Issuu on Google+

a textbook of

a textbook of fixed prosthodontics

a textbook of fixed prosthodontics is intended primarily as a guide to evidence-based fixed prosthodontics. The book offers a detailed discussion of biological considerations and pretreatment procedures – cariology, endodontics, orthodontics and periodontology – as well as the various steps that are vital to achieving a successful treatment outcome. The book includes up-to-date information about implants and their role in FDP treatment, as well as esthetics, ceramics and digital techniques. A special chapter is devoted to ways of adopting the concept of evidence-based care in the field of prosthodontics. The textbook is suitable for undergraduate students, as well as graduate students and practitioners who want to acquire, or refresh previous, knowledge about fixed prosthodontics. The majority of figures and illustrations have been revised for this new and expanded edition.

fixed prosthodontics the scandinavian approach editors krister nilner ˙ stig karlsson ˙ bjørn l. dahl

nilner · karlsson · dahl


Editors Krister Nilner, Professor emeritus Dept of Prosthodontics Faculty of Odontology Malmö University Malmö, Sweden Stig Karlsson, Professor emeritus Dept of Prosthodontics – Dental Materials Science Institute of Odontology The Sahlgrenska Academy University of Gothenburg Gothenburg, Sweden Bjørn L. Dahl, Professor emeritus Dept of Prosthetic Dentistry and Oral Function Faculty of Dentistry University of Oslo Oslo, Norway


Contributors Ingemar Abrahamsson, Associate professor Dept of Periodontology Institute of Odontology The Sahlgrenska Academy  University of Gothenburg Gothenburg, Sweden Gunnar E. Carlsson, Professor emeritus Dept of Prosthodontics – Dental Materials Science Institute of Odontology The Sahlgrenska Academy   University of Gothenburg  Gothenburg, Sweden Dan Ericson, Professor Dept of Cariology Faculty of Odontology Malmö University Malmö, Sweden Victoria Franke Stenport, Associate professor Dept of Prosthodontics – Dental Materials Science Institute of Odontology The Sahlgrenska Academy   University of Gothenburg  Gothenburg , Sweden Nils Roar Gjerdet, Professor Dept of Clinical Dentistry Biomaterials University of Bergen Bergen, Norway Klaus Gotfredsen, Professor Dept of Oral Rehabilitation Faculty of Health Sciences University of Copenhagen Copenhagen, Denmark Johan Gunne, Professor emeritus Dept of Odontology Prosthetic Dentistry Faculty of Medicine Umeå University Umeå, Sweden

Thor Henrikson, Associate professor Dept of Orthodontics Faculty of Odontology Malmö University Malmö, Sweden Arne Hensten, Professor Dept of Clinical Dentistry Faculty of Health Sciences University of Tromsø Tromsø, Norway Flemming Isidor, Professor Section of Prosthetic Dentistry Dept of Dentistry Aarhus University Aarhus, Denmark Jacobsen Knut-Erik, D.D.S. Private practice Ekebergveien 237 Oslo, Norway Anders Johansson, Professor Dept of Clinical Dentistry – Prosthodontics Faculty of Medicine and Dentistry University of Bergen Bergen, Norway Asbjörn Jokstad, Professor Dept of Clinical Sciences Faculty of Dentistry University of Toronto Toronto, Canada Mauno Könönen, Professor Dept of Stomatognathic Physiology and   Prosthetic Dentistry Faculty of Medicine Institute of Dentistry University of Helsinki Helsinki, Finland


Eva Lindquist Karlsson, Lecturer Dept of Prosthodontics – Dental Materials Science Institute of Odontology The Sahlgrenska Academy University of Gothenburg Gothenburg, Sweden

Bo Sundh, Lecturer Dept of Prosthodontics – Dental Materials Science Institute of Odontology The Sahlgrenska Academy  University of Gothenburg Gothenburg, Sweden

Percy Milleding, Odont Dr Dept of Prosthodontics The Competence Centre of Northern Norway Tromsø, Norway

Tore Tangerud, Associate professor Dept of Clinical Dentistry Faculty of Medicine and Dentistry University of Bergen Bergen, Norway

