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Fixed prosthodontics is the art and science of restoring damaged teeth with cast metal, metalceramic, or allceramic restorations and of replacing missing teeth with fixed prostheses using metalceramic artificial teeth (pontics) or metalceramic crowns over implants. Successfully treating a patient by means of fixed prosthodontics requires a thoughtful combination of many aspects of dental treatment: patient education and the prevention of further dental disease, sound diagnosis, periodontal therapy, operative skills, occlusal considerations, and, sometimes, placement of removable complete or partial prostheses and endodontic treatment. Restorations in this field of dentistry can be the finest service rendered for dental patients or the worst disservice perpetrated upon them. The path taken depends upon one’s knowledge of sound biologic and mechanical principles, the growth of manipulative skills to implement the treatment plan, and the development of a critical eye and judgement for assessing detail. As in all fields of the healing arts, there has been tremendous change in this area of dentistry in recent years. Improved materials, instruments, and techniques have made it possible for today’s operator with average skills to provide a service whose quality is on a par with that provided only by the most gifted dentist of years gone by. This is possible, however, only if the dentist has a thorough background in the principles of restorative dentistry and an intimate knowledge of the techniques required. This book was designed to serve as an introduction to the area of restorative dentistry dealing with fixed partial dentures and cast metal, metalceramic, and allceramic restorations. It should provide the background knowledge needed by the novice as well as serve as a refresher for the practitioner or graduate student. To provide the needed background for formulating rational judgments in the clinical environment, there are chapters dealing with the fundamentals of treatment planning, occlusion, and tooth preparation. In addition, sections of other chapters are devoted to the fundamentals of the respective subjects. Specific techniques and instruments are discussed because dentists and dental technicians must deal with them in their daily work. Alternative techniques are given when there are multiple techniques widely used in the profession. Frequently, however, only one technique is presented. Cognizance is given to the fact that there is usually more than one acceptable way of accomplishing a particular task. However, in the limited time available in the undergraduate dental curriculum, there is usually time for the mastery of only one basic technique for accomplishing each of the various types of treatment. An attempt has been made to provide a sound working background in the various facets of fixed prosthodontic therapy. Current information has been added to cover the increased use of new cements, new packaging and dispensing equipment for the use of impression materials, and changes in the management of soft tissues for impression making. New articulators, facebows, and concepts of occlusion needed attention, along with precise ways of making removable dies. The usage of periodontally weakened teeth requires different designs for preparations of teeth with exposed root morphology or molars that have lost a root. Different ways of handling edentulous ridges with defects have given the dentist better control of the functional and cosmetic outcome. No longer are metal or ceramics needed to somehow mask the loss of bone and soft tissue. The biggest change in the replacement of missing teeth, of course, is the widespread use of endosseous implants, which make it possible to replace teeth without damaging adjacent sound teeth. The increased emphasis on cosmetic restorations has necessitated expanding the chapters on those types of restorations. The design of resinbonded fixed partial dentures has been moved to the chapters on partial coverage restorations. There are some uses for that type of restoration, but the indications are far more limited than they were thought to be a few years ago. Updated references document the rationale for using materials and techniques and familiarize the reader with the literature in the various aspects of fixed prosthodontics. If more background information on specific topics is desired, several books are recommended: For detailed treatment of dental materials, refer to Kenneth J. Anusavice’s Phillip’s Science of Dental Materials, Eleventh Edition (Saunders, 2003) or William J. O’Brien’s Dental Materials and Their Selection, Fourth Edition (Quintessence, 2008). For an indepth study of occlusion, see Jeffrey P. Okeson’s Management of Temporomandibular Disorders and Occlusion, Sixth Edition (Mosby, 2007). The topic of tooth preparations is discussed in detail in Fundamentals of Tooth Preparations (Quintessence, 1987) by Herbert T. Shillingburg et al. For detailed coverage of occlusal morphology used in waxing restorations, consult the Guide to Occlusal Waxing (Quintessence, 1984) by Herbert T. Shillingburg et al. Books of particular interest in the area of ceramics include W. Patrick Naylor’s Introduction to Metal Ceramic Technology (Quintessence, 2009) and Christoph Hämmerle et al’s Dental Ceramics: Essential Aspects for Clinical Practice (Quintessence, 2009).
