Sinus Floor Elevation Procedures (ITI Treatment Guide, Volume 5) (ITI Treatment Guides) [1 ed.] 3938947187, 9783938947180

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ITI Treatment Guide Volume 5

ITI Treatment Guide

S. Chen, D. Buser, D. Wismeijer

Authors: H. Katsuyama, S. S. Jensen

Volume 5

Sinus Floor Elevation Procedures

Quintessence Publishing Co, Ltd Berlin, Chicago, London, Tokyo, Barcelona, Beijing, Istanbul, Milan, Moscow, New Delhi, Paris, Prague, São Paulo, Seoul, Singapore, Warsaw

German National Library CIP Data The German National Library has listed this publication in the German National Bibliography. Detailed bibliographical data are available on the Internet at http://dnb.ddb.de.

© 2011 Quintessence Publishing Co, Ltd Komturstr. 18, 12099 Berlin, Germany www.quintessenz.de 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, whether electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher. Illustrations: Copyediting: Graphic Concept: Production:

Ute Drewes, CH-Basel, www.drewes.ch Triacom Dental, D-Barendorf, www.dental.triacom.com Wirz Corporate AG, CH-Zurich Juliane Richter, D-Berlin

ISBN (ebook): 978-3-86867-496-5 ISBN (print): 978-3-93894-718-0 The materials offered in the ITI Treatment Guide are for educational purposes only and intended as a step-by-step guide to treatment of a particular case and patient situation. These recommendations are based on conclusions of the ITI Consensus Conferences and, as such, in line with the ITI treatment philosophy. These recommendations, nevertheless, represent the opinions of the authors. Neither the ITI nor the authors, editors and publishers make any representation or warranty for the completeness or accuracy of the published materials and as a consequence do not accept any liability for damages (including, without limitation, direct, indirect, special, consequential or incidental damages or loss of profits) caused by the use of the information contained in the ITI Treatment Guide. The information contained in the ITI Treatment Guide cannot replace an individual assessment by a clinician, and its use for the treatment of patients is therefore in the sole responsibility of the clinician.

The inclusion of or reference to a particular product, method, technique or material relating to such products, methods, or techniques in the ITI Treatment Guide does not represent a recommendation or an endorsement of the values, features, or claims made by its respective manufacturers. All rights reserved. In particular, the materials published in the ITI Treatment Guide are protected by copyright. Any reproduction, either in whole or in part, without the publisher’s prior written consent is prohibited. The information contained in the published materials can itself be protected by other intellectual property rights. Such information may not be used without the prior written consent of the respective intellectual property right owner. Some of the manufacturer and product names referred to in this publication may be registered trademarks or proprietary names, even though specific reference to this fact is not made. Therefore, the appearance of a name without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain. The tooth identification system used in this ITI Treatment Guide is that of the FDI World Dental Federation.

The ITI Mission is …

“… to promote and disseminate knowledge on all aspects of implant dentistry and related tissue regeneration through education and research to the benefit of the patient.”

Preface

Dental implants are routinely used throughout the world to replace missing teeth. A vast body of evidence now supports this treatment as a safe and reliable option for the majority of patients. In many clinical situations, however, inadequate bone volume precludes the placement of needed implants. The posterior maxilla is one region of the mouth where insufficient bone is a frequent occurrence. The floor of the maxillary sinus often lies in close proximity to the roots of the posterior teeth. Dynamic bone remodeling takes place after teeth are extracted, often reducing bone height and bone width and leading to vertical resorption of the alveolar ridge. This presents the clinician with significant challenges in rehabilitating this region of the dental arch. Today, bone grafts and bone substitutes are successfully used to augment the bone volume of the floor of the maxillary sinus. Volume 5 of the ITI Treatment Guide series provides evidence-based data and practical information related to sinus floor elevation procedures. Strong emphasis has been placed on proper case selection, based on a comprehensive clinical and radiological examination of the patient. Supported by the outcomes of the 4th ITI Consensus Conference held in 2008, an analytical review of the literature underpins the discussion on treatment options and on the advantages and disadvantages of the different approaches available. The book includes 13 case presentations illustrating the clinical procedures and outcomes of the transcrestal and the lateral window techniques for sinus floor elevation. A DVD is also available to illustrate

treatment procedures as well as potential complications and their management. Volume 5 of the ITI Treatment Guide series will be of great benefit to clinicians in managing patients requiring dental implants in the atrophic posterior maxilla. Stephen Chen

Daniel Buser

Daniel Wismeijer

Acknowledgment

We would like to thank Mr Thomas Kiss of the ITI Center for his invaluable assistance in the preparation of this volume of the Treatment Guide series. We would also like to express our gratitude to Ms Juliane Richter (Quintessenz Verlags-GmbH) for the typesetting and the coordination of the production workflow, Mr Per N. Döhler (Triacom Dental) for the editing support and Ms Ute Drewes for the excellent illustrations. We also acknowledge Straumann AG, the corporate partner of the ITI, for their continuing support. Additionally, we would like to acknowledge the enthusiastic support and valuable contributions received from the following clinicians in the creation of the chapter manuscripts 3, 4 and 7 for this Treatment Guide volume: Dr. Yoji Kamiura Dr. Toshifumi Kuroe Dr. Shinichiro Kuroshima Dr. Masaharu Mitsugi Dr. Kazutoshi Nakajima Dr. Yasushi Nakajima Dr. Kotaro Nakata Dr. Tsuneyuki Tsukioka Dr. Eiju Sen

Editors and Authors

Editors: Stephen Chen, MDSc, PhD 223 Whitehorse Road Balwyn, VIC 3123, Australia E-mail: [email protected] Daniel Buser, DDS, Dr med dent Professor and Chairman Department of Oral Surgery and Stomatology School of Dental Medicine University of Bern Freiburgstrasse 7 3010 Bern, Switzerland E-mail: [email protected] Daniel Wismeijer, DDS, PhD Professor and Chairman Department of Oral Function and Restorative Dentistry Head Section Oral Implantology and Prosthetic Dentistry Gustav Mahlerlaan 3004 1081 LA Amsterdam, Netherlands E-mail: [email protected]

Authors: Hideaki Katsuyama, DDS, PhD MM Dental Clinic, Center of Implant Dentistry (CID) 3F, 3-3-1 Nishi-ku, Minato-mirai 220-0012 Yokohama, Japan E-mail: [email protected] Simon Storgård Jensen, DDS Department of Oral and Maxillofacial Surgery Copenhagen University Hospital Blegdamsvej 9 2100 København Ø, Denmark E-mail: [email protected]

Contributors

Simon Storgård Jensen, DDS Department of Oral and Maxillofacial Surgery Copenhagen University Hospital Blegdamsvej 9 2100 København Ø, Denmark E-mail: [email protected] Bjarni Pjetursson Professor and Chairman Department of Reconstructive Dentistry Faculty of Odontology University of Iceland Vatnsmyrarvegi 16 101 Reykjavik, Iceland E-mail: [email protected] Vivianne Chappuis, Dr med dent Department of Oral Surgery and Stomatology School of Dental Medicine University of Bern Freiburgstrasse 7 3010 Bern, Switzerland E-mail: [email protected] Ali Tahmaseb, DDS

Department of Oral Function and Restorative Dentistry Section of Oral Implantology and Prosthetic Dentistry Academic Center for Dentistry Amsterdam (ACTA) Gustav Mahlerlann 3004 1081 LA Amsterdam, Netherlands E-Mail: [email protected] Christiaan ten Bruggenkate Professor The VU University Medical Center / ACTA De Boelelaan 1118 1081 HV Amsterdam, Netherlands E-mail: [email protected] Daniel Buser, DDS, Dr med dent Professor and Chairman Department of Oral Surgery and Stomatology School of Dental Medicine, University of Bern Freiburgstrasse 7 3010 Bern, Switzerland E-mail: [email protected] Robert A. Levine, DDS Pennsylvania Center for Dental Implants and Periodontics, One Einstein Center, Suite 211-212 9880 Bustleton Avenue Philadelphia, PA 19115, USA E-mail: [email protected] Paolo Casentini, Dr med dent Narcodont Piazza S. Ambrogio 16 20123 Milano, Italy E-mail: [email protected]

Luca Cordaro, MD, DDS, PhD Head Department of Periodontics and Prosthodontics, Eastman Dental Hospital and Studio Associato Cordaro 00198 Roma, Italy E-mail: [email protected] Waldemar D. Polido, DDS, MS, PhD Oral and Maxillofacial Surgery/Implant Dentistry Contento – Odontologia Especializada R. Marcelo Gama, 1148 Porto Alegre – RS – Brazil E-mail: [email protected] Eduardo Marini, DDS, MS Oral and Maxillofacial Surgery/Implant Dentistry R. General Osório, 329/301 Bento Gonçalves – RS – Brazil E-mail: [email protected] Sanja Umanjec-Korac, DDS, MSc Department of Oral Function and Restorative Dentistry, Section of Oral Implantology and Prosthetic Dentistry Academic Center for Dentistry Amsterdam (ACTA) Gustav Mahlerlann 3004 1081 LA Amsterdam, Netherlands E-mail: [email protected] Timothy Head, DDS Vendôme Surgical Services 5122 Sherbrooke St. West, Suite 201 Montréal, QC, H4A 1T1, Canada E-mail: [email protected] Matteo Chiapasco, MD Professor, Head Unit of Oral Surgery School of Dentistry and Stomatology

San Paolo Hospital, University of Milan Via Beldiletto 1/3 20142 Milano, Italy E-mail: [email protected]

Table of Contents

1

Introduction H. Katsuyama, S. S. Jensen

2

Proceedings of the 4th ITI Consensus Conference and Literature Review: Sinus Floor Elevation Procedures

2.1

Consensus Statements

2.2

Proposed Clinical Approaches

2.3

Literature Review

2.3.1 2.3.2

S. S. Jensen Maxillary Sinus Floor Elevation – Lateral Window Technique Maxillary Sinus Floor Elevation – Transcrestal Technique

3

Preoperative Assessment and Planning for Sinus Floor Elevation Procedures S. S. Jensen, H. Katsuyama

3.1

Anatomy

3.2

Medical History

3.2.1

General Health Status

3.2.2 3.2.3 3.2.4 3.2.5

Concomitant Medications Allergies Tobacco and Alcohol Compliance

3.3

Clinical Examination

3.3.1 3.3.2 3.3.3

Indications and Contraindications for SFE Local Risk Factors Informed Consent

3.4

Radiography, Cone-Beam CT, and Conventional CT for Implant Treatment Involving the Maxillary Sinus

3.4.1 3.4.2 3.4.3

Radiographic Techniques and Radiation Exposure Characteristics of Various Examination Techniques Clinical Application of CT Images

3.5

Non-Grafting Alternatives to SFE

3.5.1 3.5.2 3.5.3

Short Implants Angled/Tilted Implants Zygomatic Implants

3.6

Lateral Window Versus Transcrestal SFE

3.7

Simultaneous Versus Staged SFE

4

Treatment Options for Sinus Floor Elevation H. Katsuyama, S. S. Jensen

4.1

Diagnosis and Treatment Planning

4.1.1 4.1.2

Diagnosis Classification and Treatment Options

4.2

Materials and Instrumentation

4.2.1 4.2.2 4.2.3

Instrumentation for SFE Biomaterials Implant Design

4.3

Surgical Techniques

4.3.1 4.3.2

Transcrestal Technique Lateral Window Technique

4.3.3 4.3.4 4.3.5

Timetable Harvesting Site Managing Septa and Compromised Cases

5

Guidelines for Choosing the Surgical Technique and Grafting Protocol for Sinus Floor Elevation S. S. Jensen

6

Clinical Case Presentations

Transcrestal Protocols 6.1

Implant Placement with Simultaneous SFE: Transcrestal Technique with DBBM S. S. Jensen

6.2

Implant Placement with Simultaneous SFE: Transcrestal Technique with DBBM B. E. Pjetursson

Lateral Window Protocols 6.3

Implant Placement with Simultaneous SFE: Lateral Window Technique with a Composite Graft V. Chappius

6.4

Bilateral Implant Placement with Simultaneous SFE: Lateral Window Technique with a Composite Graft A. Tahmaseb

6.5

SFE with BCP using a Staged Approach C. ten Bruggenkate

6.6

SFE with a Composite Graft using a Combined Simultaneous and Staged Approach ... D. Buser

6.7

Bilateral SFE with Transcrestal and Lateral Window Technique using Various Composite Grafts R. A. Levine

6.8

SFE with a Composite Graft using a Staged Approach P. Casentini

6.9

Combined SFE and Horizontal Ridge Augmentation with Autologous Block Grafts, BCP, and GBR using a Staged Approach L. Cordaro

6.10

SFE with Particulated Autografts Combined with Vertical Ridge Augmentation using Onlay Block Grafts and a Staged Approach W. D. Polido, E. Marini

6.11

Bilateral SFE in the Edentulous Maxilla with DBBM using a Staged Approach S. Umanjec-Korac

6.12

SFE with Particulated Autografts Combined with Vertical Ridge Augmentation using Onlay Grafts and a Staged Approach T. W. Head

6.13

SFE with a Composite Graft Combined with Vertical Ridge Augmentation using Onlay Grafts and a Staged Approach M. Chiapasco

7

Complications with Sinus Floor Elevation Procedures H. Katsuyama

7.1

Intraoperative Complications

7.2

Postoperative Complications

7.3

Case Presentations of Failures and Complications

7.3.1

Membrane Perforation E. Lewis Soft Tissue Dehiscence and Correction after SFE with Vertical and Horizontal Bone Grafting

7.3.2

7.3.3

7.3.4

7.3.5

H. Katsuyama Sinusitis after Undetected Membrane Perforation during Surgery H. Katsuyama Bilateral Sinus Infection after Perforation due to Residual Non-resorbable Barrier Fragments H. Katsuyama Implant Loss due to Unsuccessful Osseointegration H. Katsuyama

7.4

Conclusions

8

References

8.1

References for Literature Review (Chapter 2.3)

8.2

Literature/References

1

Introduction H. Katsuyama, S. S. Jensen

Continuous advances in the field of implant dentistry have provided clinicians with various treatment options to facilitate the placement of dental implants in patients with vertical bone deficits in the posterior maxilla. Today, one of the most common ways to compensate for inadequate vertical bone height is to elevate the sinus floor. Often employed in combination with bone grafts and bone substitutes, sinus floor elevation procedures are of moderate to high complexity, entailing a significant risk of complications. In August of 2008, the ITI held the 4th ITI Consensus Conference to discuss a number of current issues in implant dentistry. One focus was on bone augmentation procedures in localized defects and on the clinical efficacy of the different protocols employed with the many grafting materials and techniques available today. The results of this conference were published in a supplement to the International Journal of Oral & Maxillofacial Implants in 2009. The present fifth volume in the ITI Treatment Guide series summarizes the findings and consensus statements of the 4th ITI Consensus Conference and provides an up-to-date overview of the literature on sinus floor elevation published in the past four years. Reinforced by this scientific evidence, emphasis is placed on clinical recommendations and guidelines for evaluating possible patients for sinus floor elevation and for choosing the appropriate treatment approach and augmentation protocol. All clinical procedures are illustrated and supported by detailed case reports.

As with the preceding four volumes of the ITI Treatment Guide, the authors hope that this fifth volume will prove a valuable resource and reference for clinicians placing implants in patients requiring sinus floor elevation to minimize the risk of complications and to ensure predictable and stable longterm results.

2

Proceedings of the 4th ITI Consensus Conference and Literature Review: Sinus Floor Elevation Procedures

The International Team for Implantology (ITI) is an independent academic organization that brings together professionals from the various fields in implant dentistry and related tissue regeneration. The ITI regularly publishes treatment guidelines based on evidence-based clinical studies supported by long-term clinical results. The ITI Treatment Guides have proven to be an invaluable resource for the clinician active in the field of implant dentistry. The ITI regularly organizes Consensus Conferences to review the current literature on oral implantology and to evaluate the scientific evidence supporting a wide range of clinical procedures, techniques, and biomaterials. The proceedings are published in peer-reviewed journals. The 4th ITI Consensus Conference was held in Stuttgart, Germany in August 2008. For this conference, the ITI Education Committee focused on four topics: • • • •

Risk factors for implant therapy Emerging techniques and technologies in implant dentistry Implant loading protocols, Surgical techniques in implant dentistry

(Proceedings of the 4th ITI Consensus Conference, International Journal of Oral and Maxillofacial Implants 2009. Vol. 24, Supplement.) A working group was elected for the exploration of each topic. Working Group 4, under the leadership of Stephen Chen, reviewed the literature on

surgical techniques. Sinus floor elevation procedures were one of the topics in focus of this group. The participants of Working Group 4 were: Maurício Araújo Jay Beagle Daniel Buser Paolo Casentini Matteo Chiapasco Ivan Darby Javier Fábrega Paul Fugazzotto Timothy W. Head Alessandro Lourenço Januário Simon Storgård Jensen Lars-Åke Johansson John D. Jones Dehua Li Thomas Oates Bjarni E. Pjetursson Waldemar Daudt Polido Paul Rousseau Anthony Sclar Hendrik Terheyden Alex Yi-Min Tsai Gerhard Wahl Dieter Weingart Gerrit Wyma Alvin B. K. Yeo The following section presents the consensus statements and recommended clinical procedures for sinus augmentation.

2.1

Consensus Statements

Group 4 was asked to prepare evidence-based review papers on surgical techniques in implant dentistry. Two review papers contained information related to the techniques and biomaterials used in sinus floor elevation: •

•

Simon Storgård Jensen, Hendrik Terheyden: Bone augmentation procedures in localized defects in the alveolar ridge: clinical results with different bone grafts and bone substitute materials (Jensen and Terheyden 2009) Matteo Chiapasco, Paolo Casentini, Marco Zaniboni: Bone augmentation procedures in implant dentistry (Chiapasco et al. 2009)

Definition of terms The following definitions were adopted from the Glossary of Oral and Maxillofacial Implants (Laney 2007): •

• • • •

Maxillary sinus floor elevation: An augmentation procedure for the placement of implants in the posterior maxilla where pneumatization of the maxillary sinus and/or vertical loss of alveolar bone has occurred. Autograft (synonymous with autologous/autogenous graft): Tissue transferred from one location to another within the same individual. Allograft: A graft between genetically dissimilar members of the same species. Xenograft: A graft taken from a donor of another species. Alloplast: Inorganic, synthetic, or inert foreign material implanted into tissue.

Maxillary sinus floor elevation using the transcrestal technique Maxillary sinus floor elevation using a transcrestal technique is a predictable procedure for augmenting the bone in the posterior maxilla. A

variety of grafting materials can be employed safely and predictably, either alone or in combination. These grafting materials include autografts, allografts, xenografts, and alloplastic materials. At present, it is not clear whether the introduction of a grafting material improves the prognosis.

Maxillary sinus floor elevation using the lateral window technique Maxillary sinus floor elevation using the lateral window technique is predictable for augmentation of bone in the posterior maxilla. A variety of grafting materials can be used safely and predictably, either alone or in combination. These materials include autografts, allografts, xenografts, and alloplastic materials. The use of autografts does not influence survival rates of rough-surfaced implants but may reduce healing times. Bone quantity and density in the residual maxilla influence implant survival rates, independently of the type of grafting procedure used. The survival rates for implants with rough surfaces placed in the augmented maxillary sinus are similar to those of implants inserted in native bone.

2.2

Proposed Clinical Approaches

Maxillary sinus floor elevation using the transcrestal technique •

Sinus floor elevation using the transcrestal technique can be recommended in sites where the alveolar crest is sufficiently wide, initial bone height is 5 mm or more, and the anatomy of the sinus floor is relatively flat. The main disadvantage of this technique is a risk of sinus membrane perforation, which is difficult to manage. Transcrestal procedures should only be user by clinicians experienced in performing sinus floor elevation using the lateral window technique. Primary implant stability is a prerequisite for this technique.

Maxillary sinus floor elevation using the lateral window technique •

•

•

In sites where initial bone height is limited and does not allow implants of the desired length to be placed, sinus floor elevation using the lateral window technique can increase bone height. Atrophy of the maxilla occurs three-dimensionally. The edentulous posterior maxilla should not only be evaluated in terms of initial bone height below the maxillary sinus but also in terms of vertical and horizontal deficiencies of the ridge. If a relevant vertical or horizontal intermaxillary discrepancy is present, onlay bone augmentation may be considered to create sufficient bone volume and a proper intermaxillary relationship in order to optimize implant placement and related prosthetic restoration. Data related to the initial clinical situation should be reported and defects

•

•

classified according to well-defined criteria. If the initial bone height allows primary implant stability, simultaneous implant placement (one-stage) can be recommended. Where primary stability cannot be achieved, the sinus floor should be elevated in a separate procedure, followed by delayed implant insertion (staged approach). Implants should have rough surfaces. Covering the access window with a membrane may be considered.

2.3

Literature Review Simon Storgård Jensen

Maxillary sinus floor elevation was comprehensively reviewed as a major topic at the 4th ITI Consensus Conference in August 2008. The following is a summary of the literature that was reviewed during that conference and of additional papers of significance published subsequently.

2.3.1 Maxillary Sinus Floor Elevation – Lateral Window Technique Note: To improve readability, extensive lists of references (referred to by superscript numbers in brackets) are presented separately in Chapter 8.1. Implant survival Maxillary sinus floor elevation using the lateral window technique is a welldocumented and reliable procedure to increase bone height in the posterior maxilla to allow the placement of dental implants of optimal length. Followup data for one year or more after prosthetic loading were included in 85 studies. These studies reported on 4,807 patients with 14,944 implants inserted in augmented sinuses.[1] Survival rates were 61.2% to 100% (mean: 94.2%; median: 95%) after 12 to 107 months (mean: 31.2 months; median: 29 months) of prosthetic loading. Survival rates of rough-surface implants (plasma-sprayed, acid-etched and/or sandblasted titanium, or HA-coated) were 88.6% to 100% (mean: 97.7%; median: 98.8%), compared to implants with machined implant surfaces, whose survival rates were 61.2% to 100% (mean: 87.9%; median: 89%). Rough-surface implant survival rates are comparable to those of implants in non-augmented maxillary bone. However, success rates determined by established and well-defined success criteria are rarely reported (Chiapasco et al. 2009).

Subantral bone height The vertical distance between the floor of the maxillary sinus and the crest of the posterior maxillary alveolar process constitutes the subantral bone height (also called initial bone height or residual bone height). The subantral bone height is often used to determine whether implants can be placed simultaneously with sinus floor elevation or whether a staged approach should be preferred. Judging from the data in the literature, the mean subantral bone height before grafting was calculated to be 3.8 mm. For simultaneous and two-stage implant placements, it was 4.4 mm and 2.9 mm, respectively. In two-stage procedures, the mean healing time between grafting and implant placement was 6.0 months. The mean healing time between implant placement and loading was 6.3 months. Grafting protocols A bone substitute material only was used in 19 studies (740 patients, 2,481 implants).[2] Autograft material only or a combination of autograft material and a bone substitute was used in 36 studies (1,210 patients, 4,128 implants).[3] The mean subantral bone heights for the two groups were 3.3 mm and 4.0 mm, respectively. For two-stage procedures, the mean healing times before implant placement were 6.6 months and 5.6 months, respectively. In the bone substitute only group, survival rates after 12 to 107 months of loading were 82% to 100% (mean: 96.3%; median: 97.5%). By comparison, the survival rates in the autograft group were 61.2% to 100% (mean: 92.0%; median: 94.4%) after up to 60 months of loading. Excluding studies using smoothsurface implants, survival rates were 88.6% to 100% (mean: 96.6%; median: 96.8%) with a bone substitute alone after up to 42 months of loading, compared to 96% to 100% (mean: 99.4%; median: 100%) when particulated autograft material was included after up to 60 months of loading. Eight grafting protocols for sinus floor elevation were documented in three or more studies. Deproteinized bovine bone mineral (DBBM) only was used for sinus floor elevation in 11 studies (565 patients, 1,771 implants).[4]

The initial bone height was reported in 4 of these studies with an average of 2.8 mm (70 patients, 215 implants). Survival rates after 12 to 68 months in function were 85% to 100% (mean: 96.2%; median: 97%). DBBM and particulated autograft material were used in another 11 studies. [5] However, 4 studies reported on the same pool of patients at different times (Hallman et al. 2001, 2002a, 2004, 2005). Therefore, only clinical data from the latest follow-up were included (Hallman et al. 2005). There were 411 patients receiving 1,061 implants. Initial ridge height was presented as an average of 4.4 mm for 5 patient pools. Survival rates were 89% to 100% (mean: 95.6%; median: 94.9%) with a follow-up of 12 to 60 months after loading. Autologous block grafts were used for augmenting the maxillary sinus in 10 studies, all harvested from the iliac crest.[6] In 5 studies (155 patients), 560 implants were placed simultaneously with the grafting procedure, whereas 4 studies (85 patients, 351 implants) documented a staged approach (1 study did not differentiate between staged and simultaneous implant placement). The overall survival rates after up to 58 months in function were 61.2% to 94.4% (mean: 83.5%; median: 84.9%). For simultaneous and staged implant placements in autologous bone blocks, the corresponding survival rates were 61.2% to 92.2% (mean: 78.7%; median: 79%) and 76.9% to 94.4% (mean: 87.4%; median: 89.1%), respectively. Data on sinus floor elevations using particulated autografts from different donor sites was presented in 7 studies (205 patients, 850 implants).[7] The survival rates after 12 to 54 months of loading were 82.4% to 100% (mean: 95.1%: median: 99.5%). A composite graft consisting of particulated autograft and allograft was presented in 4 studies on 94 patients with 338 implants (2 studies did not report the number of patients; Peleg et al. 1998; Mazor et al. 1999; Peleg et

al. 1999; Kan et al. 2002). All 4 studies reported 100% survival rates after loading for up to 42 months.[8] Alloplastic particulate in the form of hydroxyapatite was used as grafting material for sinus floor elevation in 3 studies by the same group (56 patients, 135 implants; Mangano et al. 2003, 2006, 2007). After up to 36 months in function, survival rates were 96% to 100% (mean: 98.7%; median: 100%).[9] A combination of DFDBA and DBBM was used in 3 studies (Valentini and Abensur 1997; Kan et al. 2002; Valentini and Abensur 2003) reporting on the augmentation of 113 maxillary sinuses (the number of patients was not reported by Kan et al.) and the placement of 283 implants. After up to 107 months in function, survival rates were 82.1% to 96.8% (mean: 90.1%; median: 90.7%).[10] Three case series (63 patients, 110 implants) presented data on sinus floor elevation without grafting material. Instead, the simultaneously placed implants acted as tent poles for the elevated Schneiderian membrane, allowing a coagulum to occupy the space created (Lundgren et al. 2004; Chen et al. 2007; Thor et al. 2007). After 12 to 27.5 months of loading, survival rates were 97.7% to 100% (mean: 99.2%; median: 100%).[11] Membrane over lateral window A barrier membrane was used to cover the lateral window in 16 studies (660 patients, 1975 implants).[12] No membrane was used in 28 studies (1,020 patients, 3,185 implants).[13] Survival rates with and without the use of a membrane were 92% to 100% (mean: 97.8%; median: 99.1%) and 61.2% to 100% (mean: 92.9%; median: 94.9%) after loading periods of up to 60 and 107 months, respectively. Excluding studies using smooth surface implants, survival rates were 92% to 100% (mean: 98.5%; median: 100%) with a barrier membrane after up to 60 months of loading compared to 93% to 100% (mean: 98.5%; median: 100%) without a membrane after up to 36 months of loading. Complications Perforation of the Schneiderian membrane was the most common

intraoperative complication and was reported in 10% to 20% of the cases (range: 0% to 58%; Pjetursson et al. 2008; Chiapasco et al. 2009). The procedure had to be aborted due to the size of the perforation in less than 1% of the cases. A few studies demonstrated a correlation between the size of the perforation and subsequent implant loss, while others failed to observe this link. Other intraoperative complications, including excessive bleeding, displacement of implant or grafting material into the sinus cavity, and damage to the infraorbital nerve were reported in only a few cases. Postoperative infectious complications were reported in 3% of the cases, with partial or complete loss of the grafting material in less than 1% of the cases. Wound dehiscence is another, less commonly reported postoperative complication.

2.3.2 Maxillary Sinus Floor Elevation – Transcrestal Technique Implant survival The transcrestal elevation of the sinus floor (also referred to as the osteotome technique) was documented in 18 studies.[14] The number of implants placed was 1,744, in 1,096 patients. The survival rates were 83% to 100% (mean: 95.9%; median: 97.3%) after 12 to 64 months of prosthetic loading (mean: 27.1 months; median: 24 months). Subantral bone height The mean initial subantral bone height was reported in 14 studies with a mean of 6.4 mm. All studies but one (Stavropoulos et al. 2007) placed the implants simultaneously with transcrestal sinus floor elevation.[15] Grafting protocol Results after elevating the sinus floor without grafting material in 249 patients (443 implants) with a mean initial bone height of 5.8 mm were reported in 8 studies.[16] Survival rates were 91.4% to 100% (mean: 95.6%; median: 96.5%) after 12 to 36 months of loading (mean: 23.3 months; median: 23 months). DBBM only was used as grafting material in 4 studies (Zitzmann and Schärer

1998; Deporter et al. 2005; Rodoni et al. 2005; Krennmair et al. 2007) on 122 patients with a mean initial bone height of 7.5 mm, in whom 195 implants were placed. Survival rates were 95% to 100% (median: 99%) after a followup period of 12 to 45 months after loading.[17] The highest number of patients (489) was grafted with autologous bone in which 771 implants were placed in subantral bone with a mean initial height of 6.6 mm and followed for 20 to 54 months after loading (Fugazzotto and De Paoli 2002; Ferrigno et al. 2006). Survival rates were 93.8% to 97.8% (median: 94.8%).[18]

3

Preoperative Assessment and Planning for Sinus Floor Elevation Procedures S. S. Jensen, H. Katsuyama

Careful patient selection is critical to the long-term success of implant treatment in cases requiring sinus floor elevation (SFE). For proper evaluation, clinicians need in-depth knowledge of the anatomy both of the maxillary sinus with its adjacent structures and of the pattern of bone modeling that takes place after tooth extraction. Relevant aspects of each medical history need to be assessed to determine the patient’s suitability for SFE. There is a need for clinicians to understand in detail the indications and contraindications, the various treatment options available, and the implications of different radiographic techniques. Only with this information can they select appropriate cases for treatment and consider non-grafting alternatives to SFE.

3.1

Anatomy

Fig 1a Frontal view of the maxillary sinus.

Fig 1b Lateral view of the maxillary sinus with limited extension of the sinus floor in an anterior and inferior direction.

Fig 1c Lateral view of the maxillary sinus with the sinus floor extending around the apices of the maxillary molars and second premolar.

Fig 2 Panoramic radiograph showing the maxillary sinus bilaterally extending to the regions of the central incisors.

The maxillary sinus is a pyramid-shaped cavity within the maxillary bone (Figs 1a-c) The base of this pyramid is formed by the lateral nasal wall and the tip within the maxillary zygomatic buttress. The roof (i.e. the cranial wall) of the maxillary sinus is also the floor of the orbit and accommodates the infraorbital canal. A communication with the nasal cavity (the semilunar hiatus) is located in the posterosuperior area of the sinus cavity just below the concha nasalis media. To minimize the risk of postoperative infective complications, this communication should be kept intact and clear of any grafting material. Anteriorly, the maxillary sinus will normally extend to the canine or premolar region, although this may vary considerably (Fig 2). The sinus floor will usually take a downward convex route with the deepest point in the first-molar region. The cavity does not occupy any significant space before the permanent teeth erupt and becomes increasingly larger throughout life. Ongoing pneumatization is seen throughout adolescence, and secondary pneumatization may follow the loss of posterior maxillary teeth. Conical elevations projecting into the cavity, reflecting the roots of the maxillary molars and premolars, are frequently observed. Bony walls or septa may project into the cavity from the sinus floor and lateral wall (Figs 3a-b).

Fig 3a Panoramic radiograph of an edentulous patient with bilateral septa in the posterior third of the maxillary sinus.

Fig 3b Coronal section of a CT scan of the same patient confirming the presence of septa. At this level, the septae completely divide the sinus into two compartments in the orofacial dimension.

In fact, septa may divide the entire sinus into two or more almost completely separated entities. Their incidence varies between 16% and 58%, most commonly taking the form of a single unilateral septum (Koymen et al. 2009). Septa are classified as primary or secondary, the former being developmental in nature, while the latter are caused by irregular pneumatization following the loss of posterior teeth. It is essential that any irregularities of the maxillary sinus floor be identified preoperatively, as such irregularities will increase the risk of sinus membrane perforation during surgery. The mucosal lining of the maxillary sinus (also known as the sinus or Schneiderian membrane) consists of normal ciliated respiratory epithelium covering a thin layer of connective tissue. It ranges in thickness between 0.45 and 1.40 mm. As a thin membrane increases the risk of intraoperative

perforation, any preoperative findings that can help predict membrane thickness are potentially useful when preparing for the surgical procedure. A number of factors are commonly associated with increased membrane thickness: thick gingival biotype and a history of chronic sinus inflammation. In contrast, smokers tend to have reduced membrane thickness (Aimetti et al. 2008; Hadar et al. 2009). SFE procedures are contraindicated if membrane thickness is increased due to existing sinus pathology (e.g. sinusitis or mucosal cysts). Conditions of this type should be treated in a separate session before the procedure. The lateral bony wall of the maxillary sinus may also vary considerably in thickness. The normal range is between 0.5 and 2.5 mm, with values generally being somewhat higher in men than women (Neiva et al. 2004; Yang et al. 2009). Preoperatively, this information can only be obtained from coronal sections of a cone-beam or traditional CT scan. The blood supply for the maxillary sinus comes from the infraorbital artery, the greater palatine artery, and the posterior superior alveolar artery. This latter vessel is a particular concern for SFE procedures, as it may pass through the area where preparation of the lateral window is planned. The distance of the intraosseous posterior superior alveolar artery to the alveolar crest is 16 to 19 mm on average (Elian et al. 2005). Cases of extensive intraoperative bleeding will usually originate at the lateral sinus wall or at a tear in the Schneiderian membrane. The sinus floor itself will rarely contain any vessels of clinical significance. However, when SFE procedures are conducted through a transcrestal technique, orofacial narrowness of the sinus may cause the osteotome to engage the lateral wall, thus inducing significant bleeding from the posterior superior alveolar artery.

3.2

Medical History

Before implant treatment and bone augmentation can be performed, it is mandatory to thoroughly review the patient’s medical history. Special attention should be devoted to patient-related factors that may affect bone healing prior to determining the suitability of a patient for SFE. A systematic approach includes: 1. 2. 3. 4. 5.

General health status Concomitant medication Allergies Tobacco and alcohol Compliance

3.2.1 General Health Status Candidates for SFE should not present with any conditions that would affect bone healing, either locally or systemically. Patients who have undergone head-and-neck radiotherapy where the field of irradiation included the maxilla should not be considered for SFE. Poor glycemic control in diabetic patients (i.e. uncontrolled diabetes) has been associated with increased susceptibility to postoperative infections; these patients should be treated with great caution. SFE procedures are not, however, contraindicated in patients with well-controlled diabetes (Tawil et al. 2008). Transplant patients may be undergoing long-term immunosuppressive therapy. While several experimental studies have shown that immunosuppressive agents like cyclosporine reduce normal bone healing around dental implants, no clinical data regarding implant placement or SFE procedures are available for patients of this type. It has been recommended that alternatives to implant treatment and bone augmentation be preferred until clinical data are available to support these procedures (Bornstein et al. 2009a). Whether osteoporosis is a risk factor for implant failure is open to debate. While it is believed that osteoporosis does not per se contraindicate implant placement or SFE, the

risk may be increased by long-term treatment with oral bisphosphonates (Bornstein et al. 2009a). Studies dealing with implant placement or bone augmentation procedures in patients with neuropsychiatric disorders are virtually non-existent. Disorders of this type are not contraindications in themselves, but may affect compliance. It is extremely important to make sure that these patients will be able to comply with postoperative instructions and to maintain an adequate level of oral hygiene.