Margareta Molin Thorén, Professor Dept of Odontology Prosthetic Dentistry Faculty of Medicine Umeå University Umeå, Sweden Gudbrand Øilo, Professor emeritus Dept of Prosthetic Dentistry and Oral Function Faculty of Dentistry University of Oslo Oslo, Norway Dag Ørstavik, Professor Dept of Endodontology Faculty of Dentistry University of Oslo Oslo, Norway Jon Ørstavik, Professor (1937–2003) Bengt Öwall, Professor emeritus Dept of Oral Rehabilitation Faculty of Health Sciences University of Copenhagen Copenhagen, Denmark Erik Saxegaard, Associate professor Dept of Prosthetic Dentistry and Oral Function Faculty of Dentistry University of Oslo Oslo, Norway

Birgit Thilander, Professor emerita Dept of Orthodontics Institute of Odontology The Sahlgrenska Academy   University of Gothenburg  Gothenburg, Sweden Annika Torbjörner, D.D.S., Chief consultant Clinic for Prosthodontics County of Värmland Karlstad, Sweden Pekka K. Vallittu, Professor Dept of Biomaterials Science and Turku Clinical Biomaterials Centre – TCBC Institute of Dentistry University of Turku Turku, Finland Per Vult von Steyern, Associate professor Dept of Material Science and Technology Faculty of Odontology Malmö University Malmö, Sweden Ann Wennerberg, Professor Dept of Prosthodontics Faculty of Odontology Malmö University Malmö, Sweden Jan L. Wennström, Professor Dept of Periodontology Institute of Odontology The Sahlgrenska Academy,   University of Gothenburg,  Gothenburg, Sweden


Contents Preface  9 The second edition  10

1. examination and diagnosis 1.1 Examination  14 Jon Ørstavik

Why Replace Missing Teeth?  15 Examination from Two Angles – Disease and Illness  16 Examination in Two Steps if Required  17 Elements to be Considered  18 Interview  19 Clinical Examination  22 Radiological Examination  26 Study Casts  27

1.2 Diagnosis  28 Jon Ørstavik

Diagnosis Related to “Disease” and “Illness”  28

2. need for prosthetic treatment and various options 2.1 Need for Prosthetic Treatment and Various   Options  34 Jon Ørstavik, Krister Nilner, Stig Karlsson and Bjørn L. Dahl

Adaptation  34 Need Related to Disease  36 Need Related to Illness (Impaired Function)  37 Summary – Need for Prosthetic Treatment  39 Treatment Options  40 Fixed Prosthetic Options  43 Concluding Remarks – Treatment Options  49

3. evidence-based medicine applied to fixed prosthodontics 3.1 Evidence-based Medicine Applied to Fixed   Prosthodontics  52 Asbjørn Jokstad

Characteristics of the Practice of Prosthodontics  53 Evidence-based Medicine  55 The Scientific Evidence for Fixed Prosthodontic Treatment  57

What are the Bases for Current Clinical Practices?  64 EBM applied to prosthodontics practice  69 Concluding Remarks   72

4. biological considerations and pretreatment procedures 4.1 Cariological and Endodontic Aspects  76 Dan Ericson and Dag Ørstavik

Reasons for Failures in Prosthetic Dentistry  77 Dental Caries and Endodontic Pathosis  78 Caries Etiology  79 Caries Pathogenesis  80 Caries Diagnosis and Risk Assessment  80 Caries Prevention, Maintenance and Control  81 Caries Treatment  82 Endodontic Aspects of Prosthodontic Treatment  82 Endodontic Diagnosis and Treatment Preparatory to   Prosthodontic Treatment  83 Chronic Apical Periodontitis (CAP) Present at the Time of   Treatment Planning  84 Proactive Measures to Prevent Endodontic   Complications  85 Restoration of the Root-filled Tooth  86 Inclusion of Root-filled Teeth in FDP Constructions  87 Endodontic Disease Subsequent to Prosthodontic   Treatment  87 Complications Subsequent to Prosthetic Function  88 Endodontic Treatment Considerations in Prosthodontic   Restorations  89 Interactions of Implants with Tooth Roots and Endodontic   Conditions  90 Concluding Remarks  90

