Fundamentals of Implant Dentistry, Second Edition

Volume 1

John III Beumer, Robert F. Faulkner, Kumar C. Shah, Benjamin M. Wu

• Publisher: Quintessence Publishing Co, Inc
• Year: 2022
• eBook ISBN: 9781647241155
• Edition: 2
• Topic: Medicine
• Subtopic: Dentistry

This book has it all and can truly be considered the definitive implant textbook. As with its predecessor, the authors provide a prosthodontic perspective to dozens of aspects of implant treatment, from the biologic mechanisms of osseointegration to implant design and configuration to maintenance and management of complications. Organized into four sections, the book systematically takes the reader through the foundational principles of implant dentistry, to evaluation and restoration of a variety of clinical situations, and into more specialized topics and treatment scenarios. Emerging digital technologies and materials used to design and fabricate implant prostheses are an important focus, as are implant positioning, angulation, and spacing for each situation. Designs of implant-assisted overdentures are described in detail as well as the various bone and soft tissue enhancement procedures currently in use, particularly in patients with unfavorable periodontal biotypes. Like its predecessor, this book focuses on the importance of interdisciplinary treatment, but because some situations can be managed by a solo practitioner, one chapter is devoted to the basic fundamentals of surgical placement, specifically targeted at nonsurgically trained dentists. In addition, a downloadable illustrated glossary is available for easy reference. Functioning as both a textbook for students and a desk reference for practitioners, this book is a must-have to complete any dental library.

III

Restoration of Partially Edentulous Patients

CHAPTER 11

Restoration of the Posterior Quadrants of Partially Edentulous Patients: Basic Principles and Patient Selection

Kumar C. Shah | John Beumer III | Robert F. Faulkner Robert M. Love | Benjamin M. Wu

Increasing numbers of patients who have lost dentition in the posterior quadrants are being restored with osseointegrated implants. To achieve predictable success, clinicians must possess a comprehensive knowledge of implant biomechanics and recognize that appropriate long-term success rates can only be achieved when the implants are anchored within an adequate volume of bone and are circumscribed with a reasonable zone of attached keratinized tissues that can be maintained by routine oral hygiene. Moreover, sufficient numbers of implants must be placed with proper positioning and angulation. In addition, a thorough knowledge of occlusion is important, and the prosthesis should be designed to minimize lateral forces (bending moments) delivered to the implants supporting the fixed dental prostheses (see chapter 3). The purpose of this chapter is to present a detailed discussion of these and related issues.

Treatment Options

Conventional approaches to restoring the partially edentulous patient should always be considered as the primary option. Studies have shown that when planned and executed properly, conventional prostheses enjoy similar functional outcomes as implant options. However, many dental schools fail to provide sufficient education and clinical training regarding conventional prosthodontic options, and this can negatively impact dentists’ perception regarding the effectiveness of removable partial dentures (RPDs) and conventional fixed dental prostheses (FDPs). It is not surprising that many patients receiving RPDs no longer wear their prostheses 5 years following delivery when taking into account the fact that <5% of casts submitted to dental laboratories have positive rests, and almost all lab prescriptions lack RPD designs. Unfortunately, history is repeating itself with regard to the use of implant-borne prostheses, because few dentists understand the basic fundamentals that are critical to their success. This problem may worsen as dental laboratory technicians are replaced with digital designers who lack a fundamental understanding of prosthodontic principles. Therefore, it is incumbent upon the dental practitioner to master these principles and assume responsibility for all aspects of design and fabrication of either conventional or implant-borne prostheses.

Implants versus RPDs

Regardless of the high predictability of implants, for the foreseeable future, RPDs will continue to be the most common method of restoring extended edentulous areas in the posterior quadrants of partially edentulous patients (Fig 11-1). RPDs are cost effective, the techniques required for their fabrication are well known to most dentists,1 and the esthetic and functional outcomes are, for the most part, equal to those achieved with implant-supported FDPs.2–7 Moreover, superior esthetic outcomes with RPDs can be achieved when restoring anterior extension-base defects with suboptimal soft tissue and bony contours (Fig 11-2). In addition, RPDs may be selected because implant placement in the posterior quadrants may be limited by the existing bony topography, vital structures, and the inability to vertically augment specific bone sites predictably.