3.2.2 Concomitant Medications A complete list of medications should be obtained well ahead of the surgical procedure, allowing the surgeon to evaluate whether any of the drugs would pose an absolute contraindication to the planned treatment. Absolute contraindications would include i.v. bisphosphonates, chemotherapy, or indeed any drug known to suppress bone healing or immune response. Other types of medication, such as antithrombotic drugs, indicate that extra caution should be exercised during surgery. Antithrombotic treatment should generally not be discontinued, as the risk of severe bleeding is usually much lower than the risk of thromboembolic events (Madrid and Sanz 2009). Discontinuation or a dose reduction from therapeutic to prophylactic levels may be indicated if a complex procedure involving an increased risk of bleeding is expected (e.g. extensive bone augmentation, extraoral bone harvesting). Any adjustments of concomitant medication should only be made in agreement with the patient’s physician. In addition, surgeons need to make sure that regular medications will not interact with drugs prescribed in relation to surgery. A number of known interactions with antibiotics and analgesics dictate that the treatment of patients on antithrombotic vitamin-K antagonists should be considered very carefully.

3.2.3 Allergies While allergies per se are rarely an issue for SFE, some patients may be allergic to any of the perioperative medications prescribed, notably including antibiotics and analgesics.

3.2.4 Tobacco and Alcohol Smoking is a risk factor for implants placed both in native bone and in the augmented posterior maxilla (McDermott et al. 2006; Huynh-Ba et al. 2008; Heitz-Mayfield and Huynh-Ba 2009). Although tobacco use should not be considered an absolute contraindication for SFE procedures, it is mandatory to inform these patients about the increased risk of implant loss and periimplant bone infection. They should be motivated to quit or at least reduce their smoking. Alcohol is known to affect bone grafting. However, the main issue with alcoholism in implant patients are presumably compounding factors such as malnutrition, poor oral hygiene and compliance (Li and Wang 2008). Therefore, patients with any kind of abuse issue should be evaluated with utmost care. In many situations, alternatives to implant therapy including SFE procedures should be preferred.

3.2.5 Compliance Patients unable to comply with postoperative instructions or presenting with inadequate oral hygiene should not be considered for SFE procedures.

3.3

Clinical Examination

3.3.1 Indications and Contraindications for SFE Careful and appropriate selection of patients based on well-defined clinical indications is critical to the long-term success of implant treatment with SFE. Proper case selection requires a thorough (clinical and radiographic) examination and careful treatment planning. In addition to the general examination requirements for implant treatment, specific aspects of the maxillary sinus need to be examined on a separate basis. Ridge morphology and interarch relations need to be assessed specifically from a restorative viewpoint. A detailed radiographic examination, usually by computed tomography, is indispensable. Following this detailed examination, the final treatment plan is developed based on the best scientific evidence available. It is recommended to pursue the following treatment objectives in the edentulous posterior maxilla requiring SFE: 1. 2. 3. 4.

Occlusion extending at least to the first molar. Surgery on an outpatient basis under local anesthesia. Bone harvesting from intraoral donor sites. Simultaneous implant placement (only if primary implant stability is ensured).

Two basic types of SFE procedures can be distinguished: the transcrestal technique and the lateral window technique. A transcrestal technique is selected when conditions in the surgical site are ideal (i.e. adequate orofacial bone width, sufficient subantral bone to achieve implant stability, acceptable interarch relation). Creating a lateral window for access is preferred when a transcrestal technique is rendered impossible by advanced resorption (lack of bone volume) or complex sinus anatomy (i.e. secondary cavity). Furthermore, it may be necessary to revert to the lateral window technique when the sinus

membrane has been perforated on attempting a transcrestal technique.

Fig 4 Narrow sinus.

3.3.2 Local Risk Factors Contraindications SFE procedures are contraindicated in irradiated patients, full-dose radiotherapy, and i.v. administration of bisphosphonates. Factors involving a high risk Chronic periodontitis is a risk factor for SFE and implant therapy. Individuals with untreated periodontitis should not receive dental implant treatment or SFE until periodontitis has been managed successfully. Even after periodontitis has been treated, there is still a trend for lower survival and/or success rates than in patients with no history of periodontitis (Heitz-Mayfield and Hyunh-Ba 2009). Consequently, patients who have a history of periodontitis need to be counseled on the increased risk of peri-implantitis and of implant failure. Acute sinusitis is a high-risk factor for SFE. Dental factors have been reported to be the cause of sinusitis in 10% to 12% of cases (Brook 2006). Teeth with periapical lesions or cysts have been implicated. In patients with periapical disease, the odds ratio for sinusitis was 3.6 (p < 0.0001) compared to controls (Abrahams et al. 1996). Also, in cases with a suspected communication between a sinus and apical tooth segment, an adequate healing period should be considered between tooth extraction and SFE to minimize the risk of perforating the Schneiderian membrane.

Significant difficulties are likely to arise in the wake of less-than-ideal postsurgical healing of soft and hard tissues. A communication between the extraction socket and maxillary sinus would increase the risk of membrane perforation and hence the surgical risk at large. This possibility needs to be carefully evaluated. Numerous cases of tooth loss due to periodontitis are followed by extensive destruction of local bone. In this situation, the resultant bone defects and their relationship with the sinus floor become complex. It should also be noted that extensive (three-dimensional) bone augmentation will be required in the presence of extreme bone resorption. Situations of this type often require bone harvesting from extraoral sources such as the iliac crest. Factors involving a moderate risk Several studies have reported higher failure rates for implants in smokers than non-smokers following SFE (Keller et al. 1999; Olsen et al. 2000; Mayfield et al. 2001; Kan et al. 2002). In a recent systematic review, the rate of implant failures in grafted sites was shown to be almost twice as high in smokers as in non-smokers (Pjetursson et al. 2008). Even though the difference was not statistically significant, caution should be exercised when considering smokers for SFE. It should be noted that smoking combined with a history of treated periodontitis has clearly been demonstrated to be a risk factor both for implant survival and for biological complications in general (Heitz-Mayfield and Hyunh-Ba 2009). Abnormalities of the sinus membrane (e.g. hypertrophy) are not a contraindication to SFE but should be considered a relative risk. Hypertrophy of the Schneiderian membrane may be caused by chronic sinus infection, radicular cysts, allergies, benign tumors, developmental cysts, or fibrous dysplasia. Infective causes of membrane thickening are diagnosed based on an examination that will include dental symptoms (e.g. dull pain, periradicular pneumatization) and the patient’s medical history (Brook 2006). Inflammatory polyp formation is a common finding in the nasal cavity. SFE can generally be safely conducted in the presence of mild membrane

thickening or where the hypertrophy is not caused by infection. Situations of aberrant site healing following extraction will involve an increased risk of sinus perforation. It is necessary to allow sufficient time for healing and restitution of the sinus membrane (van den Bergh et al. 2000a). Any abnormalities of the alveolar mucosa caused by infection, bullous disease, or aberrant healing will increase the risk of soft tissue dehiscences following surgery. Any of these conditions need to be treated and resolved prior to conducting SFE. Any secondary cavity identified in the presurgical CT study will need to be assessed for its complexity. Noncomplex secondary cavities can usually be managed at a moderate risk of perforation. The maxillary sinus is a pyramideshaped cavity; it is believed that the narrow form is often found in the anterior region of the sinus (Fig 4) (van den Bergh et al. 2000a; Velloso et al. 2006). Obtaining adequate access to this region, which is frequently the site of perforation, is difficult and may require a larger window than initially thought. In the presence of an artery, any osteotomy created in the lateral wall will increase the risk of hemorrhage during and after surgery (Greenstein et al. 2008). A detailed presurgical analysis, including a CT scan, is mandatory to identify any of these rare blood vessels in the lateral wall (van den Bergh et al. 2000a). Bone density is usually poor in maxillary posterior segments. Compared to the other major jaw segments (anterior maxilla, anterior mandible, posterior mandible), the posterior maxilla has the lowest bone density in terms of Hounsfield units (de Oliveira et al. 2008; Turkyilmaz et al. 2007). One study found this difference to be statistically significant (Fuh et al. 2010). In the presence of a minimal cortical layer, primary implant stability will be difficult to obtain. In situations when cancellous bone is non-existent, bone regeneration with bone substitute alone is very difficult, making the use of autogenous bone alone or in combination with bone substitute indispensable (Jensen and Terheyden 2009). There is also a higher likelihood of encountering unfavorable interarch relations in the posterior maxilla due to the specific three-dimensional pattern of bone resorption in the molar areas. Both vertical augmentation of the sinus floor and horizontal bone augmentation may be needed to optimize the

restorative outcome. These cases require the use of autogenous block grafts. When bone height is inadequate for implant placement due to a combination of vertical resorption of the alveolar bone and sinus pneumatization, it is necessary to explore the need for vertical bone augmentation at the crest. Although evidence for a relationship between bruxism and implant failure is lacking (Lobbezoo et al. 2006), relevant precautions should be taken for implants placed in the posterior maxilla following SFE. All biomechanical aspects relating to the span and design of the prosthesis should be carefully considered. Depending on the clinical situation, the recommendation is usually to select as many implants as possible and of the greatest length possible. An extended healing period before loading the implants helps to minimize the risk. If bone height is inadequate and not enough implants can be placed, it is preferable to use an implant-supported removable overdenture, such that the mucosa will be able to dissipate some of the load. A night guard (occlusal splint) is recommended (Zinner et al. 2008). The condition of the teeth (e.g. remaining tooth structure or pulp status) adjacent to the proposed SFE needs to be considered prior to treatment planning for SFE, so as to minimize any unexpected tooth-related complications that might otherwise persist and eventually affect the longterm outcome.

3.3.3 Informed Consent SFE for implant treatment is a complex surgical procedure. Clinicians need to explain its advantages and disadvantages for patients to give their informed consent. The following points should be considered in these discussions: 1. Alternative restorative options with their strengths and weaknesses, including fixed dental prostheses with a distal cantilever and removable dental prostheses. 2. Alternative implant options, including shortening of the dental arch, distal cantilever implants supported fixed dental prosthesis, and angled implants to increase the distal reach of the implant-supported prosthesis (see Chapter 3.5).

3. Selection of biomaterials and source (intraoral, extraoral) and volume of autogenous bone (Chen et al. 2009). 4. Short-term and long-term surgical risks (e.g. sinusitis) and long-term prognosis (survival and success rates, complication rates when SFE is performed). 5. Esthetic risk, especially in patients with broad smiles disclosing the posterior maxillary teeth (Fradeani 2004). 6. Cost of treatment, as implant procedures involving SFE are invariably more expensive than standard implant treatment. 7. Duration of treatment, as staged SFE in particular will involve protracted treatment periods. 8. Esthetic demands, patient cooperation, and consent to treatment.

3.4

Radiography, Cone-Beam CT, and Conventional CT for Implant Treatment Involving the Maxillary Sinus

3.4.1 Radiographic Techniques and Radiation Exposure Radiographic techniques for sinus imaging Radiographic imaging is indispensable to determine anatomical complexity and the most appropriate treatment approach in any type of implant treatment. Computed tomography (CT) is particularly effective when implants are planned in the atrophic posterior maxilla, offering diagnostic insight into the form of the maxillary bone that is not attainable by panoramic radiography alone (Dula et al. 1996). EU guidelines (Radiation in implantology 2004) recommended that plain dental radiography and panoramic radiography should be combined with conventional CT or cone-beam CT (CBCT). Table 1 illustrates the scheduling of these various recommended techniques. Radiation exposure Patients will be exposed to radiation in any kind of radiographic examination. It is therefore necessary to know the dose level and the anatomical structures likely to be included in the field of radiation. Structures particularly sensitive to radiation that will normally be exposed to radiation during imaging of the maxillary sinus include the corneas and salivary glands (Ekestubbe et al. 1993). The International Commission on Radiological Protection (ICRP) supports the use of radiographic imaging in the planning phase of implant treatment (2007). The disadvantage of radiation exposure is exceeded by the large body of detailed information offered by CT, such as the form of the sinus and posterior maxilla or the presence of any septa or vascular structures (Dula et al. 1996; Ganz 2009).

Table 1 Radiographic imaging of the maxillary sinus and posterior maxilla: timing and recommended techniques.

Periapical radiograph

Panoramic radiograph

•

•

Initial visit

CT or CBCT

• (Maxilla/Mandible)

Before surgery After surgery (after SFE)

•

(Maxilla)

After surgery (after placement)

•

(Maxilla)

Long-term monitoring

•

∆

Emergency

∆

•

• recommended,

justified, ∆ optional

Table 2 Stochastic effect by radiation exposure given as carcinogenesis rate and risk of fatal cancer.

Radiographic technique

Effective dose

Risk of fatal cancer

Intraoral dental radiograph

1–8 µSv

0.02–0.6 x 10-6

3.85–30 µSv

0.21–1.9 x 10-6

Panoramic radiograph

27–1073 Cone-beam CT (CBCT)

–

µSv Multi-slice CT (MCT)

474–1410 µSv

Maxilla 8–242 x 10-6 Mandible 18.2–88 x 106

A preoperative CT scan to evaluate the anatomy of the maxillary sinus is therefore strongly recommended. CBCT will involve a significantly lower effective dose of radiation than conventional multi-slice CT (MCT) in the majority of cases and is therefore usually preferred, especially because in some cases several examinations are required. Considering the risk of inducing malignancies, however, the indication for CBCT needs to be carefully assessed in each case. Table 2 summarizes the effective doses of various radiographic techniques against the risk of developing fatal cancer (EU guidelines 2004, Koong 2010). Effective doses of MCT and CBCT examinations cover a wide range. Doses delivered by MCT will vary with imaging protocols, which can be customized by the radiologist. Low-dose MCT protocols have been reported to yield diagnostic images of sufficient quality for numerous purposes in dentistry (Koong 2010). CBCT offers less control over imaging protocols than MCT. Effective doses delivered by CBCT will largely depend on the equipment used. Paradoxically, some small field-of-view units may deliver higher doses than larger field-of-view units. Various units and studies available on the subject have been found difficult to compare (De Vos et al. 2009).

3.4.2 Characteristics of Various Examination Techniques Examination by intraoral and panoramic radiography Intraoral radiography using a film retainer and a paralleling technique is a good imaging technique to obtain preliminary information and to evaluate the degree of vertical alveolar bone resorption following tooth extraction. Panoramic radiographs will also yield a good overview, but with varying degrees of vertical and horizontal distortion along the image. Varying magnification factors along the film (15% to 30%) may be present that affect the positional relationships between anatomical structures. These overview

techniques will provide a basis to assess the need for SFE and to perform a CT scan with the patient’s consent.

Figs 5a-b Presurgical examination of the subantral bone will often require more than conventional periapical radiographs. In this case, the intraoral radiograph suggested a bone height of 12.2 mm (a), but the true height demonstrated by CBCT was actually 6.5 mm (b). Three-dimensional diagnosis by CT is recommended whenever possible, even if few implants are planned.

Intraoral radiography Intraoral radiography using the paralleling technique can provide information on available bone height and trabeculation. However, as the technique does not shed light on orofacial bone width the majority of proposed implant sites cannot be properly evaluated on this basis alone. Care must be taken to account for image distortion if the film is not placed parallel to the long axis of the ridge and/or if the x-ray beam is not perpendicular to the film. Figs 5ab give an example of the potential magnitude of distortion. Intraoral radiography may suggest a bone height sufficient to place an implant without bone augmentation (Fig 5a) while CBCT may demonstrate that bone height is actually reduced to a much larger degree (Fig 5b). Diagnostic errors of this

magnitude can have significant clinical consequences. After treatment, intraoral radiography is recommended to verify the outcome of implant placement and for long-term monitoring of peri-implant bone conditions (Fig 6).

Fig 6 Intraoral radiography has the advantage of offering relatively low radiation exposure and convenient handling. It is therefore effective for initial evaluation of the subantral bone and longitudinal observation after implant installation. This image reveals peri-implant bone conditions 3 years after a mixed simultaneous and staged approach. Starting from the mesial aspect, the first implant was placed into an extraction socket, the second was placed in a simultaneous approach, and the third/fourth implants in a staged approach. Given its radiation levels, CT imaging is currently not considered appropriate for routine longitudinal examination.

Panoramic radiography This examination offers substantial information about the form of the maxillary sinus, about the form of the alveolar bone relative to the sinus floor, and about any pathological processes (e.g. in the jawbone, maxillary sinus, or temporomandibular joint) that may affect implant treatment. On the downside, no cross-sectional images are created, and the insights gained (e.g. into the presence of septa) may be inferior to CT-based information. Examiners need to watch out for an artifactual pneumatic cavity projected apically to the roots of the maxillary anterior teeth (Fig 7). To avoid this artifact, the dorsum of the tongue should be pushed against the hard palate as the radiation is applied. Computed tomography MCT consists of multiple image slices, acquired by finely collimated flat, fan- or shuttlecock-shaped beams rotating around the subject in a helical

pattern (Fig 8). CBCT images, by contrast, are obtained by a diverging cone/ pyramidal-shaped beam rotating around the subject once (Fig 9) (Scarfe and Farman 2008; White and Pharoah 2008). While MCT data are typically obtained with the patient in a supine position, a seated or standing position is selected for most CBCT scans (Koong 2010). MCT versus CBCT Clear guidelines for selecting either MCT or CBCT are currently not available. The decision must be made upon careful consideration of the differences between both technologies. It should also be noted that significant differences exist between systems from different manufacturers. What follows should therefore be regarded as a general discussion of MCT versus CBCT (Table 3).

Fig 7 Panoramic radiograph prior to SFE in the right posterior segment. Although a secondary cavity is clearly present, it is difficult to appreciate its extent and to define the height and form of the septum. A CT scan is indispensable for the final diagnosis.

Generally speaking, CBCT units will generate images at a significantly lower voxel resolution than MCT. One should realize, however, that other factors such as beam hardening and increased metal artifacts in CBCT may detract from this advantage of higher resolution (Draenert et al. 2007; Watanabe et al. 2009). As MCT units will capture a given volume faster than CBCT units, they meet with better acceptance by patients and involve less motion-related degradation. The supine position of patients during MCT scanning is likely to cause less motion-related errors than the standing or sitting position required for CBCT scanning (Koong 2010).

Table 3 Characteristics of MCT and CBCT (Revised after Koong 2010).

MCT

CBCT

0.35–0.5 mm

0.076–0.4 mm

2 Distance measurement

Good

Excellent

3 Hounsfield number

Good

NG (gray scale only)

4 Soft tissue imaging

Excellent

Poor

Short

Longer

6 Scatter

Minimal

Larger

7 Signal-to-noise ratio

Precise control

Low

8 Beam hardening

Minimal

More

More

Less

1 Voxel size

5 Scan time

9 Metal artifacts

Fig 8 Conventional CT scan. The large field of view reveals the symmetry of the maxillary sinuses and allows examination of a wide surgical field.

Fig 9 CBCT scan following bilateral SFE. CT scans with a large field size are useful if the maxillary sinuses must be examined for cavity symmetry and membrane thickening and intraoral bone harvesting is planned. This scan suggests an inflammation in the left maxillary sinus after surgery.

CBCT images are acquired with a much larger cone-shaped volume than MCT images. This increases scatter, which in turn significantly raises the level of image noise and degradation compared to images acquired with MCT. Similarly, CBCT also involves a lower signal-to-noise ratio, which will result in less image variation between structures of different densities and in “flatter” images (Koong 2010). A higher level of beam hardening associated with CBCT than MCT (Draenert et al. 2007; Sanders et al. 2007) can give rise to shadows and bands caused by dense nonmetallic structures, especially in the head-and-neck area where denser structures are in close proximity. While metal artifacts from restorations or preexisting implants play a greater role with MCT than CBCT, other limitations of CBCT such as beam hardening tend to offset this advantage, such that both techniques have similar drawbacks with regard to imaging structures close to metallic objects (Koong 2010). CBCT systems have a small footprint and can be readily installed in confined spaces. For the convenience of patients, more and more of these systems have been set up in dental offices lately. Clinicians should be aware that the responsibility for interpreting all volume data will rest with the individual obtaining the images. Ethical standards and legal requirements dictate that practitioners unable to interpret the data records in their entirety should arrange to have this performed by appropriately trained and experienced radiologists (Carter et al. 2008).

Both MCT and CBCT have been shown to have sufficient accuracy in terms of planning for implant treatment when measurements may be critical (Koong 2010). In most cases, CBCT will offer sufficient three-dimensional information on sinus anatomy to plan for an SFE procedure at a reasonably low radiation dose. The anatomical structures involved are usually well depicted. Some CBCT units rival panoramic radiography in terms of low radiation exposure while offering the added benefit of volumetric 3D data. With carefully selected equipment, a case could be made for using CBCT instead of panoramic radiography in implant planning, as patients would only be exposed to a single dose of radiation (CBCT) rather than two doses (panoramic radiography followed by CT scanning) in this way. However, MCT may still be indicated (1) to obtain detailed information about soft tissue structures such as mucosa, gingiva, and sinus membrane; (2) if a pathology of the sinus and adjacent structures is suspected; or (3) to evaluate bone density. The effective use for CBCT includes (1) image acquisition at high accuracy by taking a picture in a small radiation field, and (2) linear measurement (Figs 10a-b). Furthermore, 3D reconstruction with proprietary software as offered by most systems will permit a better understanding of the sinus anatomy but is not suitable for making actual measurements.

Figs 10a-b CBCT scans obtained after implant placement using a transcrestal technique. This image is highly accurate thanks to the narrow acquisition range (a). Following implant placement, the sinus floor is elevated and the grafting material compressed into the elevated space by the implant (b).

3.4.3 Clinical Application of CT Images CT images are reconstructed from the original digital data captured by the scanning unit. They are stored, handled, printed, and transmitted in standard DICOM (Digital Imaging and Communications in Medicine) format. Analysis using simulation software DICOM data provide the basis to reproduce the anatomical features under study. The virtual environment thus created can be used to plan implant locations using simulation software and to share this plan with other members of the dental team. Simulation software will readily disclose the need for SFE or any other bone augmentation procedures. It will also supply information about the augmentation volume required for an ideal outcome and about implant parameters such as ideal length, number, and positioning. This approach offers significant advantages especially in anatomically complex posterior segments of the maxilla (Figs 11a-b).

Figs 11a-b Simulation software offers significant advantages for implant planning. Once the form of the maxillary sinus and subantral bone has been determined (a), implants can be placed in a virtual environment (b). This will further the clinician’s understanding of the amount of bone augmentation required and of ideal implant parameters (location and length). The overall technical accuracy of the surgical procedure will be improved. Several surgical techniques are frequently combined, and simulation software allows conveying this information to the patients for consent.

Figs 12a-c In this simulated plan, SFE can be avoided by placing an implant in the premolar area in an inclined position (a). In cases such as these, the simulation software can be used to analyze the superimposed image of the final superstructure, thus rendering the treatment plan more accurate and facilitating construction of a surgical template (b and c).

Simulation software will also yield vital information to consider alternatives to SFE. A case is presented in which implants placed in the premolar areas were inclined to avoid SFE (Figs 12a-c). The sequence of procedures involving the use of simulation software includes: 1. 2. 3. 4. 5. 6.

Initial diagnosis Fabrication of a scanning stent CT scanning Treatment planning Construction of a jaw model Surgery

Software-based simulation based on CT data can be readily implemented and is an effective tool for managing the posterior maxilla. However, given the rapid developments in software applications and fabrication technologies for

surgical templates, any new processes and systems should always be carefully verified.

3.5

Non-Grafting Alternatives to SFE

3.5.1 Short Implants While the survival rates of single-tooth replacements were found to be reduced if supported by implants < 10 mm in length (Renouard and Nisand 2006) (Fig 13), interest in these short designs has been growing with the introduction of rough surfaced implants. Survival rates of rough-surfaced short implants for single-tooth replacement have been reported to approach those of implants ≥ 10 mm (Deporter et al. 2008; Corrente et al. 2009). However, this finding was predominantly obtained in the posterior mandible, where the bone is usually of higher density. Therefore, it should be expected that an implant < 10 mm placed in the posterior maxilla carries an increased risk of failure (Hagi et al. 2004). The survival rates of short implants in the posterior maxilla have never been compared to those of longer implants in combination with SFE for the same indications, nor in randomized controlled studies. Due to crestal bone loss and/or sinus pneumatization, vertical bone height will often fall short of 10 mm in the posterior maxilla. Until more data regarding the long-term survival of implants < 10 mm are available, it is still recommended to augment sufficient bone to accommodate an implant ≥ 10 mm in length. Implants < 10 mm may be considered when two or more implants are about to be placed, and provided that the implant-supported crowns are rigidly splinted.

Fig 13 Treatment options in the case of a pneumatized maxillary sinus in the second premolar region: Placement of short implant vs. placement of an implant ≥ 10 mm in combination with an SFE.

Fig 14 Placement of 4 implants for the support of a fixed bridge establishing second premolar occlusion in an atrophic posterior maxilla. The two posterior implants are angulated 45 degrees distally to avoid an SFE and to emerge in the area of the second premolars. These are rigidly fixed to the two anterior implants, which, importantly, are loaded axially.

Fig 15 Placement of 6 implants for the support of a fixed bridge establishing first molar occlusion in an atrophic posterior maxilla. The two posterior implants are anchored in the maxillary tuborosity/pterygoid plate to avoid an SFE. They are rigidly fixed to the anterior

implants, which are loaded axially.

3.5.2 Angled/Tilted Implants To avoid sinus grafting, angled implants may be anchored in the anterior or posterior sinus wall or in the pterygoid plate (Figs 14 and 15). This approach will potentially reduce the overall duration of treatment and enable the use of longer implants, thus adding to the primary stability of implants placed in the posterior maxilla. That being said, any tilted implants will need to be rigidly connected to axially loaded implants in the anterior segment. This need limits the spectrum of indications almost exclusively to completely edentulous patients and requires sufficient native bone in the anterior segment to accommodate two or more axially loaded implants. There are also high demands on restorative planning and coordination. Angled posterior implants combined with at least two anterior implants in native bone by way of cross-arch stabilization have been demonstrated to offer short-term success rates on a par with roughsurfaced implants placed in bone augmented by SFE procedures (Block et al. 2009; Jensen and Terheyden 2009; Chiapasco et al. 2009).

Fig 16a Placement of 6 implants for the support of a fixed bridge establishing first molar occlusion in an atrophic posterior maxilla. As an alternative to an SFE, the two posterior implants are anchored in the zygomatic bodies and go through the maxillary sinus bilaterally to emerge in the area of the first molars. These are rigidly fixed to the four anterior implants, which are loaded axially.

Fig 16b Panoramic x-ray of a fully edentulous patient with substantial atrophy of the maxilla and mandible. Two zygomatic implants are connected rigidly with a bar construction to the three implants placed in the anterior maxilla. Courtesy of Dr. N. Worsaae.

Fig 16c Moon-face projection of the same patient. Courtesy of Dr. N. Worsaae.

Fig 16d Anteroposterior projection of the same patient prior to prosthetic rehabilitation. Courtesy of Dr. N. Worsaae.

3.5.3 Zygomatic Implants

Another alternative to SFE in completely edentulous patients would be to place zygomatic implants. One or two implants can be anchored bilaterally in the zygomatic bodies (Figs 16a-d). With regard to splinting, the same requirement applies as for posterior tilted implants: enough bone needs to be present to anchor two to four conventional implants in the anterior segment, thus obtaining cross-arch stabilization through rigid splinting of all implants. Unlike tilted implants, zygomatic implants need to be placed under general anesthesia, although these patients can usually be discharged on the day of surgery, which is rarely possible after major bone grafting procedures with extraoral donor sites. Another advantage of zygomatic implants over staged grafting procedures is that they reduce the overall treatment time. A final prosthesis can normally be delivered within 6 months. Disadvantages of zygomatic implants include their highly operatorsensitive placement, palatal bulkiness of the final prosthesis due to their palatal emergence platform, and more serious (although rare) complications than those reported after SFE procedures. Combined with two or more anterior implants, zygomatic implants offer a survival rate similar to implants placed in grafted sites of the posterior maxilla (Block et al. 2009; Jensen and Terheyden 2009; Chiapasco et al. 2009).

3.6

Lateral Window Versus Transcrestal SFE

SFE can be accomplished either through a lateral window or through a transcrestal technique (also known as the open and closed techniques, respectively). Chapter 4 will discuss the surgical techniques in detail. In brief, the lateral window technique involves a mucoperiosteal full-thickness flap to gain access to the lateral wall of the maxilla. The size of the window to be prepared into the lateral sinus wall may vary with the desired bone volume to be augmented or the number of implants to be placed. The Schneiderian membrane is carefully elevated, whereupon a grafting material can be placed. The transcrestal technique includes elevation of the sinus floor through the prepared implant bed. After preparing the implant bed to around 1 mm short of the sinus floor, an osteotome is used to fracture the sinus floor. A grafting material may be gently compressed into the space created beneath the sinus membrane; alternatively, the space may be left empty to fill with blood. Finally, the implant is placed. The lateral window technique is capable of augmenting large volumes of bone and can be utilized irrespective of sinus anatomy. The transcrestal technique is capable of yielding only 2 to 3 mm of additional bone height (Pjetursson et al. 2009a). Considering that implants ≥ 10 mm in length are usually preferred, this approach is therefore limited to cases with an initial subantral bone height of ≥ 7 mm. A systematic review concluded that implant survival is dramatically reduced after transcrestal SFE procedures if initial bone height was ≤ 5 mm (Tan et al. 2008). As an additional limitation, the transcrestal technique should remain confined to situations where the sinus floor runs approximately horizontally. Using an osteotome to fracture an oblique sinus floor will considerably increase the risk of perforating the Schneiderian membrane. If perforation does indeed occur, it is recommended to revert to the lateral window technique, as this will allow the perforation to be repaired through the window created (see Chapter 7). Few studies have evaluated the integrity of the membrane during transcrestal SFE in a

consistent fashion, using a depth gauge to check membrane resilience and the Valsalva maneuver (nose-blowing test). While membrane perforation has been claimed to be a rare complication during transcrestal SFE, it has also been reported to occur in 10% to 26% of cases (Pjetursson et al. 2009b; Gabbert et al. 2009). For the lateral window technique, perforation rates of 10% to 20% have been documented (Jensen and Terheyden 2009; Chiapasco et al. 2009). The main advantage of transcrestal SFE is its lower morbidity in terms of postoperative swelling and pain compared to the lateral window technique. It is a common misconception that less trained surgeons should prefer the transcrestal technique. Although the surgical technique as such may be less demanding, there is always a risk of complications like membrane perforation or (less frequently) severe bleeding. As complications of this type will call for appropriate management such as opening the lateral sinus wall to repair the perforation or identifying the source of bleeding, surgeons need to master the lateral window technique even as they conduct the transcrestal technique.

3.7

Simultaneous Versus Staged SFE

Simultaneous SFE refers to elevation of the sinus floor during the same session as implant placement. An approach of this type may be considered if primary stability of the implant is attainable in the residual subantral bone. It used to be a general rule that simultaneous SFE was appropriate at sites offering a residual bone height of ≥ 5 mm. Primary stability is, however, influenced by several other factors as well. Bone density, for example, has a significant role. The quality of loosely structured trabecular bone in the maxilla may be enhanced by bone condensing. This is achieved by using only the small-diameter spiral drills to prepare the implant bed, followed by application of osteotomes or the implant itself, thus condensing the bone in a lateral direction to enhance primary stability (Figs 17a-b). Another technique to increase primary stability in trabecular maxillary bone involves the use of tapered implants. Yet another way to improve primary stability would be to use an implant with a shoulder wider than its body, such that the implant shoulder engages the cortical crestal bone. Staged SFE is recommended whenever adequate primary stability cannot be obtained. Depending on augmentation volume, sinus anatomy, and grafting protocol, the healing period may vary between 3 and 12 months until implant placement. A waiting period of 3 to 4 months may be appropriate in singletooth gaps if the sinus anatomy is narrow and an autograft (alone or in combination with a bone substitute) is used for augmentation. A total of 10 to 12 months of graft consolidation are needed before implants can be predictably inserted if an “eggshell” sinus floor is augmented with a bone substitute alone. Previously it was recommended to place autogenous bone block inlays in the maxillary sinus when the residual bone volume was insufficient to achieve primary stability, and to immobilize these blocks with the implants. Today this technique is no longer preferred, as it has been shown to involve a high rate of implant failure and technical difficulties in obtaining appropriate

implant positions driven by restorative considerations (Jensen and Terheyden 2009). No randomized controlled clinical trials have been performed to compare the simultaneous and staged SFE approaches in identical clinical situations. A review of the literature has, however, suggested that both approaches may involve similar rates of implant survival (Del Fabbro et al. 2008).

Fig 17a The implant bed is prepared by only using the narrow diameter drill.

Fig 17b The final diameter of the implant bed is reached by using osteotomes of increasing diameter, which are calibrated to the implant system that is used.

Acknowledgments Research Support Dr. Yoji Kamiura – Center of Implant Dentistry, Yokohama, Japan Dr. Tsuneyuki Tsukioka – Center of Implant Dentistry, Yokohama, Japan

4

Treatment Options for Sinus Floor Elevation H. Katsuyama, S. S. Jensen

4.1

Diagnosis and Treatment Planning

4.1.1 Diagnosis To provide a functional and predictable implant-supported restoration, the position and number of implants should be determined in accordance with a prosthetically driven treatment plan, which should take into account the specific clinical challenges of the posterior maxilla. When implant therapy is planned in the atrophic posterior maxilla, bone height is a diagnostic factor of primary importance. Inadequate height for standard-sized implants may be caused by sinus pneumatization or resorption of the alveolar ridge (Chiapasco et al. 2008, 2009). Resorption of the posterior maxilla will often proceed in all three dimensions, such that limited bone volume must be expected not only in the vertical but also in the horizontal plane. As bone resorption progresses, the vertical and horizontal deficiencies become more pronounced. In mild to moderate resorption, the interarch relationship may be acceptable and SFE may be chosen as the only adjunctive procedure. However, it should be noted that sinus grafting by itself may not create ideal tissue contours. In severe cases of resorption, as the extent of the resorption increases, a combined approach with threedimensional site development should be considered (Chiapasco et al. 2008) (Figs 1a-b and 2a-b). For this reason, not only the available bone volume but also the three-dimensional interarch relations should be evaluated when implant therapy is considered in the atrophic posterior maxilla. To select the most suitable treatment option for patients with severe horizontal and/or vertical resorption of the alveolar crest, a diagnostic wax-up involving appropriate interarch relations is mandatory. Both the (vertical and horizontal) interarch relations and the crown length can be evaluated (Figs 3a-b).

Not only can the final image be visualized, but the deficiency of tissue volume is also clarified. Subsequently, a radiographic template should be fabricated based on the diagnostic wax-up. It is recommended to perform an MCT or CBCT scan with the radiographic template in place to evaluate the relation between the desired crown position and the available bone in all three dimensions. The decision concerning implant size and number should rest not solely on the available bone volume but should also take into consideration prosthetic and biomechanical aspects. Virtual implant planning with simulation software may often enhance the flexibility of the diagnosis and treatment planning (Nikzad et al. 2010). As discussed in Chapter 3.5, augmentation sufficient to accommodate an implant ≥ 10 mm in length is recommended for single implants until more data on the long-term survival of non-splinted implants < 10 mm are available.

Figs 1a-b Three-dimensional evaluation of the atrophic maxilla for bone volume and interarch relation is a mandatory diagnostic step. This illustration displays favorable conditions for SFE. The inadequate bone height due to sinus expansion can be managed with SFE as the only adjunctive procedure.

Figs 2a-b This situation is less favorable for SFE as the only adjunctive procedure. Due to the vertical crestal resorption, longer implant crowns are necessary. In addition, the horizontal jaw relationship is not ideal. If this vertical and horizontal discrepancy is too severe, a combined approach with three-dimensional site development should be considered.

Fig 3a Set-up performed on a study cast to evaluate the three-dimensional jaw relations. The diagnostic setup in this example does not indicate any major signs of vertical ridge resorption.