4.2 Periodontal Aspects  94 Flemming Isidor

Periodontal Therapy  95 Supportive Periodontal Therapy  96 Risk Assessment  97 Furcation-involved Teeth  100 Design of the Prosthesis  104 Implants and Periodontitis – Susceptible Patients  107 Concluding Remarks  108


4.3 Orthodontic Aspects  111 Birgit Thilander and Thor Henrikson

Factors to Consider in Preprosthetic Orthodontics  112 Cases  114 Concluding Remarks  126

4.4 Functional Aspects  128 Gunnar E. Carlsson, Tore Tangerud and Anders Johansson

The Masticatory System  128 Occlusion in the Natural Dentition and Prosthetic   Rehabilitation  133 Functional Disturbances of the Masticatory System  138 Tooth Loss and Need for Replacement  143 Bruxism, Tooth Wear and Prosthodontic   Treatment  145 Dysocclusion / Phantom Bite Syndrome  147 Concluding Remarks  147

5. prosthodontic materials 5.1 Biomechanical Aspects and Material   Properties  152 Pekka K. Vallittu and Mauno Könönen

Biomechanical Properties  152 Biomechanical Design  154 Bite Force and Stress  156 Materials  156 Material Failures  166

5.2 Adverse Reactions to Dental Materials  172 Arne Hensten and Nils Roar Gjerdet

Oral Environment  172 Toxicity and Hypersensitivity  175 Incidence and Assumed Cause of Adverse Reactions  178 Disclosure of Composition  182 Concluding Remarks  182

6. treatment management 6.1 Traditional Prosthodontic Preparations  186 Percy Milleding

Definitions  187 Instrumentation  190 Basic Principles for Preparation  194

6.2 Dental Ceramics in Clinical Practice  205 Per Vult von Steyern

General Characteristics of Dental Ceramics  205 Dental Ceramics: a Clinically Adapted Classification  208 Optical Properties  211

Porcelain  212 Recommendations for Porcelain  213 Glass Ceramics  214 Oxide Ceramics  216 Recommendations for Good Esthetic Outcomes Using   Oxide Ceramics  219

6.3 Adhesive Prosthodontic Preparations  223 Percy Milleding

Anterior Ceramic Partial Crowns  224 Ceramic Laminate  225 Posterior Ceramic Restorations  228 Ceramic Inlays  228 Ceramic Onlays  229 Ceramic Single Crowns  231 All-ceramic Fixed Dental Prosthesis (FDP)  233

6.4 Prosthetic Treatment of the Endodontically   Treated Tooth  238 Annika Torbjörner

Technical Post Failures  238 Biomechanical Considerations and Functional   Stresses  240 Retention  243 Custom-cast Posts and Cores  245 Prefabricated Posts  246 Endodontic Considerations  250 Canal Preparation  251 Concluding Remarks  253

6.5 Impressions  255 Erik Saxegaard and Knut-Erik Jacobsen

Part 1 – Dental impression procedure  257 Impression Materials  257 Impression Trays  261 Exposing the Prepared Abutment Tooth  263 Impression Techniques – Implantology  271 Part 2 – Digital dental impression procedure  273 Historical background  273 CAD/CAM  274

6.6 Maxillomandibular Registration and Occlusal   Morphology  282 Tore Tangerud, Gunnar E. Carlsson and Anders Johansson

Principles and Materials for Maxillomandibular   Registration  283 Articulators and Related Instruments  285 Methods of Recording Maxillomandibular Relations  288 Extensive Reorganization of Occlusion  291 Occlusal Morphology of FDPs  296 Occlusal Design – Clinical Aspects  298


Occlusal Materials  303 Concluding Remarks  305

6.7 Interim Prostheses  309 Bo Sundh and Victoria Franke Stenport

Why Interim Prostheses?  309 Material Requirements of Interim Prostheses  311 Materials Used for Interim Prostheses  312 Interim Prosthetic Techniques  313

