 90 19. From the practice for the practice 91 20. Overview of dental ceramics – ceramic systems (fold-out page)
  5. 5. Foreword 4 Ceramics in dentistry – a success story Foreword to the English edition Dear Reader, The ceramics handbook “All-Ceramics at a Glance” for dentists and dental technicians was first published in 2006 in German for the German-speaking countries. The concise descrip- tion of treatment and insertion procedures with all-ceramic restorations was enthusiastically accepted by the specialist dental community to the extent that all copies of the first edition rapidly sold out. Moreover, dentists and dental technicians in other countries also showed interest in this handbook. This motivated the authors and the editors, the Society for Dental Ceramics, to publish an English-language edition. One of the concerns of our Society is to support a minimally destructive, highly effective and esthetic treatment of diseased teeth. Our goal is to give an overview and specific recommendations for treatment planning and therapy based on our clinically proven expertise. Our clinical long-term data are an important basis for the predictability of treat- ment success. This is to ensure that patients receive long-lasting, durable restorative care through modern, practice-proven, and evidence-based procedures. The fact that all-ceramic restorations quickly became established as a treatment option demonstrates that dentists and patients alike have accepted the concept. Nevertheless, development continues. New ceramic materials, processing methods, and luting techniques, as well as the extending range of indications, all demand attentive, competent advisors who can support dentists and dental technicians in word and deed. In addition to providing a platform for the exchange of experience, the Society for Dental Ceramics ensures that the knowledge gained is passed along: through a quality assurance project with dentists in private practice, at symposia, in publications, and through personal contacts. European initiators and co-authors representing the English language version issue cordially invite all readers and professionals in the field to participate in our work and spread the knowledge of treatment with all-ceramic restorations. Dentists are also invited to get involved in quality assurance with the help of the Ceramic Success Analysis, a computer- guided program of the Society for Dental Ceramics. Our office would be happy to provide you with more detailed information also about local quality assessment groups. Chairman of the Board Society for Dental Ceramics Arbeitsgemeinschaft für Keramik in der Zahnheilkunde e.V.
  6. 6. Foreword Our thanks go to Professors Frankenberger, Kern, Kunzelmann, Mehl, Pospiech,Tinschert and all others for their collaboration on this handbook. Their contributions, illustrations, photos and figures updated and supplemented our understanding of the materials-science and clinical aspects of dental ceramics. July 2007 In the name of all authors, Ariel J. Raigrodski DMD, MS, Seattle WA, USA Dr. Bernd Reiss, Malsch, Germany Howard E. Strassler DMD, Baltimore MD, USA Howard E. Strassler DMD Professor and Director of Operative Dentistry, Dept. of Endodontics, Prosthodontics, and Operative Dentistry, University of Maryland Dental School, Baltimore 5 Ceramics in dentistry – a success story Ariel J. Raigrodski DMD, MS Associate Professor and Director, Graduate Prosthodontics, Dept. of Restorative Dentistry, School of Dentistry, University of Washington, Seattle
  7. 7. 2. 6 All-ceramics – customized, esthetic and metal-free All-ceramics is the term for restorations consisting solely of porcelain, without any metal sup- port. Ceramics are abrasion resistant, have light-transmitting and light-fracturing properties, are absolutely color stable, and enable invisible transition of the restoration margin into the dental tissues. The materials are relatively chemically inert and are bioneutral in comparison to other restorative materials in the mouth; they are insoluble and therefore biocompatible. The durability of ceramics may even exceed that of high-noble casting alloys. During the industrial manufacturing process, the mineral building-blocks of ceramics can be selected and adjusted to yield ideal optical properties, in order to reproduce in a restoration the full range of natural tooth shades. A characteristic property of ceramics is its brittleness and, when compared to metal, its low flexural strength and fracture toughness. Ceramics are resistant to high compressive stresses but susceptible to tensile forces. In dental treatment, ceramic restorations may require more attention to clinical detail in terms of both preparation design and insertion procedures. For a given indication, ceramics must be carefully chosen and the anatomical requirements must be met. In the dental laboratory, careful attention to detail during fabrication is necessary, particularly when grinding the ceramic framework. To date, these challenges can be met with the appropriate available techniques. Research-proven systems are now available for manufacture and insertion. The low fracture resistance of individual ceramic systems can be clinically compensated for by adhesive bonding to tooth structure. All-ceramic inlays and onlays, laminate veneers, crowns, and fixed partial dentures are gain- ing increasing popularity due to their excellent esthetics and biocompatibility. To meet the high demands of mechanical loads in the oral environment, high-quality industrially pre- fabricated ceramics, which can be processed in CAD / CAM systems, are the primary choice. The surfaces of restorations made of industrially prefabricated ceramics can be individualized and characterized. Their advantage over layered restorations lies in the improved material properties and higher fracture toughness of the ceramic blanks manufactured under stan- dardized conditions. Ceramic materials are translucent like the natural tooth. Crystals reflect incident light, direct the coloration into the deeper layers, and together with the veneering porcelain provide the foundation for outstanding esthetics. Fig.: Edelhoff
  8. 8. 3. Patients tend to appreciate extensive consultation to clarify and educate on the functional and esthetic treatment options with all-ceramic restorations. Photo: SDC/AG Keramik 7 Ceramic inlays replace amalgam restorations. Photo: Leistner Proven clinical applications In terms of esthetics and biocompatibility, ceramics are the materials of choice. Today, dentists and dental technicians alike are able to create ceramic restorations which are in no way inferior to their natural counterparts regarding shape, surface-texture, shade, transparency and translucency.Adverse reactions such as allergies or toxicity are relati vely rare even with metal alloys used in dentistry. However, even high-noble metal alloys are susceptible to corrosion if processed inadequately.Thus, ceramics are the ideal alternative, because they are chemically inert and do not dissolve in the oral cavity. For the following restorations, all-ceramic materials with different physical properties have b e e n proven effective and successful with clinical evidence supporting their appropriateness and e fficacy: • Adhesively luted inlays, onlays (Class I, II and V) • Adhesively luted partial-coverage crowns (covering several cusps) • Adhesively luted Class IV restorations • Adhesively luted laminate veneers in anterior-tooth and premolar areas • Adhesively or conventionally luted anterior and posterior crowns (also for full-mouth reconstruction with restoring the vertical dimension of occlusion) • Adhesively luted crowns with endodontically treated teeth (with retention in the pulp chamber without a post) • Adhesively or conventionally luted anterior 3-unit fixed partial dentures • Adhesive fixed partial dentures of 2 – 3 units for restoration of edentulous spaces with 1 – 2 lingual wings, adhesively luted • Adhesively or conventionally luted posterior fixed partial dentures with correctly sized connectors, up to 4 units • Primary copings to accept telescoping copings for removable partial dentures • Implant abutments • Implant-supported crowns and fixed partial dentures • Retaining attachments, crowns with fixed peg attachment for retention.
  9. 9. 4. 8 Clinical use Misalignment of the anterior dentition and occlusal anomalies can be corrected with porcelain laminate veneers. Photo: Hajto General considerations: The following pages offer a practical guide for clinical and technical considerations which affect material selection for all-ceramic restorations. The following points must be considered when selecting the type of ceramic that is appro- priate to the treatment planned for different clinical indications: • Which restorations are planned? • How extensive is the tooth structure loss or the carious lesion? • Where will the preparation finish-line be placed? Supragingivally, equigingivally, or subgingivally? • Are single-tooth restorations or fixed partial dentures required? • Are the restorations in the anterior or posterior segments? • Are there signs of parafunctional occlusal habits and/or bruxism? • How are static and dynamic occlusal loads distributed? • Is the restoration to be adhesively bonded or conventionally cemented? • Is the occlusal scheme to be changed? • Are there any discolorations of the dental tissues which must be concealed? • What degree of transparency and translucency do the natural teeth possess? • How much of the tooth is visible? The broad range of possibilities offered by the currently available all-ceramic systems make it necessary to perform meticulous data collection, diagnosis and treatment planning prior to beginning treatment, because the preparation, fabrication, function and longevity of the restoration depend on it. Physical and anatomical conditions have to be taken into consider- ation, as well as the desires and goals of the patient.
  10. 10. 5. 9 Preparation design for ceramic inlays. The isthmus width and thickness should not be less than 1.5 mm occlusally. At the preparation finish-line, care should be taken to create a nearly vertical transition to the tooth cavo-surface (ca. 70 – 110°). Fig.: Mehl ca. 90° ca. 90° min. 1.5 mm All-ceramic restorations are almost completely chemically inert and function as an “insulator” between metallic restorations. Photo: Manhart All-ceramic inlays, onlays, and posterior partial- coverage crowns Different metals are not only esthetically unpleasing, but can also pose biocompatibility risks. Photo: Manhart Indications All-ceramics are suitable for treating all acquired defects and replacing missing tooth struc- ture of single teeth. For partial coverage restorations placed with adhesive bonding, it is essential to use a den- tal-dam to ensure moisture control. In contrast to conventional direct restorations and partial coverage crowns, the advantage of adhesive bonding to enamel is that even thin, structurally compromised cusps do not neces- sarily have to be covered. For the following clinical scenarios, all-ceramic restorations should not be considered: • Extremely shallow and narrow cavities where the physical properties of the porcelain cannot be fulfilled (minimum layer size) • An alternative treatment: extended fissure sealing and use of a direct composite-resin restoration • If moisture control cannot be maintained • Given bruxism or suspected parafunctional habits, and less than ideal occlusal relationship, an occlusal heat-processed acrylic resin appliance to protect the teeth and restorations during the night should be considered. Glass ceramics are the material of choice for ceramic inlays, onlays and partial coverage crowns, because they can best mimic dental enamel. Such restorations must be adhesively luted. Preparation design The following features should not be included in the preparation design for adhesively bonded all-ceramic restorations: • Bevels • Dentin support of enamel • Extensive retention forms. Enamel margins are not absolutely necessary. Nevertheless, it must be possible to apply dental-dam where cavity margins are at or below the gingival margin. Margins which are subgingival can cause problems in achieving a durable dentin-composite bond and can be problematic in the removal of excess composite-resin cement after seating and poly- merization. The use of adhesive techniques make it possible to create largely defect-oriented, tooth- structure conserving preparations. Occlusal contacts near inlay finish-lines should be avoided.