Fig 3b Diagnostic set-up indicating that considerable vertical ridge resorption has occurred. This problem cannot be solved by SFE alone.

4.1.2 Classification and Treatment Options The atrophic posterior maxilla can be categorized into four groups (see Table 1 and Figs 4 to 7). Each situation requires a different surgical approach to achieve ideal bone volume and three-dimensional interarch relations. Table 1 Classification of the atrophic posterior maxilla and related treatment options.

Classification Clinical characteristics

Surgical approach

Insufficient subantral bone height Adequate width of alveolar ridge Acceptable (vertical and horizontal) interarch relations

SFE procedure with bone substitute and/or autogenous bone from intraoral donor site

Group 2 (Figs 5a-c)

Insufficient subantral bone height Inadequate width of alveolar ridge Acceptable vertical interarch relations

SFE procedure and horizontal ridge augmentation Autogenous (horizontal) block graft (may be combined with a bone substitute and barrier membrane) Intraoral or extraoral donor site depending on the extent of atrophy

Group 3 (Figs 6a-c)

Insufficient subantral bone height Adequate width of alveolar ridge Acceptable horizontal interarch relations Unfavorable vertical interarch relations due to advanced crestal resorption

SFE procedure and vertical ridge augmentation Autogenous (vertical) block graft (may be combined with a bone substitute and barrier membrane) Intraoral or extraoral donor site depending on the extent of atrophy

Insufficient subantral bone height Unfavorable interarch relations due to advanced horizontal and vertical crestal resorption

SFE procedure and horizontal/vertical ridge augmentation Autogenous (vertical and horizontal) block graft (may be combined with a bone substitute and barrier membrane)

Group 1 (Figs 4a-c)

Group 4 (Figs 7a-c)

Figs 4a-c Expanded sinus cavity with limited bone height for implant placement. Thanks to ideal interarch relations, there is no need for procedures other than sinus floor elevation.

Figs 5a-c Expanded sinus cavity with limited bone height. Since bone width is also inadequate for implant placement, sinus augmentation in combination with horizontal ridge augmentation is indicated.

Figs 6a-c Expanded sinus cavity with limited bone height. In cases with extreme vertical atrophy, SFE may be combined with vertical ridge augmentation.

Figs 7a-c Expanded sinus cavity with limited bone height. In addition, bone width is insufficient and vertical intermaxillary distance is large. SFE in combination with horizontal and vertical ridge augmentation with block grafts is indicated.

Lateral versus transcrestal techniques Two substantially different approaches to SFE can be distinguished, both having specific advantages and disadvantages. Clinicians therefore need to make a correct decision, based on subantral bone height and sinus floor anatomy, as to which technique should be adopted. One major advantage of the transcrestal technique is its reduced invasiveness and, consequently, its substantially lower morbidity than the lateral window technique. On the downside, transcrestal SFE can increase bone height by only 2 to 4 mm and therefore requires a larger volume of preexisting native bone than the lateral window technique (Jensen and Terheyden 2009). In other words, transcrestal SFE is not appropriate for severely atrophic cases but should only be used when primary implant stability can be achieved. More than 6 mm of preexisting bone height are highly recommended to allow placement of an implant ≥ 10 mm in length. The anatomy of the sinus floor should also be included in the presurgical assessment to decide which

approach is indicated in a given situation. An oblique sinus floor will carry a significantly increased risk of membrane perforation. Regardless of which approach is being considered, obtaining CBCT or MCT scans is highly recommended. At sites exhibiting ≤ 6 mm of bone height and/or an oblique sinus floor, the lateral window technique should be used. Lateral window technique: Simultaneous versus staged approach Whenever the lateral window technique is considered, the most important prerequisite for simultaneous implant placement is the prospect of attaining primary stability (Jensen and Terheyden 2009). Residual bone volume is therefore the main criterion in deciding whether a simultaneous or staged procedure should be used (Table 2). This decision, however, is also influenced by other factors such as bone density (Jensen and Terheyden 2009) and the need for vertical and/or horizontal veneer grafts. Poor bone density may not allow for primary implant stability even if bone quantity meets the criteria for simultaneous placement outlined in Table 2. A conventional MCT scan would offer valuable information about bone density in terms of Hounsfield units (HU). Conversely, good bone density may sometimes allow adequately stable placement of a tapered implant in sites with a subantral bone height of less than 5 mm. The need for a vertical and/or horizontal veneer graft would preclude simultaneous placement of an implant. Comprehensive diagnosis is mandatory to decide on the appropriate timing of implant placement. Several case series have recently presented favorable results for simultaneous implant placement in preexisting ridges 1 to 4 mm in height (Peleg et al. 1998, 1999a; Cordioli et al. 2001; Mangano et al. 2007; Mardinger et al. 2007). Given the low-level evidence of these study designs, the recommended criteria in Table 3 are upheld until higher-level research becomes available. Table 2 Guidelines for selecting a transcrestal versus lateral window technique.

Subantral bone height > 6 mm

≤ 6 mm

Horizontal

Transcrestal

Lateral window

Oblique

Lateral window

Lateral window

Sinus floor anatomy

Table 3 Guidelines for the surgical approach with the lateral window technique (confined to lateral SFE when interarch relations are adequate).

Technique

Subantral bone height

Lateral window (simultaneous approach)

≥ 5 mm

Lateral window (staged approach)

< 5 mm

4.2

Materials and Instrumentation

4.2.1 Instrumentation for SFE SFE procedures, whether through transcrestal or lateral window techniques, rely on the principle of preparing an osteotomy to gain access to the maxillary sinus, followed by elevation of the Schneiderian membrane to create space for the grafting material and implant. Numerous instruments have been introduced for both osteotomy preparation and membrane elevation. Rotary instruments. These instruments are most commonly used to create the lateral or transcrestal osteotomy through which the sinus floor is accessed (Fig 8). For the preparation of a lateral window, a round bur is normally used to outline the shape of the window. Round-shaped rotary instruments with a smaller diameter (1.4 or 2.3 mm) are suitable for marking the outline of the lateral window. Larger instruments are more efficient for trimming the buccal bone plate when the “wall-off” technique is selected. This technique involves complete removal of the buccal plate, which may be advantageous in limited SFE procedures or in situations where infracture of the lateral window is complicated by factors such as a narrow sinus anatomy. A fine-grit large-diameter diamond bur with reverse rotation is recommended for this purpose, as this type of instrument will carry a lower risk of perforating the sinus membrane than a smaller round bur. Ultrasonic or piezosurgical devices may be preferable to reduce the risk of membrane perforation when the facial bone covering the sinus cavity is thin.

Fig 8 Rotary instruments used for the lateral window technique. The sinus cavity is accessed with round rotational burs (left to right: round carbide bur, egg-shaped bur, diamond bur).

Fig 9a Surgical instruments for window and membrane elevation. Various shapes, sizes and curvatures are needed depending on window size and sinus configuration.

Fig 9b Surgical instrument used to compress the grafting material. A flat surface is useful in shaping the material.

Hand instruments. These instruments are commonly used to elevate the sinus membrane (Figs 9a-c). In most situations, smaller instruments are used for initial liberation of the sinus membrane from the osseous wall, while larger

instruments are used to expand the elevated space. When the first window prepared is too small, a Stantze will be used to increase the size of the opening (Figs 10ab). This instrument could be used especially if the window needs to be enlarged while avoiding damage to the sinus membrane.

Fig 9c Surgical instrument used to compress the grafting material. A round shape is ideal to avoid damaging the surrounding tissue.

Fig 10a A Stantze used for bone scraping to enlarge the window carries a much smaller risk of damaging the membrane or surrounding tissue than a chisel.

Fig 10b Magnified view of Stantze tip.

Fig 11a Instruments used for transcrestal SFE. Bone condensation devices with a tapered tip and an appropriate diameter are employed to widen the implant bed.

Fig 11b Instruments used for transcrestal SFE. An osteotome with a concave tip is employed to fracture the bottom of the sinus cavity.

Figs 12a-b Examples of bone mills.

Transcrestal SFE, by contrast, requires special instruments to match the implant type selected. Tapered osteotomes are selected if an adjunctive procedure of bone condensing or spreading is required (Fig 11a). If no such

procedure is required, a concave tip should be selected to facilitate the task of fracturing the sinus floor (Fig 11b). Instruments used for harvesting and processing autogenous bone grafts. A bone mill is routinely used when large autogenous bone grafts are harvested (Figs 12ab). While different versions of this instrument exist, a sharp and efficient bone mill is indispensable to deal with autogenous bone involving a high cortical content from the chin or ramus. Both of these areas offer good quality bone with a cortical surface. It is recommended to mill the harvested bone to an appropriate size, expanding the osteogenic surface and accelerating osteoconduction. When less autogenous bone is needed for the SFE procedure, sufficient amounts can usually be harvested from the area where the lateral window is planned or from the infrazygomatic ridge using a bone scraper. Lastly, while small amounts of bone dust can be collected with a suction device during preparation of the implant bed or lateral window, the quality and safety of this grafting material is still debated. New approaches. Perforation of the sinus membrane occurs in approximately 10% of cases, being the most common intraoperative complication in SFE procedures (Chiapasco et al. 2009). Perforation may occur during the osteotomy or during elevation of the membrane. New approaches have been proposed to minimize this risk. Ultrasonic devices such as piezoelectric surgical instruments, used either alone or in combination with rotary instruments, have attracted attention as a new method of creating the osteotomy (Figs 13 and 14).

Fig 13 Piezosurgical instruments.

Fig 14 Clinical view of a piezosurgical instrument being used to open the lateral sinus wall.

It has been reported that the risk of membrane perforation may be lower with piezosurgical than with rotary instruments (Wallace et al. 2007). Another small-scale clinical study with a randomized controlled design, however, failed to confirm this difference (Barone et al. 2008). On the whole, the superiority of piezosurgery over conventional techniques has not been validated. One inherent disadvantage of piezosurgery is its lower cutting performance than the one offered by conventional rotary instruments. As more time is usually required to prepare the buccal window, piezosurgery may be suitable for delicate areas. As an alternative to hand instruments, the use of an inflatable balloon to elevate the Schneiderian membrane has been advocated. A number of clinical reports have described this technique in conjunction with transcrestal SFE (Kfir et al. 2006, 2007, 2009a, 2009b; Hu et al. 2009). According to these authors, the balloon technique was less invasive and involved a lower complication rate than conventional methods. Since these studies were case series with no control groups, the balloon approach should not be considered a routine technique at this stage.

Fig 15 Surgical infrastructure for SFE. Due to the high risk of infection and complications, an isolated and aseptic surgical room is mandatory.

Figs 16 Layout of surgical instruments for SFE.

Figs 17 A surgical microscope is beneficial for optimal surgical precision and meticulous tissue handling.

Surgical setup for SFE Being a complex surgical procedure, SFE requires an isolated and aseptic surgical environment with comprehensive surgical instrumentation as in routine oral and maxillofacial surgery (Figs 15 and 16). As shown in Figure

17, a surgical microscope and a piezosurgical device may be helpful in managing particularly complex situations.

4.2.2 Biomaterials Grafting materials Different grafting materials for SFE procedures have been studied extensively, and a wide range of grafting protocols may be considered well documented (see Chapter 2). The first decision to make is whether a grafting material should be used at all, or whether it may suffice to just elevate the Schneiderian membrane, using the implant as a tent pole, and leave the space created beneath the membrane to be filled with coagulum. There is sound evidence that 2 to 3 mm of bone height can be gained in this way. Placement of a grafting material is recommended, however, if more than 3 mm are needed to anchor an implant of adequate length or if bone formation all around the implant apex is desired. There is substantial clinical evidence that equally high implant survival rates can be obtained when SFE procedures are performed with particulated autografts or bone substitutes alone or in combination (Jensen and Terheyden 2009; Chiapasco et al. 2009). This does not imply, however, that different grafting materials will trigger the same biological response. As autogenous bone is being transplanted, osteoinductive molecules such as bone morphogenetic protein (BMP) and osteogenic cells will enter the augmented site. Bone formation is thus significantly accelerated as compared to situations in which bone substitutes are used alone (Buser et al. 1998; Jensen et al. 2006, 2007, 2009). Healing times can therefore be reduced by using augmentation materials with a high autograft content. Typically, when autografts are used alone or in combination with a bone substitute material, restorative procedures can be started 3 to 4 months after SFE procedures with simultaneous implant placement, and implants can be placed 4 to 6 months after two-stage SFE procedures in this situation. Histomorphometric evidence from human studies has revealed significantly greater bone formation within the first 9 months of healing when autografts were used. Later than 9 months, no significant differences were observed (Handschel et al. 2009). Therefore, whenever a bone substitute is used alone, extended healing times (by a factor

of 1.5 to 2) must be allowed (see Chapter 5).

It is important to realize that the osteogenic potential of autografts may vary considerably with age, the presence or absence of systemic diseases, the donor site (mandible/iliac crest, cortical/cancellous bone), and the bone harvesting technique resulting in various particle sizes of bone (bone mill, scraper, or filter on suction device). Bone harvested from elderly and osteoporotic patients with a suction device has a clearly lower osteogenic potential than milled corticocancellous bone from the iliac crest of healthy young individuals. It is highly recommended to harvest intraoral bone either locally within the same flap to reduce morbidity for the patient, or from the mandibular body and ascending ramus instead of the chin area, especially when larger amounts of the bone are needed. Bone harvested from the chin area will involve substantially more complications in terms of compromising sensory function of the mental nerve (Clavero and Lundgren 2003). Autografts used alone in SFE procedures will often result in long-term follow-up radiographs indicating re-pneumatization of the maxillary sinus in the augmented areas (Figs 18a-e), as may be observed around natural molars and premolars.

Fig 18a Periapical radiograph obtained 3 months after insertion of an implant replacing a maxillary right first molar. The implant was placed with simultaneous lateral window SFE. Primary stability was obtained by bone condensation. Autogenous grafting material was harvested from the right infrazygomatic ridge with a bone scraper. The follow-up radiographs showed gradual re-pneumatization of the sinus over the first 12 months. Thereafter, the situation remained more or less stable. (Courtesy of Dr. L.-Å. Johansson.)

Fig 18b 6 months.

Fig 18c 12 months.

Fig 18d 48 months.

Fig 18e 54 months.

Whether this phenomenon will have any clinical implications on long-term implant survival is debated but not currently known. As seen in procedures of guided bone regeneration (GBR), the resorption tendency of autografts may be reduced or even eliminated by combining the autograft with a bone substitute offering a low substitution rate (Adeyemo et al. 2008). Barrier membranes Conflicting results concerning the benefit of placing a membrane over the lateral window have been reported. Some studies revealed a tendency for better bone formation and less implant failures when the lateral window was covered with a resorbable membrane (Tawil and Mawla 2001; Pjetursson et al. 2008; Choi et al. 2009). The beneficial effect of a membrane becomes less apparent, however, when these results are cleared for confounding factors like smooth-surfaced implants and simultaneous implant placement in autogenous bone blocks (see Chapter 2, Jensen and Terheyden 2009). A recent review of clinical studies with histomorphometric data following SFE with autografts alone did not confirm any effect of a barrier membrane on

bone formation (Klijn et al. 2010). Overall, it appears that covering the lateral window with a resorbable membrane may have a limited beneficial effect. It is recommended to use a resorbable membrane over the lateral window in clinical situations characterized by a limited osteogenic potential of the patient or the grafting material used. No data are available to support the use of a non-resorbable instead of a resorbable membrane for this indication.

4.2.3 Implant Design Another consideration for implants to be placed in conjunction with SFE is the fact that bone density is often suboptimal in the posterior maxilla. It is therefore highly recommended to select an implant design whose geometry and surface characteristics can maximize primary stability. Although evidence is lacking to determine which geometric features are essential for maximum primary stability, a number of geometric designs have been proposed. These include threads with a modified shape, self-tapping threads, tapered profiles, and flared necks. On the other hand, there is strong evidence that the survival rate of implants with a roughened surface (96.9%) is significantly higher than the survival rate of implants with a machined surface (88%) (Chiapasco et al. 2009). However, since all implants with plasma-sprayed, HA-coated, and sandblasted/acid-etched surface types fall into the category of “roughsurface” implants, it is not clear how different surface treatments may affect implant survival and success. It has been suggested that healing periods before prosthetic loading can be reduced with micro-rough implants compared to implants with more traditional surface characteristics (Cochran et al. 2002; Roccuzzo et al. 2008). Recently, implants offering a chemically modified and hydrophilic microrough surface have been developed (SLActive surface). In conjunction with SFE, there is no evidence of superiority to conventional surfaces at this time, although preclinical and clinical studies have yielded promising results for this newly developed surface type (Buser et al. 2004; Ferguson et al. 2006; Schwarz et al. 2007; Ganeles et al. 2008; Roccuzzo and Wilson 2009).

4.3

Surgical Techniques

4.3.1 Transcrestal Technique Transcrestal SFE is indicated when implant stability can be achieved despite the limited bone height (Summers 1994, 1995) (see Table 2). Supported by accurate radiographic analysis, a crestal incision is performed and the implant bed prepared 1 to 2 mm shorter than the available bone height (Figs 19a-d). Following preparation of the implant bed, the osteotome (most of these devices feature a diameter of 4.0 to 5.0 mm) is utilized to fracture the sinus floor by tapping action using a mallet. Care should be taken that the osteotome does not enter the sinus cavity, thus avoiding the risk of membrane perforation. Generally, devices with concave tips are suitable for fracturing the sinus floor, while devices with tapered tips are indicated for bone condensing (Fig 20). Once the sinus floor has been fractured, autogenous bone and/or a bone substitute is delivered to the osteotomy and carefully packed into the prepared implant bed with the osteotome. The pressure from the condensed graft material elevates the Schneiderian membrane. After repeating the same procedure several times for adequate membrane elevation, the selected implant is inserted to ideal depth. It is recommended to perform the Valsalva test (nose-blowing test) prior to grafting and implant placement to verify that the membrane has not been perforated in the process of fracturing the sinus floor. Finally, the insertion torque should be measured to obtain additional information about the appropriate healing period to be selected.

Fig 19a Preparing the implant bed.

Fig 19b An osteotome is used to fracture the sinus floor.

Fig 19c The membrane is elevated by inserting graft material.

Fig 19d Implant in situ.

A periapical or other radiographic examination should be performed after surgery to verify the outcome of SFE. If a perforation of the sinus membrane is confirmed intraoperatively, the surgeon should switch to the lateral window technique (Jensen and Terheyden 2009). The healing period will be selected in accordance with implant type, surface, length, and diameter. Empirically, however, a 16-week healing period is recommended when the insertion torque is lower than 15 Ncm. A 12-week healing period is recommended in most cases when the insertion torque is between 15 and 35 Ncm. If the insertion torque is higher than 35 Ncm, the implant may be loaded after 6 weeks. Future studies will reveal whether resonance frequency analysis using ISQ measurements, performed at the time of implant placement and/or follow-up visits, are clinically helpful in determining the ideal time of prosthetic loading. A non-submerged healing protocol may be used if bone augmentation around the implant shoulder has not been performed. Only one clinical study has investigated a staged approach to transcrestal SFE (Stavropoulos et al. 2007). The justification for this approach should therefore be considered limited at present. A staged lateral window technique is recommended when subantral bone height and bone density are not sufficient to achieve primary implant stability at the time of sinus augmentation, as this approach is much better documented (20 studies; Jensen and Terheyden 2009).

4.3.2 Lateral Window Technique There is strong evidence for the lateral window technique as a predictable

procedure for sinus floor elevation using a simultaneous or staged approach (Jensen and Terheyden 2009; Chiapasco et al. 2009) (Figs 21a-c, 22). Depending upon the local conditions at the planned implant sites, a simultaneous and staged approach procedure is sometimes combined at the same surgical sites.

Fig 20 A tapered osteotome is used for bone condensation.

Fig 21a Window preparation.

Fig 21b Opening of the window toward the sinus cavity.

Fig 21c Membrane elevation.

Fig 22 Implants placed with simultaneous lateral window SFE. Just before bone grafting into sinus cavity. Implants are fixed within residual bone.

Fig 23 The incision line is designed to avoid the window, as a safety margin is required to cover the augmented site. Furthermore, adequate blood supply should be provided to avoid tissue perforation. A slight palatal incision and a sulcus incision are combined to facilitate access, along with a mesial releasing incision.

Also, the lateral window technique may be combined with various augmentation techniques for horizontal and/or vertical bone deficiencies. The incision line is designed to avoid the planned location of the lateral window

(Fig 23). Most commonly, a mid-crestal incision is selected. An incision made too far palatally may result in soft tissue dehiscence due to compromised blood supply (Kleinheinz et al. 2005). When a staged approach is indicated, the recommended approach may be to place the incision line on the facial aspect of the crest, as this may offer easier and quicker access for window opening. Care should be taken, however, that the incision line does not cross the planned area of the lateral window. Wound edges lacking bone support may give rise to soft tissue collapse or major dehiscences in the absence of blood supply. A mucoperiosteal flap is elevated and complete soft tissue debridement performed. The window size and position are determined in accordance with anatomic conditions (Figs 24a-b). While rotary instruments are commonly used for window preparation, the recent development of piezoelectric ultrasonic devices may contribute to reducing intraoperative complications such as membrane perforation (Wallace et al. 2007). Membrane perforation can be reduced by meticulous soft tissue handling and utilization of a surgical microscope. The sequences for staged and simultaneous SFE procedures are illustrated schematically in Figs 25a-f and Figs 26a-g.

Figs 24a-b Window size and position are determined in accordance with anatomic conditions. A large window, while facilitating access to the sinus cavity, would weaken the lateral wall. It is therefore recommended to create a window just large enough to achieve complete access to the sinus cavity. Window height from the residual bone is determined based on the length of the planned implant, to which at least 2 mm of extra space are added. Some bone walls are removed and utilized for bone grafting (a); others are left as is (b). This decision will be based on window size and configuration of the sinus cavity.

Sequence illustrating a staged lateral SFE procedure

Fig 25a Flap elevation and window preparation for a staged lateral SFE procedure. Note the limited bone height (indicated by arrows).

Fig 25b Elevation of trap door and sinus membrane.

Fig 25c Grafting.

Fig 25d Closed flap with barrier membrane underneath.

Fig 25e Grafted site after healing.

Fig 25f Implant following staged placement.

Sequence illustrating a simultaneous lateral SFE procedure

Fig 26a Flap elevation and window preparation for a simultaneous lateral window procedure. Note the adequate bone height for simultaneous implant placement (indicated by arrows).

Fig 26b Elevation of trap door and sinus membrane.

Fig 26c Drilling procedure for implant bed. Note that the membrane is elevated and protected by a paddle-shaped instrument to avoid perforation with the drill.

Fig 26d Sinus cavity filled with the graft material.

Fig 26e Implant inside the sinus cavity filled with graft material.

Fig 26f Closed flap with barrier membrane underneath.

Fig 26g Grafted site and elevated sinus floor after healing.

4.3.3 Timetable The timing of implant placement and loading will essentially depend on the amount of native bone. The technique and material selected enters the equation as a modifying factor that may reduce or extend the healing period. Guidelines for the healing times involved in various grafting procedures are summarized in Table 4. As discussed earlier in this chapter (see Chapter 4.2.2), the exclusive or additional use of autogenous bone is likely to allow a shorter healing period before implant placement and loading than the exclusive use of a bone substitute (Jensen and Terheyden 2009). Longer healing periods between grafting and implant placement are required for highly atrophic ridges (subantral bone height < 3 mm). The clinician should modify placement and loading protocols in accordance with clinical variables specific to each case, including radiographic findings at the grafted site, insertion torque, number and size of implants, the osteophylic properties of the utilized implant surface, and absence or presence of systemic diseases. Table 4 Timetable of various SFE approaches.

Fig 27a Exposed lateral bone surface of the planned window site.

Fig 27b Harvesting of autograft chips with a bone scraper.

Fig 27c Following flap elevation, the facial bone wall is extensively exposed to harvest bone chips with a bone scraper.

Fig 27d The sharp bone scraper is able to harvest autogenous bone chips of 1.5 to 2.0 mm in size.

Fig 27e The collected autograft chips are stored in a sterile glass dish.

Fig 27f Mixed with DBBM particles, the composite graft is applied in the created defect following elevation of the Schneiderian membrane.

4.3.4 Harvesting Site Autogenous bone for grafting should be harvested from intraoral rather than extraoral sites, as postoperative discomfort and complications will be less severe (Chiapasco et al. 2009). Whenever possible, bone should be harvested locally from the surgical area. The large area of exposed facial bone surface allows the harvesting of large amounts of autograft chips with specially designed bone scrapers and other bone collection devices. They are used on the lateral bone surface of the planned window site to harvest bone chips (Figs 27a-f). If needed, the harvesting can be extended to the tuberosity area. Autologous bone chips harvested in this way are combined with xenograft or allograft if a composite graft is preferred by the surgeon. When a large volume of autogenous bone is required (e.g. for bilateral augmentation of severely pneumatized sinuses), sufficient amounts of bone can usually be harvested from the mandible. Harvesting from extraoral sites like the iliac crest becomes necessary when larger amounts of bone are required (e.g. for

additional onlay grafts in the horizontal and/or vertical dimensions). The ramus and symphysis are most commonly selected as intraoral donor sites.

Fig 28a Incision line for ramus harvesting.

Fig 28b Flap elevation for ramus harvesting.

Fig 28c Removal of bone block.

Figs 29a-b Bone harvesting from the mandibular ramus. In this specific case, bone harvesting was performed in combination with guided bone regeneration (GBR). For bone harvesting only, the incision line would be placed far buccally. While a CT scan is not required for bone harvesting from the ramus, anatomical limitations should be respected so as not to damage the nerve and vessels. Once bone has been harvested from the ramus, a collagen sponge or some other hemostatic biomaterial is applied to avoid continued bleeding. The bone volume harvested from the ramus of this patient was sufficient (a). Bone graft material could be harvested as bone chips or bone block (b).

Fig 30a Incision line for harvesting from the symphysis.

Fig 30b Bone harvesting with trephine drill or other instruments.

Figs 31a-c Clinical sequence of bone harvesting from the mandibular symphysis. Harvesting bone from this region is easier in patients whose anterior mandible is edentulous. Significant volumes of bone can be harvested with a trephine drill or other instruments in these cases (a). Note the intact lingual cortical plate after harvesting of the corticocancellous bone chips (b). The harvested bone (c) is reduced to appropriately-sized particles for grafting using a bone mill.

While the maxillary tuberosity can be an alternative, the quality and quantity of bone harvested from this area is often poor. The mandibular ramus has been recommended as the area of choice for intraoral bone harvesting, as this location offers low complication rates, relative ease of access, and sufficient availability of bone (Figs 28a-c, 29a-b). Bone from the ramus is mostly cortical (Misch 1997), however, and contains limited concentrations of osteoinductive proteins and osteogenic cells. The second option is the symphysis area, which offers good accessibility, bone density, and bone composition, including both cancellous and cortical tissue (Capelli and Testori 2009; Misch 1997) (Figs 30a-b, 31a-c). It should be noted that grafts of symphyseal origin are associated with higher complication rates and morbidity than ramus grafts (Chiapasco et al. 1999; Clavero and Lundgren 2003; Nkenke et al. 2001, 2002; Raghoebar et al. 2001a, 2007; Misch 1997). Major complications include damage to the mandibular incisors, paresthesia,

and unexpected intraoperative hemorrhage due to rare anatomical situations such as proximity of the lingual foramen. The literature indicates that paresthesia affecting the mandibular anterior teeth has an incidence of approximately 13% in the first year after bone harvesting from the symphysis (Chiapasco et al. 1999; Nkenke et al. 2001; Raghoebar et al. 2007). Despite the attractive prospect of obtaining good bone substance, harvesting from the symphysis should nevertheless be regarded with caution. It should only be considered if a large volume of autogenous bone (as for bilateral SFE) is required and not without informing patients of the risk of protracted paresthesia affecting the mandibular anterior teeth (Nkenke et al. 2001). Bone harvesting from the ramus, on the other hand, carries a risk of damaging the inferior alveolar nerve. In other words, both donor areas will require meticulous preoperative assessment. Three-dimensional information from preoperative CBCT or MCT scans may help avoid complications.

4.3.5 Managing Septa and Compromised Cases The anatomy of the maxillary sinus may be complex, and preoperative diagnostics based solely on two-dimensional radiographs may prove inadequate, especially when sinus septa are present. These are considered to compromise SFE procedures by involving a higher incidence of complications such as membrane perforation. Meticulous diagnosis and careful treatment planning are mandatory to avoid these complications and resultant failures. The literature indicates that septa and sinus floor irregularities will often go unnoticed by two-dimensional radiographic assessment (Krennmair et al. 1999). Recent developments in CT scanning enable surgeons to obtain detailed information about internal sinus anatomy before SFE. In this way, they can evaluate the various surgical options prior to opening the sinus cavity. Surgical procedures are illustrated in the DVD version of this volume (under the heading “Various Surgical Procedures”). What follows is the outline of how to select appropriate surgical procedures for managing septa within the sinus cavity. Surgical guidelines in the presence of septa 1. The septum is higher than the length of the planned implants; the sinus cavity may be separated into two or more compartments. In this situation, it may be impossible to remove the septum and manage

the case as one cavity for sinus augmentation. Thus opening a separate window for each compartment is recommended, although opening of more than two windows is not realistic. Complex anatomical conditions like the presence of completely isolated compartments will render the procedure more difficult. 2. The septum is lower than the length of the planned implants; the sinus cavity is not separated into compartments. In this situation, it is possible to remove the septum and manage the case as one cavity for sinus augmentation. Depending on the orofacial dimension of the septum, it may still be advantageous to start out by preparing two separate window openings until the septum is identified and removed. Depending on the clinical situation, the opposite procedure may also be an option. When the height of the septum is limited on the facial aspect, the case may be approached as a single cavity in terms of initial window opening. In conclusion, septum surgery in conjunction with SFE calls for meticulous and careful analysis of the underlying anatomy. Appropriate radiographic imaging is essential to increase the predictability and reduce complications of septum surgery. Clinicians should be aware that some cases may be too severely compromised to achieve predictable sinus floor elevation. Acknowledgments Research Support Dr. Toshifumi Kuroe – Center of Implant Dentistry, Yokohama, Japan Instrument Photos Dr. Eiju Sen – Center of Implant Dentistry, Yokohama, Japan Dr. Kotaro Nakata – Center of Implant Dentistry, Yokohama, Japan

5

Guidelines for Choosing the Surgical Technique and Grafting Protocol for Sinus Floor Elevation S. S. Jensen

Potential candidates for SFE should be carefully evaluated prior to considering the surgical technique and grafting protocol to be adopted. •

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A complete medical history (health status, medications, allergies, smoking, drinking) should be obtained and the patient should be evaluated for compliance. The purpose of this assessment is to identify the presence of any general risk factors. A thorough clinical examination should be conducted prior to SFE. The parameters of this examination should include interarch relations, periodontal status, evidence of bruxism, and distance to the neighboring teeth and opposing dentition. A radiographic evaluation should be conducted. This evaluation should preferably include three-dimensional information about the residual subantral bone (volume and density), the periapical status of any neighboring teeth, sinus floor anatomy including the presence of any septa and secondary cavities, and evidence of sinusitis or any other pathologic alterations in the maxillary sinus. The purpose of these clinical and radiographic assessments is to identify any local risk factors. An overall risk assessment should be performed based on any general and/or local risk factors that have been identified in this process. If any

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absolute contraindications to SFE or associated procedures are present, alternative modalities should be considered. Potential alternatives in the presence of contraindications to major bone augmentation procedures may include the placement of short, tilted, or zygomatic implants. Toothsupported fixed restorations or removable dentures should be considered if surgical procedures as such are contraindicated. Informed consent should be obtained from each patient based on a risk assessment, and the clinician should supply explanations about the advantages and disadvantages of the planned treatment.

Three main decisions need to be made once the indication for SFE has been confirmed: 1. Technique (lateral window technique versus transcrestal technique). Indications for the transcrestal technique are limited because exacting requirements need to be met: favorable interarch relations, adequate width of the alveolar ridge, adequate bone height (> 6 mm), and horizontal anatomy of the sinus floor. However, the transcrestal technique is preferable if these requirements are met, given its lower morbidity than lateral window SFE. 2. Timing of implant placement (simultaneous versus staged approach). Simultaneous implant placement is generally preferred whenever primary stability can be obtained, reducing the number of surgical procedures and, hence, morbidity. This treatment option is also contingent, however, on achieving an ideal three-dimensional position of the implant from a restorative viewpoint. 3. Grafting protocol (autogenous bone and/or bone substitute material). Any autogenous bone included in the grafting protocol will accelerate bone formation compared to protocols using bone substitute materials alone. Bone substitute materials with a low substitution rate, on the other hand, are helpful in maintaining the volume of augmentation. The decision trees in Figures 1 and 2 offer clinical decision guidelines.

6

Clinical Case Presentations

Transcrestal Protocols

6.1

Implant Placement with Simultaneous SFE: Transcrestal Technique with DBBM S. S. Jensen

Fig 1 Lateral view of site 26 showing 2−3 mm of gingival recession on the facial and mesial aspects of tooth 27.

Fig 2 Occlusal view showing complete soft tissue healing 6 weeks after extraction of tooth 26 and sufficient width of the alveolar crest.

Fig 3 Preoperative periapical radiograph (including a 5-mm steel ball for calibration) revealing 7 mm of subantral bone height. The yellow line depicts the sinus floor, which had a horizontal appearance at site 26.

The patient was an 87-year-old woman with no general diseases, no medication, no allergies, and a non-smoker. Her maxillary left first molar had been extracted 6 weeks previously due to a root fracture. The clinical examination revealed a complete dentition, except for the maxillary left first molar, which was missing. Generalized but mild horizontal bone loss without any pathologic periodontal pockets was observed. Oral hygiene was good. Both the second premolar and the second molar had been restored with adequate gold inlays and showed 2 mm of gingival recession facing the edentulous site. The course of healing had been uneventful after extraction of the maxillary left first molar, and the width of the alveolar process was intact (Figs 1 and 2). A periapical radiograph obtained using paralleling technique, including a steel ball for calibration, revealed 7 mm of subantral bone height and a horizontal anatomy of the sinus floor (Fig 3).

Surgical Procedure Under local anesthesia using lidocaine 2% with adrenaline, a full-thickness crestal incision was made at the site of the maxillary left first molar. The implant bed was prepared to a depth of 6 mm. An osteotome was used to fracture the sinus floor (Fig 4). The integrity of the sinus membrane was checked using the Valsalva maneuver.

Using the depth gauge, deproteinized bovine bone mineral (DBBM) (BioOss; Geistlich Pharma, Wolhusen, Switzerland) was gently introduced into the implant bed (Figs 5 and 6). An implant (Straumann Wide Neck SLA, Ø 4.8 mm, length 10 mm) was placed with good primary stability (Fig 7). Two interrupted monofilament sutures (5-0) were placed for wound closure (Figs 8 and 9). Antibiotic prophylaxis with penicillin G was started 1 hour preoperatively (1.6 g) and was continued for 3 days postoperatively (0.8 g three times daily). Chlorhexidine digluconate 0.1% was prescribed for mouth rinsing twice daily until the sutures were removed 7 days postoperatively. The postoperative course was uneventful.

Fig 4 After preparation of the implant bed to a depth of 1 mm under the sinus floor, an osteotome was gently used to fracture the sinus floor.

Fig 5 A depth gauge was used to check the integrity of the Schneiderian membrane, together with a nose-blowing test. Available space for an implant 10 mm in length is verified.

Fig 6 Deproteinized bovine bone mineral (DBBM) was introduced through the implant bed and gently advanced apically using the depth gauge.

Fig 7 Postoperative periapical radiograph. The yellow line traces the new sinus floor.

Fig 8 Lateral view of the postoperative situation after simultaneous implant placement.

Fig 9 Occlusal view of the postoperative situation.

Fig 10 Clinical situation 8 weeks postoperatively at the time of connecting the abutment. Note the healthy condition of the peri-implant soft tissue.