6.8 Cementation  325 Gudbrand Øilo and Eva Lindquist Karlsson

Retentive Function  326 Accuracy of Restorations and Film Thickness  327 New Materials and Methods  328 Water-based Cements  329 Polymer-Based Cements  333 Cementation  337 Concluding Remarks  340

7. cosmetic and esthetic considerations 7.1 Cosmetic and Esthetic Considerations  344 Margareta Molin Thorén and Per Vult von Steyern

Definitions  345 Esthetic Principles  346 The science and art of shade matching  351 Color  352 Shade matching and communication  354 A shade matching guideline  355 Esthetic Considerations – New Materials and   Techniques  357

8. biology and pathology of periodontal and peri-implant tissues – maintenance therapy 8.1 Biology and Pathology of Periodontal and Periimplant Tissues – Maintenance Therapy  360 Ingemar Abrahamsson and Jan L. Wennström

Biology and Pathology of Periodontal and   Peri-implant Tissues  360 Probing Depth Assessments at Teeth and Implants  364 Maintenance Phase and Supportive Therapy  366

9. implants and their role in fdp treatment 9.1 Implants and their Role in FDP Treatment  372 Klaus Gotfredsen, Ann Wennerberg and Johan Gunne

Implant, Abutment and Supraconstruction Materials,   Design and Surfaces  373 Indications and Contraindications for Implant-supported   Prostheses  376 Examination and Treatment Planning  380 Treatment Management  382 Complications and Prognosis  391

10. longevity and complications of fdps 10.1 Longevity and Complications of FDPs  396 Krister Nilner and Bengt Öwall

Complications Influencing Longevity  396 Clinical Studies on Longevity  409 Conclusion  412

appendix Glossary  416 Index  421


Preface

This Textbook of Fixed Prosthodontics — the Scandinavian Approach is intended primarily for undergraduate students. The book has been compiled with the intention of informing students about, and accustoming them to, the idea that they should never do more than is absolutely necessary, but that they should always be prepared to do that which the situation demands. This is the Scandinavian approach in a nutshell. By its very nature, such an approach is oriented towards the clinical aspects of prosthodontics. After introductory chapters on assessment and diagnosis, the book discusses biological considerations and pretreatment procedures, with an emphasis on the need to perform prosthodontic measures in a healthy oral environment only. A chapter on the importance of evidence-based care and ways of interpreting systematic reviews in order to identify such evidence is followed by summaries of the biomechanical aspects of prosthodontic materials and potential adverse reactions. The remainder of the book focuses on various treatment options in theory and practice. We hope that this structure will also enable the book to serve as a reference guide that can keep practicing dentists up to date on the latest developments in the field of prosthodontics. Like the first edition, this book is an initiative of the Scandinavian Society for Prosthetic Dentistry. We value its support and are grateful to all of our contributors. Without their expertise, commitment and effort, we would never have been able to put the book together. Special thanks go to Jörgen Jönsson, who again designed, corrected and adjusted the illustrations. Finally we want to extend our gratitude to Gothia Fortbildning for graciously assuming all the responsibilities associated with publishing the book. Malmö, Gothenburg, Oslo, January 2013 Krister Nilner, Stig Karlsson, Bjørn L. Dahl

9


Second edition

When we began updating this textbook, we invited all of the contributors to the first edition to participate once again. Some of them courteously declined, while others agreed or suggested a colleague instead. The book still contains ten chapters. We decided to delete the former Chapter 5.1, given the availability of other excellent material. Percy Milleding has now written Chapter 6.3, “Adhesive Prosthodontic Preparations.” Growing interest in the use of all-ceramics prompted us to ask Per Vult von Steyern to write Chapter 6.2, “Ceramics in Clinical Practice.” Jon Orstavik – who wrote Chapters 1.1, 1.2 and 2 – passed away in 2003. Considering that his material retains its high scientific quality and general relevance, we have left it almost intact. A short section entitled “The Spring FDP,” which is no longer a treatment option, has been deleted. Terms such as “implant” and “implant-supported” have been added where appropriate. Several comments containing up-to-date references have also been included. Editor-in-chief Krister Nilner, with the support of the other two editors, assumed primary responsibility for these updates. The previous Chapter 10, “Evidence-based Medicine Applied to Fixed Prosthodontics,” has now become Chapter 3. Our reasoning is that readers should learn about the scientific basis of prosthodontics before tackling biological and technical considerations. The growing use of implants, along with knowledge that has emerged since the first edition of this book was published, led us to expand the chapter on their use and rename it “Implants and Their Role in FDP Treatment.” Ann Wennerberg, kindly agreed to co-author the chapter. Due to greater demand for esthetically pleasing prostheses, we have rewritten Chapter 7, “Cosmetic and Esthetic Considerations.” Margareta Molin Thorén, who was sole author of the chapter in the first edition, has been joined by Per Vult von Steyern this time around.