  11. 11. 5. 10 All-ceramic inlays, onlays, and posterior partial-coverage crowns Residual tooth structure with extensive cavities. Cuspal coverage is planned with adhesively bonded ceramic inlays. Photo: Mehl Recommended types of diamond instruments for the preparation of ceramic inlays and onlays. To finish the preparation finish-line diamond sonic and ultrasonic tips are recommended for establishing a well-formed margin. Photo: Mehl Inlays made of pressed ceramic on the master cast. Photo: Mehl The preparation design should fulfill the following requirements: • Opening angle of the cavity wall not more than 6°, diverging toward the occlusal aspect (facilitates technical and clinical processing) • The preparation should extend far enough interproximally, breaking the interproximal contacts with the adjacent teeth, making the preparation’s finish-line accessible for excess composite-resin cement removal • Rounded internal line-angles between the preparation axial walls and pulpal floor • The isthmus of an inlay preparation should be no less than the minimum of 1.5 mm • Minimum occlusal thickness of 1.5 mm at the deepest point of the central fossa • Extensions of the proximal anatomy of the restoration to achieve proximal contact should not exceed 1.5 – 2 mm • The cavo-surface margin should be a butt joint (90°) at the transition between restora- tion and tooth structure (maximizes the resistance form of marginal areas) • Complete cuspal coverage may not be necessary • Cavity walls are finished with diamond rotary instruments with an abrasive grit of up to 40 µm • If necessary, use reciprocating, safe-sided oscillating diamond files interproximally (mechanically or ultrasonically driven) • Do not leave any enamel extensions. The preparation design requirements for onlays and posterior ceramic partial coverage crowns are: • Material thickness (at least 1.5 mm) • An isthmus for improving retention is not necessary • Internal edges and line angles must be rounded • Complete cuspal coverage may not be necessary • No long, branching cavity margins • Axial depth with a remaining wall thickness of not less than 1 mm, especially in molars and premolars • Strive for box preparation with an internal 90° rounded shoulder • Chamfer preparations and slightly sloped shoulders are acceptable. Preparation design of nonvital teeth: • The same preparation design as for inlays and partial coverage crowns.
  12. 12. 5. Ceramic inlays after 3 years in situ. Photo: Mehl 11 Cuspal coverage with a conservative partial coverage crown. Photo: Kunzelmann All-ceramic inlays, onlays, and posterior partial-coverage crowns The provisional restoration – an additional procedure Depending on the manufacturing method chosen, a provisional restoration of the cavity may be necessary. If the restoration is made chairside, i.e., using a CAD / CAM system (e.g., Cerec) in one session, a provisional restoration is not needed. Provisional restorations should not be made of semi-plastic materials, but of mechanically stable Bis-GMA or PMMA resin. These materials are wear resistant and will provide posi- tional stability for the tooth preparations. Alternatively, the resin coating technique of immediate dentin sealing may be employed. Recommended clinical procedure: apply dentin adhesive immediately after cavity preparation, then finish enamel margins. Make an impression of the cavity, insert a provisional restoration with eugenol-containing cement (so the adhesive does not completely polymerize). Prior to the insertion of the definitive restoration, clean the cavity, reapply dentin adhesive, insert the restoration definitively. Shade selection • Selection should be made prior to starting the preparation. If amalgam restorations are being replaced with a ceramic restoration, the shade should be selected after the defective restorations and caries are removed (see page 49). Impression making • When a chairside CAD / CAM system is used, the impression is made using a 3D intra-oral camera directly in the mouth. • If the restoration is to be fabricated in the laboratory, a conventional impression is necessary for making the dies and for the indirect procedures necessary for the fabrica- tion of the restoration by the dental laboratory. Laboratory procedures The following steps are performed for inlays, onlays and partial coverage crowns: • Shade selection, determination of customized coloration (shade mapping) • Fabrication of the master cast: type IV dental stone, dentin-colored composite-resin or ceramic stumps are used (only for feldspathic ceramics) • Use of a die spacer for cement space (in CAD / CAM milling, the software performs this step).
  13. 13. 5. 12 A partial coverage crown digitally constructed, with 3 reconstructed cusps, using the Cerec system. Photo: Sirona All-ceramic inlays, onlays, and posterior partial-coverage crowns The CAD / CAM technique enables automatic milling of the full-contour restoration in 10 – 20 minutes. Photo: Sirona • Strict observance and following of manufacturer’s recommendations for wall thickness to prevent internal stresses and cracking, and avoid air entrapment and surface defects during fabrication is essential for the longevity of the restoration • Coordination of occlusal concepts with the dentist to minimalize time required for occlusal adjustments on the restoration by grinding, include adjustment of the opposing dentition • Fitting of the restoration on a solid unsectioned cast • If necessary, sandblast the inside of the inlay or partial coverage crown (corundum 50 µm) for cleaning and surface conditioning; do not abrade the margins. Chairside procedure For inlays and partial coverage crowns made chairside, CAD / CAM technology performs the following steps: • Restoration is constructed on the screen; strict observance of manufacturer’s recommendations on layer thickness to prevent stresses and cracking; occlusal concept is followed to ensure minimal grinding for adjustments • Automatic milling of the full-contour restoration • Removal of the milling peg and polishing. Insertion • Try-in of the ceramic restoration without pressure and without occlusal evaluation • Checking the interproximal contacts and the marginal seal with silicon (low viscosity) fit checker or powder disclosing agent • Color evaluation by trying-in with glycerin gel • Be sure to completely remove disclosing agents and completely clean the restoration after try-in • All provisional cement must be cleaned from the preparation • Moisture control with dental-dam is mandatory when using composite-resin cements for adhesive luting • Etching and conditioning of the cavity • Etching and conditioning the restoration with hydrofluoric acid and silane only shortly prior to insertion (chairside)
  14. 14. 5. 13 Adhesive luting of the restoration requires conditioning the enamel and/or dentin and the ceramic surface. Photo: Frankenberger • Apply silane, let evaporate 3 – 5 minutes • Insertion with dual-cured composite-resin cement • “Total-etch technique” is suitable for luting • Apply glycerin gel at the margins prior to curing • Remove excess composite-resin cement prior to removing dental-dam • Check occlusal contact and adjust on the luted restoration • Polish the adjusted areas. The adhesive bonding process is described in detail in Chapter “Luting Techniques“, page 51. Trimming and polishing • Check, adjust, and re-check occlusion • Remove the composite-resin excess cement, use rotary finishing diamond instruments and finishing strips (40 µm, 25 µm) • Polish • Fluoridation of the enamel surface that was treated with etching gel. Final steps • Check for excess cement • Check the occlusion • Final polish • Fluoridation of the enamel surface • Schedule recall with the patient (dental prophylaxis). All-ceramic inlays, onlays, and posterior partial-coverage crowns
  15. 15. 5. 14 Procedure for restoring a cavity with a ceramic inlayAll-ceramic inlays, onlays, and posterior partial-coverage crowns Amalgam fillings to be replaced by ceramic inlays. Etching the cavity margins with phosphoric acid. Treatment step Helpful hints Instruments / materials Caries diagnostics Repeat after removal of Mirror, fiberoptic transillumination (FOTI), existing fillings bite-wing radiographs Shade selection Moist tooth, natural light, no Proprietary shade guide of the composite bright colors like lipstick system (or Vita Color Ring) Impression making for For indirect fabrication correct Tray, impression material provisional restorations provisionals if needed Marking occlusion Avoid placing preparation margins Occlusal papers and ribbons (12 µm) points in occlusal contact areas Placement of wedges Warning: do not injure gingival Wooden wedges papillae or damage adjacent teeth during preparation Preparation, caries Minimum cavity depth (inlay layer Carbide round bur, preparation diamonds excavation thickness at least 1.5 mm) (80 µm), finishing diamonds (40 µm) Cavity cleaning Disinfection H2O2 (3 %) or CHX (0.2 %) Treating the dentin lesion If dentin is exposed close to the Apply calcium hydroxide compound – (cp), when needed pulp (< 1 mm residual dentin aqueous Ca (OH)2 suspension thickness) (e.g., Calicur, Calxyl) Base Shallow cavities: no base; Glass-ionomer cement (capsule deep cavities: cover with base compounds, e.g., Ketac Bond). or partially block Apply in excess, prepare down when hard Finishing the cavity “Rounded” inner edges; no bevelled Finishing diamonds (25 µm), edges as the ceramic will break perhaps intra-Eva head (61 LA) and there; no thinly attenuating marginal Eva files (reciprocating) cavisshape, areas, Soflex disks occlusally if bevelshape: 25 µm or Sonicsys needed (F grit), marginal smoothing (mini: torpedo attachment) Elastic impression Try in mouth tray, block off distally, Already prepare tray (stops); taking with polyether occlusal stops, if needed block select based on situation model; elastic (Impregum) or large undercuts under pontics using impression tray or hydrocolloid stick polysiloxane: first fill alginate syringed under these to individualize; retraction cords, cord tray, then inject, block areas (fixed partial denture units), inserting instrument or Heidemann spatula, out fixed partial observe manufacturer’s curing elastic impression material dentures in same jaw time! (e.g., Impregum/Pentamix, Impregum syringe) Facebow, Where occlusal situation is Facebow set, Regisil PB occlusal record ambiguous or extensive restorations exist, e.g., serial inlays Elastic impression of Already possible previously Elastic impression tray alginate opposing jaw Construction and Isolate cavity, block cervical under- Esp. where periodontally diseased insertion of provisional cuts, air-bubble-free injection of dentition exists, total impression, restoration provisional material into total preferrably vacuum-drawn heat-treated impression using a syringe, observe polyvinyl; paraffin oil, Protemp II, manufacturer’s curing time! Check Provicol, milling cutter + laboratory occlusion, determine temporary’s handpiece, occlusal papers, layer thickness to check preparation paper holder depth, insert with eugenol-free cement