Fig 11 Clinical situation after connecting a solid abutment (height: 5.5 mm).

Fig 12 Lateral view after cementation of the metal-ceramic crown.

Fig 13 Occlusal view after cementation of the metal-ceramic crown.

Prosthetic procedure Eight weeks postoperatively, a solid abutment (height: 5.5 mm) was connected (torque: 35 Ncm), and impressions were taken (Figs 10 and 11). A metal-ceramic crown was cemented 12 days later (Figs 12 to 14) and showed stable and healthy peri-implant soft tissue at 1 year despite a minor ceramic fracture at the distopalatal aspect (Figs 15 to 17).

Fig 14 Periapical radiograph after cementation of the metal-ceramic crown.

Fig 15 Lateral view after one year of prosthetic loading showing stable and healthy periimplant soft tissue.

Fig 16 Occlusal view after one year of prosthetic loading showing a minor ceramic fracture at the distopalatal aspect.

Fig 17 Periapical radiograph after one year of prosthetic loading showing stable conditions in the augmented area around the apex of the implant.

Acknowledgments Restorative Procedures Dr. Jens Malte – Private practice, Copenhagen, Denmark Laboratory Procedures Lene Hyldgaard, CDT – Dental technician, Copenhagen, Denmark

6.1

Implant Placement with Simultaneous SFE: Transcrestal Technique with DBBM B. E. Pjetursson

A 50-year-old man presented at the Department for Periodontology and Fixed Prosthodontics, University of Bern, Switzerland (Fig 1). His chewing function was impaired, as he had lost multiple teeth in the maxilla (Fig 2) and mandible (Fig 3). Four teeth remained in the mandible, all showing increased mobility. The patient had received a telescopic removable partial denture (RPD) in the maxilla and a metal-framework RPD in the mandible about 10 years previously. At that time, he could not adapt to the RPDs due to a strong gag reflex, and after a few weeks of trying, he stopped using them. At the time of presentation at the University of Bern, he had been without molars for over a decade. The patient requested a complete oral rehabilitation and insisted on fixed reconstructions after his negative experience with removable dentures. The general medical risk assessment did not reveal anything remarkable. The patient was in good general health, was not on any medication, and did not smoke. Therefore, after comprehensive periodontal treatment, there was no contraindication to implant therapy. Prosthodontic diagnosis yielded Kennedy class I in the maxilla and Kennedy class I/modification 1 in the mandible. The patient also showed generalized chronic periodontitis as defined by the European Academy of Periodontology. There were 12 remaining teeth, all vital except teeth 15 and 13. Teeth 14, 13, and 23 had been restored with telescopic crowns. Tooth 15 had been restored with an amalgam filling and teeth 12, 11, 21, and 22 with composite fillings. Attrition was found in both jaws (Fig 2 and 3), but within the normal range expected in a patient who had been using only his anterior teeth for mastication over more than 10 years.

Fig 1 Initial presentation.

Fig 2 Occlusal view of the maxilla before treatment.

Fig 3 Occlusal view of the mandible before treatment.

Fig 4 Orthopantomograph of the initial situation, which involved generalized horizontal bone loss combined with vertical bone defects. No pathological changes were visible in the maxillary sinuses.

Fig 5 Periapical radiographs of the first quadrant, revealing periapical radiolucencies at teeth 15 and 13 and the vertical bone defect at site 14. The preoperative radiographs also revealed that bone height was reduced at site 15, which was inadequate for standard implant placement.

Radiographic analysis revealed generalized horizontal bone loss combined with vertical bone defects at teeth 14, 11, and 45 (Fig 4). All four residual teeth in the mandible showed horizontal bone loss, generally down to the root tips (Fig 4). Teeth 15 and 13 were non-vital and visibly involved, as the periapical radiolucencies showed (Fig 5). The baseline radiographs revealed a bone height adequate for standard implant placement at sites 14, 24, and 25. The preoperative bone height was 5 mm at site 15 but only 1 mm at sites 16 and 26. No pathological changes were visible in the maxillary sinuses (Fig 4). Tooth 14 and all residual teeth in the mandible were considered irrational to treat based on a single-tooth preoperative risk assessment. Teeth 15 and 13 were considered questionable, due to the presence of large periapical lesions

and attachment loss. The five residual teeth in the maxillary anterior segment were regarded as safe. The treatment was to cover four phases: 1. Systemic phase. The patient was in good general health and did not smoke. There was no need for any additional examination or therapeutic measure in the systemic phase. 2. Hygienic phase. It was planned to extract all teeth that were classified as irrational to treat in this phase. The main issue was tooth 15, which had a doubtful prognosis due to its periapical lesion and attachment loss. One of the treatment options in the first quadrant was to provide a three-unit tooth-supported fixed partial denture (FPD) from tooth 15 to 13, leaving the patient with only two functional units or a premolar occlusion. When this treatment option was discussed with the patient, he requested an additional functional unit. Several longitudinal studies have shown that the use of both endodontically treated abutment teeth and cantilever units in tooth-supported fixed dental prostheses (FDP) is associated with a high failure rate. It was therefore decided to extract tooth 15 and to restore the first quadrant with implant-supported FDPs. In the hygienic phase, the six residual teeth in the maxillary anterior segment were periodontally treated by scaling and root planing. Additional endodontic treatment was performed on tooth 13. 3. Corrective phase. In the surgical part of the corrective phase, the plan was to place six implants (Straumann Regular Neck, Standard Plus, Ø 4.1 mm) 6 weeks after extraction of the remaining mandibular teeth (Type II implant placement). In the second quadrant, the plan was to place two implants (Straumann Regular Neck, Standard Plus, Ø 4.1 mm) at sites 24 and 25 to support a premolar and a molar. In the first quadrant, the plan was also to replace teeth 15 and 14 with two implants (Straumann Regular Neck, Standard Plus, Ø 4.1 mm). Bone height and crest width at site 14 allowed for standard implant placement; at site 15, however, the preoperative bone height was only around 5 mm (Fig 6). Therefore, sinus floor elevation using the transcrestal approach was planned. In the reconstructive part of the corrective phase, the plan was to restore the edentulous mandible with three four-unit implant-supported metalceramic FDPs: two cemented FDPs at the molar sites and one screw-

retained FDP in the anterior segment. In the maxilla, the old telescopic crowns were to be replaced with new metal-ceramic crowns; the missing posterior units were to be reconstructed with a premolar-shaped crown at the site of the first premolar, along with a molar-shaped crown at the site of the second premolar. As a result, the patient would have three chewing units on each side.

Fig 6 Periapical radiograph taken immediately before implant placement showing a residual bone height of approximately 5 mm.

4. Maintenance phase. Following completion of the corrective phase, the plan was to recall the patient at 6-month intervals to evaluate the residual dentition, the peri-implant soft tissue, and the reconstructions. Treatment of the mandible proceeded according to plan. In preparation of the surgical intervention in the maxilla, the patient rinsed with chlorhexidine digluconate 0.1% for 1 minute. Local anesthesia was administered buccally and palatally to the surgical field. A mid-crestal incision was made, including a small T-releasing incision in the distal area (Fig 7) and the raising of a fullthickness mucoperiosteal flap (Fig 8). With a help of a distance indicator (Fig 9), the center of the first implant at site 14 was marked with a small (1.2 mm) round bur on the alveolar crest. The distance between the distal aspect of tooth 13 and the marked position, indicating the center of the implant, was between 4 and 5 mm. The distance between the center markings for the first and second implants was 8 mm, allowing for two implant-supported crowns in a premolar-and-molar configuration (Fig 9).

Fig 7 A mid-crestal incision with a small T-releasing incision was made.

Fig 8 A full-thickness mucoperiosteal flap was raised for good access to the bone crest.

Fig 9 A distance indicator of the same diameter as the implant shoulder was used to locate the implant centers.

With round burs of two sizes (2.2 and 3.1 mm), the preparation apertures were widened to a diameter about 0.5 mm smaller than the proposed implant diameters (Fig 10). At site 14, a standard surgical procedure was selected to insert an implant (Straumann Regular Neck, Standard Plus, Ø 4.1 mm, length

12 mm) (Fig 11). Prior to placement, the distance from the crestal ridge to the cortical bone at the floor of the maxillary sinus was 5 mm, as measured on the preoperative radiograph. During surgery, this finding was confirmed by introducing a blunt periodontal probe into the preparation aperture and advancing it through the soft trabecular bone (type III or IV bone) to the sinus floor. The presence of soft (type IV) bone at site 15, together with a residual bone height of 5 mm, did not require the use of pilot drills. All that was needed for the preparation was to perforate the cortical bone at the alveolar crest with round burs (Fig 10) and then to proceed with osteotomes (Fig 12).

Fig 10 The exact position of the implant site was first marked with a small round bur, then widened with round burs of two sizes to a diameter roughly 0.5 mm smaller than the proposed implant diameter.

Fig 11 The implant at site 14 was placed in a standard surgical procedure.

Fig 12 Set of tapered osteotomes with different diameters, used to compress the residual bone and push it from the implant preparation into the sinus, elevating the sinus membrane.

The first osteotome applied to the implant site was a small-diameter tapered design (Fig 13). It was pushed toward the cortical bone of the sinus floor with light malleting. Having reached the sinus floor, the osteotome was pushed approximately 1 mm further, again with light malleting, to create a “greenstick” fracture of the cortical bone of the sinus floor. A small-diameter tapered design was used to minimize the force needed to fracture the cortical bone. The second osteotome also had a tapered design, but with a slightly larger diameter than the first one (Fig 14). It was used to increase the fracture area at the sinus floor and was applied to the same depth as the first one. The third osteotome was of a straight design, 2.8 mm in diameter and thus significantly narrower than the implant to be placed (Fig 15). After pushing the 2.8-mm osteotome up to the sinus floor but before introducing any grafting material, the sinus membrane was checked for perforation. This was achieved by using the Valsalva maneuver, i.e. the patient was asked to blow his nose against the resistance of his closed nostrils (Fig 16). Leakage of air from the implant site in this situation would indicate that the sinus membrane has been perforated and that no grafting material should be introduced into the sinus without closing the perforation first.

Fig 13 The first osteotome used at the implant site was a small-diameter tapered osteotome. This design was selected to minimize the force needed to fracture the cortical bone.

Fig 14 The second osteotome was also a tapered design but had a slightly larger diameter to increase the fractured area at the sinus floor.

Fig 15 The third osteotome was of a straight design, 2.8 mm in diameter.

Fig 16 To check the integrity of the sinus membrane, the patient was asked to blow against the resistance of his closed nostrils. In this situation, leakage of air from the implant site would indicate that the sinus membrane is perforated and that no grafting material should be introduced into the sinus cavity.

Fig 17 As the sinus membrane was intact, four cycles of filling with the grafting material could be applied.

Fig 18 Using a straight osteotome 2.8 mm in diameter, the grafting material was slowly pushed into the sinus cavity.

Fig 19 The last osteotome used was 3.5 mm in diameter with a shape and dimensions suitable for the proposed 4.1-mm implant. It is important that the last osteotome enters the preparation site only once.

As the sinus membrane was judged to be intact, the preparation was filled with deproteinized bovine bone mineral (DBBM) (Fig 17). Using the same straight 2.8-mm osteotome, the grafting material was then slowly pushed into the sinus cavity (Fig 18). This procedure was repeated 4 times or until around 0.2 g of grafting material (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland) had been pushed into the cavity below the sinus membrane. At the third and fourth entry, the tip of the osteotome was advanced roughly 1 mm into the sinus cavity to check if there was still resistance in the preparation site. The last osteotome was a straight design 3.5 mm in diameter (Fig 19) with a shape and dimensions suitable for a cylindrical implant 4.1 mm in diameter. It is important to let the last osteotome enter the preparation site only once. Multiple attempts will risk widening the preparation and jeopardize the primary stability of the implant in soft (type III or IV) bone. Conversely, if the diameter of the last osteotome is too small relative to the implant diameter, excessive torque will be needed to insert the implant; overcompression of the bone will result in greater bone trauma and bone resorption, potentially delaying osseointegration. Especially when implants are placed at sites with reduced bone volume, it is important to strike a fine balance between good primary stability and bone trauma. Throughout the preparation procedure, it is crucial to maintain precise control of the penetration depth. Regular osteotomes have cutting edges that increase the risk of membrane perforation upon entering the sinus cavity. For the osteotome technique performed with grafting materials, the osteotomes

should not enter the sinus cavity. Repositioned bone particles, grafting materials, and trapped fluid will create a hydraulic effect, moving the fractured sinus floor and the sinus membrane upward. This type of fluid pressure is less likely to cause a sinus-membrane perforation. The final step before placing the implant was to verify that the preparation was patent to the planned insertion depth of 8 mm. A depth gauge suitable for the implant diameter was advanced to the predetermined length (Fig 20). After repeating the Valsalva maneuver, an implant (Straumann Regular Neck, Standard Plus, Ø 4.1 mm, length 8 mm) was placed with excellent primary stability. Two cover screws were inserted into the implants at sites 15 and 14 (Fig 21). The mucoperiosteal flap was closed using seven interrupted 5.0 sutures, and the implants were allowed to osseointegrate in a submerged position (Fig 22). In the same surgical session, two implants (Straumann Regular Neck, Standard Plus, Ø 4.1 mm, length 12 mm) were inserted at sites 24 and 25. Postoperative care, in addition to standard self-performed hygiene, included chlorhexidine gluconate 0.1% twice daily for the first 3 weeks after implant surgery. Since bone substitutes had been used, the patient was also placed on antibiotics for the first week.

Fig 20 The final step before placing the implant was to verify that the preparation was patent to the planned insertion depth. A depth gauge suitable for the implant diameter was inserted to the predetermined length.

Fig 21 Two implants were placed at sites 15 and 14. Excellent primary stability was obtained.

Fig 22 The mucoperiosteal flap was closed using interrupted sutures (5-0), and the implants were allowed to osseointegrate in a submerged position.

Fig 23 Uncovering the implants. The punch technique was avoided as it jeopardizes attached keratinized mucosa buccal to the implants. A small crestal incision was made along the center of the implants, combined with a semilunar incision toward the palate.

Fig 24 Clinical view of the freshly uncovered implants after replacing the cover screws with 3-mm healing abutments. No suturing was required.

Healing was uneventful. After 10 weeks, surgical reentry was performed. Rather than using the punch technique, risking the loss of all attached keratinized mucosa to the buccal of the implants, a small crestal incision was made along the center of the implants, combined with a semilunar incision toward the palate (Fig 23). The cover screws were removed and two 3-mm healing caps inserted. No suturing was required, as the incisions followed the outlines of the implants (Fig 24).

Fig 25 Teeth 13 and 23 were prepared for metal-ceramic crowns. In addition, four 7-mm solid abutments were attached.

Fig 26 The master cast.

Fig 27 Try-in of the metal frameworks.

Fig 28 Occlusal view of the treatment outcome.

Two weeks later, the old telescopic crowns were removed from teeth 13 and 23. Both teeth were prepared for metal-ceramic crowns. Four 7-mm solid abutments were attached to the implants at the posterior sites with a torque of 35 Ncm (Fig 25). An impression was taken in polyether material (Impregum Penta; 3M ESPE, Seefeld, Germany) using impression baskets and position cylinders. The restorations were fabricated in the laboratory based on the

master casts (Fig 26). Tooth-supported metal-ceramic crowns were fabricated for sites 13 and 23 and implant-supported splinted crowns for sites 15 and 14 as well as 24 and 25. Great care was taken to ensure that the interproximal spaces between the implants were accessible with interdental brushes. After trying in the metal frameworks (Fig 27), the technician proceeded to add the veneering ceramic. Once it had been verified that the occlusal relations and lateral movements followed the occlusal scheme of canine guidance, the reconstructions were cemented with glass-ionomer cement (Ketac Cem; 3M ESPE, Seefeld, Germany). The implant-supported crowns at the second premolar sites were shaped like molars. The patient’s request to have three complete chewing units on each side was met in accordance with Kayser’s definition (Fig 28). The final step of this extensive treatment was to fabricate an occlusal stent for use as a night guard to protect the ceramic work against fracture and chipping.

Fig 29 Final reconstructions 2 years after treatment.

Fig 30 Orthopantomograph showing a stable clinical situation 2 years after treatment. A dome-shaped structure was apparent at site 15, indicating a substantial increase in bone

volume compared to the initial situation. The dome was surrounded by a new cortical bone plate.

Fig 31 Smile of the patient after completion of treatment.

The patient was recalled at 6-month intervals. Both the clinical (Fig 29) and the radiographic findings (Fig 30) obtained 2 years after completion of active treatment indicated that the periodontal and peri-implant situation was stable. A new sinus floor was identified above the apex of the 8-mm Straumann implant at site 15, indicating 4−5 mm of bone gain from the time of transcrestal sinus floor elevation. No technical complications like ceramic chipping occurred within the first 2 years of function, even though the patient was unable to wear the night guard due to an excessive gag reflex. He was satisfied both with his chewing ability and with the esthetic outcome (Fig 31). Acknowledgments Laboratory Procedures Labor Nowaki and Kernen, Master Dental Technicians – Bern, Switzerland

Lateral Window Protocols 6.3

Implant Placement with Simultaneous SFE: Lateral Window Technique with a Composite Graft V. Chappius

A 68-year-old woman presented for treatment to replace her maxillary right second premolar and first molar. Three years previously, her general dental practitioner had extracted tooth 16 because of a perforated root canal with a developing interradicular lesion (Fig 1). The patient was satisfied with the chewing function of her premolar occlusion until tooth 15 became symptomatic 2 months before presentation. Since a root fracture had developed, this tooth had to be extracted as well (Fig 2). The patient reported an uncomplicated medical history. She had mild allergic asthma induced by hay fever, requiring the use of a cortisone spray on very rare occasions during acute episodes. In addition, she reported some allergic reactions to penicillin and mefenamic acid.

Fig 1 Periapical radiograph of the right posterior segment of the maxilla 3 years prior to referral. Presumably due to a root perforation, the first molar (tooth 16) showed an interradicular radiolucency and had to be extracted by the patient’s general dentist.

Fig 2 The second premolar (tooth 15) became symptomatic 2 months prior to referral. Extraction was required.

Fig 3 The patient’s oral status was generally excellent. Her gingival biotype was classified as medium, and her dentition exhibited some signs of bruxism.

Fig 4 Clinical view of the maxillary right posterior segment. Good soft tissue healing was observed 2 months after extraction of the second premolar, with obvious buccal flattening of the alveolar crest in the area of the first molar.

The patient was a non-smoker. She had continuously received dental care by her private practitioner. Her plaque control and gingival health was, for the most part, excellent. Periodontal probing depths never exceeded 3 mm. She

displayed a medium smile line; her esthetic demands were moderate to high. Her gingival biotype was classified as medium, and the dentition revealed signs of bruxism (Fig 3). Two months after the second premolar had been extracted, the right posterior segment of the maxilla had a clinical appearance of good soft tissue healing with obvious buccal flattening of the alveolar crest at the site of the first molar (Fig 4).

Radiographic Analysis Cone-beam computed tomography (CBCT) was performed for radiographic analysis. The Schneiderian membrane did not reveal any abnormalities. A bony septum was observed in the anterior portion of the maxillary sinus (Fig 5). Site 16 exhibited a vertical bone height of 6 mm and a crest width of 5 mm (Fig 6). The corresponding figures for site 15 were 8 mm and 5 mm (Fig 7). The septum extended all the way from the basal to the cranial aspect of the maxillary sinus, progressing from its mesial anterior to its distal palatal wall (Fig 8). This configuration was clearly visible in the three-dimensional reconstruction image (Fig 9). The bone volume would allow for implant placement with simultaneous augmentation of the maxillary sinus. Due to the complexity of the bony septum, a lateral window technique was indicated and recommended to the patient.

Fig 5 Cone-beam computed tomography (CBCT) was performed for radiographic analysis. The Schneiderian membrane did not reveal any abnormalities. A bony septum was observed in the anterior portion of the maxillary sinus. The septum extended all the way from the basal to the cranial aspect of the maxillary sinus.

Fig 6 CBCT: Site 16 exhibited a vertical bone height of 6 mm and a crest width of 5 mm.

Fig 7 CBCT: Site 15 exhibited a vertical bone height of 8 mm and a crest width of 5 mm.

Fig 8 The septum extended all the way from the basal to the cranial aspect of the maxillary sinus, progressing from its mesial anterior to its distal palatal wall.

Fig 9 This configuration was clearly visible in the 3D reconstruction image.

Figs 10a-b After local anesthesia, a crestal incision was made along a slightly palatal route from site 14 to site 17, including two vertical releasing incisions mesial to tooth 14 and at site 17. A full-thickness mucoperiosteal flap was raised.

Fig 11 Autologous bone chips were harvested locally with a bone scraper. The crest was flattened to create sufficient interocclusal space. Diamond burs were used to reduce the buccal bone wall.

Fig 12 Due to the presence of a bony septum, the bone in the window area had to be completely removed.

Treatment Plan The patient requested a fixed restoration in the right posterior segment of her maxilla. Two treatment options were discussed: 1. Placement of one implant at site 15 with simultaneous guided bone regeneration (GBR) and sinus floor elevation. A single crown would have been provided for prosthetic restoration. This solution would have offered a second-premolar occlusion. 2. Placement of two implants at sites 15 and 16 with simultaneous GBR and sinus floor elevation. Two single crowns would have been provided for prosthetic restoration. This solution would have offered a first-molar occlusion. The patient selected the latter option, as she also felt esthetically compromised.

Surgical Procedure An oral dose of clindamycin 600 mg was given 2 hours before surgery. Following local anesthesia, a crestal incision was made along a slightly palatal route from site 14 to site 17, including two vertical releasing incisions mesial to tooth 14 and at site 17. A full-thickness mucoperiosteal flap was raised (Figs 10a-b). Autologous bone chips were harvested locally with a bone scraper. The crest was slightly flattened to create sufficient interocclusal space. Diamond burs

were used to reduce the buccal bone wall (Fig 11). Due to the presence of a bony septum, the bone in the window area was completely removed (Fig 12). The bony septum was resected with a piezosurgical instrument (Mectron Piezosurgery; Mectron, Carasco, Italy) to minimize the risk of perforating the Schneiderian membrane (Fig 13). In addition, the Schneiderian membrane was elevated from the anterior and palatal aspects of the sinus, thereby facilitating bone regeneration from the intact palatal bone wall (Fig 14).

Fig 13 The bony septum was removed with a piezosurgical instrument (Mectron Piezosurgery; Mectron, Carasco, Italy) to minimize the risk of perforation.

Fig 14 The Schneiderian membrane was elevated from the anterior and palatal aspects of the sinus to facilitate bone regeneration from the intact palatal bone wall.

Figs 15a-c Site 15 was prepared to receive a standard-diameter implant (Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 10 mm). Site 16 was prepared to receive a widediameter implant (Straumann Regular Neck 4.8 mm, Ø 4.8 mm, length 10 mm).

The next step was to prepare the implant bed. Site 15 was prepared to receive a standard-diameter implant (Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 10 mm). Site 16 was prepared to receive a wide-diameter implant (Straumann Regular Neck 4.8 mm, Ø 4.8 mm, length 10 mm) (Figs 15a-c). The autologous bone chips were mixed with deproteinized bovine bone mineral (DBBM) approximately 1 : 1 (Bio-Oss, large granules; Geistlich Pharma, Wolhusen, Switzerland). This composite graft was then introduced (Fig 16). The implants were placed with good primary stability.

Fig 16 The composite graft (autologous bone chips and deproteinized bovine bone mineral mixed approximately 1 : 1) was inserted before placing the implants.

Fig 17 Both implants were placed with good primary stability. The implant at site 15 exhibited an apical fenestration defect.

The implant at site 15 exhibited an apical fenestration defect (Fig 17). This defect was repaired by autologous bone chips, which were placed over the implant surface along with a second layer of DBBM for contour augmentation (Figs 18a-b) (Bio-Oss, small granules; Geistlich Pharma, Wolhusen, Switzerland). Two layers of a collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) were applied to cover the grafted site (Figs 19ab). After a releasing incision of the periosteum, primary wound closure was achieved (Fig 20).

Figs 18a-b The fenestration defect was repaired by autologous bone chips, which were placed over the implant surface along with a second layer of deproteinized bovine bone mineral for contour augmentation.

Figs 19a-b The grafted site was covered with two layers of a collagen membrane.

Fig 20 After a releasing incision of the periosteum, primary wound closure was achieved.

A postoperative radiograph was obtained (Fig 21). After a healing phase of 6 months, implant stability quotients (ISQ) were analyzed and found to be 83 (implant at site 15) and 82 (implant at site 16). At this point, the patient was referred back to her practitioner for prosthetic treatment. At the 1-year recall, the peri-implant soft tissue was healthy and the bone

condition stable (Figs 22a-c). The restorative dentist had added a nonocclusal distal cantilever for esthetic reasons. Acknowledgments Restorative Procedures Dr. Reto Meier – Kirchberg, Switzerland

Fig 21 Postoperative radiograph.

Figs 22a-c At the 1-year recall, the peri-implant soft tissue was healthy and the bone condition stable. A non-occlusal distal cantilever had been added.

6.4

Bilateral Implant Placement with Simultaneous SFE: Lateral Window Technique with a Composite Graft A. Tahmaseb

A 57-year-old woman was referred for dental implant treatment. Her maxilla had been edentulous for at least 20 years (Figs 1a-b). In the mandible, the residual dentition consisted of teeth 43 to 35. The left second premolar was extremely weak and had deep caries. The residual dentition was mutilated due to parafunction and the framework present. At the time of presentation, the patient was on her third complete denture in the maxilla and her fourth partial denture in the mandible. Despite several adjustments and remakes, her maxillary complete denture had been unsatisfactory over the previous 5 years, while her mandibular partial denture had never functioned adequately. She complained about poor stability as well as pain and discomfort in both jaws. The patient’s medical history did not reveal any significant findings. An intraoral examination was performed and revealed considerable bone resorption in the maxilla. In the mandible, extreme resorption was noted in the edentulous posterior segments. Less resorption had occurred in the anterior segment due to the residual teeth in that area. As a result, there was a significant discrepancy of bone height between the posterior segments and the anterior segment of the mandible. The residual height and width of the maxillary anterior segment, characterized by a knife-edge ridge close to the nasal cavity, was insufficient for implants. Starting from the canines into the posterior segments, bone width was adequate while bone height was not suitable for implant placement (varying from 1 to 4 mm) due to extreme resorption and pneumatization of both maxillary sinuses. Due to this extreme bone loss, we recommended a removable prosthetic solution in the maxilla so that adequate support could be established for the upper lip to meet the patient’s esthetic and phonetic expectations.

Fig 1a Preoperative radiograph.

Fig 1b Preoperative radiograph.

The following treatment plan was proposed: 1. 2. 3. 4. 5. 6.

Extraction of the mandibular residual dentition Bilateral sinus floor elevation Two endosseous implants in the mandible (interforaminal region) Mandibular overdenture supported by one bar Four endosseous implants in the maxilla Maxillary overdenture supported by two bars

The treatment options were discussed with the patient. Our recommendation was to complete the surgical procedure in a single session — including extraction of the mandibular dentition, bone harvesting at the extraction sites, placement of mandibular implants, bilateral sinus floor elevation, and immediate placement of maxillary implants (provided that sufficient primary stability could be achieved). The patient was informed of the risks and gave her written informed consent.

Surgical Procedure The existing maxillary denture was duplicated, and a corresponding surgical guide was fabricated for intraoperative use (Fig 2). In the mandible, the residual dentition was extracted in local anesthesia, followed by elevating a flap in the interforaminal region (Fig 3). Using a piezosurgical device (Mectron Piezosurgery; Mectron, Carasco, Italy), bone was harvested by collecting the interproximal bone chips and cutting back the alveolar ridge. Two standard implants (Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 12 mm) were inserted at the canine sites of the mandible at a safe distance from the mental foramen. The procedure was completed for transmucosal healing (Fig 4).

Fig 2 Duplicate of the existing maxillary denture, used to fabricate a surgical guide.

Fig 3 Alveolar ridge immediately after extraction.

Fig 4 The alveolar ridge of the mandible was cut down to harvest bone and to create vertical space for the future prosthesis. Two implants were inserted.

Fig 5 Incision and flap elevation in the maxilla.

Fig 6 Mucoperiostal flap to create access to the maxillary sinus.

Figs 7a-b A bone scraper was used both to partially remove the buccal wall of the maxillary sinus and to simultaneously collect the bone thus removed.

Fig 8 A piezosurgical device was used to further enlarge the opening to the maxillary sinus.

Fig 9 Clinical view after complete removal of the buccal sinus wall. The Schneiderian membrane is visible.

In the maxilla, a mucoperiostal flap was elevated from the mesial aspect of the canine to the tuberosity under local anesthesia (Figs 5 and 6). A bone scraper (Meta, Reggio Emilia, Italy) was used to harvest bone by removing the buccal bony wall of the maxillary sinus. The buccal wall was thinned out

until the Schneiderian membrane became visible (Figs 7a-b). Then a piezosurgical device (Mectron Piezosurgery; Mectron, Carasco, Italy) was used to complete the sinus osteotomy by enlarging and rounding off the access to the sinus (Figs 8 and 9). The next step was to elevate the Schneiderian membrane using a wide sinus elevator (PESIM1; Hu-Friedy, Tuttlingen, Germany). To release the tension in the membrane, this elevation procedure was commenced from an apical direction so any membrane perforations could be managed more easily (Fig 10). The membrane was completely elevated all the way to the medial wall of the maxillary sinus (Fig 11). After placing the surgical guide in the oral cavity, the stage was set for implant positioning and orientation (Fig 12). Given the very thin residual crest, the osteotomies were slightly underprepared in diameter to optimize primary stability.

Fig 10 The Schneiderian membrane was gently elevated using a wide sinus elevator.

Fig 11 The membrane was completely elevated all the way from the buccal to the medial wall of the maxillary sinus.

Fig 12 Placement of the surgical guide to facilitate ideal implant positioning. The osteotomy was executed before placing the graft material.

Fig 13 DBBM was used to partially fill the sinus cavity before placing the implants.

Figs 14a-b Placement of the implants.

Fig 15 The sinus cavity was additionally filled with harvested autograft and more DBBM.

Fig 16 Implants in situ. Bone chips were used to cover the small (fenestration-type and dehiscence-type) defects at the implant necks.

Fig 17 A resorbable collagen membrane was used to cover the sinus and the fenestration at the implant neck.

Before placing the implants, the palatal aspect of the sinus cavity was partially filled with DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland), ensuring that the space palatal to the implant was filled (Fig 13). Two implants (Straumann Tapered Effect, Regular Neck 4.8 mm, Ø 3.3

mm, length 10 mm) made from a titanium-zirconium alloy (Roxolid; Straumann, Basel, Switzerland) were inserted at the canine site and between the premolar/ molar sites (Figs 14a-b). Then the bone chips, which had been harvested from the buccal walls of the mandible and maxilla, were used to partially fill the remainder of the sinus cavity adjacent to the implant threads (Fig 15). DBBM was used for coverage. The small fenestrations at the implant necks were grafted with a double layer of autologous bone chips and DBBM (Fig 16). A resorbable collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) was used to cover the defect (Fig 17). The procedure was repeated on the contralateral side. Once again, two implants (Straumann Tapered Effect, Regular Neck 4.8 mm, Ø 3.3 mm, length 10 mm) made from a titanium-zirconium alloy (Roxolid) were placed with the help of a drill guide. Primary stability in the range of 20 to 25 Ncm was obtained for all maxillary implants. Finally the flaps were closed for submerged healing. An effort was made to achieve tension-free closure with Gore-Tex (WL Gore & Associates, Flagstaff, Arizona, USA) suture material (Fig 18). A panoramic radiograph was taken to evaluate the postoperative outcome (Fig 19). Postoperative prescriptions included analgesics, antibiotics, and chlorhexidine digluconate 0.2% for rinsing. The patient was instructed not to wear her dentures for 2 weeks. She returned to our office 2 weeks after surgery. Removal of the sutures was followed by soft relining of the dentures. At 3 months after surgery, a panoramic radiograph was obtained to document the healing progress and peri-implant bone condition (Fig 20). The graft was found to be stable in the radiograph. No significant problems were noted. At 6 months after surgery, a minor flap was elevated under local anesthesia to uncover the implants. Resonance frequency analysis (Ostell, Göteborg, Sweden) was used to verify that the implants were stable. Values ≥ 70 were obtained throughout, indicating that the implants had integrated successfully by that time.

Fig 18 Multiple continuous sutures were used to close the incision. The flap was closed in a tension-free manner.

Fig 19 Postoperative panoramic radiograph.

Fig 20 Panoramic radiograph 3 months after surgery, demonstrating stable peri-implant conditions.

Fig 21 Radiograph at the time the impressions were taken.

After taking impressions, standard prosthodontic procedures with bite registration, wax-up and framework try-in were performed to fabricate the overdentures. The mandible was restored with one bar on two implants and the maxilla with two bars, one on each side and both being supported by two implants (Figs 21 to 23).

Figs 22a-b Prosthetic bars in the maxilla and mandible.

Figs 23a-c Overdentures for the maxilla and mandible.

The patient was pleased both with the esthetic outcome and with the wearing comfort (Fig 24). She returned to the office twice for minor adjustments. After 1 year, a clinical and radiographic follow-up took place, revealing stable conditions of the peri-implant soft and hard tissues (Fig 25). Acknowledgments Laboratory Procedures C. Verschuren, Dental Lab Van Der Bijl – Tilburg, Netherlands E. Schildermans, ES Healthcare – Hasselt, Belgium

Fig 24 Esthetic overview.

Fig 25 Panoramic radiograph 1 year after surgery.

6.5

SFE with BCP using a Staged Approach C. ten Bruggenkate

Fig 1 Baseline orthopantomogram disclosing that subantral bone height was limited at sites 15 and 16.

Fig 2 Occlusal view of the partially edentulous right maxilla at baseline.

Fig 3 Lateral view of the partially edentulous right maxilla at baseline.

A 53-year-old woman was referred to the Department of Oral and Maxillofacial Surgery for implant treatment of her partially edentulous right maxilla. Teeth 15 and 16 had been extracted 1 year previously. The patient complained of inadequate chewing ability on the right side. She had tried a partial removable denture but found the discomfort unacceptable. Her teeth were in a fairly good condition, although tooth 14 had been endodontically treated without success and was recurrently causing discomfort. In the panoramic radiograph, it was found to be associated with a periapical lesion. Teeth 41 and 31 were congenitally missing (Fig 1). The patient was in a good state of health overall. She did not use any medication and did not smoke. Her alcohol use was confined to limited amounts at social events. She had been referred by her dental practitioner for implant placement in the upper right space. The referring dentist also suggested that tooth 14 should be removed, due to its poor prognosis. The height of the alveolar crest (5 mm) was inadequate for implant placement. Sinus floor elevation was suggested to prepare the implant site. A decision was made to extract tooth 14 and to elevate the sinus floor, such that two implants could be inserted at sites 14 and 16 for a three-unit fixed partial denture (FPD). Biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland) was selected as grafting material with hydroxyapatite and tricalcium phosphate at a 60 : 40 ratio, since the native alveolar bone height of 5 mm would ensure that the proposed implants could be placed with reasonably good stability. A staged protocol was planned, involving a delay of 6 months from sinus floor elevation to implant surgery (Figs 2 and 3).

Treatment Sinus floor elevation was performed in accordance with Tatum’s lateral window technique 1 month after removal of tooth 14. Local anesthesia was administered and a midcrestal incision placed from site 14 to site 16, including a releasing incision on the distal side of tooth 13 (Fig 4). A round diamond bur was used to create the lateral trap-door preparation.

The outline of the preparation followed the outline of the maxillary sinus as envisioned in the orthopantomogram. The next step was to luxate the trap door, turning it inward and upward. At the same time, the Schneiderian membrane was carefully prepared with hand instruments specially designed for sinus floor elevation (Salvin Dental Specialties Inc., Charlotte, North Carolina, USA) until the trap door was lifted into a horizontal position. Then the Schneiderian membrane was elevated at the nasal sinus wall to the same level as the trap door (Fig 5). A small septum was noticed between sites 16 and 15. Neither perforations of the Schneiderian membrane nor hemorrhages were observed.