10


A majority of the figures and illustrations have been revised for this edition. Our hope is that the scientific and technical information and guidance provided by the book, along with the illustrations and use of current terminology, will help uphold the Scandinavian approach as a viable model in the field of modern prosthodontics.

11


6.2

treatment management

color of the reconstruction. In summary, it is important to choose the type of ceramic based on the optical prerequisites of each case and the esthetic expectations.

Porcelain The same treatment principles apply to the use of both porcelain and glass ceramics, but they differ on a couple of points. Porcelain is more technically susceptible than glass ceramics, but offers the greatest esthetic potential, without limitations, to replicate the natural appearance of a tooth. It is used chiefly for laminate veneers and laminate veneer crowns for single restorations with limited loss of tooth structure. Since porcelain is built up layer by layer by porcelain powder that is available in a wide range of colors and optical effects; the natural appearance of the tooth can be fully replicated (Fig. 3). The disadvantage of porcelain is that the technique is considered to be difficult, demanding a great deal of manual dexterity and expertise by the dental technician. Far from all dental laboratories therefore offer this technique. When one considers the extent to which porcelain is used for all ceramic prosthetics, it is clear that porcelain makes up a negligible proportion of the total number of laminate veneers and restorations that use all-ceramic materials. The leading application for porcelain is therefore currently as a veneer material for porcelain fused to metal (PFM) or oxide ceramics. Since the flexural strength of porcelain is relatively low and stress formation can build up within the material during the firing process, it is recommended that the preparation be designed with allowance for a relatively even material thickness of 0.7–2.0 mm all over the recona

b

Fig. 3. Four porcelain laminate veneers 12–22. Provisional crowns after preparation (a). Note the supragingival finish line and the dark cervix of 11 as compared to (b). The opaque temporary cement and provisional crown blocks out the light and casts both the visible root and the surrounding gingiva in a shadow. The optical properties of the porcelain laminate veneer allow for the incident light to be transmitted through both porcelain and cement, leaving the visible part of the root and the gingiva illuminated (b).

212


dental ceramics in clinical practice

struction. The preparation surfaces should not have any sharp angles that could potentially cause fractural impressions in the porcelain. The preparation margin should be positioned in the enamel, with a cervical chamfer of 0.5 mm preparation depth. Before cementing, it is particularly important that both the enamel and the porcelain are properly etched all the way out to the periphery in order to avoid loss of adhesion where the risk of marginal leakage and discoloration is greatest.

Recommendations for Porcelain • Supragingival preparation margins with the periphery in enamel. • Etched cementation surface of the porcelain. Preferably etched at the dental laboratory. Do not try the porcelain on a working model subsequent to etching. Avoid touching the etched surface. Make sure that the porcelain is etched all the way to the periphery of the restoration, as this is the most critical area for retention and for avoiding microleakage. • Silane-treated porcelain surface (the reconstruction is silane-treated after try-in and subsequent cleaning at the clinic). • Pigment-free (transparent) light-curing adhesive cement of a true resin type. • Cure the cement with a small cement excess that is removed and polished away only after final curing. The last recommendation is the only method that leaves a cement margin without any excess or shortfall. Techniques that involve breaking away fully or partly cured cement leave a cement surface along the margin with small alternating cement excesses and shortfall. It is also impossible to remove surplus cement before curing with any great precision. In both cases there is a major risk of marginal discoloration. Reviewing the literature on the clinical results of porcelain laminate veneers is encouraging, and if porcelain fused to metal (PFM) is considered to be the “gold standard” concerning treatment outcomes, porcelain laminate veneers show results that are equal to, or maybe better than, those for PFM.9, 10 One should, however, be careful with such comparisons, as PFM could perhaps have been chosen in more mechanically demanding cases than the porcelain laminate veneers. It is also important to state that the good results comprise veneers bonded to enamel and that veneers that are bonded to dentin show lower survival rates than those supported by preparations with periph-