  16. 16. 5. Procedure for restoring a cavity with a ceramic inlay 15 Ceramic reconstruction of teeth 44 – 46. All photos: Kunzelmann Insertion of a ceramic inlay with removal of excesses. All-ceramic inlays, onlays, and posterior partial-coverage crowns Treatment step Helpful hints Instruments/materials Removal of provisional Do not damage cavity margins Claw forceps, scaler restoration Tooth cleaning Polishing paste (e.g., Zircate), polishing cup or brush Inlay try-in No occlusion check, just check fitting Dental floss, loupes; accuracy and approximal contacts if needed “softprobe” and fine diamond (perhaps with wedging) abrasive tips Dental-dam placement When using clamps, do not injure Dental-dam sheet – medium; frame, tooth or gingiva if needed clamps and forceps, Wedjets (Hygienic) (expensive), alternatively: rubber tabs Adhesively pretreat Etch ceramic inlays 60 s; dilute or HF (e.g., Vita Ceramics Etch), inlay (etch, silanize, neutralize HF before disposal; let silane silane solution (e.g., Monobond S), bond) solvent evaporate (5 min); do not cure bonding agent (see DBA), brush, dentin bonding agent (DBA); in many receptacle for solutions, diamond- cases laboratory will etch the ceramic coated tweezers Pretreat tooth (etch Strictly follow manufacturer’s Phosphoric acid and application syringe, enamel and / or enamel instructions; touch primer and dentin adhesive and bonding agent, and dentin, dentin adhesive monomers only with a brush, several brushes or applicators and bonding agent) enamel 30 s, dentin 15 s Mix and apply luting In deeper defects use only dual-curing Luting composite (e.g., Sonocem, composite composites; adapt luting composite to Variolink Ultra), spatula, block, ultrasound all cavity walls with a spatula insertion device Insert inlay Carefully press in inlay, if needed Diamond-coated tweezers, use ultrasound device to bring it into if needed ultrasound device with definitive position (for 3 to 5 s) with special attachment Remove excesses Very carefully check for excesses Dental floss, scaler, loupes approximally Apply glycerine gel Necessary if excesses are completely Airbloc, application syringe removed before curing Light curing At least 40 s from each side Polymerization lamp, perhaps protective eyewear Remove dental-dam Check to ensure no bits of dental-dam clamp forceps, if needed dental-dam remain scissors or dental floss, scaler Probe gingival sulcus Cured excesses of DBA often remain Scaler / curette otherwise overlooked in the sulcus, despite rubber-dam Occlusion check Also check latero- and mediotrusion If needed fine-grain diamond instrument Polishing Do not treat adhesive joint with Polish adhesive joint areas with abrasive polishing paste, otherwise alumina disks (Soflex), ceramic surfaces groove-like abrasions form if needed with diamond polishing paste or ceramic polisher Fluoridation Use clear fluoride varnish Elmex fluid or Fluorprotector Follow-up Check restoration again a few Mirror, probe, loupes days later; excesses are then easier to see
  17. 17. 6. 16 Porcelain laminate veneers, anterior ceramic partial- coverage crowns White spots on facial surfaces of 11, 12, 21, 22. Minimally invasive preparation with no wrapping of incisal edge. Veneers fabricated with Cerinate porcelain, adhesive material Visar-Seal and Ultra-Bond luting cement (Den-Mat) 15 years postop. Indication diastema closure. The patient viewed a diagnostic wax-up to accept treatment. Preparation minimally invasive, flattening of the facial surface with wrapping of incisal edge to reinforce the porcelain extension closing the diastema. No cervical chamfer. All photos: Strassler Defining terminology All-ceramic veneers and adhesively luted ceramic partial-coverage crowns are also referred to as ceramic facings, laminates, laminate veneers, anterior-tooth partial coverage crowns, and veneer shells. Based on an official statement by the DGZMK (GSDOM, German Society of Dentistry and Oral Medicine), a partial-coverage crown is a restoration in which, when in a defect-oriented preparation, the incisal edge and/or the interproximal surfaces are completely or partially included in the tooth preparation. Indications The porcelain laminate veneer is not a restoration limited only to the anterior dentition; it can also be applied to premolars and molars. Veneers and ceramic partial-coverage crowns may often make it possible to avoid a complete-coverage crown. The veneer is indicated for • Correcting tooth shape • Correcting tooth position and diastema closure • Restoration of fractured teeth • Shade corrections of discolored natural teeth which may be caused by fluorosis, endodontic staining or tetracycline staining • Repair of prosthetic elements with ceramic or composite veneers • Correcting static and dynamic occlusion, bite position changes (palatal canine veneers, occlusal surface veneers), occlusal shells, rebuilding occlusal surfaces. Materials and manufacturing To meet high esthetic demands, ceramic veneers are almost exclusively made of silicate ceramic (glass ceramic). Manufacturing procedures include: • Pressing (e.g., Empress and others) • Additive construction by layering of optimized glass ceramic for inlays and veneers (comparable to veneer ceramic) • Subtractive construction by milling feldspathic ceramic blanks (e.g., Vitablocs, ProCAD, EmpressCAD, Everest G-Blank, Procera Laminates).
  18. 18. 6. 17 Preparation design for all-ceramic partial-coverage crowns, which in the anterior region corresponds to a veneer preparation. Interproximally and palatally, all defects are Included in the preparation. Photo: Pröbster Feldspathic ceramic restorations after first firing. Defect-oriented preparation was performed. Photo: Pröbster The veneers with Cerinate porcelain, Visar-Seal adhesive resin and Ultra-Bond as luting cement, 20 years postop. Photo: Strassler Porcelain laminate veneers, anterior ceramic partial- coverage crowns Customization The following staining techniques are recommended: • External ceramic stains applied labially • Composite colorants (no ceramic stains) applied to the internal surface of the veneer; the shading effect depends on the layer thickness and the translucency of the ceramic • The layering technique, possibly combined with a base of pressable glass-ceramic (e.g., Empress) or milled feldspathic ceramic (e.g., Vitablocs). Esthetic appearance The quality of the veneer’s blending with the natural dentition depends on • The color stability of the veneer foundation • The precision of the marginal fit and placement • Shade variation. Getting ready First, the following must be discussed with the patient: • Shape and shade ideas, also characteristics such as custom stains and cracks • Performing excursive movements or mounted casts allow for analysis to make it possible to determine whether/to what extent shape modifications can be accomplished • Excessive contacts on the incisal edges may lead to delamination and fracture of the porcelain, especially if anterior the teeth are lengthened. The following can be used as aids: • Diagnostic wax-up • Diagnostic mock-up • Imaging (digital modifications of clinical photographs).
  19. 19. 6. 18 Porcelain laminate veneers, anterior ceramic partial- coverage crowns Inadequate anterior composite-resin restorations and incisal fracture of ceramic veneers on teeth 11,12, 21, 22 The following information should be documented and communicated to the dental techni- cian using the laboratory work authorization: • Shade selection • Shade details, e.g., by indicating light/dark boundaries, characteristics • Form of the face with smile lines, lips, tooth shape, occlusion, gingiva (with photos) • Shade selection in the lab, because the lighting there is the same as during the fabrication of the restoration. The dental technician may also determine the shade with the dentist and patient in the practice • Alternative: The dental technician creates custom ceramic samples (just for dentin shade) so that the dentist can select the shade with the patient and thus facilitate good coordination with the laboratory process. Preparation and preparation design Prior to the tooth preparation appointment, the following should be conducted: • Tooth cleaning 1 week before treatment (during this time, periodontal inflammation present can heal, remove all plaque/deposits) • Plan for tooth bleaching as a pretreatment, if necessary • Shade selection • Make a diagnostic wax-up and use it to fabricate preparation template/guide, provide this information to the dental technician if positional changes are planned • Make a silicon matrix to check preparation thickness • If necessary, carefully retract the gingiva with retraction cords to avoid injury. Note: Remove cords during preparation • Construct the provisional restoration. When making multiple ceramic veneers, attempt to work as symmetrically as possible. If required, replacement of existing direct restoration should be included in the preparation (defect-oriented adhesively luted partial-coverage crowns). The preparation finish-line must then overlap the existing direct restorations. To ensure conservative tooth reduction, employ only a finishing diamond instrument (25 – 40 µm): • The enamel layer should largely be conserved • Acid-etching provides for better retention than a coarse-grained diamond. Diastema and inadequate composite-resin restoration Ceramic veneers on teeth 11, 12, 21, 22 All photos: Hajto
  20. 20. 6. 19 Preparation of tooth 13 for a veneer. Etching with phosphoric acid. Insertion with excess of composite-resin cement. All photos: Kunzelmann Porcelain laminate veneers, anterior ceramic partial- coverage crowns To establish adequate tooth reduction and depth marking, the following must be examined and evaluated: • Age-dependent tooth color, existing discoloration • Keep in mind that with increasing age, the enamel becomes thinner due to erosion, abrasion, and attrition • Necessity of alignment correction as indicator of the thickness of the veneer • At least 0.7 mm thickness of ceramics is required in order to attain discernable shade correction • Carefully consider the balance between conserving tooth structure and achieving the required ceramic thickness to attain the desired esthetic effect • Prepare finish lines even if the ceramic is very thin, because it allows the dental technician to recognize preparation limit and is important for the definitive positioning of the veneer during insertion procedures. Required preparation depth into enamel is established by • Setting horizontal orientation grooves using groove cutter or round bur. Cervical, incisal, interproximal, palatal preparation technique: • Buccal enamel reduction • “Wrapping” the incisal edge, in case crown lengthening is necessary • Shaping of incisal overlay (minimum thickness 1.5 mm); if needed, “wrapping” the edge toward the palatal aspect of the tooth • Extend the preparation into the interproximal areas • Place the interproximal margins in the non-visible area • Use a cervical chamfer at the finish-line • Place the finish-line equigingivally and/or slightly supragingivally, depending on smile line of the lips • In color masking scenarios, a certain layer thickness is also necessary at the the finish-line • For diastema closure, prepare far enough palatally (convex shape) • Set visible preparation limits • Maintain minimal interocclusal distance.