Fig 4 Maxillary right posterior segment upon exposure. Note the healing extraction sockets at sites 14 and 15.

Fig 5 A top-hinge trap door was made in accordance with Tatum and was rotated inward and upward into the maxillary sinus, leaving the antral mucosa intact.

Fig 6 Biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland) with hydroxyapatite and tricalcium phosphate at 60 : 40 was mixed with the patient’s fresh blood.

Fig 7 The sinus floor was filled with the bone substitute, filling up the space below the lifted trap door and the Schneiderian membrane.

Fig 8 Hand instruments were used to gently condense the graft into position.

Fig 9 Buccal view showing the graft in place.

Fig 10 Wound sutured and covered with Solcoseryl (ICN Pharmaceuticals, Frankfurt, Germany) oral wound dressing.

The space created underneath the lifted trap door was filled with two containers of biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland soaked in blood (Figs 6 to 9). No barrier membrane was placed over the lateral window into the sinus wall. The flap was repositioned and sutured with non-resorbable expanded polytetrafluoroethylene (ePTFE) sutures (WL Gore & Associates, Flagstaff, Arizona, USA) (Fig 10). The postoperative orthopantomogram showed proper graft placement and fill of the sinus floor. The patient was prescribed 0,5 g of amoxicillin four times daily during 7 days. Postoperative healing was uneventful. The sutures were removed after 10 days. Ridge-mapping and orthopantomography was conducted 5 months after sinus floor elevation and revealed favorable bone dimensions for the implant procedure scheduled to take place 1 month later (Figs 11 to 13). Six months after sinus floor elevation, a second surgical procedure was

performed to place the implants. A single dose of 3 g amoxicillin was administered 1 hour before implant surgery. Under local anesthesia, a midcrestal incision was made from site 14 to site 16. A mucoperiosteal flap was raised, including a papilla-sparing releasing incision on the distal side of tooth 13 (Fig 14). The alveolar crest was found to exhibit good healing and favorable dimensions for implant placement.

Fig 11 Postoperative orthopantomogram.

Fig 12 Clinical view of the maxillary posterior segment 6 months after sinus floor elevation and grafting.

Fig 13 Lateral view 6 months after sinus floor elevation and grafting.

Fig 14 Surgical field after reflection of a full-thickness mucoperiosteal flap.

Fig 15 Clinical view after implant placement at sites 14 and 16.

Fig 16 Orthopantomogram obtained after implant placement at sites 14 and 16.

Fig 17 Orthopantomogram taken at the end of the 3-month osseointegration period. The graft was found to be stable.

Two implant-bed preparations were made with regular spiral drills to accommodate the proposed implants (Straumann AG, Basel, Switzerland). Two implants (Straumann Regular Neck, Standard Plus, Ø 4.1 mm, length 10 mm) were placed at sites 14 and 16 (Figs 15 and 16). Once inserted, healing caps 3 mm in height were attached. The mucoperiosteal flap was repositioned and closed with ePTFE sutures (WL Gore & Associates, Flagstaff, Arizona, USA). The postoperative orthopantomogram revealed that the implants were favorably positioned and surrounded by sufficient amounts of grafting material. Postoperative healing was uneventful. The sutures were removed after 10 days. After 3 months of healing, an orthopantomogram was obtained and the stability of the implants evaluated (Fig 17). They were well integrated.

Fig 18 Three-unit FPD on implants 14 and 16. Clinical view after 3 months.

Fig 19 Three-unit FPD on implants 14 and 16. Orthopantomogram after 3 months.

Fig 20 Three-unit FPD on implants 14 and 16. Lateral view after 1 year of function.

Fig 22 Three-unit FPD on implants 14 and 16. Lateral view after 2 years of function.

Fig 21 Three-unit FPD on implants 14 and 16. Orthopantomogram after 1 year of function

Fig 23 Three-unit FPD on implants 14 and 16. Orthopantomogram after 2 years of function

Prosthetic treatment consisted of taking impressions with the respective impression components. A three-unit ceramic fixed partial denture on a gold framework was made by the patient’s dental practitioner. The patient expressed her appreciation of her new teeth, stating that they felt just like natural teeth (Figs 18 and 19). After 1 and 2 years, the peri-implant soft tissue was found to be healthy, without any pockets or bleeding on probing, and the peri-implant bone levels were stable (Figs 20 to 23). Acknowledgments Prosthetic Procedures Dr. J. W. Roeloffs – Katwijk, Netherlands

6.6

SFE with a Composite Graft using a Combined Simultaneous and Staged Approach D. Buser

A 38-year-old woman was referred to our department for implant therapy. She was healthy and a non-smoker. The referring dentist had been forced to extract the second premolar in the right maxilla and requested a detailed examination for implant therapy. The clinical examination revealed a singletooth gap with healed mucosa. The crest width was considered adequate for implant placement (Fig 1). The adjacent first molar had been restored with a crown and displayed a metal margin, which bothered the patient from an esthetic viewpoint (Fig 2). A periapical radiograph was obtained, showing remnants of the extraction socket and sufficient bone height in the edentulous area. The adjacent first molar was associated with a periapical radiolucency, although the extent of this chronic lesion was unclear (Fig 3). It was decided to use a cone-beam computed tomography (CBCT) system (Accuitomo; Morita, Kyoto, Japan) to evaluate the anatomical situation in detail. The three-dimensional image revealed a surprisingly large cystic lesion (Figs 4 and 5).

Fig 1 Initial clinical status with a single-tooth gap at site 15 following extraction by the referring dentist. The mucosa was healed, and the crest showed adequate width for implant placement in the edentulous area.

Fig 2 This facial view did show any significant buccal flattening. However, the visible metal margin of the crown restoration on the first molar greatly bothered the patient.

Fig 3 In the periapical radiograph, the previous extraction socket at site 15 could still be identified. The first molar was associated with a periapical radiolucency, although the extent of this lesion was not clearly visible.

Fig 4 The panoramic view of the CBCT scan revealed a large cystic lesion at the two buccal roots of the first molar.

Fig 5 This orofacial section of the CBCT scan clearly illustrated the extent of the radicular cyst.

Fig 6 Clinical status after flapless extraction of the first molar.

Fig 7 Extracted first molar with the cyst attached to the buccal roots.

Fig 8 Following debridement of the extraction socket, a collagen plug was applied to stabilize the blood clot.

After discussing the situation with the patient, the following treatment plan was agreed upon: 1. Flapless extraction of the first molar. 2. After 3 months of healing, placement of an implant at site 15 with simultaneous sinus floor elevation and ridge augmentation at site 16 (window technique with a collagen membrane). 3. After another 2 months, restoration of implant 15 with a provisional crown. 4. Around 6 months after sinus grafting/ridge augmentation, placement of an implant at site 16. 5. Loading of the implants with cemented crowns. The first molar was extracted without flap elevation (Figs 6 and 7). The extended bone lesion was degranulated, rinsed, and filled with a collagen plug (Tissuecone; Baxter, Volketswil, Switzerland) to stabilize the blood clot (Fig 8). This approach was chosen to achieve intact soft tissue with additional keratinized mucosa at the proposed surgical site.

Fig 9 Clinical view after 3 months. Good healing of the mucosa was apparent. Roughly 5 mm additional keratinized mucosa was present in the first molar site.

Fig 10 The periapical radiograph confirmed a large bone defect at the first-molar site. Bone healing was more advanced at site 15.

Fig 11 Intraoperative view after elevation of a trapezoidal full-thickness flap, removal of existing granulation tissue, and preparation of a window to elevate the Schneiderian membrane. The buccal bone wall of the ridge was completely absent at site 16.

Fig 12 At site 15, a tissue-level implant was inserted with good primary stability. At site 16, the bone was locally augmented with a composite graft in order to gain height and to re-establish a buccal bone wall. A composite graft with locally harvested autologous bone chips and DBBM particles was applied.

After an uneventful soft tissue healing period of 3 months, a periapical radiograph was obtained (Fig 9). Extraction site 15 had normally healed and revealed a bone height of approximately 10 mm. Site 16 exhibited an extended bone lesion and was opened with a trapezoidal mucoperiosteal flap (Fig 10). As anticipated, the ridge at site 16 showed a large defect in the facial wall, due to resorption of bundle bone following extraction. As expected, implant placement was not possible at that site, and horizontal and vertical bone augmentation was necessary to allow implant placement in a second surgical procedure. To do this, a staged sinus floor elevation using the window technique was combined with a horizontal ridge augmentation procedure using GBR. A typical window was prepared with diamond drills and a piezosurgical device (Mectron Piezosurgery; Mectron, Carasco, Italy) to mobilize and elevate the Schneiderian membrane. This was successfully achieved without tearing the mucosa (Fig 11). The space created was then filled with a composite graft (Fig 12). We routinely use a 1: 1 mixture of autologous bone chips on the one hand, and a hydroxyapatite-based bone substitute offering a low substitution rate on the other. The bone chips are routinely harvested with a bone scraper (HuFriedy, Chicago, Illinois, USA) from the facial bone wall within the same flap. Our preferred bone substitutes are DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland) or, as an alternative, biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland). Both fillers are well documented and offer a low substitution rate, which is important for long-

term maintenance of the bone volume created (Jensen et al. 2006; Jensen et al. 2007; Cordaro et al. 2008).

Fig 13 Following the principle of guided bone regeneration (GBR), the augmentation material was covered with a resorbable collagen membrane as a temporary barrier.

In the present case, a composite graft with DBBM particles was applied, followed by the insertion of a standard tissue level implant (Straumann Regular Neck, SLActive, Ø 4.1 mm, length 12 mm) at site 15 in accordance with the treatment plan. Following the principle of guided bone regeneration (GBR), the augmentation site was then covered with a non-crosslinked, porcine-derived, resorbable collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) used as a temporary barrier during initial bone healing (Fig 13). The surgery was completed with a primary wound closure for submerged healing of the biomaterials applied (Fig 14). The postoperative radiograph demonstrated the inserted and well-positioned implant at site 15 and the applied graft material used for sinus floor elevation and ridge augmentation at site 16 (Fig 15). The originally planned provisional restoration of implant 15 was declined by the patient due to budget constraints. The implant remained unrestored over the entire period of bone healing. A radiograph was obtained 6 months after sinus grafting, revealing a wellintegrated implant at site 15 and advanced bone healing with adequate bone height at site 16 (Fig 16). An occlusal view showed a well-preserved ridge at site 16 and the absence of peri-implant mucositis at implant 15 (Fig 17).

Fig 14 Surgery was completed with tension-free primary wound closure.

Fig 15 Postoperative radiograph showing the tissue-level implant at site 15 and the bone graft at site 16.

Fig 16 After 6 months, the implant was well integrated. Bone healing had reached an advanced stage at site 15, while at site 16, bone healing had progressed well and allowed the placement of the second implant.

Fig 17 Occlusal view of the local status 6 months after bone augmentation.

Fig 18 After elevating two small flaps to minimize morbidity, a second Straumann implant was inserted. Note the magnetic post, which was attached to measure the ISQ value.

Fig 19 The obtained ISQ value of 56 was clearly below the threshold of 70.

Fig 20 Adapting the small flaps marked the beginning of non-submerged healing.

Fig 21 Postoperative radiograph with both implants appropriately positioned and inclined.

For the second implant procedure, a minimally invasive approach with small flaps and short releasing incisions was utilized. The ridge had nicely regenerated and allowed the insertion of a wide-body implant (Straumann Regular Neck, Ø 4.8 mm, length 12 mm) featuring a hydrophilic SLA surface with a micro-rough topography (SLActive; Straumann AG, Basel, Switzerland). A magnetic post was attached (Fig 18) to measure the ISQ value (Implant Stability Quotient; Osstell, Göteborg, Sweden). The obtained reading of 56 was slightly less than average (Fig 19). Subsequently, a 3-mm healing cap was attached for non-submerged healing of the implant at site 16 (Fig 20). A postoperative radiograph was obtained, showing that both implants were favorably positioned (Fig 21).

Fig 22 Occlusal view 6 weeks later, showing good healing of the peri-implant soft tissues.

Fig 23 Repeated evaluation of the ISQ values to monitor the progress of osseointegration.

Fig 24 The ISQ of the molar implant had clearly increased to 78, exceeding the threshold of 70 at this point.

Fig 25 The ISQ of the premolar implant was 80. Both implants were now ready to be restored.

A clinical examination performed 6 weeks later revealed good integration of both implants without any signs of inflammation (Fig 22). The ISQ of implant 16 had markedly improved to 78 (Figs 23 and 24). Implant 15, by comparison, showed an ISQ of 80 (Fig 25). Successful tissue integration of both implants was also confirmed radiographically (Fig 26). With both ISQ values clearly exceeding the threshold of 70, indicating that restorative treatment could be initiated, the patient was referred back to her dentist, who proceeded to restoring both implants with cemented crowns (Figs 27 and 28).

Fig 26 Periapical radiograph confirming normal bone integration of both implants. Some remodeling had taken place at crest level.

Fig 27 Clinical view after both implants had been restored with cemented crowns by the referring dentist. Treatment had resulted in a pleasing outcome.

Fig 28 Periapical radiograph confirming normal bone integration of both implants.

Fig 29 Clinical view more than 5 years after the second implant procedure, demonstrating good integration of the implants and stability of the peri-implant soft tissues.

Fig 30 More than 5 years after implant placement, the peri-implant bone levels were stable. Both implants have an excellent long-term prognosis.

More than 5 years after the second implant procedure, a follow-up examination confirmed that both implants were successfully integrated and that crestal bone levels were stable (Figs 29 and 30). Thanks to the successful regeneration of the large bone defect at the molar site, both implants have an excellent long-term prognosis.

Discussion This case required a staged approach to sinus floor elevation combined with ridge augmentation, due to a large bone defect at site 16 associated with inadequate bone height and complete absence of the buccal bone wall. As the crest was over 6 mm wide, a particulate composite graft could be used for the bone augmentation procedure. A block graft was not required, eliminating the need for an additional donor site in the chin or mandibular retromolar area, which would have involved extra morbidity. At site 15, a sinus floor elevation was simultaneously conducted to accommodate an implant of adequate length. Early loading with a temporary crown was planned to improve the chewing comfort. Mainly due to budget constraints, however, the patient decided against a temporary crown. A composite graft was used for sinus grafting and ridge augmentation. Combining autografts with a low-substitution bone filler offers two advantages. Firstly, the autologous bone chips with their content of noncollageneous proteins such as BMPs and other growth factors will expedite and reinforce the formation of new bone. Local harvesting of these bone chips from the facial bone wall with a sharp bone scraper did not involve

additional morbidity. Secondly, DBBM particles are well documented to offer both a low substitution rate and excellent dimensional stability over time. The use of implants featuring a hydrophilic SLActive surface offered the advantage of reducing the healing periods involved (Buser et al. 2004; Ferguson et al. 2006; Weber et al. 2009). Early loading is today routinely applied in a distinct majority of patients. A healing period of 3 to 4 weeks is commonly used for standard sites (Bornstein et al. 2009b; Bornstein et al. 2010), while 6 to 8 weeks are used at sites with regenerated bone or with simultaneous guided bone regeneration or sinus floor elevation. However, it is important for clinicians to evaluate primary and secondary implant stability objectively. Resonance frequency analysis (RFA) is now routinely used for this purpose. ISQ values have proved very helpful for clinicians by disclosing at what time an implant can be loaded (Oates et al. 2007; Valderrama et al. 2007; Bornstein et al. 2009). In the case discussed, the ISQ clearly improved from 56 at baseline to 78 after 6 weeks, enabling us to give the go-ahead for the restorative phase, since a threshold ISQ of 70 should be exceeded for this decision. The restorative dentist decided to splint the two implants, although this measure is no longer considered necessary but has clearly become a matter of preference. Acknowledgments Restorative Procedures Dr. Markus Salm – Bern, Switzerland

6.7

Bilateral SFE with Transcrestal and Lateral Window Technique using Various Composite Grafts R. A. Levine

A 53-year old woman, a non-smoker, presented with failing crown and bridge restorations in both maxillary posterior segments. In addition, she was dissatisfied with the esthetics of her mandibular anterior sextant (Figs 1 to 4). She had recently lost the distal abutment (tooth 16) of a three-unit fixed partial denture (FPD) to dental caries, whereupon the bridge structure was sectioned distal to site 15. The patient’s medical history was noncontributory. The following periodontal risk factors were identified and discussed with the patient: • Familial history of periodontal disease. • Poor/erratic compliance with preventive care.

Clinical Examination Periodontal probing depths ranged up to 3 mm in the maxilla and 4 mm in the mandible, with generalized bleeding upon probing. Only tooth 14 was found to be significantly mobile (class 1 mobility). Inadequate attached keratinized gingiva was noted at teeth 33 and 43, including 7−10 mm of facial attachment loss and 0 mm of attached gingiva (Fig 1). The patient was made aware that the mandibular anterior segment was hopeless. It was decided to address this situation upon completion of the maxillary restorations. A severe ridge defect was noted, which was due to trauma when the patient had lost her four mandibular incisors. The width of the maxillary posterior ridge seemed adequate but was significantly reduced in height because of sinus pneumatization. Occlusal relations were Angle class 1 with 4 mm of overbite and 2 mm of overjet. The patient expressed a strong desire to have a fixed provisional restoration installed during the healing phase to avoid a transitional removable denture.

Diagnosis • • • •

Inadequate vertical bone height in the posterior maxilla. Localized advanced attachment loss at teeth 33 and 43 with inadequate attached keratinized gingiva. Localized advanced periodontitis at teeth 33 and 43. Vertical and horizontal ridge defect extending from tooth 33 to tooth 43.

Fig 1 Initial presentation.

Fig 2 Pretreatment occlusal view.

Fig 3 Baseline view of the maxillary left segment.

Fig 4 Pretreatment panoramic radiograph.

Fig 5 Pretreatment CBCT scan of site 26.

Fig 6 Pretreatment CBCT scan of site 27.

Prognosis Tooth 14 was considered hopeless; 25, 28, 38, 33 and 43 were guarded. The

following treatment sequence was recommended: 1. Full-mouth periodontal scaling in one visit with plaque control reinforcement. 2. Maxillary CBCT scan to evaluate sinus health and bone volume (Figs 5 and 6). 3. Prosthetic planning to restore teeth 17, 13, 24, 28 and replace 16 (small tooth cantilever), 15, 14, 25, 26 and 27 with dental implants. Fabrication of a surgical guide template on the basis of mounted study casts. 4. Delivery of a temporary fixed denture to the maxillary right quadrant (sites 18 to 13). 5. Extraction of tooth 14, followed by immediate implant placement at sites 15 (including sinus floor elevation using the transcrestal osteotome technique) and 14. Sinus floor elevation through a lateral wall approach was planned in the maxillary left quadrant. 6. Provisionalization of the maxillary left segment (sites 24 to 28) with a surgical guide fabricated for implant placement at sites 25, 26 and 27. Initiation of the restoration of the maxillary right quadrant with a single crown at site 17 and a cantilever FPD at sites 14, 15 (16), to be performed 4 months after surgery. 7. Another 8−9 months later: surgical extraction of tooth 25 with placement of implants at sites 25, 26 and 27. 8. Another 2−3 months later: restoration of the maxillary left segment with single crowns at sites 24 through 28 (including a night guard). 9. Periodontal maintenance alternating between offices at 3-month intervals. 10. CBCT-based treatment planning for the mandibular anterior segment.

Treatment Elevation of the maxillary left posterior sinus floor following a lateral wall approach. Prior to commencing the procedure and applying local anesthesia, blood was drawn from the patient in the office to collect plasmarich growth factors (PRGF). Three fractions were extracted: fraction 1 was used as a membrane; fraction 2 was mixed with bone graft material, and fraction 3 served as liquid PRGF for delivery through a syringe. Sulcular incisions were made with crestal incisions over the edentulous site 26.

Following vertical releasing incisions on the mesiobuccal aspects of 24 and 28, a full-thickness flap was raised by blunt dissection to extend the flap into the vestibule to beyond 15 mm from the ridge. The flap was then sutured to the buccal mucosa of the cheek to improve surgical vision/access and to protect it against excessive trauma. A window into the sinus floor was created, with the apical border 15 mm and the coronal border just 2−3 mm apical to the sinus floor. Using a size 4 round high-speed diamond, the window was created to a point at which the membrane could just be visualized. It was then completed with OT5 and OT1 piezosurgical instruments tips (Mectron Piezosurgery; Mectron, Carasco, Italy) to help avoid tearing of the sinus. Further dissection was initiated with the EL1 instrument tip and completed with special hand instruments designed for sinus procedures.

Fig 7 Lateral wall preparation at sites 25 to 27. A customized collagen membrane was placed over the elevated sinus membrane.

Fig 8 DBBM with a 1 : 1 ratio of large to small particles was mixed with PRGF and loaded into a syringe for easy delivery.

Fig 9 Completion of sinus grafting.

Fig 10 A resorbable collagen membrane was stabilized over the prepared window with a single surgical tack.

Upon completion of membrane elevation, the new sinus floor was covered with a resorbable membrane (Bio-Mend; Zimmer Dental, Carlsbad, California, USA) (Fig 7). Fraction 2 of the collected PRGF was mixed with small and large particles of DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland) in equal parts to a total of 3 grams. This mixture was then delivered with a plastic carrier and packed thoroughly with condensing sinus instruments starting medially and anteriorly until the sinus cavity was completely filled (Fig 8). A resorbable collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) (Fig 9) was anteriorly secured with a single surgical tack (Fig 10) to cover the window. The membrane extended at least 3 mm in all directions from the lateral wall preparation. Fraction 3 of the PRGF was liberally applied under the flap before closure, which was accomplished by replacing and suturing with a combination of 4-0 silk and 4-0 chromic gut, also including 6-0 vicryl to suture the releasing incisions (Fig 11). Postoperative care included 10 days of antibiotic coverage (Augmentin), hydrocodone with paracetamol/acetaminophen as needed, a steroid pack for 6 days, and rinsing with chlorhexidine 0.12% for 2 weeks. The patient was seen for postoperative care 1 week later.

Fig 11 Closure of the surgical flap.

Fig 12 Clinical view 8 months after surgery. A laboratory-processed temporary prosthesis was used to replace 24 to 28 in anticipation of extraction and implant surgery at 25 and placement of implants at 26 and 27.

Fig 13 Surgical guide template mimicking the temporary FPD. Note the small mesiodistal diameters of the teeth to be replaced.

Fig 14 Presurgical panoramic radiograph taken 8 months after sinus grafting. The maxillary right quadrant was restored with a cantilevered cemented FPD (sites 16 to 14) and a single crown (site 17).

Fig 15 Completed prosthesis in the maxillary right quadrant, along with a temporary prosthesis covering sites 24 to 28.

After a healing period of 4 months, the final restoration of the maxillary right quadrant was initiated along with removal of the bridgework in the maxillary left quadrant, fabrication of a surgical guide, and completion of a laboratoryprocessed temporary fixed prosthesis covering sites 24 to 28 (Figs 12 to 15). At 8 months after sinus grafting, a follow-up panoramic radiograph was obtained and the patient scheduled for implant surgery. Surgical procedure for implant placement at sites 25 to 27 (Fig 16). After local anesthesia , lingual crestal incisions were made, extending sulcularly to the distal buccal of 23, maintaining the full papillae with a mesiodistal horizontal incision. Piezosurgery tips (EX1, EX2, EX3) were used to create a trough circumferentially around tooth 25 under copious water irrigation, such that the tooth could be easily removed with minimal trauma while preserving the buccal plate (Figs 17 to 19). Small surgical spoon excavators and an OT4

tip were used to debride the socket. This was followed by multiple intramarrow penetrations with the OP4 tip, taking care to avoid the thin buccal plate.

Fig 16 Maxillary left quadrant at the day of implant surgery. Tooth 25 was deemed hopeless.

Fig 17 Elevated flap revealing solid bone fill of the prepared window site.

Fig 18 Extraction of tooth 25 assisted by a piezosurgical device. A trough is created around the tooth to allow for minimally traumatic removal.

Fig 19 Tooth 25 following extraction. Note the short root length with removal of the periodontal ligament into the apical third as a result of using piezosurgical instrumentation.

Fig 20 Osteotomies completed at sites 25, 26, and 27.

Fig 21 Insertion torque values were measured and recorded for each implant site.

As the teeth to be replaced were reduced in mesiodistal width, it was necessary to respect the inter-implant distances to allow for proper emergence profiles of the final restorations. The use of bone-level implants offered additional space. The presurgical plan had been to use bone-level implants

(Straumann Bone Level, Regular CrossFit, SLActive; site 25: Ø 4.8 mm, length 14 mm; site 26: Ø 4.1 mm, 12 mm; site 27: Ø 4.8 mm, 12 mm). Type 2 bone density was noted throughout the preparation. Insertion torque values were 35 Ncm at sites 25 and 26, 25 Ncm at site 27 (Figs 20 to 23). A horizontal defect dimension to the facial of implant 25 was measured as 3 mm, and a procedure of guided bone regeneration was completed after placing the cover screw, using an equal-part mixture of Cerasorb (Riemser Arzneimittel, Greifswald, Germany), decalcified freeze-dried bone allograft (DFDBA; LifeNet Health, Virginia Beach, Virginia, USA), and sterile calcium-sulfate powder, which in turn was mixed with the patient’s blood (Fig 24). This mixture was thoroughly condensed to the buccal and lingual surfaces (Fig 25).

Fig 22 Clinical view after implant placement with the surgical guide in situ.

Fig 23 Favorable biological inter-implant distances.

Fig 24 Bone graft consisting of an equal-part mixture of Cerasorb (small particles), DFDBA, and calcium sulfate, which in turn was mixed with the patient’s blood from under the palatal flap.

Fig 25 Two bottle-shaped 4-mm RC healing abutments at sites 26 and 27. RC cover screw at site 25. The buccal and lingual horizontal defects were packed with the bone graft material.

A resorbable collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) moistened with saline was used for coverage (Fig 26). A connective-tissue graft was harvested from the undersurface of the palatal flap at sites 24 and 25 (Fig 27). The graft was then placed over the membrane and under both (the buccal and lingual) flaps for unimpeded healing, prevention of early membrane dissolution, and improved esthetics by facial contour enhancement. The original incisions were located on the palatal aspect of the ridge, thus requiring the facial keratinized gingiva to be reduced before flap closure, preserving the tissue and positioning it anteriorly so that interproximal papillae were present immediately after the procedure. Prior to suturing, the lengths were reduced by approximately half to establish a butt joint with the

palatal flap (Figs 27 and 28). Bottle-shaped healing abutments 4 mm in height were inserted at sites 14 and 15. Postoperative medications were similar to the first surgical visit, except that amoxicillin was given.

Fig 26 A moistened resorbable collagen membrane was customized for guided bone regeneration (full coverage of site 25).

Fig 27 A palatal CT graft was harvested from the bottom surface of the palatal flap and was positioned over the collagen membrane and under the flaps. Interproximal papillae were created from the scalloping of the buccal flap.

Fig 28 Final suturing.

Fig 29 Second-stage surgery to expose the implant at site 25, conducted 11 weeks after placement. Papilla-sparing incisions were used. During the same visit, a reverse-torque test at 35 Ncm was successfully completed.

Fig 30 After attaching an RC conical healing abutment (6 × 6 mm) to the implant at site 15, the tissue was sutured. Impression-taking was scheduled for 3−4 weeks later.

After a healing period of 11 weeks, a second-stage procedure was conducted to expose the implant at site 25. At the same visit, the bottle-shaped healing abutments were replaced with conical (6 × 4 mm) ones to “stretch” the tissue to develop the ”transition zone” for final impressions. Papilla-sparing incisions were used mesially and distally, with an additional palatocrestal incision to maintain keratinized gingiva on the facial aspect. Prior to placing the healing abutments, the bone was tested for each implant, using the reverse-torque test at 35 Ncm with Regular CrossFit (RC) sterile implant carriers and a Straumann torque driver (Figs 29 and 30). The soft tissue around implant 25 was closed with a 4-0 resorbable chromic gut suture. The radiographic assessment confirmed final bone healing. A waiting period of 3 to 4 weeks would permit adequate soft tissue healing for the final impressions.

Prosthetic Phase The patient returned to her restorative dentist 4 weeks after the second-stage procedure. This visit was used for final impressions using a closed tray technique. Subsequently the laboratory-customized stock abutments for 25 and 26 plus the waxed 27 were scanned for custom abutments using CAD/CAM technology (Figs 31 to 33). The case was inserted as single crowns and cemented with permanent cement (Figs 34 to 39).

Fig 31 Scanned laboratory wax-up of customized milled abutment for 27 (Etkon; Straumann, Basel, Switzerland).

Fig 32 Prosthetic abutments: 25 and 26 were customized stock RC abutments; 27 was a custom abutment based milled on the basis of a wax-up (far right) which was fabricated (Etkon; Straumann AG, Basel, Switzerland).

Fig 33 Good restorative position of the final abutments; non-reflective scan paste was applied to all abutments for scanning of the final case (Etkon; Straumann, Basel, Switzerland).

Fig 34 A restoratively driven surgical guide facilitated the establishment of appropriate emergence profiles and implant depths.

Fig 35 Final design with zirconia copings at sites 24, 25, 26 and 28. Ceramic veneers were to be added in the laboratory. The restoration at site 27 was custom-milled after being designed as noted above.

Fig 36 Final restorations in the maxillary posterior segments.

Fig 37 Final clinical view of the single crowns at sites 24, 25, 26, 27, and 28.

Fig 38 Occlusal view of the final outcome.

Fig 39 Final radiographs obtained after 3 months.

Fig 40 Final case at 12 months.

Fig 41 Final radiograph at 12 months.

Fig 42 Completed case one year after bone augmentation using titanium mesh in the mandibular anterior sextant. Two NCx12 mm implants were placed to support a 5-unit fixed bridge using CAD/CAM technology and custom zirconium abutments. Single crowns were placed on 34 and 44. Compare with Fig 1.

Fig 43 Final radiograph upon case completion 12 months after mandibular anterior ridge reconstruction and 19 months after completion of the maxillary left reconstruction.

Treatment Outcome The esthetic treatment outcome is shown in Fig 40. Horizontal and lateral

ridge augmentation had been completed 4 months previously using titanium mesh and bone grafting. A fixed provisional 34 to 44 was placed prior to GBR (Fig 41). The final restoration consisted of single crowns on 34 and 44 plus a FDP from 33 to 43 supported by two NCx12 mm implants (Figs 42 and 43). Only 5 teeth are present on the FDP due to a tooth archsize discrepancy.

Maintenance Phase After completion of the maxillary case, an alternating 3-month protocol was instituted with the patient’s restorative dentist and the patient’s compliance history to preventive care has been excellent.

Conclusion A team approach to complex surgical-restorative cases encourages proper sequencing of care based on a restoratively driven approach. This will facilitate appropriate three-dimensional surgical positioning of implants for the desired esthetic outcome. The use of “new technologies” such as the ones applied in SLActive surfaces, bone-level implants, piezoelectric bone surgery, plasmarich growth factors (PRGF) and CAD/CAM-assisted prosthetics will ensure improved patient esthetics, morbidity and patient outcomes. Acknowledgments Restorative Procedures Dr. Zola Makrauer – Private practice in advanced restorative dentistry, Huntingdon Valley, Pennsylvania, USA; Fellow of the International Team for Implantology (ITI) Laboratory Procedures Robert Burns, MDT – Pennsylvania, USA

Benchmark

Dental

Studio,

Southampton,

6.8

SFE with a Composite Graft using a Staged Approach P. Casentini

A 58-year-old man with missing teeth distal of 24 and 35 was referred for treatment. He reported a history of recurrent caries and endodontic complications as the reason for previous tooth extractions. The patient’s dental history showed no evidence of periodontal disease and bruxism. He complained about inadequate chewing ability and was dissatisfied with the esthetics of his smile. His desire was to have the edentulous areas rehabilitated in a stable and comfortable fashion. The patient did not have any systemic diseases, was not on any medication, and did not smoke. An extraoral inspection revealed an edentulous area in the left distal aspect of his smile. Intraorally, partial edentulism was noted in the maxillary left posterior segment distal to tooth 24. The left mandibular molars were also missing. Intermaxillary relations were normal in the edentulous areas, as was the interarch distance (Fig 1). Also, the edentulous ridges were found to have a favorable shape with a rounded profile. Tooth 35 had been restored previously with a metal-ceramic crown, which was inadequate in terms of esthetics and fit. While the residual dentition presented some vestibular gingival recessions in both jaws, the periodontal tissues were healthy. There were no signs of inflammation or pathology on probing. Occlusion was normal in the right side of the mouth, with the dentition extending to the second molar. Oral hygiene was considered adequate, even though a slight modification of the brushing technique was suggested to arrest progression of the buccal recessions. No pathology of the oral mucosa could be diagnosed. The patient was considered to have realistic esthetic expectations.

Preliminary periapical radiographs disclosed adequate bone height in the left distal mandible, the presence of a pneumatized sinus, and inadequate bone volume in the left distal maxilla (Fig 2).

Fig 1 Clinical view before treatment.

Fig 2 Preliminary radiograph before treatment. The residual bone volume did not allow for implant placement in the posterior maxilla.

Figs 3 and 4 Diagnostic radiopaque stents were obtained from a wax-up.

Treatment Planning

In accordance with the patient’s request, an implant-supported fixed rehabilitation was planned to replace the missing teeth in the maxilla and mandible. It was decided that a rehabilitation extending to the first molar would offer adequate esthetics and occlusal function. A wax-up of the planned rehabilitation was obtained from mounted casts, and a stent including radiopaque teeth (barium sulfate) was fabricated (Figs 3 and 4). A computed tomography (CT) scan was prescribed to verify the bone volumes and the condition of the maxillary sinus. During the scanning procedure, the patient was asked to wear diagnostic stents. The CT scan confirmed both that the bone volume was inadequate for implant placement and that the maxillary sinus was healthy. The residual bone was considered insufficient to achieve primary implant stability (Figs 5a-b and 6a-c).

Figs 5a-b A CT scan yielded useful details about the sinus anatomy.

Figs 6a-c CT scans confirming that the sinus was healthy and providing a basis to simulate implant placement after sinus floor elevation with dedicated computer software (Simplant; Materialise, Leuven, Belgium).

Figs 7a-b A scraper was used to obtain some autologous bone chips from the distal area of the mandibular implant site.

Based on the clinical and radiographic situation, the following treatment plan was proposed to the patient: • •

•

Placement of a single implant at the site of the mandibular left first molar. Sinus floor elevation in the posterior left maxilla, followed by delayed placement of two implants at the sites of the second premolar and first molar. Prosthetic rehabilitation using a two-unit restoration in the posterior maxilla and a single implant-supported restoration at site 36 associated with a single crown on tooth 35.

The patient accepted the treatment plan and gave his informed consent. First surgical stage. Local anesthesia was administered and, since implant surgery in the mandible was expected to be uncomplicated, sinus floor elevation was carried out during in the same session. In this way, autologous bone chips could be harvested with bone scraper distal to the mandibular site (Figs 7a-b). Mandibular implant surgery was completed by inserting an implant (Straumann SLActive Wide Neck 6.5 mm, Ø 4.8 mm, length 10 mm) (Figs 8a-b).

Figs 8a-b Placement of a Wide Neck implant in the posterior mandible.

A crestal incision, including vertical releasing incisions, was extended to the tuberosity area in order to access the lateral sinus wall. Since the periodontal status of the adjacent premolar was optimal, a para-marginal incision not involving the gingival sulcus was selected. Prior to establishing access to the sinus, the same scraper was applied once again to collect more autologous bone chips from the lateral wall of the maxilla (Fig 9). The lateral window was outlined with a round diamond bur (Ø 3 mm) mounted on a right-angled handpiece at a speed of 20,000 rpm (Fig 10). The sinus membrane was then gently elevated with hand instruments reaching the medial wall, and as the lateral window was extended mesially to allow for better control in that area (Fig 11). No perforation of the membrane was identified, and the membrane continued to exhibit normal movements during breathing.