213

6.2


9

implants and their role in fdp treatment

Implants and their Role in FDP Treatment Klaus Gotfredsen, Ann Wennerberg and Johan Gunne

An oral implant can be defined as an alloplastic material inserted in hard and soft tissues of the oral cavity in order to provide retention or support for the replacement of a tooth. Oral implants have been used for a very long time. The Mayas (100–1500 A.D.) used implants to replace lost teeth. Reports maintain, however, that implants were used in China as early as 3000 B.C. A renaissance in the use of oral implants occurred in the 1940s, when subperiosteal implants were described.1 Four main categories of oral implants have been described since then, depending on their relation to oral tissue: intramucosal, subperiosteal, transmandibular and endosseous. Only the endosseous implants have presented with enough clinical documentation to be considered ethically justifiable, and they are the only ones used in Scandinavia. After successful experimental animal studies on bone anchorage, Per-Ingvar Brånemark, who had developed a screw-shaped implant in commercially pure (c.p.) titanium (grade 1), treated his first patient in 1965. The method was described for the edentulous patient in 1969, and the term osseointegration, defined as direct structural and functional connection between ordered living bone and the surface of the load-carrying implant was coined by Brånemark in 1977.2 But the osseointegration concept was not accepted by the odontological community at that time. Independently of Brånemark in Sweden, André Schröeder in Switzerland and Willy Schulte in Germany, demonstrated a similar ankylotic contact between bone and endosseous implants in the late 1970s.3 Since then, many publications have analyzed and described the osseointegrated bone/implant interface at different levels: clinical, radiographical, tissue, cellular and molecular.

372


implants and their role in fdp treatment

Albrektsson et al.4 described the following parameters as especially important for the establishment of reliable osseointegration: Variables important for obtaining osseointegration 1. implant material 2. implant design 3. implant surface 4. state of the bone 5. surgical technique 6. loading conditions.

Briefly, successful osseointegration requires oral implant material with a high biocompatibility, as well as appropriate design and surface properties. Furthermore, the bone tissue must be of good quality and sufficient quantity, and an atraumatic surgical and prosthetic technique has to be used. Successful osseointegration also implies that it be maintained. Implant survival and success are other frequently used terms, and several definitions have been proposed, for example by Albrektsson et al.5 Implant survival • The implant is still in the mouth but not tested, or has not necessarily reached the criteria, for success. Implant success • The implant is immobile when tested clinically. • The radiograph does not demonstrate any evidence of peri-implant radiolucency. • The vertical bone loss should be less than 0.2 mm annually after the 1st year. • There should be no persistent and/or irreversible signs and symptoms, such as: pain, infection, neuropathies or paresthesia.

Implant, Abutment and Supraconstruction Materials, Design and Surfaces Implant Endosseous implants, often referred to as fixtures (Fig. 1), have been fabricated in various designs, with different surface properties and in

373

9


implants and their role in fdp treatment

Interim restorations Various solutions exist depending on the extent of the prosthetic rehabilitation. Single tooth restoration For replacement of a single unit, several possibilities are available, both removable and fixed. The choice of the solution depends on esthetic demands, comfort demands and the expected time that the prosthesis will be used. Examples of solutions are: • temporary, partial, acrylic RDPs • resin-bonded bridges (Fig. 10) • vacuform retainer (Fig. 11) • orthodontic wire.

Fig. 10. A fiber-reinforced resin-bonded FDP 11, 12, 13 as a temporary solution.

Multiple tooth restoration If the patient has a PRDP, this may be used. Remove enough of the acrylic for an even thickness of temporary relining material and reline. If the old PRDP does not fit, or is evaluated to be insufficient, a new temporary PRDP has to be made. If the implants are placed in a posterior position a temporary solution is not always needed.

