Titelblatt
Copyright-Seite
Preface
Acknowledgment
Editors and Authors
Contributors
1 Introduction
2 Proceedings of the Third ITI Consensus Conference: Implants in Post-Extraction Sites
2.1 Consensus Statements and Recommended Clinical Procedures Regarding the Placement of Implants in Post-Extraction Sites
2.1.1 Consensus Statements
2.1.2 Proposed Clinical Approaches
2.1.3 Conclusions
2.2 Implants in Post-Extraction Sites – A Literature Update
2.2.1 Classification for the Timing of Implant Placement After Tooth Extraction>
2.2.2 Literature Update
Healing of Extraction Sockets – Histological Events
Healing of Extraction Sockets – Dimensional Changes Following Tooth Extraction
2.2.3 Healing Adjacent to Implants in Post-Extraction Sites
2.2.4 Implant Survival
2.2.5 Esthetic Outcomes
3 Pre-Operative Assessment and Treatment Options for Post-Extraction Implants
3.1 Factors Influencing the Treatment Outcomes of Implants in Post-Extraction Sites
3.1.1 Introduction
3.1.2 The Patient
3.1.3 The Biomaterial
3.1.4 The Treatment Approach
3.1.5 The Clinician
3.2 Advantages and Disadvantages of Treatment Options for Implant Placement in Post-Extraction Sites
3.2.1 Treatment Time and Number of Surgical Procedures
3.2.2 Site Factors
Resolution of Local Infection
Dimensional Changes and Morphology of the Peri-Implant Defect
Simultaneous Bone Augmentation
Adjunctive Connective-Tissue Grafting
Socket Morphology
Achieving Primary Implant Stability
Flapless Procedures
3.2.3 Summary
3.3 Recommendations for Selecting the Treatment Approach
3.3.1 General Recommendations
3.3.2 Recommendations in the Anterior Maxilla
4 Clinical Case Presentations Based on Different Implant Placement Protocols
Immediate Implant Placement (Type 1)
4.1 Immediate Placement of an Implant in a Maxillary Right Central Incisor Site
Acknowledgments
4.2 Immediate Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
4.3 Immediate Flapless Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
4.4 Immediate Placement of an Implant in a Mandibular First Molar Site
Acknowledgments
4.5 Immediate Flapless Placement of an Implant in a Maxillary Right Second Premolar Site
Acknowledgments
4.6 Immediate Flapless Placement of an Implant in a Maxillary Right Lateral Incisor Site
Acknowledgments
4.7 Immediate Flapless Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
Early Implant Placement (Type 2)
4.8 Early Placement of an Implant a Maxillary Right Central Incisor Site
Acknowledgments
4.9 Early Placement of Implants in a Mandibular Left Second Premolar and Second Molar Site
4.10 Early Placement of an Implant in a Maxillary Left First Premolar Site
Acknowledgments
Early Implant Placement (Type 3)
4.11 Early Implant Placement in a Maxillary Lateral Incisor Site
Acknowledgments
4.12 Early Placement of an Implant in a Maxillary Left First Premolar Site
Acknowledgments
Late Implant Placement (Type 4)
4.13 Late Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
4.14 Late Flapless Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
4.15 Late Placement of an Implant in a Maxillary Left Central Incisor Site
Acknowledgments
5 Complications
5.1 Complications Following Implant Placement in Post-Extraction Sites
5.2 Peri-Implant Infection Following Early Implant Placement
Discussion
5.3 Loss of an Immediate Implant with Immediate Restoration Due to a Post-Operative Peri-Implant Infection
Discussion
5.4 Peri-Implant Infection Three Years Following Immediate Implant Placement
Discussion
5.5 Mucosal Recession Following Flapless, Immediate Implant Placement in a Maxillary Central Incisor Site
Discussion
Acknowledgments
5.6 Mucosal Recession Following Immediate Implant Placement in a Maxillary Lateral Incisor Site
Discussion
Acknowledgments
5.7 Mucosal Recession Following Immediate Implant Placement in a Maxillary Central Incisor Site
Discussion
5.8 Conclusions
Literature/References
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 athttp://dnb.ddb.de.
© 2008 Quintessence Publishing Co, Ltd
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All rights reserved. This book or any part thereof may not be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher.