Fundamentals of Fixed Prosthodontics F ourth Edition Cover design based on a photograph of Monument Valley on the Navajo Reservation in northern Arizona taken at sunrise by Dr Herbert T Shillingburg, Jr FUNDAM ENTALS O F FIXED PROSTHODONTICS F OURTH E DITION Herbert T S hillingburg, Jr, DDS David Ross Boyd Professor Emeritus Department of Fixed Prosthodontics University of Oklahoma College of Dentistry Oklahoma City, Oklahoma with David A S ather, DDS Edwin L Wilson, Jr, DDS , M Ed Joseph R C ain, DDS , M S Donald L Mitchell, DDS , M S Luis J B lanco, DM D, M S James C Kessler, DDS Illustrations by Suzan E Stone Quintessence Publishing Co, Inc Chicago, Berlin, Tokyo, London, Paris, Milan, Barcelona, Istanbul, Moscow, New Delhi, Prague, São Paulo, and Warsaw Library of Congress Cataloging-in-Publication Data Fundamentals of fixed prosthodontics / Herbert T Shillingburg Jr [et al.] - 4th ed p ; cm Includes bibliographical references and index ISBN 978-0-86715-475-7 I Shillingburg, Herbert T [DNLM: Denture, Partial, Fixed Crowns Dental Prosthesis Design Prosthodontics methods WU 515] 617.6'9 dc23 2011041249 54321 © 2012 Quintessence Publishing Co, Inc All rights reserved This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher Quintessence Publishing Co, Inc 4350 Chandler Drive Hanover Park, IL 60133 www.quintpub.com Editor: Leah Huffman Design: Ted Pereda Production: Patrick Penney Printed in the USA Dedication In Memoriam Constance Murphy Shillingburg 1938–2008 This book is dedicated to the loving memory of Constance Murphy Shillingburg We met at the University of New Mexico at the beginning of her freshman year in 1956 We were married years later, week after she graduated During my first years in dental school, I made 13 trips, totaling over 22,000 miles, from Los Angeles to Albuquerque She shared all of the triumphs and disappointments of my last years in dental school It was not my career; it was our career She supported me in all that I did She didn’t question my leaving practice to start a career in academics or our moving from California to Oklahoma We had three daughters along the way Although she had three open-heart surgeries in her teens because of rheumatic fever and then two cancer surgeries later in life, she was the most optimistic person I ever met She accompanied me on 29 trips outside the United States At first she came along because she loved to travel, and I didn’t enjoy the trips nearly as much without her However, I very quickly learned that my hosts and audiences were enchanted by her They enjoyed her as much or more than they did me, and she used what she learned on those trips in her teaching She died weeks after we celebrated our 48th wedding anniversary There is a song on the most recent Glen Campbell album, Ghost on the Canvas, that sums it up perfectly: “There’s no me…without you.” Authors Luis J Blanco, DMD, MS Professor and Chair Department of Fixed Prosthodontics University of Oklahoma College of Dentistry Oklahoma City, Oklahoma Joseph R Cain, DDS, MS Professor Emeritus Department of Removable Prosthodontics University of Oklahoma College of Dentistry Oklahoma City, Oklahoma James C Kessler, DDS Director of Education L D Pankey Institute Key Biscayne, Florida Donald L Mitchell, DDS, MS Professor Emeritus Department of Oral Implantology University of Oklahoma College of Dentistry Oklahoma City, Oklahoma David A Sather, DDS Associate Professor Department of Fixed Prosthodontics University of Oklahoma College of Dentistry Oklahoma City, Oklahoma Herbert T Shillingburg, Jr, DDS David Ross Boyd Professor Emeritus Department of Fixed Prosthodontics University of Oklahoma College of Dentistry Fig 29-7 (a) Open tray hex impression coping with attachment screw and laboratory implant analog, shown separately and combined (b) Buccal view of open tray impression copings seated on study cast with attachment screws F inal impression and master cast fabrication As explained earlier, the authors believe the open tray impression technique will produce a more accurate cast than a closed tray impression