Prosthetic technique Two principles for the retention of a prosthetic construction are available: screw-retention or cementation. The major advantage of screwretained constructions is the ability to easily remove them for repair or other adjustments (Fig. 12). Cemented constructions have some esthetic advantages, since the access hole does not penetrate the crown. Cemented constructions are mainly used in Scandinavia for singletooth replacement and in the front region (Fig. 13). The prosthetic procedure is, in principle, similar to that for conventional fixed prosthodontics. Prosthetic procedures 1. Abutment connection with healing or temporary abutments before a final standard abutment or individually prepared (customized) abutment is placed. 2. Impression; especially for single-tooth restorations, most impressions are taken on the implant level. 3. Jaw registration.

Fig. 11. A vacuform retainer with a compo­ site tooth 13 as temporary solution.

Fig. 12. A screw-retained, 12-unit, implantsupported FDP at a cast model. The 6-screw access holds are placed at lingual and occlusal positions.

385

9


9

implants and their role in fdp treatment

4. Try-in of the metal frame or ceramic frame. 5. Try-in of the tooth set-up. 6. Try-in of the final reconstruction. 7. Delivery of the prosthesis (screw tightening or cementation). 8. Control.

a

b

Fig. 13. A cemented implant-supported single crown 22 seen from a buccal (a) and lingual (b) position. Crown constructed without screw access hole.

386

A common prosthetic procedure for a complete screw-retained prosthesis can be summarized as follows. After the soft tissue adjacent to the healing abutments has healed, an impression is taken. Impression copings are attached to the implants or to the abutments with guide-pins (Fig. 14) or screwed directly to the abutment. An elastic impression material of high viscosity is used in a custom tray, which is topless over the implants, if the impression coping is attached with guide-pins. After the material has set, the guidepins are unscrewed and the tray removed (pick-up technique). In the case of impression copings screwed to the abutments, the copings are unscrewed and placed in the impression (transfer technique or replacement technique). If the impression is done on the implant level, a special impression post should be used. New techniques are constantly developing and oral laser scanning has become an alternative to traditional impression. Digital virtual models will be created and constructions produced with CAD-CAM technique. A milling technique is the most frequent one, but other techniques are also available, such as laser sintering, fused deposition modelling and electron beam melting. A working cast is fabricated in the laboratory. In situations of occlusal instability, a wax occlusion rim for fixation on some of the implants is also fabricated for jaw registration. Otherwise, a normal jaw registration is performed. In many cases a try-in of the tooth setup is performed before the metal framework is fabricated, which makes it easier to give the metal frame an optimal design. A gold alloy, c.p. titanium or Co-Cr is used for the frame. The alloy or the metal may be cast, but if titanium or Co-Cr is used, several CAD-CAM techniques are available. The design of the frame is related to the choice of material for the tooth and the surrounding soft tissue. Previously, acrylic resin teeth or teeth in composite material were used. Today, ceramic is the material of choice, especially in partially dentate jaws. All ceramic crowns and FDPs may also be considered, but preferably only for few-unit FDPs. Larger-unit FDPs still suffer from frequent chip-off fractures.12 The framework is tried-in for check


a textbook of

a textbook of fixed prosthodontics

a textbook of fixed prosthodontics is intended primarily as a guide to evidence-based fixed prosthodontics. The book offers a detailed discussion of biological considerations and pretreatment procedures – cariology, endodontics, orthodontics and periodontology – as well as the various steps that are vital to achieving a successful treatment outcome. The book includes up-to-date information about implants and their role in FDP treatment, as well as esthetics, ceramics and digital techniques. A special chapter is devoted to ways of adopting the concept of evidence-based care in the field of prosthodontics. The textbook is suitable for undergraduate students, as well as graduate students and practitioners who want to acquire, or refresh previous, knowledge about fixed prosthodontics. The majority of figures and illustrations have been revised for this new and expanded edition.

fixed prosthodontics the scandinavian approach editors krister nilner ˙ stig karlsson ˙ bjørn l. dahl

nilner · karlsson · dahl


9789172057968