Fig 9 The same scraper was used to collect more autologous bone from the lateral sinus wall.

Fig 10 Design of the lateral window created in the maxillary sinus wall.

Fig 11 Elevation of the membrane after mesial extension of the mesial window.

A composite graft including autologous bone chips and DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland) was prepared and then inserted into the sinus (Figs 12a-b and 13a). Autologous bone chips were considered an important part of the mixture, as they are expected to accelerate bone regeneration and the osseointegration of DBBM granules in widely pneumatised sinuses. The lateral window of the treated sinus was sealed with a collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) (Fig 13b). Moreover, tension-free closure of the flap was obtained through single interrupted 5-0 polyamide sutures (Fig 14). A periapical radiograph confirmed adequate elevation of the sinus floor and a uniform radiopaque aspect of the graft (Fig 15). The patient was prescribed antibiotics (for 6 days postoperatively), non-steroidal anti-inflammatory drugs and chlorhexidine mouth rinses for 10 days. He was also instructed to avoid blowing his nose for the first few weeks after surgery.

When the sutures were removed after 10 days, the patient reported no significant symptoms other than moderate swelling.

Figs 12a-b A composite graft of autologous bone and DBBM (deproteinized bovine bone mineral) was prepared.

Figs 13a-b The graft was inserted into the sinus and protected with a collagen membrane.

Fig 14 A tension-free suture was obtained.

Fig 15 A periapical radiograph taken directly after sinus floor elevation.

Fig 16 Clinical view after 6 months of uncomplicated healing.

Figs 17a-c Restoratively driven implant placement in the grafted area.

Fig 18 Upon completion of transmucosal implant placement, 6-0 polyamide sutures were used for soft tissue adaptation.

Second surgical stage. The maxillary implants were scheduled for placement after a 6-month period of uneventful healing (Fig 16). The same surgical access was selected, although flap reflection was reduced compared to the first procedure. A restoratively driven approach was taken to prepare the implant osteotomies, using the same radiopaque guide that had been used for diagnosis and obtained by the diagnostic wax-up. One standard implant

(Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 10 mm) and one wideneck implant (Straumann SLActive Wide Neck 6.5 mm, Ø 4.8 mm, length 10 mm), were selected to obtain appropriate emergence profiles for premolar and molar units (Figs 17a-c). Implants featuring a (highly osteoconductive and rapidly osseointegrating) SLActive surface were selected because there was a need to expedite osseointegration and to minimize the risk of failure. These requirements are considered particularly important in time-consuming rehabilitations involving multiple treatment steps. Both implants achieved good primary stability. Polyamide sutures (6-0) were used to bring about accurate adaptation of the soft tissue structures to the machined implant collars for transmucosal healing (Fig 18). Restorative procedures. The clinical appearance after 8 weeks indicated healing of the soft tissue and osseointegration of the implants (Fig 19). Now the final rehabilitation was initiated by attaching snap-on Synocta transfers and taking a closed-tray polyether impression (Figs 20a-b). The same visit was used to check the patient’s occlusion and to obtain a bite record with the opposing arch. Bite registration devices relined with a self-curing resin were used to record the opposing arch at implant sites (Figs 21a-b).

Fig 19 Clinical view after 8 weeks, indicating healing of the peri-implant soft tissues.

Figs 20a-b Impression-taking with Synocta snap-on transfers and a polyether material in a closed tray.

Figs 21a-b Interarch bite registration.

Figs 22a-b Framework try-in and radiographic verification.

Figs 23a-b Final restorations on the master cast before delivery.

The dental laboratory selected appropriate implant abutments (straight Synocta abutments for cemented restorations) and prepared the metal frameworks for the definitive rehabilitation. An intraoral try-in was performed to obtain clinical and radiographic verification of both precision and passivity, and another bite record was obtained with a small amount of self-curing resin (Figs 22a-b). Subsequently, the case was sent back to the dental laboratory for ceramic veneering of the final gold-ceramic restorations (Figs 23 a-b).

Figs 24a-d Intraoral appearance of the final restorations after delivery.

At delivery of the final rehabilitation, precision and occlusion were checked again, titanium abutments were tightened to a 35 Ncm torque, and the implant-supported restorations were cemented with a non-eugenol cement based on an acrylic-urethane polymer (Implacem; Dentalica, Milan, Italy) (Figs 24a-d). The crown on the natural abutment 35 was cemented with a glass-ionomer definitive cement. A final periapical radiograph confirmed correct adaptation of the definitive restoration (Fig 25).

Fig 25 Final radiographic verification of fit.

Fig 26 Extraoral view of the patient’s smile.

Figs 27a-b Clinical and radiographic follow-up after 2 years.

The patient’s smile did not display any black triangles and was considered adequate (Fig 26). Follow-up visits and professional maintenance sessions were scheduled every 6 months. Radiographic follow-up examinations took place once a year. After 2 years, the peri-implant areas revealed neither signs of soft tissue inflammation nor signs of bone resorption (Figs 27a-b). The patient was perfectly satisfied with the esthetics and function provided by his implantsupported rehabilitation. Acknowledgments Laboratory Procedures Carlo Pedrinazzi, Roberto Colli – Milan, Italy

6.9

Combined SFE and Horizontal Ridge Augmentation with Autologous Block Grafts, BCP, and GBR using a Staged Approach L. Cordaro

Various patterns of alveolar bone resorption are known to occur in the posterior maxilla. Following tooth loss, resorption may take a buccopalatal direction, resulting in a narrow ridge displaced toward the palate. Resorption may also proceed vertically in an apical direction, reducing the vertical dimension of the ridge and increasing the interocclusal space. Another common pattern of atrophy is caused by volume increases of the maxillary sinus, which will reduce the residual bone volume in an occlusal direction due to downward displacement of the sinus floor. Most cases are characterized by combined defects, leading to a variety of atrophy configurations. Whenever there is a greater need for augmentation than elevating the sinus floor with an inlay bone graft, horizontal and vertical augmentation of the residual ridge may be accomplished by intraoral harvesting of autologous onlay block grafts in the same surgical procedure. We refer to this procedure as “inlay-onlay” grafting of the posterior maxilla. With this approach, the reconstruction is carried out 4 to 6 months before implant placement. During the reconstructive phase, the posterior maxilla is approached with a wide mucoperiosteal flap designed through a crestal incision and two vertical releasing incisions. The same technique of elevating the sinus membrane is used as in any sinus floor elevation. Either the trapdoor technique may be adopted, or a window may be designed to remove the lateral sinus wall. Bone harvesting is not commenced before the sinus mucosa has been elevated and the clinician has confirmed the need for a horizontal or vertical onlay graft.

Generally, the ramus is chosen as donor site, but the mandibular symphyseal region may be used when a need for a large graft in the inlay procedure is anticipated. In this event, screws are employed to secure the bone blocks to the recipient site, while part of the graft is milled and used in particulate form to fill the space beneath the elevated sinus membrane. Depending on the clinical situation, bone substitutes may be added and covered with a resorbable membrane. In some situations, the clinician may choose to mix the selected bone substitute with the milled autologous bone for sinus grafting. The flap is released and sutured. Implants may be placed after 4 months if the inlay graft is made of particulate autologous bone, or after 6 months if a bone substitute was added to the autologous bone. Implant loading will usually take place 8 weeks after implant placement. A clinical case is presented to illustrate the surgical procedures. A 41-yearold man was referred for treatment of his partially edentulous right maxilla. He was a non-smoker. Teeth 17 and 13 were present. Teeth 14, 15 and 16 were missing. The canine was intact, and the second molar had an amalgam filling. Oral hygiene was inadequate. A panoramic radiograph was obtained and clearly revealed a vertical bone deficiency at the molar and premolar sites (Fig 1). The sinus floor required elevating and grafting for implants to be placed. The clinical situation suggested that a horizontal deficiency was present in the area of the first and second premolar.

Fig 1 Orthopantomogram clearly illustrating that the sinus was pneumatized. Mesial to the residual second molar, vertical resorption of the alveolar ridge in an occlusoapical direction was noticed. This radiographic technique did not yield any information about the horizontal dimension of the residual ridge.

The occlusal and lateral views (Figs 2 and 3) demonstrated the horizontal deficiency that was observed at the first visit. The patient was informed and scheduled for sinus floor elevation. He was also informed that an onlay procedure might be necessary and that autologous bone may be harvested from the mandible during the procedure.

Fig 2 Occlusal view of the edentulous area. A horizontal bone defect was anticipated.

Fig 3 Lateral view confirming the horizontal defect and revealing a slight vertical deficiency. Soft tissue conditions (quality and quantity) were ideal and expected to be beneficial for the planned surgical procedures.

Surgery was carried out in an outpatient setting under local anesthesia. Continuous sedation was not planned, as the patient was very cooperative. The procedure started by elevating a wide flap. A crestal incision line was used and continued into the gingival sulcus of adjacent teeth. Mesial and distal vertical releasing incisions were performed; the mesial incision was placed immediately distal to the canine to reduce visibility of the resulting scar. The lateral surface of the maxilla was exposed, and a bony window was opened with a round bur (Fig 4). Once the access osteotomy had been completed, the bony window was removed, bringing to light an intact mucosa

of the maxillary sinus (Fig 5). The sinus membrane was carefully elevated. At this point, it was confirmed that a three-dimensional reconstruction was needed, including horizontal ridge augmentation and sinus floor elevation. Bone was therefore harvested from the right mandibular ramus using a standard technique (Fig 6).

Fig 4 Access to the edentulous area was gained through a full-thickness flap with mesial and distal vertical releasing incisions and a mid-crestal incision. The residual crest width was between 2 and 3 mm.

Fig 5 Access to the sinus membrane was established after removal of the bony window. The intact sinus mucosa is clearly visible.

Fig 6 Harvesting of a bone block from the mandibular ramus. The cortical block is outlined and is out-fractured. Access to the mandible was achieved through a mucosal incision 3−4 mm away from the mucogingival line.

Part of the graft was milled and inserted below the sinus membrane (Fig 7). The remainder was divided, securing two block grafts to the recipient site to achieve horizontal augmentation (Fig 8). Only one lag screw 1.5 mm in diameter was used for each piece. Bone substitute consisting of biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland) was added at the periphery of the block grafts (Fig 9) and covered with two layers of collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) (Fig 10). The flap was then mobilized with the aid of periosteal horizontal releasing incisions and closed with interrupted sutures (Fig 11).

Fig 7 Part of the block was milled and grafted into the sinus (inlay graft) after mixing it 1 : 1 with a bone substitute.

Fig 8 The block was divided in two and grafted to achieve horizontal and vertical augmentation (onlay graft). The blocks were stabilized over the residual ridge with titanium screws 1.5 mm in diameter.

Fig 9 The bone substitute was then added at the periphery of the block grafts.

Fig 11 Periosteal releasing incisions allowed for repositioning of the buccal flap, which was stabilized with interrupted sutures.

Fig 10 Two layers of a collagen membrane were used to cover the composite reconstruction.

After 4 months of uneventful healing, the case was ready for the second-stage surgery, including removal of the lag screws and implant insertion (Fig 12). A panoramic radiograph was obtained to evaluate the outcome of the grafting procedure (Fig 13). The vertical-inlay bone graft was visible, and the block grafts with the stabilizing screws were found to have remained in place. The clinical views indicated the amount of bone reconstruction achieved at this stage (Figs 13 and 14).

Fig 12 Clinical view 4 months after reconstruction and immediately prior to implant surgery (stage 2).

Fig 13 Radiograph obtained before the second-stage intervention. Elevation of the sinus floor is evident, and the vertical bone reconstruction achieved in a coronal direction is clearly visible.

Fig 14 Occlusal view demonstrating the presence of a nice wide ridge.

Fig 15 A flap was raised to expose the screws and the reconstructed ridge. Sufficient width was available to place one Standard implant and one Wide Neck implant.

Fig 16 After removal of the screws, the implant sites were prepared. Direction indicators for the 2.2-mm pilot drill were used here to demonstrate ridge width.

Fig 17 A standard implant (Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 14 mm) was placed at the site of the first premolar, and a wide-neck implant (Straumann Wide Neck 6.5 mm, Ø 4.8 mm, length 10 mm) was placed at the site of the first molar.

Fig 18 A non-submerged healing protocol was used in this case

Second-stage surgery (Figs 15 to 18) included a smaller flap, with only a small vertical distal releasing incision, to expose the reconstructed alveolar crest. The amount of horizontal bone augmentation was clearly visible at this stage. There was minimal graft resorption, as demonstrated by the level of the

lag screws in relation to the bone surface. One wide-diameter implant (Straumann Wide Neck 6.5 mm, Ø 4.8 mm, length 10 mm) was positioned at the site of the first molar. One standard implant (Straumann Regular Neck 4.8 mm, Ø 4.1 mm, length 14 mm) was placed at the site of the first premolar. The hole of the removed lag screw was clearly visible, and the grafts were excellently incorporated in the recipient bone. A transmucosal technique was employed, and the mucosa was adapted to the implant healing caps and sutured.

Fig 19 Radiographic view of the final restoration in place.

Fig 20 Final restoration. Three-unit fixed partial denture on two implants and nicely supported by the surrounding hard and soft tissue structures. The crowns exhibited a normal vertical dimension.

Fig 21 Occlusal view of the abutments in place, demonstrating excellent horizontal tissue support.

A three-unit fixed partial denture was delivered 8 weeks later. Both the occlusal view of the abutments and a panoramic radiograph demonstrated the success of the three-dimensional reconstruction (Figs 19 to 21). Acknowledgments Restorative Procedures Dr. Vincenzo Mirisola – Torresanto, Italy Laboratory Procedures Massimo Corona, CDT – Eastman Dental Center, Rome, Italy Aristide Ficuciello, CDT – Eastman Dental Center, Rome, Italy

6.10 SFE with Particulated Autografts Combined with Vertical Ridge Augmentation using Onlay Block Grafts and a Staged Approach W. D. Polido, E. Marini

Fig 1 Panoramic radiograph before the first grafting treatment failure.

Fig 2 CT scan before the first grafting treatment failure.

A 44-year-old man presented mainly because his complete denture in the maxilla was unstable and to get an opinion on a previous surgical reconstruction. He had worn a complete denture since he was 20 years old, following extraction of his entire dentition. His desire for treatment had led him to undergo bone grafting from the iliac crest, performed in a different oral surgery clinic around 1 year previously. Unfortunately, this treatment had failed because numerous technical issues involved in a surgical procedure as complex as this one had not been adequately observed. Despite this experience, the patient was determined to wear a maxillary fixed

denture and therefore sought further treatment. He was in good health and did not smoke. Pretreatment panoramic radiographs and CT scans had been obtained before the previous surgical procedure. The panoramic radiograph obtained at baseline showed complete pneumatization of the sinuses and alveolar atrophy in both maxillary posterior segments (Fig 1). A CT scan obtained prior to the first treatment failure aimed at bilateral sinus floor elevation and anterior onlay grafting had confirmed this pretreatment situation (Figs 2 to 5). Clinical views from that time were not available.

Fig 3 CT scan before the first grafting treatment failure (axial view).

Fig 4 CT scan before the first grafting treatment failure (maxillary left posterior segment) showing severe atrophy.

Fig 5 CT scan before the first grafting treatment failure (maxillary right posterior segment).

Fig 6 Anterior view with the maxillary denture in place.

Fig 7 Anterior view with the maxillary denture removed.

Fig 8 Right lateral view. A previous attempt at bone grafting had failed.

Fig 9 Left lateral view. A previous attempt at bone grafting had failed. A Chiapasco class H three-dimensional interarch relationship was observed.

Fig 10 Occlusal view at baseline. Note the volume of bone placed during the failed grafting attempt.

A clinical examination was performed, revealing a complete denture in the maxilla that was relined with a soft tissue conditioner and offered a poor fit and poor occlusal stability. The residual dentition in the mandible (48/45 and 43−34) presented with old restorations (Fig 6).

On removing the denture, the alveolar crest was found to involve irregularities due to incorrect positioning of the bone graft in the previous procedure. Occlusal and frontal views were obtained, revealing that the bulk of the graft had an excessively apical position toward the buccal vestibule. A scar was observed in the alveolar sulcus, possibly resulting from a sulcular incision with flap elevation performed from the apical to the alveolar, which may have limited the surgical field and led to poor adaptation of the graft (Figs 7 to 10). A large interarch distance was noted, compounded by the absence of teeth in the posterior mandible. The case was classified as Chiapasco Class H (Chiapasco et al. 2008). New panoramic radiographs and CT scans were ordered. A few issues were noted at this point (around 12 months after the previous grafting attempt). The panoramic view revealed that fixation screws were placed in an arrangement that would not allow for rigid stabilization of the grafts. Filling of the sinus areas with the bone graft was less than optimal, including areas of low-density bone (Fig 11). The CT scan of the posterior maxilla revealed that bone was irregularly distributed in the sinus cavity (Figs 12 to 14). As a possible explanation, the sinus membrane may have been elevated inadequately and, thus remaining attached to the palatal wall. Another common cause of irregular bone formation is failure to deliver enough bone and to compact it against the anterior and palatal walls, thus causing problems with implant placement in the grafted sites at a later stage. In the anterior region, the bone block completely lacked adaptation, giving rise to interposition of soft tissue between the graft and the maxillary anterior wall (Fig 15).

Fig 11 Panoramic radiograph after the first grafting treatment failure.

Fig 12 CT scan after the first grafting treatment failure.

Fig 13 CT scan after the first grafting treatment failure (axial view). Note the posterior horizontal deficiency.

Fig 14 CT scan of the maxillary right posterior segment. Note the poor adaptation of the bone graft inside the sinus, possibly due to inadequate elevation of the sinus membrane or inadequate compaction of bone.

Fig 15 CT scan of the maxillary left posterior segment. Inadequate graft positioning on the sinus.

Fig 16 Occlusal surgical view. Note that the fixation screws vastly protruded from the bone. The incision line was located palatal to the alveolar crest.

Fig 17 Anterior surgical view. Note the lack of contact between the block on the left side and the bulk of bone malpositioned on the right side.

Fig 18 Anterior view following removal of the screws and loose bone fragments. Note the sinus window opening on the left.

Fig 19 Window created to the left sinus. Note the elevated sinus mucosa, which had been perforated in a distal and upward direction.

Fig 20 Window to the left sinus, which communicated with the oral cavity on the palatal side of the alveolar bone.

A new surgical intervention was proposed, aiming to reconstruct the atrophic maxilla with a special focus on the sinus grafts. Difficulties were anticipated, considering that these areas had been subjected to surgery previously. As it was expected that the sinus membrane would rupture, coverage with a resorbable membrane was planned in conjunction with autologous corticocancellous bone (block and particles) harvested from the iliac crest. Under general anesthesia, corticocancellous bone was harvested from the anterior iliac crest in the form of a block and curetted cancellous chips. In the meantime, the maxilla was exposed by extending a palatally shifted crestal incision from tuberosity to tuberosity, including a midline releasing incision. This configuration allows for better vascularization of the flap (according to anatomical studies by Kleinheinz et al. 2005) and optimizes vision of the alveolar crest in both the anterior and posterior segments. The flap was reflected from the crestal toward the apical, extending it as far apical as possible to the subperiosteal level without damaging the infraorbital nerves. This maneuver will render the flap more amenable to mobilization and repositioning, thus eliminating the need for extended periosteal releasing incisions in achieving wound closure. Exposing the anterior maxilla revealed that the anterior grafts had been completely maladapted (Figs 16 and 17). After perforating and rupturing the sinus membrane (Figs 18 and 19), a round #6 diamond bur was used to open a large window for better evaluation of the sinus defect. The membrane had already been perforated, and the remaining portion was carefully released and

elevated on both the vestibular and palatal aspects to open the site for the new graft. A communication of the alveolar area with the sinus was noticed on the left side (Fig 20).

Fig 21 Window to the right sinus. The resorbable membrane was used to protect the perforated mucosa. On the lower aspect, an overhang was left to the outside of the sinus window. Cancellous chips had already been positioned on the anterior aspect.

Fig 22 Sinus window, completely filled. Bone was positioned level with the anterior block lateral to the window. Both grafts were covered with a resorbable membrane.

Fig 23 Lateral and vertical augmentation with a corticocancellous block over the left side. The sinus was already filled with cancellous bone and protected with a resorbable

membrane over the apical, distal, and palatal aspects. An L-shaped block was adapted, with cancellous bone toward the ridge and cortical bone to the buccal aspect.

Fig 24 Final view of the lateral and horizontal left graft after stabilization with fixation screws. Note the low position of the screws to stabilize the block over the sinus window in the residual alveolar bone.

After removal of the anterior screws and loose fragments of the remaining bone, the anterior maxilla was cleaned until it was free of debris. Decorticalization of the anterior bone was performed with a #1/4 round bur under copious saline irrigation. A resorbable membrane (Ossix; Biomet 3i, Palm Beach Gardens, Florida, USA) was placed to contain the grafted bone in the posterior segment. In addition, a piece of the membrane was placed against the bone on the palatal aspect and covered by the local periosteum at the site of communication between the oral cavity and the sinus. The corticocancellous particulated graft from the iliac crest was prepared and packed into the maxillary sinus cavity. A resorbable membrane was used to cover the graft apically and palatally, thus preventing particles from dislodging into the sinus cavity. A corticocancellous block was used to gain vertical and horizontal bone volume in the anterior maxillary segment. The block was sculpted to the shape of an L, adapted, and stabilized with titanium screws. Another piece of the corticocancellous bone block was placed laterally and vertically over the sinus window, followed by stabilization with screws in the most anterior region (Fig 19). On the right side, a corticocancellous particulated graft was placed horizontally and vertically outside of the filled sinus window, and a

resorbable membrane (Ossix; Biomet 3i, Palm Beach Gardens, Florida, USA) was used for protection (Figs 21 to 24). Closure of the wound was achieved with 4-0 vicryl for interrupted mattress sutures, also using a periosteal releasing incision.

Fig 25 Buccal view 6 months after grafting.

Fig 26 Occlusal view 6 months after grafting.

The patient remained without a restoration for 4 weeks. After removing the suture, an impression was taken and a new temporary complete denture fabricated. Adhesive paste was needed to stabilize the denture. Healing was uneventful. No graft exposure or infection was observed. Every 4 weeks, the patient was seen to monitor the progress of mucosal/bone healing and to adjust the denture as needed to avoid compression of the graft. A clinical examination performed after 6 months revealed an excellent contour of the reconstructed ridge in the vertical and horizontal planes (Figs 25 and 26). A new CT scan was ordered, using a radiopaque stent to identify the most appropriate sites for implant placement.

Fig 27 Panoramic radiograph prior to implant placement.

Fig 28 CT scan 6 months after grafting and prior to implant placement.

Fig 29 CT scan after grafting (axial view). Note the lateral augmentation in the posterior maxilla.

The CT scan showed excellent bone healing and 3D volume, allowing for optimal positioning of the implants (Figs 27 to 31). Implants were planned at sites 16/14/13/11/21/23/24/26 to allow rehabilitation with a fixed dental prosthesis, to be delivered as four segments, each spanning three units.

Fig 30 CT scan 6 months after grafting (maxillary left posterior segment). Note the excellent adaptation with bone fill in the sinus-floor area and good bone density.

Fig 31 CT scan 6 months after grafting (maxillary right posterior segment). Note the excellent adaptation with bone fill in the sinus-floor area and good bone density.

Fig 32 Occlusal view 6 months after grafting, including a surgical guide.

Fig 33 Anterior view during implant surgery. Note the membrane fragment on the right side.

Fig 34 Occlusal view during implant surgery. Note the comprehensive adaptation of the grafts. Low remodeling of the graft (as determined by the distance from the fixation screw head) was observed.

Fig 35 Close-up view of the grafted window in the right sinus. Fragments of the membrane are still visible.

Fig 36 Close-up view of the grafted window and the horizontal/vertical block graft in the left sinus.

The following implant type was selected: Straumann Tapered Effect, Regular Neck 4.8 mm, Ø 4.1 mm, length 10 mm, featuring an SLA surface. Different implants were only used at sites 16 and 26: Straumann Wide Neck TE, Regular Neck 6.5 mm, Ø 4.8 mm, length 10 mm. Surgery for implant placement was conducted with local anesthesia and intravenous sedation. A restoratively driven surgical guide was used (Fig 32). A palatally shifted crestal incision was made to place thick mucosa to the buccal aspect of the implants during wound closure. Occlusal and buccal views showed adequate bone height and width, with minimal resorption observed along the distance from the bone to the fixation screws. Fragments of the resorbable membrane were visible on the left side (Figs 33 to 36).

Fig 37 Occlusal view of the maxilla with the implant sites. Note the vitality of the bone.

Fig 38 Occlusal view during implant surgery. Implants were placed at sites 16/14/13/11/21/23/24/26.

Fig 39 Implants at exposure, 70 days after implant placement.

Fig 40 View of the patient’s smile with the final restorations 2 years after loading.

Fig 41 Anterior view of the final restorations 2 years after loading.

Fig 42 Occlusal view of the final restorations 2 years after loading.

Standard protocols were used to conduct the osteotomies and subsequent implant procedures. Excellent bone density with good primary was noted and was improved by the shape of the (Straumann Tapered Effect) implants used. Complete closure of the implants was performed (Figs 37 and 38). The implants were exposed under local anesthesia 70 days after placement. This was followed by taking impressions (2 weeks later) and delivering a provisional segmented prosthesis (another 2 weeks later) (Fig 39). After 60 days of using the provisional prosthesis to allow for bone and soft tissue remodeling and occlusal adjustments, the final metal-ceramic restoration of a fixed dental prosthesis in four segments spanning three units each, was cemented to solid abutments. Different views of the final restoration are provided here, including the patient’s smile line (Fig 40), a buccal view (Fig 41), and an occlusal view (Fig 42) taken 24 months after loading. Figure 43 displays a panoramic

radiograph obtained during the same time.

Fig 43 Panoramic radiograph 2 years after loading.

Fig 44 Buccal view 5 years after loading.

Fig 45 Panoramic radiograph 5 years after loading.

Figures 44 and 45 represent a panoramic radiograph and a buccal view obtained 5 years after loading. Note the discrete bone remodeling in the cervical implant regions and the small vertical bone loss between the implants at sites 23 and 24.

In discussing the outcome achieved, we suggest that a number of factors may influence the outcome of large bone grafts in severe bone atrophy. • Correct incision design and flap management will improve visualization, closure, and vascularization. • The need for a resorbable membrane to cover the sinus window and the anterior blocks will promote healing of the graft. If the sinus membrane gets perforated, it is used to protect the graft internally. • Perfect adaptation of the block graft is needed because it will improve healing with less resorption. • Complete filling of the sinus floor with good compaction of the corticocancellous chips may also improve healing and result in greater bone density. • Tapered implants (Straumann Tapered Effect) will optimize primary stability. However, the large cervical surface may enhance bone resorption in that region. Today we suggest the use of Bone Level implants for this indication, as they offer a primary stability that is similarly excellent to Tapered Effect implants while featuring a more bone-friendly interface at the implant neck, which may result in less resorption and better bone stability around the cervical region. Acknowledgments Prosthetic Procedures João Emilio Roehe Neto – Porte Alegre, Brazil

6.11 Bilateral SFE in the Edentulous Maxilla with DBBM using a Staged Approach S. Umanjec-Korac

A healthy 56-year-old woman was referred to our Department of Oral Implantology for complete rehabilitation of both jaws. She was a non-smoker and requested being treated with fixed restorations. The patient was dissatisfied with her appearance, particularly with the excessive length of her mandibular dentition. Her dental history was extensive. Over the previous 20 years, she had undergone periodontal and orthodontic treatment but also orthognathic surgery to advance the mandible. Clinical examination revealed good oral hygiene. The patient wore a maxillary denture, and the roots of teeth 13 and 23 were endodontically treated. Panoramic radiographs were obtained, indicating pneumatization of the sinuses and an inadequate vertical dimension of the alveolar process distal to both maxillary canines (Fig 1).

Fig 1 Baseline panoramic radiograph. Note the endodontically treated canines, the wide sinuses, and the inadequate vertical dimension for implant placement distal to the canines.

Fig 2 Anterior view of maximum intercuspation. Note the maxillary denture and the shortened occlusal line in the mandible with pronounced outgrowth of the lower incisors.

Fig 3 Baseline lateral view (right side).

Fig 4 Baseline lateral view (left side).

Fig 5 Occlusal view of the maxilla at initial presentation.

The mandibular dentition showed pronounced hypereruption. Only one-third of the periodontal attachment remained. The anterior teeth had been splinted to reduce their mobility (Figs 2 to 5). Several factors need to be considered and evaluated before implant-supported fixed rehabilitations in the edentulous maxilla can be proposed. A diagnostic wax-up is useful in evaluating the smile line, lip support, and interarch space. Three phases of treatment were planned: 1. Bilateral sinus floor elevation. Including extraction of all residual teeth in the mandible, followed by immediate delivery of a removable denture. 2. Implant surgery after 4 months. Six implants in the maxilla (four in the posterior segments and two in extraction sockets 13 and 23 by way of immediate placement) and another six implants in the mandible. 3. Restorative phase. Delivery of the final maxillary and mandibular fixed dental prostheses (FDP). Two alternative implant protocols are available in conjunction with sinus lift procedures: simultaneous or delayed placement. Which of both should be selected depends on the vertical dimension of the residual crest, which in turn influences the chances of primary implant stability. Attaining optimal mechanical stability in ridges less than 4 mm high is well known to be a challenge. In the diagnostic phase of the treatment, cone-beam computed tomography (CBCT) was used to evaluate the three-dimensional architecture of the

maxillary bone, the anatomical characteristics of the maxillary sinuses, and the height of the alveolar processes. At the site of the first molar, the residual alveolar process was found to be 4 mm high. Considering that primary implant stability might be compromised by pursuing the simultaneous implant protocol, it was decided to use the staged protocol on both sides. A modified lateral window technique was used to augment the maxillary sinuses (Boyne and James 1980). The procedure was started via a crestal incision (Fig 6). Vertical releasing incisions were placed anteriorly and posteriorly (Fig 7). A mucoperiosteal flap was prepared and elevated, thus exposing the lateral sinus wall (Fig 8). A bone scraper was used to collect autologous cortical bone chips from the lateral sinus wall (Fig 9). A piezoelectric window osteotomy was performed to open the sinus window (Figs 17 to 19). An outline was drawn using insert OT5 of a kit specially designed for sinus floor elevations (Mectron Piezosurgery; Mectron, Carasco, Italy). The cortical plate was removed and a flat curette applied to elevate the Schneiderian membrane (Fig 10). The membrane was dissected from the antral lateral wall, floor, and medial wall (Figs 11 and 12). Care was taken not to perforate the sinus membrane.

Fig 6 Incision line on the right side of the maxilla.

Figs 7 and 8 A mucoperiosteal flap was elevated.

Fig 9 Bone chips were harvested from the lateral sinus wall.

Figs 10 to 12 A lateral window was created and the Schneiderian membrane elevated with a flat curette.

DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland) was used to fill the cavity (Figs 13 and 20). The cortical window was replaced (Figs 14 and 15).

Fig 13 The maxillary sinus was filled with DBBM.

Figs 14 and 15 The cortical bone of the window was placed over the graft.

The defect of the lateral sinus wall was covered with a resorbable collagen membrane (Bio-Gide; Geistlich Pharma, Wolhusen, Switzerland) (Fig 16). The mucoperiosteal flap was repositioned and sutured. A panoramic

radiograph was obtained immediately after surgery, displaying adequate bone height distal to the maxillary canines (Fig 21).

Fig 16 A resorbable membrane was placed over the lateral window.

Fig 17 Preparing the lateral window with a piezosurgical device (left side).

Figs 18 and 19 Outlining the lateral window.

Fig 20 Grafting the maxillary sinus with DBBM.

Fig 21 Panoramic radiograph obtained after bilateral sinus augmentation, demonstrating that the vertical dimension had improved distal to both maxillary canines.

Fig 22 Teeth extracted from the mandible. Note the loss of periodontal attachment.

Fig 23 Anterior view of the maxillary and mandibular temporary dentures.

Fig 24 CBCT scan obtained before implant surgery, indicating sufficient bone height for implant placement in the posterior maxillary segments and insufficient bone width and height in the maxillary anterior segment.

Postoperative Healing The patient received 3 g amoxicillin 1 hour before surgery and 500 mg every 8 hours for 5 days after surgery. The patient was instructed to rinse twice daily with a chlorhexidine solution (0.2%) for 2 weeks. Postoperative wound healing was uneventful. No complications occurred.

Implant Surgery After 8 weeks, the patient was scheduled for complete extraction of her mandibular dentition. An immediate complete denture was delivered (Figs 22 and 23). A CBCT scan was obtained 4 months after bilateral sinus augmentation, indicating sufficient height of the alveolar bone in both maxillary posterior

segments (Fig 24). The ensuing implant procedure included placement of four implants (Biomet 3i Osseotite implants, Florida, USA; sites 16 and 26: prosthetic platform 4 mm, endosseous Ø 4 mm, length 13 mm; sites 15 and 25: prosthetic platform 4 mm, endosseous Ø 3.75 mm, length 13 mm) in the areas previously treated by sinus floor elevation (Figs 25 and 26). Good primary stability was obtained in all cases. Once the implants were in place, healing abutments were attached and torqued to 15 Ncm. The canines ware carefully extracted with periotomes to avoid damage of bone and soft tissue. Two implants (Biomet 3i Osseotite implants, Florida, USA; prosthetic platform 4 mm, endosseous Ø 4 mm, length 13 mm) were placed in a correct three-dimensional position, and the facial gap between the implants and the bony socket walls were augmented with DBBM (Bio-Oss; Geistlich Pharma, Wolhusen, Switzerland). Subsequently the grafted areas were covered with a resorbable collagen membrane and sutured (Fig 27).

Fig 25 Implants at sites 15 and 16.

Fig 26 Implants at sites 25 and 26.

Fig 27 Occlusal view of the maxillary implants after suturing.

Implant surgery was performed in the mandible. Six implants were placed (Biomed 3i Osseotite implants, FL, USA; sites 31/33,/41/43: restorative platform 4 mm, endosseous Ø 3.75 mm, length 11 mm; sites 36/46: restorative platform 4 mm, endosseous Ø 3.75 mm, length 8.5 mm). Good primary stability was obtained in all cases (Fig 28). Healing abutments were positioned, and the denture was adjusted and relined with a soft lining material.

Fig 28 Panoramic radiograph obtained after implant placement in the maxilla and mandible.

Fig 29 Healing of the maxillary soft tissues 4 months after implant placement.

Fig 30 Anterior view of models mounted in an articulator according to the facebow registration.

Fig 31 Wax try-in illustrating mandibular tooth length (cervical crown segments to ridge). Pink ceramic material was required to mask tooth length.

Fig 32 Milled mesostructure in situ.

Prosthetic Phase The restorative procedures were initiated 4 months after implant placement (Fig 29). Using screw-on impression copings, the final upper and lower impressions were taken at the implant level. Facebow registration was used to record the interarch relationship, and the patient was re-scheduled for a wax try-in 2 weeks later (Fig 30). The wax try-in indicated adequate facial and lip support. Also, the requirements for pink resin to mask the length of the mandibular teeth (cervical crown segments to ridge) were identified on this basis (Fig 31). The angulations of implants at sites 13 and 23 posed an esthetic challenge with regard to the original plan of delivering a conventional screw-retained implant prosthesis, as the screw access holes on the facial aspect were anticipated to compromise esthetics. Keeping that in mind, the most viable solution was to fabricate two mesostructures (splinting implants 16-15-13 and 23-25-26) and to use palatal screws for fixation (Figs 32 to 34). The maxillary and mandibular FDPs were delivered and checked for proper occlusion (Fig 37).

Fig 33 Final maxillary FDP.

Fig 34 Final maxillary FDP with palatal screw access holes.

Fig 35 Anterior view of the final prostheses in maximum intercuspation.