  21. 21. 6. 20 Porcelain laminate veneers, anterior ceramic partial- coverage crowns Fig. 1: Function-correcting veneer: On the attrition sur- face of the mandibular canine, a small kidney-shaped cavity was prepared in the exposed dentin core in order to lute the incisal edge buildup (Empress) in the right position. Fig. 2: Correction of function and canine buildups with palatal veneers (Empress) on the canines – in situ since 1992. These veneers replaced the previously usual precious metal pinledges. Photos: Stachniss The Cerec 3D system makes the contralateral replica of a natural anterior tooth possible for constructing a same-shape veneer for the adjacent tooth. Veneers can also be used to correct the function of occlusal surfaces and to build up canines (see Figs 1 and 2). Tooth reduction dimensions: • Partial veneer (maxillary incisor), incisal third, mesial aspect, horizontal extension 4.0 mm, vertical extension 3.5 mm, depth of 0.7 mm, incisal reduction 1.0 mm • Partial veneer to reconstruct canine guidance, horizontal extension 4.0 mm, depth 0.7 mm, incisal reduction 1.0 mm • Partial veneer (mandibular incisor), incisal third, circular edge up, margin 3.0 mm apical to the incisal edge, depth 0.7 mm, incisal reduction 1.0 mm • Traditional veneer, conservation of interproximal contacts, margins as chamfer, margin 0.5 mm incisal to the CEJ. Labial reduction: cervical third 0.2 – 0.3 mm, middle third 0.5 mm, incisal third 0.5 – 0.7 mm • Complete veneer with deep wrap-around, with removal of interproximal contacts, margin 0.5 mm incisal to the CEJ. Incisal reduction 1.5 mm (tooth 41), 2.0 mm (teeth 11, 13). Elastomeric impression making • Place retraction cords • With intact interproximal contacts, insert matrix strips in the interproximal contacts (they are integrated in the impression, makes it easier to separate the teeth) • Gingival retraction • Use of polyether or addition silicone (vinylpolysiloxane), retraction cord remains in situ • If remaining tooth substance is thin, a reinforcement groove should be cut into the elastomeric impression after removal, in order to prevent breakage of the tooth in the master stone cast • If necessary, make a composite-resin stump. With chairside CAD / CAM procedures (e.g., Cerec), conventional impressions are not neces- sary. Instead, data are acquired intraorally with a triangulation camera to create a “digital cast.” The diagnostic mock-up can be copied three dimensionally and serve as a shape template for the ceramic veneer.
  22. 22. 6. 21 Paper-thin veneers of alumina ceramic by Procera. Photo: Nobel Biocare Diastematas, incisal edge fracture, and tooth-position anomalies are modified with ceramic veneers. Photos: Hillmann, Linne† Porcelain laminate veneers, anterior ceramic partial- coverage crowns Dentin protection and provisional restorations • Preferred option: adhesively pre-treat exposed dentin upon insertion. Alternative option: apply DBA (dentin bonding agent) prior to making a definitive impression, e.g., where hypersensitivity exists etc. • If esthetic demands are very high: insert a lab-manufactured provisional veneer • Otherwise: in situ with elastomeric impression or vacuum-formed tray (use sharp-relief tray) • The disadvantage of direct application of the provisional material is that trimming can damage and compromise the preparation finish-line from which an impression has already been made • Insertion: spot etching, adhesive, and low-viscosity flowable composite (e.g., Heliobond) • Remove excess prior to curing • Instruct the patient to minimize the function and load with the provisional restoration. Provisional restorations for partial-coverage crowns For partial-coverage crowns with classical retention, use eugenol-free provisional cement. Laboratory fabrication • When using rigid elastic impression materials, the danger of breaking off stone teeth exists upon removing the impression tray • If the transition from preparation border of veneer 1 to the contact point of the adjacent veneer 2 is too tight, the dentist should separate the teeth with matrices (Frasaco strips, metal matrices); otherwise a master cast cannot be constructed. Especially with CAD / CAM production, the preparation limit must be clearly discernable • The difference in resistance between pressable ceramics and millable ceramics (CAD / CAM) is not relevant, because the clinical longevity depends mainly on the adhesive technique • When hand-layering porcelain (stacked, fired technique) on a refractory die, the thickness of the veneer can be reduced to 0.4 mm, and using a platinum foil as a base, down to 0.2 mm • Thicker layers enable greater color control and modifications, thinner layers are more translucent • The thermal expansion of the refractory investment must match that of the veneer ceramic.
  23. 23. 6. 22 Porcelain laminate veneers, anterior ceramic partial- coverage crowns Perfect veneers after insertion. Photo: Baltzer Veneers made of pressable ceramic (Empress 1). Photo: Hillmann, Linne † • The layers consist of a) binder, b) dentin powder 1, c) corrective firing 1, d) corrective firing 2, e) final firing • Scheduling: plan 5 – 7 work days for the fabrication. Time requirement for a CAD / CAM veneer made chairside: 1 – 1.5 hours. Time requirements: • Cast fabrication: 0.5 days • Shade selection parallel to this • Laminating and firing – 4 to 6 units per day • Fitting and polishing: 0.5 day • Transport and time allowed for repeating steps. Insertion • Try-in and adjustment option (try-in before noon, insert in afternoon, adjustment and glazing in between) • Try-in: glycerine gel, shade evaluation,interproximal contacts and marginal fit evaluations. Ceramic pre-treatment: • Given several veneers, proceed symmetrically from the center • Etch veneer for 30 to 60 s with 5 % hydrofluoric acid (HF) (the laboratory will often etch the porcelain) • Apply silane, let the solvent evaporate for 5 min., blow dry • Apply resin adhesive bonding agent to the ceramic surface. Preparing the tooth for bonding: • Absolute moisture control and isolation with dental-dam • Protect adjacent teeth with matrices; this also facilitates removal of excess composite- resin cement. Shade assessment: The choice of shade of the luting composite-resin cement can influence or determine the resulting tooth color of the veneer. By using shaded try-in pastes (glycerin gel), different color alternatives can be tested in vivo.
  24. 24. 6. Insertion procedures: • Remove the provisional veneer and/or the provisional cement • Retouch the area of the spot etching (fine-grain diamond) • Use light- or dual-curing luting composite • Acid etch tooth, apply adhesive to the tooth • Handling the veneer with the diamond tweezers is more reliable than with the adhesive stick • Position the veneer with pressure but without diamond forceps (scratches ceramics) • Stabilize the veneer using a brush holder with Fermit on the facial surface on the veneer • Remove excess cement with probe (Heidemann) and dental floss • Check the marginal integrity • Light cure • Tooth cleaning (e. g., with Occlubrush). 23 Veneers have a high survival rate. Photo: Hirschfeld, Bellmann Preparations for veneers. Veneers of leucite-reinforced silicate pressed ceramic. Photos: Edelhoff Porcelain laminate veneers, anterior ceramic partial- coverage crowns
  25. 25. 7. 24 Monolithic, anatomically milled complete-coverage crown of silicate ceramic. Photo: KaVo / Ivoclar-Vivadent Crowns, fixed partial dentures, telescopic crowns, and implant- supported restorations Fixed partial denture framework of high-strength zirconia, in part implant-borne, during try-in. Photo: Tinschert Range of indications of all-ceramic materials in prosthodontics • Anterior crowns • Posterior crowns • Anterior fixed partial dentures • Posterior fixed partial dentures • Resin-bonded fixed partial dentures in the anterior area (Maryland fixed partial dentures) • Primary copings for telescopic restorations • Implant fixtures and abutments • Implant-supported crowns and fixed partial dentures. The foundation restoration Foundation restorations (post and cores, and core build-ups) must be placed in order to create simple structures. If irregular points and edges remain after caries excavation, they make it difficult to achieve adequate and accurate fit. The esthetic appearance is likewise influenced by irregular layer thicknesses in the restoration. Large variations in layer thickness hinder the uniform transmission of light within the ceramic. For these reasons, natural tooth- colored foundation restorations are essential, especially for the anterior dentition. Materials Further development in traditional veneering ceramics have led to a variety of modern ceramic materials, which differ considerably in their properties.These ceramic materials can be classi- fied into: • Silicate ceramics, such as Empress CAD, ProCAD, Cergo, Everest G-Blank, Vitablocs – lithium disilicate ceramics, such as Empress 2, e.max Press, e.max CAD • Glass-infiltrated oxide ceramics such as In-Ceram Spinell, Alumina, Zirconia • Densely sintered oxide ceramics, e.g., Procera crown copings (Al2O3 or ZrO2) and Procera fixed partial denture frameworks (ZrO2) • Partially sintered zirconia ceramics, Y2O3 partially stabilized, polycrystalline zirconia for crown copings and fixed partial denture frameworks which will be then veneered, e.g., In-Ceram AL, Lava Frame, Cercon base, In-Ceram YZ, inCoris AL/ZI, Everest ZS-Blank, e.max ZirCAD • Densely sintered HIP zirconia for crown copings and fixed partial denture frameworks for veneering, such as Everest ZH-Blank, DC-Zirkon. All-ceramic fixed partial denture for Straumann implants with full abutments. It was possible to create torque protection during milling. Photo: Pospiech
  26. 26. 7. 25 Fundamental distinctions: Silicate ceramics fulfill high esthetic demands – high-strength oxide ceramics are suitable for frameworks (crowns, fixed partial dentures). All-ceramic systems Source: Pospiech Silicate ceramics Glass-rich silicate matrix Multiphase structure Crystalline phases, glass phases Relatively low sintering temperatures < 1000 °C Feldspathic ceramics Ground feld- spathic glass (powder), conventional technical proces- sing. Example: usually veneer ceramics Vitablocs Jacket crowns Densely sintered Direct shaping of the frameworks System: Procera HIP CAD/CAM milling of a high-strength material Systems: DentoCAD digiDent Etkon Everest Neo Cynovad Precident DCS Presintered blanks CAD/CAM milling with subsequent final sintering Systems: Cercon Everest Etkon in-Lab LAVA Zeno Tec e.max ZirCAD Glass ceramics Starting point glass which undergoes a crystallization process. Example: Empress Empress 2 e.max Press e.max CAD Glass- infiltrated Partially sintered alumina powder (white blanks), then glass infitration (30 vol %), material of the In-Ceram system ppos Crowns, fixed partial dentures, telescopic crowns, and implant-supported restorations Oxide ceramics Characterization: monophase and single-component metal-oxides (> 90%) polycrystalline ceramics high sintering temperatures >1400°C Glass ceramics Starting point glass which undergoes a crystallization process. Example: Empress Empress 2 e.max Press e.max CAD Glass- infiltrated Partially sintered alumina powder (white blanks), then glass infitration (30 vol %), material of the In-Ceram system