Fig 11-1 Completed bilateral distal-extension RPDs for the mandible and maxilla. The masticatory efficiency achieved with these prostheses is similar to that achieved with implant-supported FDPs. (Courtesy of Dr A. Davodi.)

Fig 11-2 An RPD restoring both full anterior and posterior edentulous defects. (a) The canines have been fitted with surveyed metal-ceramic crowns with cingulum rests. (b) The RPD in position. Note that the facial contours of the crowns have been contoured so that the I-bars engage the abutments close to the gingival margin, limiting their visual display during (c) a full smile. Note that the incisal edges have been configured to idealize the smile line. This is a 9-year follow-up photograph. (Reprinted from Chang et al1 with permission.)

The evidence does not support the often-cited belief that compromise of the remaining teeth is a consequence of RPD use.8 There is good evidence that a properly designed RPD with correctly positioned positive rests and appropriately designed and positioned retainers with appropriate extensions results in the preservation of the periodontium of the abutment teeth in a compliant patient. The most important factors in maintaining the dentition of RPD users are patient compliance and close follow-up.

Bassi et al9 provided some interesting insights into the issues that arise during treatment planning for partially edentulous patients. Among a series of 40 consecutive patients screened for consideration of the placement of dental implants, only one patient eventually was restored with implants. Several reasons precluded the use of implants in the other patients, including cost, anatomical limitations, and the patient’s poor compliance, satisfaction with the existing RPDs, fear of surgery, or skepticism regarding the result. Based on these data and the current cost structure for implants, probably many partially edentulous patients will not be restored with implants. The remainder will be restored with RPDs and fixed partial dentures (FPDs) or will not be restored at all.

Potential patients should be informed that, based on the available evidence, implant-supported FDPs offer little or no advantage over RPDs from the perspective of masticatory function and the impact on dietary selection. In a series of classic prospective longitudinal clinical outcome investigations, Kapur2–6 conducted a series of randomized clinical trials to determine whether implant-supported FDPs, using endosteal blade implants splinted to natural tooth abutments, offered an acceptable substitute for mandibular, unilateral or bilateral, distal base extension RPDs (Kennedy Class I and Class II). Surgical and prosthodontic treatment procedures were strictly controlled. A board-certified prosthodontist monitored the activities of the laboratory technicians and the participating investigators so that all treatment and laboratory procedures met prespecified requirements and clinical standards. A total of 218 patients completed the study.

Altered cast impressions were used for all RPDs to idealize the coverage of the edentulous denture foundation areas (Fig 11-3). Resin denture teeth were used to restore the dentition of all the RPDs. The implant was splinted to natural tooth abutments anteriorly, and the definitive prosthesis was cemented (Fig 11-4). Where possible, occlusion was developed to provide anterior guidance; otherwise, group function on the working side was developed with near contact on the balancing side.

Fig 11-3 (a and b) Altered cast impressions were made for all patients enrolled in the study by Kapur2–6 to ensure ideal coverage of the edentulous foundation areas. Note the positive rests on the mesial side of the left premolar and the cingulum rest on both canines. (Reprinted from Chang et al1 with permission.)

Fig 11-4 (a) Implant-tooth– supported FDP of the same type that was fabricated for the study by Kapur.2–6 The implant and the natural tooth abutment have been connected with a pontic between them. (b) There is no attachment between the natural tooth and the implant, and the anterior portion of the prosthesis is cemented to a coping on the natural tooth.

Several parameters that are pertinent to modern implant systems were compared, including differences in masticatory performance, dietary selection and food preferences, overall patient satisfaction, and the cost of initial and follow-up treatment. The researchers reported that both treatments were equally effective in improving chewing function. No significant differences were noted between the two groups for any of the 30 variables assessing food choices and dietary intake. In addition, a large number of patients in both groups expressed satisfaction with their prosthesis. However, an increase in satisfaction was more frequent with impla...

Table of contents

• Cover
• Half Title Page
• Copyright Page
• Title Page
• Contents
• Dedication
• Preface
• Acknowledgments
• Contributors
• Section I: Foundational Principles
• Section II: Restoration of Edentulous Patients
• Section III: Restoration of Partially Edentulous Patients
• Section IV: Special Topics
• Index
• Back Cover