Fig 36 Anterior view of tooth display during smiling.

Fig 37 Panoramic radiograph at delivery.

Fig 38 Anterior view obtained after 1 year.

Fig 39 Occlusal view of the maxillary FDP after 1 year.

Fig 40 Occlusal view of the mandibular FDP after 1 year.

Fig 41 Panoramic radiograph after 1 year.

The milled mesostructures (Fig 32) and retaining screws of the final mandibular FDP were tightened to 35 Ncm. The maxillary prosthesis was retained on a mesostructure with palatal screws. Wax was used to cover the screw heads of the mandibular FDP, and the screw access channels were sealed with light-curing composite. The occlusion was carefully checked and adjusted (Figs 35 and 36). The FDPs were contoured to allow for adequate

self-performed hygiene. The patient received maintenance instructions and was recalled for follow-up visits every 6 months during the first year. After 1 year of function, the patient continued to be very satisfied with the function and esthetics of his FDPs (Figs 38 to 40). Another panoramic radiograph was obtained (Fig 41). Acknowledgments Laboratory Procedures Arnold Ngariman – K & J Tandtechniek, Haarlem, Netherlands

6.12 SFE with Particulated Autografts Combined with Vertical Ridge Augmentation using Onlay Grafts and a Staged Approach T. W. Head

A 61-year-old woman was referred for assessment of the possibility of bone grafts for implant placement to reconstruct her severely atrophic maxilla. She was a healthy non-smoker. Since her thirties she had worn a complete upper denture against a natural lower dentition. Ten years prior to the consultation, five implants had been placed in the maxilla for a fixed prosthesis. One implant failed immediately, and others failed over the ensuing 10 years. In the previous 2 years, she had been wearing a complete denture without retentive elements over the last two implants (Fig 1). Her primary concern was the instability of her denture. She had great difficulty with mastication and felt insecure when speaking. Her desire was to have a fixed prosthesis. At the consultation appointment, one implant remained in the anterior maxilla (Fig 2). Clinical and radiographic examination revealed that the maxillary alveolar ridge was completely resorbed from site 15 to site 25. The posterior maxilla had maintained its form, but due to the presence of pneumatized sinuses, it exhibited no bone mass (Figs 3 and 4).

Fig 1 Panoramic radiograph 1 year prior to consultation.

Fig 2 Intraoral view at the consultation appointment.

Fig 3 CT scan demonstrating severe anterior maxillary atrophy in sagittal views.

Fig 4 CT scan demonstrating severe atrophy and sinus pneumatization. The transverse cuts 13-16 correspond to tooth sites 15 and 14, and cuts 9-12 correspond to tooth sites 17 and 16.

Fig 5 Harvesting of a corticocancellous block graft and PBCM (particulate bone and cancellous marrow). The patient’s head was oriented to the left, and her leg to the right. The straight line indicates the midline of the lumbar spine and sacrum.

Fig 7 View of the exposed maxilla after elevating buccal and palatal flaps. Note the absence of anterior alveolar bone. Also apparent are the site of the removed implant and the non-resorbed but pneumatized posterior segments.

Fig 6 Corticocancellous block to be shaped to the anterior maxilla, and PBCM (particulate bone and cancellous marrow) to be packed into the sinuses and around the anterior block graft.

Fig 8 View after placing the anterior corticocancellous block and creating the right lateral sinus-wall osteotomies.

Based on the clinical and radiographic evaluation, this case was classified as complex (SAC classification), involving a high risk of complications and graft or implant failure. Risk factors associated with surgery included: limited soft tissue for graft coverage in the anterior maxilla; the need to obtain horizontal and vertical augmentation in jaw segment 15 to 25 and vertical augmentation in the posterior maxilla; and complete absence of residual alveolar bone to contribute to implant stability and osseointegration. In consultation with the prosthodontist, it was decided that eight implants (at sites 11/21, 13/23, 16/17, and 26/27) to support a fixed prosthesis should be planned for. The surgical plan included an autologous corticocancellous block onlay graft to the anterior maxilla and bilateral sinus floor elevation with particulate bone and cancellous marrow (PBCM) grafts. The volume of bone required indicated harvesting from the posterior illium. Implants would be placed in a second-stage procedure 4 to 6 months later. Under general anesthesia, the patient was placed in prone position. A 6-cm incision was created for bone harvesting (Fig 5). The graft consisted of a corticocancellous block, to be shaped for the onlay graft of the anterior maxilla, and PBCM to be densely packed around the anterior block graft and into the maxillary sinuses (Fig 6). Subsequently the patient was turned into a supine position. An incision was created in the keratinized mucosa, extending from the right to the left tuberosity, to expose the maxilla (Fig 7). The corticocancellous block graft was shaped to the desired curvature of the anterior maxilla and fixed in position with 1.7-mm titanium screws (Fig 8). Then the maxillary sinuses

were entered by creating osteotomies in the lateral sinus walls (Fig 9) and elevating the Schneiderian membrane with the lateralwall segment (Fig 10). The space created in the inferior aspect of the sinus was filled by densely packing PBCM into it. PBCM was also densely packed around the anterior corticocancellous block onlay graft (Fig 11). Continuous chromic gut sutures were used to close the mucoperiosteal flaps (Fig 12).

Fig 9 The Schneiderian membrane and the lateral sinus wall segment were elevated to place the sinus floor at a more superior position.

Fig 10 View of the elevated left sinus floor. A space 15 mm in height was created for the cancellous bone graft.

Fig 11 Cancellous bone graft was also packed around the anterior block graft.

Fig 12 The mucoperiosteal flaps were closed with 3-0 chromic continuous horizontal mattress sutures.

Fig 13 Fistulae developed 2.5 months after grafting.

Fig 14 Defects left in the anterior maxilla after debridement of fistulae.

Fig 15 Axial CT scan illustrating voids in the anterior onlay graft following debridement. Note the increased radiodensity created by the PBCM grafts in the sinuses.

Initial healing was very good, although two fistulae developed in the anterior maxilla 2.5 months after grafting (Fig 13). These areas were explored and found to contain necrotic bone and granulation tissue, which was removed by curettage. This left large void areas in the anterior block graft (Fig 14). A CT scan was obtained, demonstrating the extent of the defects in the anterior maxilla (Figs 15 and 16) but also indicating good healing progress of the sinus grafts (Fig 17). Another intervention was performed to graft the voids in the anterior maxilla with PBCM from the proximal tibia 1 month later.

Fig 16 Sagittal CT views of the anterior maxilla, demonstrating voids in the onlay graft.

Fig 17 Transverse CT views of the posterior maxilla, demonstrating the bone mass created by the cancellous graft inside the sinus.

The surgical plan of placing eight implants was implemented 4 months after the second grafting procedure in the anterior maxilla. Following a crestal incision from the right to the left tuberosity, a buccal mucoperiosteal flap was raised to expose the maxilla. Abundant viable bone was found at both the anterior onlay graft and the posterior sinus grafts (Fig 18). A surgical guide provided by the prosthodontist was used to position the implants (Fig 19). Four implants (Straumann Bone Level, Regular Cross Fit, Ø 4.1 mm, lengths 10 and 12 mm) were placed in the anterior maxilla, and four implants (Straumann Wide Neck, SLActive, Ø 4.8 mm, length 12 mm) were placed in the posterior maxilla (Fig 20). Plain 4-0 gut sutures were used to close the mucoperiosteum, obtaining primary closure over the anterior implants and open closure around the posterior implants. The patient’s conventional denture was relined with a soft material 2 weeks after implant placement. Because of the lack of keratinized mucosa on the labial aspect of the four anterior implants, free gingival grafts from the palate were placed labial to these implants while changing to longer abutments (Figs 21 and 22). The denture was again relined with soft reline material.

Fig 18 Four months after the second grafting procedure in the anterior maxilla, the reconstructed alveolar ridge was exposed via a crest incision and elevation of a buccal mucoperiosteal flap.

Fig 19 A surgical guide was used to place the implants at the sites required by the prosthodontist.

Fig 20 Eight implants were placed, including 10-mm designs at sites 11/21, 12-mm designs at sites 13/23, and 12-mm designs at sites 16/17/26/27.

Fig 21 View obtained 6 weeks after implant placement. Note the non-keratinized mucosa at the crest of the maxillary anterior ridge.

Fig 22 Free gingival grafts were placed labial to the anterior implants.

Fig 23 Soft tissue healing 6 weeks after placing the free gingival grafts.

Fig 24 Panoramic radiograph 3 months after implant placement. The patient was referred back to the prosthodontist at this time.

Fig 25 Labial view of the prosthesis in situ.

Fig 26 Buccal view of the prosthesis in situ (right side).

Fig 27 Buccal view of the prosthesis in situ (left side).

Fig 28 The smile of the patient.

After 6 weeks of soft tissue healing, the patient was referred back to the prosthodontist for fabrication of the prosthesis (Figs 23 and 24). The final prosthesis was delivered 4 months after implant placement (Figs 25 to 28). Radiographic follow-up examinations were performed after 6 months (Fig 29) and 1 year (Fig 30) after delivery. Acknowledgments Restorative Procedures Dr. Robert Valiquette – Greenfield Park, Québec, Canada Laboratory Procedures Eric Fortin, CDT – Le Groupe Dentachrome, Montréal, Québec, Canada

Fig 29 Panoramic radiograph 6 months after delivery.

Fig 30 Panoramic radiograph 1 year after delivery.

6.13 SFE with a Composite Graft Combined with Vertical Ridge Augmentation using Onlay Grafts and a Staged Approach M. Chiapasco

A 40-year-old woman with partial edentulism in both maxillary posterior segments was referred for consultation and treatment (Figs 1 to 4). Her main concern was the missing posterior teeth, which compromised mastication and were detrimental to her facial esthetics. She requested to have her appearance improved with a fixed prosthesis supported by oral implants. The patient reported a previous history of periodontal disease as the main cause of tooth loss in the posterior maxilla. She was in good general health, did not take any medications, and did not smoke.

Figs 1 and 2 Initial clinical and radiographic situation. The patient had previously undergone treatment for periodontal disease.

Figs 3 and 4 Edentulism in the maxillary posterior segments, associated with intermaxillary discrepancies in the horizontal and vertical planes.

An intraoral examination was conducted, indicating edentulism in the maxilla distal to the cuspids. Horizontal and vertical resorption of the alveolar ridge was present and associated with an increased interarch distance (notably on the left side). Gingival recessions resulting from periodontal disease were noticed on teeth 12, 13, 22 and 23 (Figs 1, 3 and 4). A panoramic radiograph and CT scans were obtained, demonstrating that bone availability at the premolar and molar sites was bilaterally reduced, as the maxillary sinuses had expanded in conjunction with alveolar ridge resorption. Nor did the bone volume in these areas seem to be adequate for implants with reduced dimensions (Figs 5 to 8). A “simple” procedure of sinus floor elevation was also excluded, as this would not have included grafting of the vertical and horizontal ridge resorption.

Figs 5 and 6 CT scans indicating that the maxillary sinuses were severely expanded in conjunction with the vertical and horizontal ridge atrophy.

Figs 7 and 8 3D CT scans confirming the presence of vertical atrophy.

Figs 9 to 11 A corticocancellous bone block was harvested from the anterior iliac crest.

Fig 10

Fig 11

Figs 12 and 13 The lateral window (with the alveolar antral artery) was prepared and the sinus membrane elevated.

It was decided to proceed with an augmentation procedure that included sinus floor elevation in association with vertical and horizontal autologous bone grafts. This procedure would not only adequately reconstruct the bone volume for implant placement but would also establish favorable intermaxillary relationships. In this way, a restoratively driven approach with ideal implant placement could be pursued. It was also planned to insert the implants after consolidation of the grafts in a second-stage procedure. Due its complexity and duration, the reconstructive procedure was conducted under general anesthesia with nasotracheal intubation. The first step was to harvest a corticocancellous bone block from the medial side of the anterior iliac crest (Figs 9 to 11). The next phase was to elevate a mucoperiosteal flap to expose the posterior maxilla. A bony window was created so that the sinus membrane could be elevated (Figs 12 and 13).

The cancellous component of the iliac graft was particulated, mixed with biphasic calcium phosphate (Straumann BoneCeramic; Straumann, Basel, Switzerland), and used to fill the cavity created after sinus floor elevation. At the same time, iliac bone blocks were fixated with titanium microscrews to graft the vertical and horizontal deficit of the left maxilla (Figs 14 to 16). After creating adequate releasing incisions, the flap was eventually sutured for non-permeable and tension-free closure (Fig 17). The same procedure was repeated on the right side, again including sinus floor elevation in conjunction with vertical and horizontal bone grafting (Figs 18 and 19).

Fig 14 A composite graft including autologous bone (particulated chips) and a bone substitute was used to fill the cavity created after elevation of the sinus membrane

Fig 15 The vertical deficit was grafted with an autologous bone block from the ilium.

Fig 16 The horizontal deficit was simultaneously grafted with another autologous bone block fixated with titanium microscrews.

Fig 17 Eventually the mucoperiosteal flap was adequately released and the surgical field closed with a non-permeable suture.

Figs 18 and 19 The same procedure was used on the right side, including sinus floor elevation with particulated bone and a bone substitute in conjunction with horizontal and vertical autologous grafts from the iliac crest.

Fig 20 A panoramic radiograph was obtained after reconstructive surgery, demonstrating its outcome in terms of bone gain and reconstruction of the interarch relation.

After surgery, a panoramic radiograph was obtained along with intraoral clinical views. These images demonstrated the increase in bone volume obtained (Figs 20 to 22). A waiting period of 4 months was observed to allow for undisturbed healing. No removable prosthesis was allowed to circumvent any risk of wound dehiscence, infection, inadequate graft incorporation, or graft resorption. After this period had elapsed, the patient was ready to receive implants. The flap on the left side was elevated, revealing that the graft was excellently integrated in the absence of resorption (Fig 23). Three implants (Straumann Bone Level, Regular Cross Fit 4.1 mm, Ø 4.1 mm, length 10 mm) were placed as dictated by the surgical guide provided. The implants were left to heal in a submerged fashion (Figs 24 to 27).

Figs 21 and 22 Clinical views 4 months after reconstructive surgery. Its outcome (dimensional changes of the edentulous areas and correction of the initial deficit) is clearly visible. The patient showed an adequate bone volume and a favorable interarch relation,

thus allowing implants to be placed in a restoratively driven approach.

Fig 23 Surgical exposure of the grafted area.

Figs 24 and 25 Three bone-level implants were inserted as dictated by a previously fabricated surgical template in the left maxilla 4 months after reconstructive surgery.

Figs 26 and 27 A submerged healing protocol was selected, such that the grafted area remained protected during osseointegration of the implants.

Figs 28 and 29 The same procedure was followed on the right side. Three bone-level implants of the same dimensions were placed in the grafted areas.

The same procedure was repeated on the right side. Again, no resorption of the graft was observed at the time of implant surgery. The implants could be placed in restoratively driven ideal positions and were completely surrounded by healthy and vital bone (Figs 28 to 30). Bone-level implants were favored over tissue-level designs to allow for submerged healing and to promote continued undisturbed and “protected” healing of the bone grafts with integration/revascularization.

Fig 30 A panoramic radiograph was obtained after placing the implants in a restoratively driven fashion, showing correct alignment of the implants.

Figs 31 and 32 To gain keratinized tissue around the implants, a partial-thickness flap with a palatal incision was elevated and transposed to the buccal side at the time of implant reopening. Prosthetic rehabilitation commenced 2 months later.

After 2 months of healing, the implants were uncovered with a partialthickness flap, using palatal incisions on both sides, in order not to expose the underlying bone and to “transpose” the keratinized tissue toward the buccal side (Figs 31 and 32). After 2 months, impressions were taken for final rehabilitation, using a polyether material and an open-tray technique (Figs 33 and 34). Subsequently the case was sent to the dental laboratory where customized titanium abutments and the final metal-ceramic FPDs were fabricated (Figs 35 to 37).

Figs 33 and 34 Impressions were taken for definitive rehabilitation, using a polyether material and an open-tray technique.

Figs 35 and 36 Customized titanium abutments and final metal-ceramic FPDs.

Fig 37 Customized titanium abutments and final metal-ceramic FPDs before delivery.

The prostheses were delivered to the patient. Thanks to the previous bilateral reconstruction of the alveolar ridge, the ceramic crowns appeared well integrated with the rest of the dentition, including appropriate dimensions and good emergence profiles (Figs 38 to 41). The patient was satisfied with the esthetic and functional outcome (Fig 42). A panoramic radiograph obtained immediately after completion of the prosthetic restoration demonstrated excellent integration of the implants in the grafted areas (Fig 43).

Fig 38 Clinical verification after completion of the restoration.

Figs 39 and 40 Occlusal view of the rehabilitation and extraoral view of the patient’s smile.

Figs 41 and 42 Intraoral lateral views of the final restorations in the right and left posterior maxilla.

Figs 43 to 45 Radiographs 2 years after loading demonstrated that the peri-implant bone was stable.

Figs 46 to 48 Radiographs 3 years after loading. No resorption of the peri-implant bone was detectable compared to the previous radiographs.

Since restorative treatment was completed, the patient has returned for annual periodic recalls. Radiographic follow-up examinations performed after 2 years (Figs 43 to 45) and 3 years (Figs 46 to 48) demonstrated a stable outcome without relevant peri-implant bone loss. Acknowledgments Restorative Procedures Dr. Claudio Gatti – Milan, Italy Laboratory Procedures Sandro Bertoglio, MDT, Gianni Zibetti, MDT – Busto Arsizio, Varese, Italy

7

Complications with Sinus Floor Elevation Procedures H. Katsuyama

Sinus floor elevation (SFE) using the lateral window technique is a predictable procedure involving a low complication rate and high implant survival rates (Jensen and Terheyden 2009). Though considered predictable, complications and failures do occur with these procedures and are generally difficult to manage. This chapter will discuss the etiology and management of intraoperative and postoperative complications.

7.1

Intraoperative Complications

Lateral window technique Tables 1 and 2 provide an overview of potential complications affecting the intraoperative donor and recipient sites in SFE. Uneventful healing of the augmented site occurs in the vast majority of cases after lateral window SFE (Chiapasco et al. 2009). Perforation of the sinus membrane is reported to occur in approximately 10% of cases (range: 4.8% to 56%), the most common intraoperative complication (Chiapasco et al. 2009). Usually these perforations are repaired with collagen sponges, various membranes, or allograft sheets. Only in less than 1% of patients did the grafting procedure have to be discontinued due to extensive membrane ruptures (Chiapasco et al. 2009). However, it should be noted that membrane perforations are not always detected intraoperatively due to the difficult access to some areas of the sinus cavity (e.g. superomesial or posterodistal regions). Perforations of this type may be detected in postoperative radiographs. They should be suspected whenever the elevated sinus floor has an indistinct border or when some of the grafting material is found to have spread. The clinical management of membrane perforations is shown in section 7.3.1. Some studies have described a correlation between membrane perforations and implant survival rates (Hernández-Alfaro et al. 2008), while others reported no such correlation (Nkenke and Stelzle 2009). Potential intraoperative complications also include bleeding due to engagement of the superior posterior alveolar artery (Pjetursson et al. 2008), nerve damage or exposure (Engelke et al. 2003), inadequate primary stability of the implant when a simultaneous approach is utilized (Lee et al. 2008), and migration of grafting material due to membrane perforation (Nkenke et al. 2009). Lateral window SFE has been reported to involve a 2%−3% incidence of bleeding (Zijderveld et al. 2008;

Kim et al. 2009). The incidence of neurovascular damage is not well documented. Inadequate primary stability of the implant will heavily depend on bone density, bone quantity, implant bed preparation, and implant design. It was reported in a case series to affect 3.9% of cases (Schwartz-Arad et al. 2004). Finally, dislodgement of the implant into the sinus cavity is seen in less than 0.5% of cases (Schwartz-Arad et al. 2004; Velich et al. 2004). While the precise indications for repair of membrane perforations have not been well defined, such repair would be indicated when collagen sponges, various types of membranes, or fibrin gel can be used to preserve the grafting material.

Transcrestal technique Intraoperative complications of transcrestal SFE are also shown in Table 1. These procedures are usually less invasive than the lateral window technique. Quite similar complications have been documented, however, including membrane perforation (Pjetursson et al. 2009a, 2009b), bleeding (Nkenke et al. 2002; Tan et al. 2008), and inadequate primary stability of the implants (Fermergård and Åstrand 2008). The most common intraoperative complication of transcrestal SFE is membrane perforation, whose presence can be confirmed by a Valsalva test (Pjetursson et al. 2009a, 2009b). This verification technique is, however, not successful in all clinical situations. Another option to confirm the results of transcrestal SFE would be to employ a fiber endoscope, although some unnoticed perforations have even been reported with these devices (Nkenke et al. 2002). An acknowledged complication of membrane perforation is migration of grafting material (Nkenke et al. 2002). Membrane perforations should be expected to occur approximately as often with transcrestal SFE as with lateral window SFE (Gabbert et al. 2009). They are considerably underreported, however, perhaps due to the “closed” nature of transcrestal SFE. The increased risk of perforations due to the shape of the sinus cavity and the existence of septa has been discussed in preceding chapters and related to the selection of surgical procedures; no correlation between complications and implant survival rate has been identified (Pjetursson et al. 2009a).

Donor sites

In treatment cases involving autogenous bone grafts, complications may also occur at the donor site. Potential intraoperative complications of intraoral harvesting include neurovascular damage or exposure. Extraoral bone harvesting is indicated whenever major reconstructions of the maxilla are required to compensate for adverse intermaxillary relations and to perform major vertical augmentation. Table 2 gives an overview of intraoperative complications at extraoral donor sites. Intraoral donor sites include the maxillary tuberosity and the mandibular symphysis and ramus. The most common intraoperative complication at donor sites is damage to neurovascular structures, which could be minimized by careful and accurate preoperative evaluation of the site anatomy using 3D imaging. Table 1 Intraoperative complications at (lateral window and transcrestal) SFE recipient sites.

Lateral window SFE

Transcrestal SFE

Intraoperative complications

Reported rates of occurrence

1. Membrane perforation 2. Poor primary stability of implant 3. Bleeding from injured vessels 4. Implant migration within the sinus 5. Graft migration within the sinus 6. Nerve exposure or injuries

10% (4.8%−56%) 3.9% 2%−3% 0.27%−0.47% − −

1. Sinus membrane perforation 2. Bleeding caused by blood vessel injuries 3. Poor primary stability of implants

3.8% (0%−26%) − − −

4. Migration of bone graft within the sinus

Table 2 Intraoperative complications at donor sites (used for bone harvesting).

Donor sites

Intraoral

Intraoperative complications

Chin

1. Nerve exposure or injury (inferior alveolar nerve or mental nerve) 2. Bleeding caused by injury to the - inferior alveolar artery - mental artery - submental artery 3. Sensory disturbance of mandibular anterior teeth

Ramus

1. Nerve exposure or injury (inferior alveolar nerve) 2. Bleeding caused by injury to the inferior alveolar artery or sublingual artery 3. Mandibular fracture

Ilium

Iliac crest

1. Injury to lateral femoral cutaneous nerve 2. Injury to superior gluteal nerve 3. Injury to sciatic nerve 4. Injury to superior gluteal artery

Parietal bone

1. Injury to diploic and emissary veins 2. Injury to median meningeal artery Calvarium 3. Dural tear 4. Intracranial hemorrhage 5. Air embolism 6. Death

Mandible

Extraoral

7.2

Postoperative Complications

Postoperative complications at SFE donor and recipient sites are summarized in Table 3. A definition of what constitutes an early or late complication has been provided by Pikos (Pikos 2006). Early complications occur within 7 to 10 days of surgery and commonly include bleeding from the incision line, nasal bleeding, paresthesia, infection, wound dehiscence, hematoma, and swelling. Late complications are rare. The incidence of dehiscence at surgical sites ranges from 2.7 to 8.4% (van den Bergh et al. 2000b; Raghoebar et al. 2001b; Chiapasco et al. 2008). Postoperative infections occur in 2.7% of cases (Pjetursson et al. 2008), bleeding has been observed in 0.46% (Khoury 1999) to 16.6% (Zijderveld et al. 2005). Different definitions of bleeding may account for this vast difference in postoperative bleeding reported. The incidence of hematoma is not well documented. Late complications of SFE may include loss of the implant and (acute or chronic) sinusitis, the latter being reported as occurring in 2.5% of cases (Chiapasco et al. 2009). Correlations have been reported with pre-surgical chronic sinusitis, membrane hypertrophy, and post-extraction timing of the surgical procedure (Timmenga et al. 1997). Graft loss or failure due to membrane perforation has been reported to occur at an incidence of 1.9% (0−17.9%; Pjetursson et al. 2008) or 1% (0−20%; Chiapasco et al. 2009) and might be the cause of postoperative sinusitis. Although one might speculate that the use of resorbable grafting materials (e.g. autografts) would minimize the risk of long-term complications in the presence of membrane perforation, this assumption has never been scientifically documented. Potential complications after SFE procedures include sinusitis and infection. While both eventualities are primarily caused by membrane perforation, sinusitis may even occur following uneventful surgical procedures. Infection and sinusitis may occur soon after surgery or may only show after several months. It is sometimes difficult to diagnose sinusitis extraorally, as the symptoms are similar to the ones observed in nasal conditions. Several

follow-up examinations with CT scanning may be required. Another possible sequela of SFE is insufficient bone augmentation. While outcomes of this type are not strictly regarded as a complication, they do have implications for subsequent implant placement. A transcrestal technique combined with implant placement could be considered if sufficient bone augmentation is not attained, but the clinical parameters for this approach are as yet unclear. Given the relative weakness of the elevated bone area, realizing an adequate bone gain is an essential goal of surgery. If primary implant stability cannot be achieved with staged or simultaneous SFE, an extended healing period may be indicated. Prolonged healing will, however, offer no benefit in regaining stability if implant mobility becomes apparent in the follow-up period. What is indicated in this situation is to remove the implant and to consider replacement once the site has been carefully reexamined. Donor sites used for bone harvesting may include postoperative infections, paresthesia, and hematoma (Table 2). Paresthesia is a frequent complication in the mandibular symphysis and has been reported to occur in 10 to 50% of cases postoperatively (Chiapasco et al. 1999; Clavero and Lundgren 2003; Nkenke et al. 2001, 2002; Raghoebar et al. 2001a, 2007; Misch 1997). In 8% of cases, the sensory disturbances associated with this complication may last for up to 1 year. In the mandibular ramus, paresthesia may occur in up to 5% of cases, with 0.5% being affected by persistent sensory disturbances for over 1 year (Chiapasco et al. 2008, 2009). Currently, the intraoral donor site of choice is the mandibular ramus. Table 3 Postoperative complications at SFE recipient sites.

Postoperative complications

Reported rates of occurrence

1. 2. 3. 4.

2.3%−12.1% 2.7%−8.4%

Implant loss Wound dehiscence Infection Maxillary sinusitis

Lateral window SFE

5. 6. 7. 8.

Total/partial graft loss Bleeding Hematoma Necrosis of the bone graft 9. Inadequate bone volume 10. Cyst formation 11. Air embolism 12. Pain (temporary or protracted)

1. Implant loss Transcrestal SFE 2. Maxillary sinusitis 3. Infection

2.7% 2.5% 1% (0%−20%) 1.9% (0%−17.9%) 0.46%, 16.6% − − − − −

4% (0%−17%, 64 months) – –

Figs 1a-b Membrane perforation and repair with a collagen membrane.

Lateral window SFE is a reliable technique to place implants of ideal length in the atrophic posterior maxilla. Nevertheless, implant failures do occur. The mean implant survival rate is 94.2% after approximately 3 years. Roughsurfaced implants have a mean survival of 97.7%, compared to 87.9% for implants with machined surfaces. Repair of a membrane perforation is indicated if it is small (under 10 mm) and the grafting material can be preserved in the site. Possible materials for repair include resorbable (e.g. collagen) membranes, fibrin glue or allograft sheets. An autogenous bone graft or resorbable grafting material may be indicated to minimize the risk of infection associated with any dispersal of grafting material into the sinus cavity. However, scientific evidence to support this assumption remains scarce.

Figs 2a-b Soft tissue dehiscence after simultaneous and staged sinus floor elevation using a lateral window technique. One implant was placed in the premolar area using a simultaneous approach; at the distal implant site, a staged approach was selected using PRP (platelet-rich plasma) and a resorbable membrane. Soft tissue dehiscences and edema were noted early into the healing phase. In the majority of cases, healing and soft tissue closure can be achieved with additional antibiotics and regular cleansing of the site.

Figs 3a-d Subcutaneous bleeding (hemorrhage) may occur not only at the surgical site following SFE but also at other sites due to the tendency of additional surgical trauma. Being very difficult to predict, this complication should be included in the informed consent obtained prior to surgery.

Figs 4a-d Subcutaneous bleeding (hemorrhage) after bone harvesting from the ramus (ac) and chin (d). Frequently, the procedure used for bone harvesting will be more invasive than the SFE procedure itself. Postoperative pain and swelling occurs in most cases. The informed consent obtained needs to include postoperative symptoms.

Fig 5a Grafting material retained on the implant surface.

Fig 5b Site after implant removal.

Implant instability or mobility may occur as a result of unsuccessful osseointegration. As mobile implants will rarely reach the point of successful osseointegration, removal and re-treatment is required in these cases. Figure 5a shows an implant with grafting material retained on its surface. Implant mobility may be caused by excessive loading in the healing phase, poor maturation of the augmented site, infection, or inadequate primary stability. In most cases of implant removal, bleeding will be minimal and healing uneventful (Fig 5b).

7.3

Case Presentations of Failures and Complications

The following cases are presented to demonstrate the range and potential severity of complications associated with SFE.

7.3.1 Membrane Perforation E. Lewis This is a case of a 70-year-old man who presented with an edentulous left posterior maxilla, preceded by a complicated extraction. He was an otherwise healthy non-smoker and denied having any current symptoms in the area. A clinical examination revealed that he was partially dentate. Teeth 25, 26, 27, 28 were missing in the left maxilla. His residual posterior dentition was heavily restored but well maintained. A four-unit FPD was present in the opposing arch. The patient’s oral hygiene was satisfactory, with no signs of active periodontal disease. The alveolar ridge in the left posterior maxilla was characterized by adequate horizontal width and covered by healthy mucosa. A panoramic radiograph disclosed insufficient bone height in the left posterior maxilla. The following options were discussed with the patient: (i) No treatment (ii) Removable partial denture (iii) Implant-supported FPD After a detailed discussion with the patient, he elected to proceed with surgical treatment. A treatment plan was developed as follows: (i) SFE with allograft bone augmentation (ii) Placement of implants at sites 25 and 27 after 6 months of healing (iii) Delivery of a three-unit FPD

Fig 1 Intraoral photograph with the patient’s left posterior dentition in occlusion.

Fig 2 Occlusal view of the left posterior maxilla.

Fig 3 Preoperative panoramic radiograph showing insufficient bone height in the left posterior maxilla.

Fig 4 Occlusal view of the midcrestal incision with anterior and posterior releases.

Fig 5 Elevation of the mucoperiosteal flap exposing the lateral wall of the maxilla, which included a previous fracture line in its posterior buccal ridge.

After obtaining the patient’s consent, the procedure was performed under local anesthesia on an outpatient basis. A midline crestal incision was made with a posterior and anterior vertical release of the mucosa of the left posterior maxilla, followed by elevating a full-thickness mucoperiosteal flap to expose the lateral wall of the left maxilla. A vertical defect was noted in the buccal plate at site 26, probably being the outcome of a large buccal plate fracture in the past, and was filled with fibrous tissue. The fibrous tissue was curetted away from the defect, and an oval-shaped osteotomy of the lateral wall of the maxilla approximately 12 × 8 mm in size was performed using the Piezosurgery® system (Mectron SpA, Carasco, Italy) with a combination of osteotomy tips (OT1 and OT5). Once the osteotomy was completed, a Piezosurgery elevation tip (EL1) was employed to initiate separation of the sinus membrane from the sinus floor. Sinus curettes were used to complete membrane elevation in an inferior-to-superior direction. This time, however, a large perforation developed as the membrane

adhered to the buccal plate defect. Upon completion of the elevation maneuver, a perforation of the membrane roughly 1 cm in diameter was noted. The oval-shaped bony window was rotated inside the sinus to become the roof of the graft site. Finally, a small resorbable collagen membrane (BioGide®; Geistlich Pharma AG, Wolhusen, Switzerland) was trimmed and carefully placed over the membrane defect.

Fig 6 View of the lateral wall osteotomy with fibrous tissue at the preexisting fracture site in the buccal plate.

Fig 7 A large perforation was noted on elevating the sinus membrane.

Fig 8 Placing the collagen membrane over the membrane defect.

Fig 9 Packing DFDBA into the sinus floor.

Fig 10 DFDBA grafting completed.

Fig 11 Placing a collagen membrane over the entire bone graft.

A 2-cc block of Regenaform® (Exatech, Gainsville, Florida, USA) demineralized freeze-dried bone allograft (DFDBA) was placed into a warming bath (43°C to 49°C) for 5 minutes and was then transferred to the surgical site. Using curettes and pluggers, the allograft was gently packed

into the sinus cavity in a layered fashion, from inferior to superior, ensuring that the collagen membrane remained over the defect. Once an adequate height was achieved (approximately 12 mm), the remaining bone was placed over the sinus window. A large resorbable collagen membrane (Bio-Gide®, Geistlich Pharma AG, Wolhusen, Switzerland) was placed over the lateral aspect of the bone graft, tucking the medial edge under the palatal edge of the mucosa. After some careful irrigation with sterile saline, the mucoperiosteal flap was replaced and reapproximated using a 4-0 resorbable braided Vicryl suture material. Upon completion of the procedure, a baseline postoperative CBCT scan of the graft was obtained. The patient was given general postoperative instructions with a special emphasis on sinus precautions. Prescriptions were issued for a 1-week course of oral antibiotics (Amoxicillin 500 mg p.o. three times daily), for oral analgesics, and for rinsing with chlorhexidine digluconate 0.12%. At the 1-week follow-up, the surgical site was examined for incision closure and absence of infection. Following removal of the remaining sutures, the patient was instructed to continue with sinus precautions for another week. Six months after SFE, implants were placed under local anesthesia at sites 25 and 27. A mid-crestal incision was made with elevation of a minimal mucoperiosteal flap. Subsequently a standard drilling protocol was followed, using a surgical template, for preparation of the implant osteotomies. The Astra Tech Implant System™ (Astra Tech Dental, Mölndal, Sweden) was used, placing a 4.0S 13 mm and a 5.0S 9 mm OsseoSpeed implant at sites 25 and 27, respectively, in a single-stage procedure without complications. Immediately after implant placement, a panoramic radiograph was obtained.

Fig 12 Incision closed primarily with resorbable interrupted sutures.

Fig 13 Postoperative panorama CBCT showing the baseline bone augmentation.

Fig 14 Postoperative tangential CBCT showing vertical augmentation at site 25.

Fig 15 Postoperative tangential CBCT showing vertical augmentation at site 27.

Fig 16 Panoramic radiograph obtained immediately after implant placement.

Fig 17 Intraoral view of the left posterior dentition 6 months after delivering the threeunit FPD.

Fig 18 CBCT panoramic view 12 months after implant placement.

Fig 19 CBCT tangential view 12 months after implant placement at site 25.

Fig 20 CBCT tangential view 12 months after implant placement at site 27.

The patient was subsequently restored with a three-unit FPD. Figures 17 to 20 illustrate the clinical and radiographic findings obtained 6 and 12 months after implant placement. In summary, this case illustrates how a significant perforation of the sinus membrane (occurring during SFE) was managed. Perforations during SFE are not uncommon, especially in the presence of anatomical anomalies like the buccal plate fracture by which this case had presumably been afflicted in the past and which resulted in scarring and tethering of the sinus membrane to the fracture line. The report demonstrates that membrane perforation can be successfully managed with a collagen membrane as barrier. It was possible to complete the procedure with careful postoperative follow-up in a standard fashion. Also highlighted is the fact that the presence of a sinus membrane perforation did not compromise the success of the case.