  27. 27. 7.1 26 Incorrect chamfer finish-line. “J-lipping” or steps are contraindicated. Correct chamfer finish-line. A chamfer with a 6-degree axial convergence is ideal for the circular crown margin. Anterior crowns Shoulder finish-line: the rounded shoulder is particularly suitable for the telescopic crown technique with all-ceramic primary copings. The occlusal contact points also determine the level of stress development in the restoration. Fig.: Pospiech. Source: Vollkeramik- Kompendium, 3M EspeOrigin of tensile stress Origin of compressive stress Indications For extensive defects with loss of enamel and dentin. The choice of ceramic is based on the loading of the crown (remaining dentition, dynamic occlusion) and the optical properties of the material. However, the preparation design, available space, at the axial walls and crown margin, and the desired luting technique also influence the material selection. In selecting the material, the following parameters are also considered: • The type of foundation restoration • Indications and materials for post and core systems • Quality of the dentin (opacity, translucence, color) • Shade selection: especially for anterior crowns, it is recommended that the dental technician select the shade. Preparation design The general principles of metal-ceramic crown preparation are also valid for all-ceramic crowns. The largest circumference of the tooth is at the gingival preparation limit. It must be anatomically prepared, i. e., the shape and position of the tooth must be considered. Occlusal surfaces and facets must be angled according to their original natural form. Thus, reconstruction of the original anatomy with a uniform ceramic thickness is feasible without overcontouring.The respective antagonistic surfaces should contact each other with occlusal forces directed axially and thus achieve the highest possible compressive load. This mini- mizes the prospect of developing tensile and flexural stresses which are detrimental for ceramics. Feather-edge or knife-edge finish-lines are absolutely contraindicated. The knife-edge finish-line is unsuitable for all-ceramic complete-coverage crowns, because a correct, anatomi- cal contour can never be constructed. It is also unsuitable for all-ceramics because it can initiate ten- sile stresses and fractures. All Figs.: VITA Zahnfabrik
  28. 28. 7.1 The edges and transitions must at least match the radius of the abrasive stones in the milling machine. Fig.: Pospiech. Source: Vollkeramik-Kompendium, 3M Espe 27 Thickness of framework and veneering ceramics for lithium disilicate ceramic crowns. min. 1.5mm Thickness of framework and veneering ceramics for oxide ceramic crowns (Al2O3, ZrO2). min. 0.7 to max. 2.0mm min. 0.5mmmin. 0.8mm Anterior crowns Material thickness for free silicate ceramic crowns. max. 0,7– 2.0mm min. 1.0mm Depending on the material selected, an even rounded shoulder, or a deep chamfer should be prepared. A shoulder with rounded internal line-angles is preferable: • Silicate ceramics such as feldspathic and glass ceramics. A chamfer can also be used for ceramics with increased flexural strength (over 350 MPa) such as: • Lithium-disilicate ceramics • Glass-infiltrated oxide ceramics • Polycrystalline oxide ceramics. The following framework thicknesses in the marginal area of anterior crowns must be observed: • For silicate and lithium-disilicate ceramics, 0.8 to 1.0 mm • For oxide-ceramics, zirconia ceramics 0.5 mm. The thickness of the veneering porcelain at the occlusal/incisal aspect: • Maximum 1.5 to 2.0 mm, strive for minimal layer thicknesses. Finish line placement for all-ceramic crowns with circumferential chamfer or circumferentially rounded shoulder: • Whenever possible, place the finish-line supra- or equigingivally • A convergence angle of 4 – 6° is indicated. Negative example:
  29. 29. 7.1 28 Anterior crowns Horizontal grooves with depth defined by ball diamond diameter. A silicon key to evaluate tooth reduction. Internal gingivectomy with a zirconium dioxide tip. Photos: Pospiech Process-dependent details should be discussed with the dental technician. The thickness of the veneering ceramic should not exceed the given maximum, because of the prospective risk of fracture and delamination. The angle of convergence of the axial walls should be 4 to 6 degrees to allow for adequate mechanical retention and resistance. The crowns must be seated definitively and firmly on the abutment tooth without rotating. A merely linear fit at the crown margin and filling-in the gaps with the cement is unacceptable. For short clinical crowns, interproximal grooves 1 mm wide and 0.5 mm deep must be made in order to ensure firm seating, resistance and retention. Orientation during tooth reduction A silicon matrix / key made of the dental arch prior to preparation is cut open horizontally and vertically.The matrix facilitates the evaluation of the thickness of tooth structure already removed (tooth reduction) in comparison to the initial condition. Impression making technique Fundamentally, every type of impression making technique is acceptable if the dentist has had success with it. For optimal results, addition silicone (vinylpolysilane) or polyether impression materials with the heavy body/light body technique are ideal, because elastomeric impressions can be made without pressure and the materials are hydrophilic. The chairside CAD/CAM system (Cerec) has eliminated conventional impression procedures for crowns.A digital video impression (data) of the preparation is acquired with an intra-oral camera. Morphological data for the planned crown can be obtained from copies of an existing shape, from various tooth databanks, diagnostic wax-ups, and by mirroring a contralateral tooth. Tissue management A perfect impression can only be made of an area which is visible and is kept dry. Finish-lines placed deep in a gingival sulcus or at the level of the alveolar crest jeopardize the prospects for a successful restoration. Therefore: expose the preparation finish-line and ensure adequate moisture control and isolation. Retraction cords are non-invasive and well suited for displacing subgingival finish-lines. Application of epinephrine, aluminum chloride etc. has a local hemostatic effect. For placing the cords, the double cord technique has proven effective: place a size-1 cord, cut to fit. Place a size-2 cord. Then place a cotton roll, apply suction, compress cords. Make the impression after 10 minutes. If the sulcus is shallow, remove the retraction cords prior to making the impression.
  30. 30. 7.1 29 The wall thickness of zirconia (Lava) anterior crown copings can be reduced down to 0.5 mm. This conserves tooth structure and/or allows room for multi-layered veneers. Photo: Edelhoff Gingivectomy Excess or diseased tissue is removed with a scalpel blade, electrosurgery or laser. A rotating zirconia tip (turbine, max. rpm) without water cooling removes the gingival tissue via friction- generated heat without pressure. Gingivectomy to achieve an esthetic result is sometimes desired. Provisional restorations The provisional restoration can be constructed as for all other complete-coverage restora- tions. For difficult situations or high esthetic demands during the interim, a wax-up can be con- structed on an anatomical planning cast. Marginal seams can be slightly reinforced, in order to have some substance for trimming the provisional restoration.The cast is duplicated using a vacuum-formed polyethylene sheet (1.0 – 1.5 mm thick). Because the polyethylene sheet is transparent, photopolymerizing composite-resin can also be used as the provisional material.The sheet should be slowly filled from the occlusal aspect outwards in order to avoid bubbles. In the elastic phase, the sheet is removed, excess material is trimmed with scissors, and the sheet is replaced in position. After complete curing, trim and polish the provisional restoration. It is recommended that the provisional restoration be constructed prior to making the defin- itive impression, because at that point it is still possible to determine whether sufficient tooth structure has been removed. The provisional restoration can serve as an evaluation guide for the amount of tooth reduction. Provisional crowns are inserted with eugenol-free provisional luting cement. No provisional restoration is needed if the anterior crown is made with a CAD/CAM sys- tem in the practice and inserted during the same appointment. Criteria for framework-based restorations The procedures involved in framework fabrication and the time required depend on the material selected and the fabrication system (pressing, slipping, CAD / CAM). The framework design should allow for the application of veneering ceramic with a uniform thickness. To avoid the risk of fracturing the veneering porcelain, it should not exceed a maximum thickness of 2.0 mm, incisally or occlusally. Anterior crowns
  31. 31. 7.1 30 Anterior crowns Preoperative condition for anterior crowns. Photo: Hirschfeld Anterior crowns with ZrO2 framework, veneered on the cast. Photo: Hirschfeld, Bellmann A foundation restoration can facilitate the fabrication of a restoration with an optimal thickness for both the coping and the veneering ceramics. The ceramic restoration should only be finished (contouring etc. with fine-grained diamond abra- sives in an air turbine or angled handpiece) under water cooling. This also applies to chairside adjustments during framework try-in. In some cases it may be necessary to adjust the opposing teeth. If this is done, a new opposing impression and cast must be provided to the dental lab. Sharp-edged instruments, instruments with a low surface area, diamond separating disks – all of these are contraindicated for corrective reshaping.The largest instrument that can accomplish the task for a given adjustment is recommended to avoid spot overheating and notching. It is advisable not to use a separating disk to open the gingival embrasures of fixed partial den- tures at the connectors. After adjustments have been made, the surface of veneering ceramics should be improved by performing final firing again or careful polishing, for example, with diamond polishing pastes with a buff wheel. Try-in procedures The crown framework should be stable on final seating without rotation on the abutment tooth. To test the accuracy of fit, a try-in with a dark, low-viscosity silicon impression material or fit checker is recommended. Depending on the extent of restoration or esthetic demands, a bisque bake try-in is recom- mended. After the try-in, surface characterization and final glaze or final firing is conducted. Inter- dental / interproximal areas should not be shaped or polished after this procedure is complete. Chairside adjustment should only be done with a super fine-grained diamond (yellow or white ring). Subsequently, diamond-impregnated silicon polishing tools are used for polishing. Insertion procedures For conventional metal-ceramic crowns and fixed partial dentures, it is often recommended that the restoration be “test worn“ prior to definitive insertion. In terms of strength, this would be conceivable for oxide-ceramic frameworks. However, the manufacturers of all-ceramic systems explicitly warn against such a procedure, since removing the restoration, especially single crowns, bears with it a high risk of damaging or fracturing the restoration. If, in cases of esthetic and functional doubt (e. g., in the anterior region or extensive quadrant restorations), temporary trial cementation of the crown cannot be avoided, this can only be done with oxide-ceramic frameworks (see manufacturer’s specifications). The patient must be instructed that the crown is not definitively cemented and therefore must not be subjected to maximum loading during this short phase – up to a week. For trial cementation, the same eugenol-free provisional cement can be used as for the provisional restorations. To facilitate removal, some vaseline can be added to the mix. If this is done, the tooth preparation must be thoroughly cleaned to remove any residual Vaseline before definitive cementation.