Medical Editing: Dr. Kati Benthaus, CH-Basel
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Copyediting: Triacom Dental, D-Barendorf, www.triacom-dental.de
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ISBN: 1850973466
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 research, development and education to the benefit of the patient.”
Today, the use of dental implants has become a standard of care in many clinical situations. A vast body of evidence proves implant therapy to be a safe and efficient treatment option. The undisputed advantages that implant therapy offers over conventional therapeutic intervention in many cases has further contributed to the swift growth of the number of implants placed.
The rapidly increasing relevance and popularity of this still relatively new therapeutic approach does not only entail advantages, but it also harbors risks. In addition to treatment outcomes being largely dependent on the clinician’s level of education, practical expertise, and sense of responsibility, one has to be aware of the uncertainties regarding the uses and successes of new treatment modalities, as these have not yet been sufficiently evaluated and documented in clinical long-term studies.
The present Volume 3 of the ITI Treatment Guide series has been designed to provide clinicians with practical and evidence-based data on implants inserted in post-extraction sockets.
Based in part on the results of the Third ITI Consensus Conference held in 2003, this ITI Treatment Guide volume provides an up-to-date analytical review of the current literature. In addition, it also offers an extensive overview of the advantages and shortcomings of the different treatment options in post-extraction sites.
In addition to 15 case presentations that illustrate the application of the various placement protocols in clinical practice, factors influencing treatment outcomes of implant therapy in post-extraction sites are discussed, as are potential complications.
Volume 3 of the ITI Treatment Guide series is aimed at assisting clinicians in their evidence-based choice of implant placement protocol, at the same time supporting detailed treatment planning and execution. In this respect, Volume 3 of the ITI Treatment Guide series represents another effort to accomplish the mission of the ITI, which is “… to promote and disseminate knowledge on all aspects of implant dentistry [...] to the benefit of the patient.”
Daniel Buser
Daniel Wismeijer
Urs C. Belser
The authors wish to express their special thanks to Dr. Kati Benthaus for her excellent support and outstanding commitment to maintaining the high quality of this third volume in the series of ITI Treatment Guides.
We would also like to thank Straumann AG, our corporate partner, for their continuing support, without which the realization of the ITI Treatment Guide series would not have been possible. The ITI and the authors are solely responsible for its scientific content.
Urs C. Belser, DMD, Professor
University of Geneva
Department of Prosthodontics
School of Dental Medicine
Rue Barthélemy-Menn 19,1211 Genève 4, Switzerland
E-mail: urs.belser@medecine.unige.ch
Daniel Buser, DMD, Professor
University of Bern
Department of Oral Surgery and Stomatology
School of Dental Medicine
Freiburgstrasse 7, 3010 Bern, Switzerland
E-mail: daniel.buser@zmk.unibe.ch
Stephen Chen, MDSc, Dr
School of Dental Science
The University of Melbourne
720 Swanston Street
Melbourne, VIC 3010, Australia
E-mail: schen@balwynperio.com.au
Daniel Wismeijer, DMD, Professor
Academic Center for Dentistry Amsterdam (ACTA)
Free University
Department of Oral Function
Section of Implantology and Prosthetic Dentistry
Louwesweg 1, 1066 EA Amsterdam, Netherlands
E-mail: d.wismeij@acta.nl
Jay R. Beagle, DDS, MSD
3003 East 98th Street, Suite 200
Indianapolis, IN 46280, USA
E-mail: jbeagledds@aol.com
Marina S. Bello-Silva, DMD, PhD Student
University of São Paulo
LELO - Center of Research,
Teaching and Clinics of Laser in Dentistry
School of Dentistry
Av. Prof. Lineu Prestes, 2227
São Paulo, SP, 05508-000, Brazil
E-mail: marinastella@usp.br
Shayne Callis, M Dent (Wits), ADC, BDS (Wits)
Balwyn Periodontic Centre, 223 Whitehorse Road
Balwyn, VIC 3013, Australia
E-mail: shaynecallis@optushome.com.au
Luiz O.A.Camargo, DMD, PhD
Av. Brig. Faria Lima, 1478 Cj. 2205/2208
Sao Paulo 01451-001 Brazil
E-mail: luizotavio.camargo@special-odonto.com.br
Roberto Cornelini MD, DDS
Assistand Professor, Department of Oral Pathology,
University of Geneva
Piazza Tre Martini 38, Rimini 47900, Italy
E-mail: rcornel@libero.it
Anthony J. Dickinson, BDSc, MSD
1564 Malvern Road
Glen Iris, VIC 3146, Australia
E-mail: ajd1@iprimus.com.au
Christopher Evans, BDSc Hons (Qld), MDSc (Melb)
75 Asling St., Brighton
Melbourne, VIC 3186, Australia
E-mail: cdjevans@mac.com
German O. Gallucci, DMD, Dr med dent
Harvard School of Dental Medicine
Department of Restorative Dentistry
and Biomaterial Sciences
188 Longwood Avenue, Boston, MA 02115, USA
E-mail: german_gallucci@hsdm.harvard.edu
Christopher Hart, BDSc, Grad Dip Clin Dent, MDSc
4 Linckens Cres
Balwyn, VIC 3103, Australia
E-mail: cnhart@mac.com
Lisa J. A. Heitz-Mayfield, BDS, MDSc, Odont Dr, Assoc Prof.