technique because the impression coping remains within the impression material when the impression tray is removed from the mouth.6–9 The authors recommend the use of the open tray impression technique for taking a final impression and fabricating a master cast The open tray is fabricated on the study cast with the open tray impression coping attached to the laboratory implant analog with the attachment screw (Fig 29-7b) The fabrication of a multiple-tooth dental implant restoration requires a very accurate cast in order to avoid the need for cutting and soldering the definitive restoration The reason the master cast must have a high degree of accuracy is because the definitive restoration contains machined components that must have a passive fit To achieve a master cast of the desired quality, the open tray impression copings should be luted together in the mouth prior to taking the final impression An initial laboratory procedure will facilitate this clinical step of luting the open tray impression copings together intraorally This initial laboratory procedure consists of placing the open tray impression copings on the study cast with attachment screws The open tray impression copings are to be enclosed in autopolymerizing acrylic resin to accurately record their relationship to each other To facilitate the addition of the acrylic resin around the top of the open tray impression copings, a scaffold is formed with dental floss to support the autopolymerizing acrylic resin (Fig 29-8a) The dental floss scaffold should be in the middle third of the open tray impression coping One end of the dental floss is secured around one of the open tray impression copings with an overhand knot Next, a figure eight is formed around the open tray impression copings, and the scaffold is finished with a circumferential wrap The ending portion of the dental floss is tied off with the loose end of the starting piece of floss Autopolymerizing acrylic resin is then placed around the open tray impression copings with a paintbrush The dental floss scaffold supports the autopolymerizing acrylic resin, which should not be in contact with the study cast (Fig 29-8b), so that it will be surrounded by impression material when the final impression is made After polymerization of the autopolymerizing acrylic resin, a separating disk (Fig 29-8c) is used to separate the open tray impression copings (Fig 29-8d) The addition of all of the autopolymerizing acrylic resin can be done intraorally However, the authors prefer to perform this initial procedure in the laboratory because it reduces chair time and a smaller volume of autopolymerizing acrylic resin, with its inherent shrinkage, is used intraorally Fig 29-8 (a) Buccal view of open tray impression copings seated on study cast with attachment screws Note the use of dental floss as a scaffold for the autopolymerizing acrylic resin (b) Buccal view of open tray impression copings seated on study cast with attachment screws Note the addition of autopolymerizing acrylic resin (c) A separating disk is used to section the acrylic resin between the open tray impression copings (d) Note the separation between open tray impression copings The study cast is blocked out around the dentition with two sheets of pink baseplate wax (approximately mm thick), leaving the top two-thirds of the attachment screws exposed Four vertical stops for the impression tray during the impression-taking process are cut through the occlusal surface of the block-out wax The vertical stops should be well spaced to provide impression tray stability They should not be placed immediately adjacent to the implant site because the impression tray may need adjustment in this area, which may eliminate the vertical stops The custom impression tray may be fabricated from the tray material of choice The tray material should be pressed firmly to record the vertical wax cutouts and over the impression coping attachment screws to record their location After the impression tray material has polymerized, the impression tray is removed from the study cast Any block-out wax remaining in the custom impression tray is removed A hole is created in the custom impression tray to provide access to the impression coping attachment screws (Fig 29-9) The access hole in the top of the open tray should allow at least mm of space around the impression coping attachment screws A multiple-implant open tray impression will likely have the impression coping attachment screw holes joined, forming one large opening (Fig 29-9, inset A) A piece of boxing wax will be placed over the access hole to contain the impression material within the impression tray while it is being carried and seated in the patient’s mouth (Fig 29-9, inset