  32. 32. 7.1 The choice of luting materials for definitive insertion depends on the ceramic material selected. In general: • Silicate ceramics are bonded with composite-resin cements. • All-ceramic restorations made of lithium-disilicate and oxide ceramics may also be conventionally cemented (glass-ionomer cement, resin-modified glass ionomer cement, zinc-phosphate cement). The greater the remaining enamel proportion, the more advantageous is adhesive resin luting. The literature often reports a value of ca. 350 MPa flexural strength as the lower limit for con- ventional luting. This value is not yet evidence-based and serves only as an approximate guide. For more details on luting materials and adhesive mechanisms, see the chapter on luting techniques, page 51. 31 Anterior crowns with Lava manufactured frameworks in situ. Photo: Hirschfeld, Bellmann Anterior crowns
  33. 33. 7.2 32 Molar crowns of In-Ceram Alumina veneered. Photo: VITA Zahnfabrik, Huiss Posterior crowns Ceramic Material properties: (E-modulus, KIC value (fracture toughness)) Time “Corrosion” Luting Type of cement Modulus of elasticity Polymerization shrinkage Polymerization mode Water sorption Workability Material processing Dental technician: Accuracy of fit Surface quality Wall thickness Dentist Tooth substance Dentin age Dentin depth E-modulus Conditioning Bonding Adhesive procedures Wetting Preparation design Prep. angle Prep. finish line Loading Type of force distribution Direction Duration Occlusal relationships Crown strength The strength is influenced by the type of preparation design, material selection, and bonding to the remaining tooth. Fig.: Pospiech. Source: Vollkeramik-Kompendium, 3M Espe Indications For extensive defects with loss of enamel and dentin. Materials All categories of materials are approved for single crowns; silicate-ceramics and leucite- reinforced pressed ceramics (Empress) must be adhesively bonded. Infiltrated or densely sintered alumina and zirconia ceramics as well as disilicate ceramic can be used for crown copings for molars and can be conventionally or adhesively luted. When in doubt, higher material strength should take preference over esthetic demands. Factors affecting strength The fracture resistance of crowns is based on several factors. The material selection and long-term stability of the crown is influenced by the mechanical properties of the ceramic and the masticatory loads (remaining dentition, dynamic occlusion), and is dependent on both the abutment preparation and the condition of the foundation restoration (core buid- up or post and core).The material is selected according to the discoloration of the abutment, dentin quality (opacity, translucency), and the space available, while taking the planned luting technique into consideration. Luting Type of cement Modulus of elasticity Polymerization shrinkage Polymerization mode Water sorption Workability
  34. 34. 7.2 33 Framework made of zirconia ceramic can be colored like dentin. Photo: VITA Zahnfabrik Posterior crowns with framework of press-sintered alumina oxide ceramic in veneered condition. Photo: Procera Shade selection Select prior to initiating tooth preparation. It is recommended to let the dental technician who is making the restoration also select the shade. For particularly high esthetic demands, the dental technician uses custom shade samples which simulate the color of the dentin core. This is especially helpful with very thin, trans- lucent restorations. Preparation design Depending on the material selected, an even rounded shoulder, or chamfer finish-line should be performed. A butt joint preparation with a rounded internal line-angle should be preferred for • Silicates like feldspathic and glass ceramic. For ceramics with higher flexural strength (over 350 MPa), a chamfer preparation can also be selected: • Lithium-disilicate ceramics • Glass-infiltrated oxide ceramics • Polycrystalline oxide ceramics. The following minimum ceramic thicknesses must be maintained in the marginal areas of posterior crowns: • Silicate ceramic, lithium disilicate ceramic 0.8 –1.5 mm • Oxide ceramic, zirconia ceramic 0.5 mm. Occlusal layer thickness: • Max. 1.5 – 2.0 mm, strive for minimum layer thickness. At least 2 mm under the cusps of framework-free silicate crowns. The margins of an all-ceramic crown with circumferential chamfer or circumferentially rounded shoulder: • Whenever possible, place margin supra- or equigingivally. Circumferential chamfers or butt joint with rounded internal line-angles are recommended as preparation finish-lines. A total angle of convergence of 4° to 6° is indicated. Posterior crowns
  35. 35. 7.2 Posterior crowns 34 Fig. 2: Minimum preparation depth for crowns of oxide ceramic (Al2O3, ZrO2) copings Preparation depth: Crown margin at least 0.5 mm; buccal 0.8 mm occlusal 1.5 – 2.0 mm Fig. 3: Wall and layer thicknesses for crown copings of silicate ceramic Preparation depth: Crown margin at least 0.8 mm; buccal at least 1.7 mm; crown coping wall thickness 1.0 – 1.2 mm; veneering ceramics 0.7 – 2.0 mm Veneering ceramics min. 0.7 mm max. 2.0 mm Crown coping min. 0.8 – 1.2 mm min. 0.8mm min. 1.5mm 2mm 0.8mm 0.5mm min. 1.5mm min. 2 mm A total angle of convergence 4–6º 1.0 – 1.5 mm 0.8 mm The various strengths of framework / coping ceramics influence the minimal preparation depth and the wall thickness of the crown coping. High-strength ZrO2 ceramic copings require thinner walls than copings made of silicate-ceramics. The following points apply to minimal wall thicknesses and preparation rules: see Figs 1 to 5. A reduction of the veneer layer thickness can be used for wall reinforcement of the crown coping, especially with frameworks of Al2O3 or lithium-disilicate ceramic. Process-dependent details should be discussed with the dental technician. The thickness of the veneering ceramic should not exceed the given maximum, because the risk of fracture and delamination of the veneering ceramics would otherwise arise. Tissue management, gingivectomy The same considerations apply as for anterior crowns (page 28). Impression making technique Making impressions for all-ceramic restorations requires methods which are no different from the ones used for other types of restorations. When working with chairside CAD / CAM (Cerec), impression data are acquired with an intra-oral camera. Morphological data for the planned crown can be obtained from copies of the existing occlusal surface, from various tooth databanks, diagnostic wax-ups, and by mirroring the contralateral tooth. Fig. 1: Minimum preparation depth for framework- free crowns with silicate-ceramic copings Preparation depth: Crown margin at least 0.8 mm; buccal 1.0 – 1.5 mm; occlusal 1.5 – 2.0 mm; a total angle of convergence 4 – 6°
  36. 36. 7.2 35 Fig. 5: Basic principles of framework design for crown copings The framework of Al2O3 or ZrO2 ceramic must support the veneering ceramics. Where framework support is lacking, e.g., under cusps and marginal ridges, the danger of stresses under masticatory loading arises. The crown coping may not possess any sharp transitions or edges. The thickness of the veneering ceramics must not exceed 2.0 mm. Veneering ceramics min. 0.7 mm max. 2.0 mm No sharp transitions and edges permited Provisional restorations The same steps are taken as for anterior crowns (page 29). No provisional restorations are required for chairside CAD / CAM crowns. Framework manufacture The working steps depend on the selected ceramic material and the fabrication process as related to different systems.The same considerations are valid as described for anterior crowns (page 29). Try-in procedures The same considerations are valid as described for anterior crowns (page 30). Depending on the restoration extent and / or esthetic demand, a bisque bake try-in may be recommended. Insertion procedures Insertion follows the same rules as described for anterior crowns (page 30). Fig. 4: Wall and layer thickness for the anatomically reduced crown of ZrO2 ceramic veneered Preparation depth: Crown margin at least 0.5 mm; buccal 0.5 – 1.2 mm; crown coping wall thickness 0.5 mm; veneer 0.7 – 2.0 mm Lacking framework support ZrO2- Crown coping min. 0.5 mm Veneering ceramics max. 2 mm Posterior crowns
  37. 37. 7.3 36 Frameworks for a 3- and 4-unit anterior fixed partial denture. Even on tooth 23 with the pronounced recession, the preparation ends at the cementoenamel junction. Photos: Pospiech All-ceramic fixed partial dentures Range of indications: • Anterior fixed partial dentures • Posterior fixed partial dentures. 7.3.1 Anterior fixed partial dentures Indications • Restoring edentulous spaces • Cantilever all-ceramic fixed partial dentures are indicated for replacing a maxillary lateral incisor or mandibular incisors. Limitations No more than two pontics included in one fixed partial denture. Exception: if the span length is small, up to 4 pontics are possible as in the mandibular anterior region. Connector design In every case, the vertical height of the connector is to be given more volume than the hori- zontal width. This increases the durability of the connector. The connector of silicate-ceramic, lithium-disilicate ceramic framework should be designed more carefully than one of oxide ceramics. The space available for the connector can be easily determined using a periodontal probe. Current CAD / CAM systems display the connector cross-sections and warn the user if the construction has less than the minimum allowable cross-sectional area. Factors affecting strength The fracture resistance of fixed partial dentures is based on several factors. The choice of materials and the longevity of the restoration are influenced by the occlusal forces (remaining dentition, dynamic occlusion) and dependent on the abutment preparation and the condition of the foundation restoration. In addition, materials are selected with reference to the dis- coloration of the abutment tooth, the dentin quality (opacity, translucency), and inter and intra occlusal space available. While selecting the material of choice, the desired luting tech- nique is taken into consideration, and careful thought is given to the material’s mechanical properties.
  38. 38. 7.3.1 37 Anterior fixed partial denture of lithium-disilicate (Empress 2) and ovate pontics. A lithium-disilicate fixed partial denture, 4 years in situ. Photos: Edelhoff Anterior fixed partial denturesMaterials for anterior fixed partial dentures • Lithium-disilicate ceramics and infiltrated ceramics are indicated only for 3-unit fixed partial dentures • Lithium-disilicate ceramic are indicated for 3 units up to the 2nd premolar – such as e.max Press, e.max CAD – luted adhesively or conventionally • Infiltrated-oxide ceramics are indicated for 3-unit fixed partial denture framework – as in In-Ceram Alumina, Zirconia, and densely sintered alumina ceramic such as In-Ceram AL – luted adhesively or conventionally • Sintered zirconia ceramic as multi-unit fixed partial denture framework – such as Sirona inCoris AL/ZI, Procera Zirconia, Cercon Smart, Lava Frame, Everest ZS-Blank and ZH-Blank, In-Ceram YZ, e.max ZirCAD, DC-Zirkon – luted adhesively or conventionally • Removable telescopic fixed partial dentures: zirconia for primary copings and crown frameworks • Recommendation: When in doubt, material strength should take preference over esthetic demands. Shade selection Select prior to preparation. It is recommended to let the dental technician who is making the restoration also select the shade. Preparation design For the preparation of anterior fixed partial denture abutments, the same recommendations apply as for anterior crowns (see page 26): • Framework of lithium-disilicate ceramics Reduction at crown margin at least 0.8 mm Buccal reduction 1.0 – 1.5 mm Incisal reduction 1.5 – 2.0 mm • Framework of oxide ceramics (Al2O3, ZrO2) Reduction on crown margin at least 0.5 mm Buccal reduction 0.7 – 1.2 mm Incisal reduction 0.7 – 2.0 mm • Horizontal angle > 5° for CAD / CAM scanner • Crown margin: chamfer or rounded shoulder • Finish-line placement supragingivally 0.5 mm or coronaly, to protect gingiva • Rounded line angles, no sharp edges, avoid undercuts • Otherwise follow the same preparation concepts as for anterior crowns.