Clinical Recommendations It is often difficult to predict the complication of sinus membrane perforation in connection with SFE. While bone anatomy and membrane thickness can be assessed by obtaining a preoperative CBCT, the sinus cavity is a complex shape. Sometimes these issues will not come to light any earlier than during surgery. Perforations of the sinus membrane should be examined for size and location. While small perforations can be managed without modifying the surgical plan, larger perforations either should be repaired immediately with resorbable sutures or should be isolated with a barrier (e.g. a collagen membrane). The patient should then be followed closely in the early postoperative period and be given strict instructions to avoid increased sinus pressure. If multiple perforations exist or if a perforation is very large, consideration should be given to aborting the procedure, closing the incision and allowing the area to heal. Depending on the nature of the perforation, a second attempt could be made later. With the advent of the Piezosurgery system, the ultrasonic cutting technique may be helpful in avoiding membrane perforation at the time of conducting the lateral window osteotomy. A careful surgical technique using various straight and angled curettes will also assist in separating the intact sinus membrane from the bony walls of the sinus cavity.

7.3.2 Soft Tissue Dehiscence and Correction after SFE with Vertical and Horizontal Bone Grafting H. Katsuyama A 42-year-old woman received implant treatment in the mandible and requested a fixed restoration in the maxilla. Surgery was postponed for treatment of sinusitis until a healthy sinus was confirmed. The maxillary right posterior segment was edentulous from the first premolar to the second molar (Fig 1). Also noteworthy is the patient’s history of bilateral hip-joint replacement.

A CT scan of the site was obtained to investigate the local anatomy and for presurgical treatment planning. The bone at the sinus floor was found to be very thin. In addition, SFE alone was not able to meet all clinical requirements due to the presence of an intermaxillary discrepancy. While the sinus cavity itself showed no abnormalities, a damaged bone wall in the sinus floor was confirmed (Fig 2). It was proposed to wait for the bone wall to heal and then to perform SFE in conjunction with vertical and horizontal ridge augmentation. The patient was duly informed about the surgical procedure. She accepted the risks involved and the need to harvest large amounts of autogenous bone. The iliac crest was ruled out as donor site due to her history of bilateral hip-joint replacement. It was therefore decided to use the tibia for harvesting (Fig 3). While the tibia is an ideal donor site for cancellous bone, it will yield limited amounts of cortical bone. A mucoperiosteal flap was prepared for lateral window SFE, using divergent relieving incisions (Fig 4). Routine methods were used to prepare the window, grafting a mixture of autogenous bone and β-TCP into the sinus cavity (Fig 5). More grafting material was added to augment the vertical and horizontal space, followed by the application of a titanium mesh (Fig 6). Several screws were used for fixation of the titanium mesh to ensure stability of the augmented site (Fig 7). Tension-free primary soft tissue closure was obtained by adapting the flap carefully with a Vicryl® suture (Johnson & Johnson Medical, Cornelia, Georgia, USA), using a releasing incision into the periosteum (Fig 8). Upon completion of the procedure, a CT scan was obtained to confirm the surgical outcome (Fig 9). The threedimensional result of augmentation was found to be ideal. The elevated membrane was intact, as was the horizontal and vertical graft. The sinus cavity was filled with blood or exudate.

Fig 1 Preoperative view of the surgical site. While the mucogingival junction is located near the crest of the ridge, the mucosal status appears healthy.

Fig 2 CT scan displaying the limited vertical and horizontal bone volume. Unfavorable intermaxillary relations were confirmed. Vertical and horizontal ridge augmentation was planned in conjunction with SFE. Surgery was performed under general anesthesia due to the large amount of bone required.

Fig 3 Bone harvesting from the tibia. An adequate volume could be harvested, which, however, consisted mostly of cancellous bone.

Fig 4 A lateral window was prepared using the routine technique with rotational devices and traditional instruments. No membrane perforation was observed.

Fig 5 A mixture of autogenous bone and β-TCP was grafted into the sinus cavity.

Fig 6 Following horizontal and vertical placement of the grafting material, a titanium mesh was applied and trimmed for space preservation and stabilization of the composite autogenous bone and β-TCP graft.

Fig 7 Fixation of the titanium mesh with screws.

Fig 8 Primary wound closure was achieved using a releasing incision into the periosteum and an appropriate flap design. Vicryl suture material was used for secure flap adaptation.

Fig 9 CBCT scan obtained after SFE and three-dimensional bone augmentation. Threedimensional conditions were found to be ideal at the augmented site.

Fig 10 After 1 week, a soft tissue dehiscence with necrotic mucosa was observed. Oral rinses were locally applied to prevent infection, including an antiseptic (benzethonium chloride 0.2%; Nippon Shika Yakuhin, Yamaguchi, Japan) and an antibiotic gel (gentamicin sulfate 0.1%; MSD KK, Tokyo, Japan).

Fig 11 Clinical view 2 months after surgery. Note the exposure both of the titanium mesh and of the fixation screws located buccally. Oral rinses were applied, including an antiseptic (benzethonium chloride 0.2%; Nippon Shika Yakuhin, Yamaguchi, Japan) and an antibiotic gel (gentamicin sulfate 0.1%; MSD KK, Tokyo, Japan).

Fig 12 This view was obtained 1 month after removal of the titanium mesh, which was removed 3 months after surgery. While soft tissue covering the raw surface is apparent under the titanium mesh, the soft tissue situation at the site is suboptimal.

Fig 13 Soft tissue correction and implant placement was simultaneously performed 5 months after initial surgery and 2 months after removal of the titanium mesh. A submerged healing protocol was used.

A dehiscence of the surgical wound, but without any signs of infection, was noted soon after the procedure (Fig 10). There were no signs of infection, but the patient was instructed to exercise prophylaxis by applying an antibiotic gel to the exposed titanium mesh. She was also told to use oral rinses of an antiseptic twice daily (benzethonium chloride 0.2%; Nippon Shika Yakuhin, Yamaguchi, Japan) and an antibiotic gel (gentamicin sulfate 0.1%; MSD KK, Tokyo, Japan). The titanium mesh was left in situ for maturation of the underlying tissue. Periodic recall visits were scheduled to verify the continued absence of infection. At the 2-month follow-up, the center of the titanium mesh and the fixation screw on the buccal aspect were exposed without showing any signs of infection (Fig 11). At the 3-month follow-up, the titanium mesh was removed. Newly formed tissue was present beneath the mesh. While the dehiscence wound was surgically corrected to ideal tissue form at this time, wound healing was less than ideal and the dehiscence recurred. Healing as such was uneventful (Fig 12). Another 2 months later, an implant was placed in the augmented site, with soft tissue plastic surgery being performed simultaneously. A submerged healing protocol was used (Fig 13). Due to the repeated soft tissue surgery, the mucosa was fragile and soft tissue healing less than ideal around the implants, particularly on the buccal aspect

Fig 14 Clinical view 1 month after implant placement of a Straumann Standard Plus implant (Regular Neck, Ø 4.1 mm, length 12 mm). Due to the fragility of the soft tissue, the implant shoulders became exposed, and the condition of the soft tissue conditions on the buccal aspect was suboptimal.

Fig 15 Clinical view 2 months after implant placement. An aberrant soft tissue situation is evident on the buccal aspect. Note the shallow buccal vestibulum.

Fig 16 Vestibuloplasty with a CO2 laser was performed to correct the soft tissue situation on the buccal aspect.

where the vestibulum was shallow. The final step was to enhance the soft tissue situation by performing vestibuloplasty with a CO2 laser (Fig 16). In summary, this case illustrates a significant complication that occurred in conjunction with a complex grafting procedure. There was a need not only to elevate the sinus floor but also to achieve lateral and vertical augmentation of the site. A titanium mesh was used for space preservation. Wound dehiscence occurred as a major complication because the mucosa was overstressed and the vascular supply to the flap edges was compromised. Meticulous postoperative care was the key to managing this complication, which also highlights the difficult soft tissue conditions that can arise from wound dehiscences and the subsequent difficulty of soft tissue management.

Clinical Recommendations

Three-dimensional bone augmentation in combination with SFE is a complex procedure, not only to achieve ideal bone augmentation but also in the surgical handling of the soft tissues. SFE with three-dimensional hard-tissue augmentation requires the following criteria to be observed: – Healthy soft tissue conditions – No inflammation around the surgical site – Adequate blood supply (to be considered in flap design, incision lines and flap management) – Well-trained and experienced surgeon (capable of managing any complications that may arise)

7.3.3 Sinusitis after Undetected Membrane Perforation during Surgery H. Katsuyama A 62-year-old woman visited our clinic to receive implant treatment in the right posterior maxilla. SFE using a staged approach was performed 2 months after extraction of the second molar (Fig 1). The pre-surgical CBCT scan did not show any absolute or relative contraindications to SFE. After establishing access and elevating the sinus membrane through a lateral window, a mixture of β-TCP and autogenous bone was grafted to the sinus floor. Membrane perforation was not detected during surgery. A postsurgical orthopantomograph revealed that grafting material had been lost into the sinus cavity through a posteriorly located perforation of the membrane that was unnoticed during surgery (Fig 2). A clear image of the graft loss was obtained by CBCT (Fig 3). A postsurgical orthopantomograph obtained 1 month into uneventful healing showed that the augmented site had changed to a uniform clear round shape (Fig 4). The site was left for further maturation without applying any specific treatment. After 4 months had elapsed since surgery, the patient returned to the clinic because of symptoms related to the surgical site. Examination by CBCT clearly revealed the presence of infection in the right sinus (Fig 5). Antibiotic treatment was therefore initiated, using levofloxacin hydrate (Cravit 500 mg; Daiichi Sankyo, Japan) in combination with L-carbocisteine (Mucodyne 500 mg, 3 times daily; Kyorin Pharmacuticals, Japan) and carried on for 2 weeks. Upon completion of this course, the patient’s discomfort had disappeared. After another 2

months, however, she returned with nasal symptoms. A CBCT examination confirmed the presence of bilateral sinusitis (Fig 6). Another course of antibiotic treatment (fosfomycin calcium 500 mg, 3 times daily over 14 days; Foxmicin, Meiji, Japan) was prescribed but failed to resolve the infection. After concluding that antibiotic treatment alone would not bring about resolution, it was decided to surgically debride the affected sinus under local anesthesia. A panoramic radiograph was obtained after debridement (Fig 7). While the bulk of the graft had been eliminated, some radiopaque remnants were still visible. The symptoms resolved after debridement. Nevertheless, the unfavorable incision line and flap elevation over the lateral window resulted in the formation of an oroantral fistula. Another surgical procedure was conducted to close the fistula (Fig 8). The remainder of healing was uneventful. Complete resolution of the sinusitis was finally confirmed by the absence of signs and symptoms of infection and by a CBCT-based radiographic examination (Fig 9).

Fig 1 Presurgical situation 2 months after extraction of the maxillary right second molar. A staged approach was planned for implant placement.

Fig 2 SFE was uneventful, and a mixture of β-TCP and autogenous bone was grafted. Panoramic radiograph showing an unclear situation at the augmented site and low density

of the graft.

Fig 3 CT scan showing distinct loss of grafting material into the sinus cavity. The perforation was not noticed during surgery but could have been due to fragility of the sinus membrane at the extraction site.

Fig 4 Panoramic radiograph 1 month after surgery. While the graft appeared stable, the volume of its posterior portion has been reduced by the graft loss.

Figs 5 and 6 Sinusitis was suspected based on clinical symptoms and the patient complaining of discomfort. A CT scan confirmed the presence of sinusitis on the right (Fig 5). Antibiotic treatment was prescribed. Following an initial decrease of symptoms, the patient reported bilateral pain in both sinuses 2 months after antibiotic treatment. Upon confirmation by CT that sinusitis had developed in both cavities, another course of

antibiotic treatment was prescribed.

Fig 7 Panoramic radiograph after debridement of the right sinus. While most of the grafting material has been removed, some radiopaque bone substitute is still apparent in the crestal area.

Fig 8 The incision line for debridement was placed above the original lateral sinus window, leaving a fistula. No discharge of pus was confirmed.

Fig 9 CT scan confirming that the sinusitis had resolved.

In summary, this case illustrates a significant late complication following SFE. The sinusitis was presumably caused by loss of grafting material into

the sinus cavity through an undetected membrane perforation. Postsurgical assessment is therefore mandatory to confirm the results. Some cases of sinusitis can be difficult to treat once they have developed. A decision must be made as to whether antibiotic treatment will suffice or should be combined with surgical debridement to resolve the infection.

Clinical Recommendations Clinicians should be aware that perforating the sinus membrane will increase the infection risk. The situation needs to be carefully assessed. A summary of clinical recommendations follows: – If membrane perforation is confirmed during surgery, a non-resorbable grafting material may not be the treatment of choice. It may be better to select resorbable materials like autogenous bone and/or an appropriate bone substitute. – It is strongly recommended to obtain a postsurgical radiograph. If signs or symptoms of infection are present, additional diagnostic tests such as CBCT may be considered. – In the presence of sinusitis without any signs of acute infection such as bleeding or pus discharge, antibiotic treatment is the first choice. – If antibiotic treatment alone does not solve the problem, surgical debridement should be considered the first treatment of choice. – Clinicians who are not used to handling such complications should consider prompt referral to a specialist. – While CBCT or MCT are useful and convenient techniques to examine the sinus cavity, any prospect of conducting multiple examinations of this type should be carefully considered and discussed with the patient because of the radiation exposure involved. – If surgery for debridement of the sinus cavity is planned to deal with SFErelated complications, the incision line should not be placed over the previous window, as this position will carry a higher risk of wound dehiscence due to compromised blood supply. – SFE planned near post-extraction sites will require a careful examination, as they involve a risk of communication into the sinus cavity via the healing socket. – The risk of perforation is increased in post-extraction sites, as the sinus

floor will show an uneven contour near the root sockets in this situation.

Fig 1 Baseline situation 2 months after extraction of the maxillary left premolars and molars.

Fig 2 A panoramic radiograph obtained after bilateral implant placement (first-premolar sites) and bilateral SFE. An extensive perforation of the sinus membrane occurred on the left. Note that the graft in the posterior portion of the left sinus showed irregularities. The differential radiopacity of the left and right grafts is due to different grafting materials used (right sinus: autogenous bone and HA//-TCP compound; left sinus: autogenous bone and TCP).

7.3.4 Bilateral Sinus Infection after Perforation due to Residual Non-resorbable Barrier Fragments H. Katsuyama A 45-year-old man presented at our center for fixed implant restorations in both posterior segments of the maxilla. He had received implant treatment in the left mandible 10 years previously. The natural dentition of in the maxillary left posterior segment had been extracted 3 months prior to this consultation. A clinical examination revealed that soft tissue healing was

uneventful. With regard to the planned SFE procedures, a panoramic radiograph and CBCT scan did not reveal any evidence for pathological or anatomical problems (Fig 1). Lateral window SFE was performed bilaterally with simultaneous implant placement at the premolar sites. While no intraoperative membrane perforation was noticed in the right sinus, a large perforation resulted in the left sinus (Fig 2). A collagen sponge reinforced by a silicone membrane (Olympus Terumo Biomaterials, Tokyo, Japan) was used to repair the perforation. Full coverage of the perforated sites was confirmed by direct mirror visualization through an operative microscope. A panoramic radiograph obtained postoperatively showed that the repair attempt had failed. There was loss of grafting material in the posterior part of the augmented site. Autogenous bone and a composite bone substitute (HA and β-TCP) was grafted into the right sinus. In the left sinus, autogenous bone and resorbable β-TCP was used to avoid adhesion of grafting material to the sinus wall. No signs of infection were observed bilaterally in the early postoperative period.

Fig 3 View obtained 2 months after bilateral sinus augmentation. There is evidence of sinusitis in the left maxillary segment filling more than half of the sinus cavity, possibly caused by membrane perforation or hemorrhagic effusion. In the right maxillary segment, some hypertrophy of the sinus membrane is apparent.

Fig 4 CBCT scans obtained 2 weeks later (i.e. 10 weeks after SFE). Sinusitis had developed bilaterally by that time, with the patient complaining of left nasal bleeding. Note the cobweb-like membrane hypertrophy.

Two months after surgery, the patient returned to report bleeding into the oral cavity. A CBCT was obtained for proper diagnosis and revealed membrane perforation in the left sinus (Fig 3). Antibiotic treatment was initiated but did not prevent sinusitis from developing 2 weeks thereafter (Fig 4). A CBCT scan revealed that sinusitis had developed bilaterally with a cobweb-like appearance of the membrane hypertrophy. A second course of antibiotic treatment was prescribed. The symptoms then gradually abated, even though mild bleeding into the oral cavity persisted. Steps that followed included debridement of the left sinus and removal of the silicone membrane, which had been used to reinforce the collagen sponge. After this intervention, the symptoms of infection appeared to have resolved in both sinuses (Fig 5). Another 6 weeks later, however, the patient reported symptoms in the right nostril and, once again, bleeding into the oral cavity. A CT scan demonstrated recurrence of the infection in the right sinus (Fig 6). This time the treatment decision involved a radical surgical approach with creation of a lateral window to remove all infected membrane tissue from the right sinus. After hospitalization for radical sinus surgery, two implants already installed at the first premolar sites were used for Locator attachments to stabilize a partial denture.

Fig 5 Following antibiotic treatment, the left sinus was debrided. Any residual fragments of the silicone membrane were removed. Indications are that the inflammation has resolved in both sinuses.

Fig 6 Later on, the patient experienced symptoms from the right nostril. A CT scan revealed some residual fragments in the wall of the right sinus. After recurrence of sinusitis was diagnosed, radical surgery was performed to remove all infected membrane tissue from the right sinus.

The case presented here can be summarized as follows: for unknown reasons, sinusitis may develop not only in the sinus where membrane perforation occurred but also in the contralateral non-perforated sinus. Some cases of sinusitis can be difficult to treat by antibiotic treatment alone, once they have developed.

Clinical Recommendations A collagen sponge reinforced by a silicone membrane was used to repair the sinus perforation in the present case, which involved a need for stronger

support. However, any non-resorbable silicone that may be retained after complete resorption of the collagen will potentially increase the risk of sinusitis. – Any confirmed perforation of the sinus membrane should preferably be managed with a resorbable grafting material. Grafting should only take place upon successful repair of the perforated sinus. – Aggressive membrane repair may not be indicated if the membrane perforation is too large to support the grafting material and a barrier membrane. The chances of successful repair will depend on the size of the perforation and on the position/configuration of the sinus cavity. Once SFE has been aborted, at least 6 months should be allowed for complete healing of the membrane. In most cases, the second attempt at SFE will be more complicated. An alternative treatment option may need to be considered. – Recent extraction sites may carry a higher risk of sinus membrane perforation, due to irregularities of the sinus floor and to fibrous adhesions. An adequate healing period will be required if a communication between the extraction site and the sinus floor has been confirmed at the time of tooth removal.

7.3.5 Implant Loss due to Unsuccessful Osseointegration H. Katsuyama A 60-year-old man, whose residual dentition was reduced to a few teeth in the mandibular anterior segment, presented himself for treatment. His desire was to have implant-supported fixed restorations in both jaws. He smoked more than 10 cigarettes/day, but did not have any systemic health problems. Soft tissue conditions in the maxilla were less than ideal, including ulcers and a flabby anterior ridge (Fig 1). Bone quantity was adequate in the mandible, but the maxilla was extremely atrophic (Figs 2 and 3). Treatment was planned for a fixed rehabilitation of the mandible and for a staged procedure with SFE prior to implant placement in the maxilla. A CBCT scan was obtained for careful evaluation of the maxillary anatomy, which revealed mild hypertrophy of the right sinus membrane and an extremely thin layer of cortical bone on both sides (Figs 4 and 5). Placing implants simultaneously with SFE was not an option. Therefore a staged approach was planned, starting with a mixture of autogenous bone and bone substitute (HA granules)

to augment the bone volume at the sinus floor, and continuing with a separate procedure to place the implants. The buccal cortical bone was so thin and fragile that it fractured from the needle when administering local anesthesia. It was extremely difficult to prepare the window and elevate the sinus membrane, which resulted in perforation of the membrane bilaterally even with infiltration anesthesia. Both perforations were successfully repaired, and no indication of graft loss was evident on the postoperative orthopantomograph (Fig 6). After 6 months of healing, two implants were placed into each of the elevated sinus sites. Ideal primary stability was not attained (less than 15 Ncm) due to the low density of the cortical layer and the augmented sites (Fig 7). A submerged healing protocol was used, and the complete denture was relined with a soft tissue conditioner. After 1 month, the right distal implant was found to be mobile and was removed (Fig 8). The next implant to be lost was the left mesial implant, and eventually all implants were lost (Figs 9 and 10). We did not attempt to perform another SFE but proceeded to deliver a complete denture.

Fig 1 Soft tissue conditions in the maxilla at initial presentation. Note the mucosal ulceration and bluish hue.

Fig 2 Severely resorbed maxilla of an edentulous patient.

Fig 3 Panoramic radiograph displaying the severity of the resorption in the maxilla.

Fig 4 CT scan used for initial treatment planning. Both sinuses revealed a thin layer of cortical bone at the floor and walls. Membrane proliferation was observed in the right sinus.

Fig 5 Magnified image of left sinus. Only 1 to 2 mm of a thin bone wall remained at the floor and buccal aspect of the sinus cavity. No cancellous component was observed at the

site.

The treatment plan was to provide implant-supported fixed restorations in the maxilla and mandible. A staged approach was taken in the maxilla due to the reduced bone height, with bone augmentation followed by a second procedure to place the implants.

Fig 6 A staged approach starting with lateral window SFE was used in both sinuses. The buccal wall of the sinus cavity was extremely thin and soft, and perforation of the buccal bone wall was confirmed during surgery. The staged approach was performed successfully.

Fig 7 After a healing period of 6 months, four implants were placed in a flapless approach. While stability was obtained, the final insertion torque was less than 15 Ncm for all four implants.

Fig 8 After a healing period of 1 month, the right distal implant was found to be mobile and was removed.

Fig 9 The left mesial implant was found to be mobile and was removed 8 weeks after implant placement.

In summary, a thin cortical layer is a risk factor for SFE. Even if SFE is successful, the low potential for new bone formation may compromise new bone maturation. In situations of this type, extraoral bone harvesting may be considered to obtain a sufficient amount of autogenous bone grafts with a high osteogenic potential, compensating for the reduced potential of bone healing. Smoking is a risk factor in any implant treatment. Especially when it comes to SFE procedures, smoking is the predominant risk factor for surgical complications and poor implant survival. Age may be a risk factor if additional bone harvesting or radical surgery becomes necessary.

Clinical Recommendations Two risk factors need to be considered in patients exhibiting a thin cortical

layer: a reduced potential for primary implant stability, and a reduced capacity for bone formation. Compromised situations such as these should be managed with autogenous bone that has osteogenic potential. – The severely resorbed maxilla is usually characterized by a thin cortical layer. Three-dimensional bone augmentation is often required in this type of situation. – Extraoral bone harvesting may be considered in the severely resorbed maxilla to obtain a sufficient bone volume which, in addition, will offer an increased osteogenic potential. – Controlling functional loading forces during the healing period is critical in fully edentulous patients. A submerged healing protocol for the implants is recommended to reduce the risk of excessive loading.

Fig 10 Eventually, 10 weeks after implant placement, all maxillary implants were lost because of mobility.

7.4

Conclusions

SFE is a predictable surgical procedure when performed following appropriate diagnosis and meticulous treatment planning. However, some failures and complications must still be anticipated even if these requirements are met. As a result of its anatomic features, the sinus cavity is susceptible to infection. The incidence of complications is modified by the presurgical state of the sinus cavity and anatomical conditions. Risk factors include parameters related to the sinus membrane, soft tissue conditions, healing capacity of the surrounding bone, and not least the surgeon’s experience. Clinicians performing SFE procedures need to understand the difficulties and morbidity arising in the event of complications. They must be able to correctly judge the individual risk and the presence of modifying factors that may cause these complications. Acknowledgments Research Support Dr. Shinichiro Kuroshima – Hokkaido University, Sapporo, Japan Dr. Yoji Kamiura – Center of Implant Dentistry, Yokohama, Japan Dr. Kazutoshi Nakajima – Center of Implant Dentistry, Yokohama, Japan Dr. Yasushi Nakajima – Center of Implant Dentistry, Yokohama, Japan Surgical Procedures Dr. Masaharu Mitsugi – OMS, Takamatsu, Japan

8

References

8.1

References for Literature Review (Chapter 2.3)

To improve the readability of the chapter itself, the extensive reference lists for the literature review in Chapter 2.3 have been placed here. List numbers refer to the superscript numbers in brackets in Chapter 2.3. For complete bibliographic data, please consult Chapter 8.2, Literature/ References. List 1 Lateral window technique; 85 studies Kent and Block 1989; Tidwell et al. 1992; Block and Kent 1993; Raghoebar et al. 1993; Small et al. 1993; Chiapasco and Ronchi 1994; Blomqvist et al. 1996; Hürzeler et al. 1996; Lundgren et al. 1996; Triplett et al. 1996; Wheeler et al. 1996; Block and Kent 1997; Daelemans et al. 1997; Lundgren et al. 1997; Raghoebar et al. 1997; Valentini and Abensur 1997; Block et al. 1998; Blomqvist et al. 1998; Fugazzotto and Vlassis 1998; Peleg et al. 1998; van den Bergh et al. 1998; Watzek et al. 1998; Zitzmann and Schärer 1998; De Leonardis and Pecora 1999; Johansson et al. 1999; Keller et al. 1999; Khoury et al. 1999; Lekholm et al. 1999; Mazor et al. 1999; Peleg et al. 1999a, 1999b; Kassolis et al. 2000; Lorenzoni et al. 2000; Olson et al. 2000; Mazor et al. 2000; Valentini et al. 2000; van den Bergh et al. 2000b; Wannfors et al. 2000; Cordioli et al. 2001; Hallman et al. 2001; Kahnberg et al. 2001; Raghoebar et al. 2001a; Tawil and Mawla 2001; Hallman et al. 2002a; Hallman et al. 2002b; Kan et al. 2002; Pejrone et al. 2002; Engelke et al. 2003; Mangano et al. 2003; McCarthy et al. 2003; Philippart et al. 2003; Pinholt 2003; Reinert et al. 2003; Rodriguez et al. 2003; Stricker et al. 2003; Valentini and Abensur 2003; Hallman and Nordin 2004; Hallman and Zetterqvist 2004; Hatano et al. 2004; Iturriaga and Ruiz 2004; Lundgren et al. 2004; Shlomi et al. 2004; Simion et al. 2004; Velich et al. 2004; Butz and Huys 2005; Hallman et al. 2005; Rodoni et al. 2005; Wiltfang et al. 2005; Zijderveld et al. 2005; Mangano et al. 2006; Orsini et al. 2006; Peleg et al. 2006; Becktor et al. 2007; Chen et al. 2007; Galindo-Moreno et al. 2007; Krennmair et al. 2007; Mangano et al. 2007; Marchetti et al. 2007; Mardinger et al. 2007; Thor et al. 2007; Bornstein et al. 2008; Chiapasco et al. 2008; Kahnberg and Vannas-Löfqvist 2008; Chaushu et al. 2009; Dasmah et al. 2009; Degidi et al. 2009; Ferreira et al. 2009.

List 2 Bone substitute material only; 19 studies Small et al. 1993; Valentini and Abensur 1997; Zitzmann and Schärer 1998; Valentini et al. 2000; van den Bergh et al. 2000b; Tawil and Mawla 2001; Hallman et al. 2002b; Kan et al. 2002; Mangano et al. 2003; Valentini and Abensur 2003; Hallman and Nordin 2004; Rodoni et al. 2005; Mangano et al. 2006; Orsini et al. 2006; Mangano et al. 2007; Mardinger et al. 2007; Ferreira et al. 2009; Dasmah et al. 2009; Chaushu et al. 2009. List 3 Autograft material only or a combination of autograft material and a bone substitute; 36 studies Blomqvist et al. 1996; Lundgren et al. 1996; Daelemans et al. 1997; Lundgren et al. 1997; Blomqvist et al. 1998; Peleg et al. 1998; van den Bergh et al. 1998; Johansson et al. 1999; Keller et al. 1999; Mazor et al. 1999; Peleg et al. 1999b; Wannfors et al. 2000; Hallman et al. 2001; Kahnberg et al. 2001; Raghoebar et al. 2001a; Hallman et al. 2002a, 2002b; Kan et al. 2002; Pejrone et al. 2002; Reinert et al. 2003; Stricker et al. 2003; Hallman and Zetterqvist 2004; Hatano et al. 2004; Shlomi et al. 2004; Hallman et al. 2005; Wiltfang et al. 2005; Becktor et al. 2007; Chen et al. 2007; Krennmair et al. 2007; Marchetti et al. 2007; Bornstein et al. 2008; Kahnberg and VannasLöfqvist 2008; Degidi et al. 2009. List 4 DBBM only; 11 studies Zitzmann and Schärer 1998; Valentini et al. 2000; Tawil and Mawla 2001; Hallman et al. 2002b; Valentini and Abensur 2003; Hallman and Nordin 2004; Rodoni et al. 2005; Orsini et al. 2006; Mangano et al. 2007; Mardinger et al. 2007; Ferreira et al. 2009. List 5 DBBM and particulated autograft material; 11 studies Hatano et al. 2004; Shlomi et al. 2004; Hallman et al. 2005; Krennmair et al. 2007; Marchetti et al. 2007; Bornstein et al. 2008; Degidi et al. 2009. List 6 Autogenous block grafts; 10 studies Daelemans et al. 1997; Lundgren et al. 1997; Blomqvist et al. 1998; Johansson et al. 1999; Keller et al. 1999; Wannfors et al. 2000; Kahnberg et al. 2001; Raghoebar et al. 2001b; Pejrone et al. 2002; Becktor et al. 2007. List 7 Particulated autografts from different donor sites; 7 studies Lundgren et al. 1996; van den Bergh et al. 1998; Wannfors et al. 2000;

Hallman et al. 2002b; Stricker et al. 2003; Wiltfang et al. 2005; Kahnberg and Vannas-Löfqvist 2008. List 8 Composite graft consisting of particulated autograft and allograft; 4 studies Peleg et al. 1998; Mazor et al. 1999; Peleg et al. 1999; Kan et al. 2002 List 9 Alloplastic particulate in the form of hydroxyapatite; 3 studies Mangano et al. 2003; Mangano et al. 2006; Mangano et al. 2007 List 10 DFDBA and DBBM; 3 studies Valentini and Abensur 1997; Kan et al. 2002; Valentini and Abensur 2003 List 11 No grafting material; 3 studies Lundgren et al. 2004; Chen et al. 2007; Thor et al. 2007 List 12 Barrier membrane; 16 studies Small et al. 1993; Peleg et al. 1998; Zitzmann and Schärer 1998; Mazor et al. 1999; Valentini et al. 2000; Cordioli et al. 2001; Hallman et al. 2002b; Shlomi et al. 2004; Orsini et al. 2006; Krennmair et al. 2007; Mardinger et al. 2007; Bornstein et al. 2008; Chaushu et al. 2009; Dasmah et al. 2009; Ferreira et al. 2009. List 13 No membrane; 28 studies Blomqvist et al. 1996; Lundgren et al. 1996; Daelemans et al. 1997; Lundgren et al. 1997; Valentini and Abensur 1997; Blomqvist et al. 1998; van den Bergh et al. 1998; Peleg et al. 1999a; van den Bergh et al. 2000b; Hallman et al. 2001; Kahnberg et al. 2001; Raghoebar et al. 2001b; Hallman et al. 2002a, 2002b; Mangano et al. 2003; Reinert et al. 2003; Stricker et al. 2003; Valentini and Abensur 2003; Hallman and Zetterqvist 2004; Hatano et al. 2004; Lundgren et al. 2004; Mangano et al. 2006; Becktor et al. 2007; Chen et al. 2007; Mangano et al. 2007; Marchetti et al. 2007; Thor et al. 2007; Kahnberg and Vannas-Löfqvist 2008. List 14 Transcrestal elevation; 18 studies Zitzmann and Schärer 1998; Fugazzotto and De Paoli 2002; Winter et al. 2002; Brägger et al. 2004; Deporter et al. 2005; Leblebicioglu et al. 2005; Rodoni et al. 2005; Ferrigno et al. 2006; Stavropoulos et al. 2007; Krennmair

et al. 2007; Nedir et al. 2009b; Schleier et al. 2008; Schmidlin et al. 2008; Sforza et al. 2008; Fermergård and Åstrand 2009; Gabbert et al. 2009; Nedir et al. 2009; Pjetursson et al. 2009a. List 15 Subantral bone height; 14 studies Stavropoulos et al. 2007 List 16 No grafting material; 8 studies Winter et al. 2002; Leblebicioglu et al. 2005; Fermergård and Åstrand 2008; Schleier et al. 2008; Schmidlin et al. 2008; Fermergård and Åstrand 2009 (same patients as 2008 publication); Gabbert et al. 2009; Nedir et al. 2009a, 2009b. List 17 DBBM only; 4 studies Zitzmann and Schärer 1998; Deporter et al. 2005; Rodoni et al. 2005; Krennmair et al. 2007 List 18 Autologous bone; 2 studies Fugazzotto and De Paoli 2002; Ferrigno et al. 2006

8.2

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FOR YOUR LIBRARY D. Buser, U. Belser, D. Wismeijer (Edit.)

ITI Treatment Guide Vol. 1: Implant Therapy in the Esthetic Zone – Single-Tooth Replacements 268 pages • 833 images • hardcover • ISBN 978-3-938947-10-4 Languages: English, German, Italian, Portuguese, Japanese, Chinese, Russian ITI Treatment Guide Vol. 1 focuses on implant therapy for single-tooth edentulous spaces in the esthetic zone. It takes its readers through the entire process, starting with the assessment of the patient’s individual esthetic risk profile and proceeding to ideal three-dimensional implant placement and proven prosthetic management options. The various aspects are illustrated using patient case studies. Detailed illustrations serve to clarify any potential ambiguities. An analysis of the potential complications in esthetic implant dentistry completes this first volume.

D. Wismeijer, D. Buser, U. Belser (Edit.)

ITI Treatment Guide Vol. 2: Loading Protocols in Implant

Dentistry – Partially Dentate Patients 184 pages • 420 images • hardcover • ISBN 978-3-938947-12-8 Languages: English, German Italian, Portuguese, Japanese, Chinese, Russian ITI Treatment Guide Vol. 2 is devoted to the restoration of partially dentate patients. Central to this volume of the ITI Treatment Guide are loading protocols available to the clinician and the patient and how they relate to various treatment indications, including both single and multiple missing teeth in the posterior and anterior regions of the mouth.

D. Buser, D. Wismeijer, U. Belser (Edit.)

ITI Treatment Guide Vol. 3: Implant Placement in PostExtraction Sites – Treatment Options 216 pages • 553 images • hardcover • ISBN 978-3-938947-14-2 Languages: English, German, Japanese, Chinese ITI Treatment Guide Vol. 3 was created to provide clinicians with practiceoriented information about implants inserted in post-extraction sites. It aims at supporting clinicians not only in their evidence-based choice of the appropriate implant placement protocol but also in their detailed treatment planning and execution.

D. Wismeijer, D. Buser, U. Belser (Edit.)

ITI Treatment Guide Vol. 4: Loading Protocols in Implant Dentistry – Edentulous Patients 248 pages • 746 images • hardcover • ISBN 978-3-938947-16-6 Languages: English, German, Italian, French, Spanish, Portuguese, Japanese, Chinese ITI Treatment Guide Vol. 4 presents implant therapy approaches and procedures in the edentulous jaw with a special focus on loading protocols. After discussing the current evidence base in the literature and a summary of the most recent relevant ITI Consensus Statements it proceeds to guide readers through the entire treatment process. 13 detailed case studies and illustrations clarify potential ambiguities and complications to help clinicians master the most common challenges in clinical practice.

For further information, please visit www.quintessenz.de/iti