B) Fig 29-9 Custom open impression tray Note the opening in the impression tray (A) to gain access to the impression coping attachment screws when the impression is taken Note that boxing wax is placed (B) prior to impression taking to contain impression material while seating the impression tray To take the final impression, the implant healing abutments are removed from the patient’s mouth, and the open tray impression copings with their attachment screws are transferred from the study cast to the patient (Fig 2910a) The authors strongly recommend that a radiograph be taken at this time to ensure that the impression copings are fully seated onto the dental implants before luting them together.10 This radiograph will also provide information regarding the amount and quality of the bone surrounding the dental implant at the time of implant restoration This is the first time during patient restorative treatment that a radiograph needs to be taken This radiograph will serve as a baseline to monitor long-term implant health After radiographic verification that the open tray impression copings are fully seated on the dental implants, autopolymerizing acrylic resin is used to reconnect the previously sectioned open tray impression copings intraorally (Fig 29-10b) The luted open tray impression copings are examined to make sure that the autopolymerizing acrylic resin does not contact the proximal teeth or the gingival tissue (Fig 2910c) A piece of boxing wax is placed over the opening for the abutment screws on the open tray impression to contain the impression material in the custom impression tray The use of the final impression material is opposite that of the standard fixed prosthodontic technique in that the heavy-body impression material is injected around the open tray impression copings, and the impression tray is filled with medium-body impression material The heavybody impression material is placed around the open tray impression copings to minimize any movement that may occur during the removal of the impression tray and pouring of the master dental cast During the impression-taking process, the custom impression tray must be oriented to allow the impression coping abutment screws to penetrate the boxing wax placed on the custom impression tray (Fig 29-11) before the impression material sets Upon polymerization of the impression material, any wax around the implant abutment screws is removed to provide access to them The implant abutment screws are unscrewed and removed through the top of the open impression tray The final impression is removed from the patient’s mouth, and the healing abutments are replaced on the dental implants The authors believe the open tray impression is the most accurate technique because the heavy-body impression material stabilizes the open tray impression copings, which remain undisturbed within the impression material before the master cast is poured in dental stone The final impression is evaluated for completeness, and it is confirmed that the surface of the open tray impression copings that were in contact with the dental implants is free of impression material10 (Fig 29-12) The open tray impression coping attachment screws, which had been removed from the impression tray in order to remove the impression tray from the patient’s mouth, are reinserted into the open tray impression copings (Figs 29-13a and 29-13b) The laboratory implant analogs are secured to the open tray impression copings with the attachment screws (Figs 29-13c and 29-13d) The laboratory implant analog hex must be correctly aligned with the open tray impression coping hex to be seated fully (Fig 29-13e) Care must be taken when securing the attachment screws with the hex driver not to overtighten the attachment screws There is a risk of dislodging the open tray impression copings from the autopolymerizing acrylic resin that is luting them together if too much torque is applied to the attachment screw with the hex driver This would render the master cast inaccurate Fig 29-10 (a) Buccal view of open tray impression copings seated in the patient’s mouth with attachment screws (b) Intraoral addition of autopolymerizing acrylic resin to lute open tray impression copings together (c) Intraoral view of open tray impression copings luted together with autopolymerizing acrylic resin Fig 29-11 Taking the final impression with a custom open tray technique (inset) Custom open tray impression with attachment screws protruding through boxing wax placed to contain the impression material while seating the tray Fig 29-12 Intaglio surface of the final impression Note the impression coping surface that was in contact with the dental implant is impression material free The two different impression