  39. 39. 7.3.1 38 Anterior fixed partial dentures Pre-oprative: Restoration with a zirconia based fixed partial denture and a zirconia based crown is planned. The mandibular first molar is prepared with a 360-degree rounded shoulder finish line. All photos: Raigrodski Impression technique The impression-making technique for all-ceramic anterior fixed partial dentures does not dif- fer from that of other types of restorations. Provisional restorations The same procedures are performed as for anterior crowns (page 29). Framework fabrication for anterior fixed partial dentures The procedures depend on the ceramic material selected and the manufacturing system. The connector surface areas as related to fixed partial denture units must not be less than: • 12 mm2 with lithium-disilicate ceramics • 10 – 12 mm2 with infiltrated-oxide ceramics • 9 mm2 with sintered alumina and zirconia ceramics. A framework try-in is recommended to evaluate clinical fit prior to veneering to full contours. For the minimal wall thicknesses of fixed partial denture retainers, use the values given on page 33 – 35. The thickness of the veneering ceramic should be uniform and must not exceed 2.0 mm. Try-in procedures The same considerations hold as described for anterior crowns (page 30). Depending on the extent of the restoration or esthetic demands, a bisque bake try-in is recommended. Insertion procedures Insertion procedures follows the same considerations as described for anterior crowns (page 30).
  40. 40. 7.3.2 39 The zirconia coping for the mandibular first molar crown. Note the excellent marginal fit. Occlusal view of the fixed partial denture and crown which have been in situ for over 4 years. All photos: Raigrodski It is imperative to evalute the framework clinically prior to veneering to full contours. Indications • Restoring tooth-bordered edentulous spaces in the posterior segments • Cantilever fixed partial dentures are suitable for replacing a premolar. Limitations No more than two pontics should be included in one restoration. Connector design In every case, the vertical extension of the connector is to be given more volume than the horizontal. This increases the strength of the connector. The connector of a silicate ceramic framework should be designed more carefully than one of oxide ceramic (16 mm2). As with anterior fixed partial dentures, the space available for the connector can be easily determined using a periodontal probe. Factors affecting strength The choice of material depends on various factors. Due to the high occlusal force in the posterior region, the flexural strength of the framework ceramic should exceed 350 MPa (oxide ceramic). Materials for posterior fixed partial dentures • Lithium-disilicate ceramics are only approved for fixed partial dentures up to the 2nd premolar, and are not suitable for fixed partial dentures in the molar region (Empress 2, e.max Press) • Infiltrated oxide ceramics are only approved for 3-unit fixed partial dentures, e.g., In-Ceram Zirconia – adhesively or conventionally luted • Sintered zirconia ceramic as multi-unit fixed partial denture framework up to 45 mm anatomic width – such as Sirona inCoris AL / ZI, Procera Zirconia, Cercon Smart, Lava Frame, In-Ceram YZ, Everest ZS-Blank and ZH-Blank, e.max ZirCAD, DC-Zirkon – adhesively or conventionally luted • Removable telescopic fixed partial dentures: zirconia and alumina are suitable for primary copings (secondary copings are fabricated using the galvanoceramic technique) and crown copings. Posterior fixed partial dentures
  41. 41. 7.3.2 40 Posterior fixed partial dentures Veneer min. 0.7mm max. 2.0mm Fig. 2: Wall and layer thicknesses for crown copings of lithium-disilicate ceramic Crown coping min. 0.8–1.5mm min. 0.8mm Veneer min. 0.7mm to max. 2.0mm Fig. 1: Minimum preparation depth for crowns made of oxide ceramics (Al2O3, ZrO2) min. 1.5mm 2mm 0.8mm 0.5mm Fig. 3: Wall and layer thicknesses for the anatomically reduced crown of Al2O3 and ZrO2 ceramic Al2O3, ZrO2- Crown coping min. 0.5mm Shade selection Select prior to initiating tooth preparation. It is recommended that the dental technician who is making the restoration also select the shade. Preparation design for posterior fixed partial denture abutments Depending on the material selected, a rounded shoulder, or a chamfer finish-line should be performed. For frameworks made of lithium-disilicate ceramic, a butt joint finish-line or a rounded shoulder should be preferably done.All sharp edges should be eliminated and inter- nal line angles rounded. A total convergence angle of 4 – 6° is indicated. The following minimum ceramic layer thicknesses should be maintained in marginal areas of fixed partial denture abutments (Figs 1 to 3): • Lithium-disilicate ceramic, min. 0.8 – 1.5 mm • Oxide ceramics, zirconia ceramic, min. 0.5 mm Occlusal thickness of the veneering ceramics: • Max. 1.5 – 2.0 mm, strive for minimum layer thickness. A minimum layer thickness of 2 mm under cusps of framework-free silicate ceramic crowns. Finish line placement with circumferential chamfer or circumferentially rounded shoulder: • Supra- or equigingivally whenever possible. The following points apply to minimum wall thicknesses and preparation rules: Minimum preparation depth for abutment teeth restored with frameworks of oxide ceramic (Al2O3, ZrO2). • Preparation depth: Crown margin at least 0.5 mm Axial reduction 1.0 – 1.2 mm depending on expected load for zirconia ceramics 1.2 – 1.5 mm for infiltrated oxide ceramics Occlusal reduction 1.5 – 2.0 mm • Abutment total angle of convergence 4 – 6° to allow for adequate scanning
  42. 42. 7.3.2 41 4-unit fixed partial denture with ZrO2 framework (Lava), in situ for 4 years. Photos: Groten 4-unit fixed partial denture with zirconia ceramic framework, veneered, with well-formed connectors. Posterior fixed partial dentures• Crown margin: chamfer or rounded shoulder (knife edge or feather edge are contraindicated) • The finish-line placement 0.5 mm supragingivally or higher, to protect the gingiva • Rounded line angles, no sharp edges, avoid undercuts. A reduction of the veneer thickness can be used for reinforcing the abutment coping. Process-dependent details should be discussed with the dental technician. The thickness of the veneer ceramic should not exceed the given maximum, because the risk of fracture and delamination of the veneering ceramics. Impression technique The impression-making technique for all-ceramic fixed partial dentures do not differ from that for other types of restorations. Provisional restorations The same procedures hold here as for posterior crowns (page 29). Framework fabrication for posterior all-ceramic fixed partial dentures The procedures depend on the ceramic material selected and the manufacturing system. The connector surface area as related to the fixed partial denture units must not be less than: • 16 mm2 for lithium-disilicate ceramics (only premolars) • 12 mm2 for infiltrated oxide ceramics • 9 mm2 for zirconia ceramics. The minimum wall thicknesses of the retainers are: • Lithium-disilicate ceramics 0.8 mm • Infiltrated oxide ceramics 0.5 mm • Sintered alumina and zirconia ceramic 0.5 mm • The minimum framework wall thickness of 4-unit fixed partial dentures of sintered alumina, zirconia: with 2 pontics at least 0.7 mm, in cantilever fixed partial dentures at least 0.7 mm • Framework try-in is recommended prior to the application of the veneering porcelain Fixed partial denture framework for 4-unit fixed partial dentures of ZrO2 (Lava).
  43. 43. 7.3.2 Posterior fixed partial dentures 42 Fixed partial denture units require sufficient connector surfaces in vertical, oval form, since the tensile and flexural stresses concentrate here. Fig.: Pospiech ZrO2 fixed partial denture framework (Lava) for narrowed gap around tooth 46. Teeth 45 and 47 with chamfer, connector cross-section 12 mm. Photo: Lauer, Bauer 3-unit fixed partial denture of leucite-reinforced silicate ceramic, a model of esthetics. Photo: Ivoclar Vivadent, Brix 3-unit fixed partial denture of In-Ceram Zirconia. Glass-infiltrated oxide ceramic is suitable for fixed partial dentures of up to 3 units. Photo: VITA Zahnfabrik • The thickness of the veneering ceramic should be uniform and not exceed 2.0 mm. Otherwise, the same considerations apply as described for anterior fixed partial dentures (page 38). Try-in procedures The same considerations apply as described for anterior fixed partial dentures (page 38). Depending on the extent of restoration or the esthetic demands, a bisque bake try-in is recommended. Insertion procedures Insertion is performed according to the same rules as described for anterior crowns (page 30). Adjustments As a rule adjustments must be made under water cooling, in order to prevent partial over- heating. Overheating can jeopardize the longevity of the restoration. Special diamond adjustment instruments are recommended for zirconia.
  44. 44. 7.4 43 Primary copings of zirconia ceramic combined with galvanically fabricated secondary coping. Cold welding as for metal telescopic crowns is thus avoided. Galvano copings as secondary structure for telescopes. Photos: KaVo, Freitag All-ceramics for telescopic crowns Indications Includes all indications which are valid for the classical telescopic technique. Materials for primary and secondary copings • Primary copings of polycrystalline oxide ceramics (alumina or zirconia ceramic, partially sintered or lithium-disilicate ceramic hot pressed) • Secondary coping of galvanogold. Shade selection Usually, the oxide ceramic blanks are white opaque. However, some high-strength zirconia ceramics can be shaded (e. g., Lava Frame, In-Ceram YZ, inCoris ZI); this enables adaptation of the crown’s and / or fixed partial denture’s color at the ceramic soft-tissue interface. Space related prerequisites Sufficient space must be provided for the restorative materials, because 2 copings will be placed on one abutment tooth (primary ceramic coping, and a secondary glavanogold coping). Substance removal on abutment teeth will be relatively extensive. • Crowns must be veneered in visible areas. • Optimal path of insertion must be created. Preparation design • Preparation design is the same as for the conventional telescopic technique • For the primary coping, a clear rounded shoulder or chamfer must be made • The secondary, metal coping should end 1 – 2 mm incisal to the crown margin, to allow light transmission at the soft-tissue interface • Space requirements: primary coping 0.4 – 0.5 mm; galvanogold coping 0.1 – 0.2 mm; tertiary structure 0.3 mm; veneering porcelain > 0.8 mm = ca. 1.7 mm total • Preparation finish-line: chamfer or rounded shoulder • Total angle of convergence 4 – 6°. Impression technique The impression-making technique for primary copings does not essentially differ from that for other types of restorations. • Manufacture of a duplicating cast (composite-resin) for the fixed partial denture framework.
  45. 45. 7.4 44 All-ceramics for telescopic crowns Cerec-manufactured primary copings of ZrO2 and the completed overlay prosthesis with galvanogold copings, bonded in the mouth with the cast tertiary structure, are ready for cementing. Photo: Wiedhahn Provisional restorations The same procedures are employed here as for anterior crowns (page 29). After inserting the primary copings, a second provisional restoration is fabricated. Telescopic crowns fabrication procedures • Sectioned master cast: generously design the base of the individual dies/abutments • Determine path of insertion • Determine the thickness of the primary coping • Framework fabrication procedures depend on the selected manufacturing system • Parallel-milling of the primary copings, adjustment milling, finishing of the roughening depths • Copings with 1 – 2° taper to keep friction down • Shape the supporting butt joint on the oral aspect, if necessary • Cleansing firing, steam clean, polish the margins of the copings • Primary copings finished. Further procedures, conventional method: • Try-in of the copings in patient’s mouth using transfer copings • Pick-up impression • Fabrication of master cast • Face-bow transfer • Jaw relation records • Mounting casts on the articulator • Waxup fitting on plastic baseplates to check esthetics and jaw relation. Framework manufacture: • Galvano copings • Tertiary structure • Bonding • Framework try-in • If applicable, bisque try-in of veneers or with trial fitting • Completion. Alternative procedures: • Try-in of primary copings • Manufacture of galvano framework • Manufacture of tertiary structure • Try-in of secondary copings and tertiary crowns • Bonding of framework and tertiary structure in the mouth • Bonding of primary copings • Total impression of entire overlay denture, determine jaw relation, face-bow transfer, trial fitting, completion.
  46. 46. 45 7.4 / 7.5 Customizing the gingival aspect of a ZrO2 abutment. The white material prevents the titanium from shining through and supports the esthetics of the definitive all-ceramic crown. Photo: Lauer All-ceramic endosteal implant parts made of ZrO2. Photo: Kern All-ceramics for telescopic crownsInsertion • Adhesive or conventional luting of primary copings (zirconia or alumina) on the abutment teeth • Secondary copings and tertiary structure are always adhesively bonded • Metal / ceramic bonding between zirconia or alumina primary coping and galvano coping (secondary coping) is friction-free and unsurpassed as a tribological system; the initial resistance in the capillary space and the Van der Waals forces provide the “gentle bonding” effect of the connecting element. All-ceramics in implantology Endosteal dental implants facilitate the replacement of missing teeth without further dam- aging the existing dentition and allow conservation of the bone in the edentulous area. By using all-ceramic materials, the esthetic potential of implant-supported prostheses is opti- mally realized. All-ceramic implants Zirconia ceramics are now also used to manufacture endosteal dental implants. Prospective clinical studies are currently examining the clinical benefits and long-term performance of all-ceramic implants. All-ceramic implant abutments Currently, implant abutments of two-part implant systems can be fabricated out of high- strength alumina or zirconia ceramic rather than of metal. In esthetic cases in particular, all- ceramic abutments offer great esthetic advantages. The grayish discoloration of the gingiva caused by the metal reflecting through is avoided. Furthermore, all-ceramic crowns achieve their best esthetic potential only with all-ceramic abutments, because the translucency is not impaired such as in the case of a metal abutment. Depending on the implant system used, prefabricated all-ceramic abutments with and with- out a titanium basis are available, can also be custom made using CAD / CAM techniques. Custom-made abutments improve the soft-tissue support and optimize the transition from the circular implant platform to the anatomic tooth form (emergence profile). The all-ceramic abutments should be screwed onto the implants with the system-specific torque. After sealing the screw access with a provisional composite-resin material, the all- ceramic crowns and fixed partial dentures should be cemented according to the guidelines for adhesive luting. Transparent dual-curing or self-curing composite-resin cements should be used. All-ceramic implant abutments, and implant-supported crowns and fixed partial dentures
  47. 47. ZrO2 abutment (Lava) with metal insert and matching crown. All-ceramic implant abutments, and implant-supported crowns and fixed partial dentures 7.5 46 ZrO2 abutment with subgingival part screwed in. Endosteal part of implant and abutment of ZrO2, crown of fluorapatite sintered veneer ceramic. All photos: Wolfart When abutments made of oxide ceramics are used, all-ceramic crowns and fixed partial dentures should be placed on them to take advantage of natural light penetration through the entire construction, which improves the esthetics. Indications • Abutments as a foundation on the endosteal portion • Crowns on implant superstructures and implant abutments • Implant-supported fixed partial dentures • Primary copings with telescopic crown system for removable partial dentures. Materials • For abutments: fully-sintered zirconia ceramic and densely sintered alumina ceramic • As framework material for crowns and fixed partial dentures: lithium-disilicate ceramic (crown), infiltrated oxide ceramic, zirconia ceramic • For veneering: other materials as well as silicate fuse-on ceramic with an appropriate coefficient of thermal expansion • The selection of material is based on loading and type of restoration and its position in the mouth (single-tooth or fixed partial denture construction). Prerequisites • Optimal insertion direction must be created • All-ceramic primary copings and primary bars for superstructures, also with terminal attachment or latches, are technically possible • Tension-free tight fit in the mouth via intraoral bonding. Preparation design for implant abutments Implant abutments supporting an implant-supported fixed partial denture are prepared as described for posterior crowns (page 27 and 33 – 35). Sufficient space is required for primary copings. Impression technique The impression-making technique for ceramic abutments does not essentially differ from that for other abutment materials. • Pick-up impression of the primary copings with secondary copings in place to position them • Duplicate cast is necessary for fixed partial denture framework fabrication.
  48. 48. 47 7.5 ZrO2 abutments screw into endosteal implant to support a multi-unit fixed partial denture. Fig.: Nobel Biocare Superstructure, screw-on ZrO2 implant abutment with framework-free silicate ceramic crown. Photo: Kurbad, Reichel All-ceramic implant abutments, and implant-supported crowns and fixed partial dentures Natural light penetration through ZrO2 abutment and ceramic crown. Photo: Wolfart Framework manufacture The procedures depend on the selected ceramic material and manufacturing system: • Reshape the prefabricated abutment. Ensure a uniform path of insertion • Fabricate the crowns and fixed partial denture framework of ceramic. The connector surface areas for the fixed partial denture units must not be less than: • 12 mm2 for infiltrated oxide ceramics • 9 mm2 for zirconia ceramics. The minimum wall thicknesses of the crown copings are: • 0.5 mm for alumina ceramics • 0.5 mm for zirconia ceramics • The veneer ceramic layer thickness should be uniform and must not exceed 2.0 mm. Otherwise, the same considerations apply as described for anterior crowns (page 27 and 33). Try-in procedures A custom abutment in the laboratory should be tried in prior to further processing. This prevents discrepancies between the situation intraorally and on the master cast. Try-in of the crown framework: the crown must sit rotation-free on the abutment. Assess the accuracy of fit with a disclosing agent such as a dark, low-viscosity silicon impression material or fit checking material. Insertion procedures The “superstructure” is cemented on the abutments. Depending on treatment concept, this type of restoration can also be temporarily luted.
  49. 49. 8. 48 Indications for ceramic materials Crown Crown Fixed Fixed Telescopic Implant- Abut- Inlay Partial- Veneer Inlay Resin- partial partial crown supported ment coverage fixed bonded denture denture primary crown partial fixed copings denture partial denture anterior posterior anterior posterior anterior Feldspathic Silicate ceramic Lithium- disilicate up to 2nd ceramic premolar Glass infiltrated oxide ceramic: Spinell Alumina Zirconia Polycrystalline oxide ceramic Zirconia oxide * Alumina oxide The materials in this table are suitable for the restoration types given, and have been clinically proven in practice. *) To date, inlay fixed partial dentures have only been experimentally constructed and have not yet been sufficiently tested clinically. Source: SDC / AG Keramik
  50. 50. 9. 49 VITA 3D-Master shading system. Fig.: VITA Zahnfabrik Shade selectionShade selection for all-ceramic restorations An industrially prefabricated shade guide is normally used to determine the natural tooth color. Digital shade scanners can be used as support or to double-check. Ideally, the dental technician who is constructing the restoration also determines the shade. This helps prevent transfer errors. The actual tooth color is that of the dentin. The enamel modulates color perception by its transparency and thickness. Enamel transparency can be determined by alternately holding black or white pieces of paper (ca. 4 x 5 cm) behind the tooth (press onto the tooth’s palatal surface). The more intensively the background shines through the tooth, the greater the transparency of the selected (fuse-on) ceramic must be. The dentin color can best be observed cervico-buccally, because the enamel is thinner at that site. A distance of 1 – 2 mm from the gingiva should be maintained to exclude the gingiva’s red tone. To standardize subjective color perception as much as possible, it is recommended that color determination always be carried out in one certain place in the practice, because this enables the dentist to rely on previous experience with color-taking. To check one’s work, a second person (assistant) can be asked to perform color-taking. The following factors in the practice environment should be considered during shade selection. Surroundings for color-taking: • Muted coloring (furniture, walls, clothing, cosmetics) • No direct sunlight. Lighting: • Daylight, if possible from the north (less of the red spectrum) • Artificial light: fluorescent tubes with daylight quality (e.g., Osram Lumilux DeLuxe Daylight 12-950) as the ceiling light • Turn away OP lamps (halogen lamps have high red proportion).
  51. 51. 9. 50 Shade selection Digitale shade scanner. Fig.: VITA Zahnfabrik Conditions for patient: • No lipstick, highly-colored make-up, or bright scarves • Clean tooth surfaces • Patient participates in selection after the dentist has pre-selected. Color-taking: • Moisten teeth, do not let dry out • Constant distance between eye and object • Short observation times only, to avoid accommodation and fatigue of the eyes • Use shade guide, place shade sample on the tooth • First determine color value of the tooth, then color saturation, lastly tooth shade • Determine transparency extent of enamel with paper (white, black) • If necessary, repeat shade measurements, secure results. Documentation: • Record characteristics as a sketch (enamel cracks, mamelons, enamel spots, erosion). If esthetic demands on the restoration are very high: • Take photos (tooth shape, lip shape, smile-line, gingiva shape, facial expression, overall impression) • Individual shade selection with especially manufactured ceramic shade samples (veneers).

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