materials used can also be seen Fig 29-13 (a) Impression coping attachment screw being reinserted into the final impression (b) The second impression coping attachment screw being reinserted into the final impression (c) Laboratory implant analog being attached to the open tray impression coping with an attachment screw (d) The second laboratory implant analog being attached to the open tray impression coping with an attachment screw (e) Laboratory implant analogs seated in final impression, ready for cast to be poured Note the two different impression materials used Improved restorative esthetics can be achieved when the top of the dental implant is approximately to mm below the surrounding gingival tissue However, an impression of a dental implant that is lower than the surrounding gingival tissue will yield a stone cast with a laboratory implant analog that is below the level of the surrounding dental stone The surrounding dental stone will restrict access to the top of the laboratory implant analog during restoration fabrication To facilitate restoration fabrication, a soft tissue replica material is placed around the portion of the open tray impression coping that was below the level of the gingival tissue intraorally but is now exposed because the impression is a negative representation of the intraoral morphology The presence of the soft tissue replica material on the master cast is helpful because it is removable, allowing access to the top of the implant laboratory analog during restoration fabrication Fig 29-14 (a) Placing soft tissue replica material in the final impression to simulate gingival tissue (b) Soft tissue replica material is only placed around the impression copings that were subgingival in the patient’s mouth Fig 29-15 (a) Pouring dental stone around the laboratory implant analogs (b) Pouring the remainder of the impression Fig 29-16 Master cast with external hex laboratory implant analogs surrounded by soft tissue replica material Soft tissue replica material will adhere to many impression materials A separating medium provided by the soft tissue replica manufacturer should be applied to the area of the intaglio surface of the final impression that surrounds the exposed portion of the open tray impression copings and approximately mm onto the laboratory implant analogs The soft tissue replica material is applied around the exposed open tray impression coping and up approximately mm onto the laboratory implant analogs (Fig 29-14a) The soft tissue replica material should not extend into the impression of the teeth proximal to the dental implants (Fig 29-14b) Pouring of the final impression is begun by placing dental stone around the laboratory implant analogs (Fig 29-15a) The remainder of the impression is then poured in dental stone to fabricate the master cast (Fig 29-15b) Separation of the master cast from the final impression requires removal of the attachment screws In the master cast, the soft tissue replica material surrounds the top of the laboratory implant analogs (Fig 29-16) Fig 29-17 (a) Internal hex and nonhex machined metal cylinders with waxing sleeves Note internal differences (b) Occlusal view of nonhex machined metal cylinders with waxing sleeve secured with abutment screws on master cast (c) Waxing cylinders equilibrated into occlusion Definitive Implant R estoration Prefabricated cast machined metal cylinder abutments with plastic waxing sleeves are used as the foundation upon which the definitive restoration is built The prefabricated cast machined metal cylinder abutment with plastic waxing sleeve comes in two styles, hex and nonhex (Fig 29-17a) An internal or external hex machined metal cylinder abutment is needed for a single dental implant restoration to prevent restoration rotation The hex surfaces of the prefabricated machined metal cylinders fit precisely with the vertical machined surfaces of the internal or external hex dental implant However, it is almost impossible to surgically place two or more dental implants perfectly parallel to each other Attempting to use two or more hex machined metal cylinders that are luted together may cause difficulty in seating the definitive restoration on the dental implants This is due to the interference of the machined metal surfaces with the path of insertion The use of a nonhex machined metal abutment reduces the possibility of this problem.11 Articulation of the master cast The maxillary master cast and opposing mandibular cast are articulated Prefabricated machined metal nonhex cylinders with attached plastic waxing sleeves (waxing abutments) are secured to the laboratory implant analogs in the master cast with abutment screws (Fig 29-17b) The waxing abutments, when in place on the articulated master cast, will create a premature occlusal contact requiring equilibration.11 Completion of the waxing abutment equilibration will reestablish normal occlusion (Fig 29-17c) The plastic sleeve of the waxing abutment has horizontal ridges placed by the manufacturer to aid in wax retention However, there is often a need for the placement of additional retention to prevent wax rotation around the waxing abutment It is strongly recommended to roughen the plastic sleeve of the waxing abutments and/or place vertical grooves for additional wax retention The abutment screw access hole in the plastic sleeve of the waxing abutment should be obturated with a cotton pellet prior to initiating restoration waxing to prevent wax from obstructing the hex of the abutment screw Fig 29-18 (a) Occlusal view of full-contour wax-up showing lingual screw access hole (b) Buccal view of full-contour wax-up of the implant-retained restoration (c) Occlusal view of wax pattern with buccal and occlusal buccal cusp reduction Note that there is no occlusal wax reduction around the abutment screw access holes Fig 29-19 Definitive restoration Note the porcelain-metal junction Retention screw access holes should be in metal Restoration wax-up The restoration is waxed to full contour (Figs 29-18a and 29-18b) The full-contour wax-up is then cut back to allow for the addition of porcelain The preferred cutback retains a metal occlusal surface with the abutment screw access holes in metal to avoid fracture of unsupported porcelain Metal occlusal surfaces are preferred because they are easier to equilibrate and repolish and are less damaging to the opposing dentition than porcelain The desired wax cutback includes the buccal surface, extending to one-third of the lingual surface of the buccal cusps (Fig 29-18c) Restoration placement The completed dental implant restoration can provide a natural-looking restoration (Fig 29-19) The abutment screw access holes are encircled with metal to prevent the fracture of unsupported porcelain The abutment screw access holes are closed by first placing cotton pellets over the top of the abutment screws to within mm of the access hole openings to protect the hex of the abutment screws The cotton pellets are then covered with a 2-mm layer of light-polymerizing resin.11 The use of a wet cotton-tipped applicator to remove excess and smooth the light-polymerizing resin prior to polymerization should produce a surface that will require no further finishing R eferences van Steenberghe D The application of osseointegrated oral implants in the rehabilitation of partial edentulism: A prospective multi-center study on 558 fixtures Int J Oral Maxillofac Implants 1990;5:272–281 Jemt T, Lekholm U Oral implant treatment in posterior partially edentulous jaws: A 5-year follow-up report Int J Oral Maxillofac Implants 1993;8:635–640 Chiche GJ, Pinault A Considerations for fabrication of implant-supported posterior restorations Int J Prosthodont 1991;4:37–44 Weber HP, Cochran DL The soft tissue response to osseointegrated dental implants J Prosthet Dent 1998;79:79–89 Centerpulse Dental Inc Tapered Screw-Vent and AdVent Restorative Manual, 2002:12–14,15–17 Naconecy MM, Teixeira ER, Shinkai RS, Frasca LC, Cervieri A Evaluation of the accuracy of transfer techniques for implant-supported prostheses with multiple abutments Int J Oral Maxillofac Implants 2004;19:192–198 Filho HG, Mazaro JV, Vedovatto E, Assuncão WG, dos Santos PH Accuracy of impression techniques for implants Part 2—Comparison of splinting techniques J Prosthodont 2009;18:172–176 Dumbrigue HB, Gurun DC, Javid NS Prefabricated acrylic resin bars for splinting implant transfer copings J Prosthet Dent 2000;84:108–110 Hariharan R, Shankar C, Rajan M, Baig MR, Azhagarasan NS Evaluation of accuracy of multiple dental implant impressions using various splinting materials Int J Oral Maxillofac Implants 2010;25:38–44 10 BIOMET 3i Inc Restorative Manual for Osseotite Certain and Osseotite External Hex Implant System, 2003:11–13 11 Zimmer Dental Inc Dental Tapered Screw-Vent and AdVent Restorative Manual, 2006:104–108 ... patient interview A brief palpation of the masseter (Fig 1- 8), temporalis (Fig 1- 9), medial pterygoid (Fig 1-1 0), trapezius (Fig 1-1 1), and sternocleidomastoid (Fig 11 2) muscles may reveal tenderness... anticoagulants for a variety of reasons: prosthetic heart valves, myocardial infarction (MI), stroke (cerebrovascular accident [CVA ]), atrial fibrillation (AF), deep venous thrombosis (DVT), or unstable angina.13... Professor and Chair Department of Fixed Prosthodontics University of Oklahoma College of Dentistry Oklahoma City, Oklahoma Joseph R Cain, DDS, MS Professor Emeritus Department of Removable Prosthodontics