University of Sydney
NSW, 2000, Australia
E-mail: heitz.mayfield@iinet.net.au
Yasushi Nakajima, DDS
Center of Implant Dentistry
Minatomirai Nishiku 3-3-1,
Yokohama, 220-841, Japan
E-mail: njdc3805@crest.ocn.ne.jp
Robert Nieberler, Dr med dent
Lochhauserstrasse 4, 82178 Puchheim, Germany
E-mail: dr.nieberler@t-online.de
Mario Roccuzzo, DMD, Dr med dent
Corso Tassoni 14, Torino 10143, Italy
E-mail: mroccuzzo@iol.it
Anthony Sclar, OMS
Director of Clinical Research
and Dental Implant Surgery
Department of Oral and Maxillofacial Surgery
Nova South Eastern School of Dentistry
South Florida
7600 Red Road, Suite 101
Miami, FL 33143, USA
E-mail: anthonysclar@aol.com
Pedro Tortamano-Neto, DMD, PhD
Rua Jeronimo da Veiga, 428 cj. 51
Itaim Bibi, Sao Paulo, 04536-001 Brazil
E-mail: tortamano@giro.com.br
Over the last decade, the evolution of implant dentistry has continued, with significant advances in biomaterials and clinical techniques through ongoing research and development. To a large extent, this evolution has reflected the change in the demographics of individuals going to dental offices for treatment today. While in the past, most patients presented with edentulous spaces, today the majority seek replacement of teeth that require extraction prior to implant placement. In these cases, the clinician must make a very important decision, i.e. to recommend the best time to place an implant after the tooth has been extracted. The clinician must also select the most appropriate biomaterials to be used. The need for functional and esthetic outcomes as well as a desire for reduced treatment times must be weighed carefully against the pretreatment conditions of the site, dimensional changes that will occur following extraction, the predictability of the planned treatment approach, and the related risk of complications.
In August 2003, the ITI met at the Third ITI Consensus Conference to discuss a number of issues in implant dentistry, one of them being the subject of implant placement in post-extraction sites. The proceedings of this conference were published in a supplement to the International Journal of Oral & Maxillofacial Implants in 2004. Four years later, the issue of post-extraction implant placement continues to be of great interest.
In this Treatment Guide, a summary of the findings and consensus statements from the Third ITI Consensus Conference is provided, supplemented by an update of the literature pertaining to post-extraction implants published in the last four years. Based on this evidence, recommendations for the various treatment approaches are provided and supported by detailed case reports.
As with the preceding two volumes of the ITI Treatment Guide, the authors hope that this volume will present a valuable resource to clinicians who in their daily practice must provide predictable treatment for the benefit of their patients.
The International Team for Implantology (ITI) is an independent academic network that unites professionals from all fields of implant dentistry and related tissue regeneration. It is active in the fields of research, development, and continuing education, and is dedicated to the promotion and spread of knowledge about all aspects of implant dentistry and related tissue regeneration for the benefit of patients. To date, the ITI unites about 5000 Fellows and Members in more than 40 countries.
The ITI regularly draws up and publishes treatment guidelines that are based on comprehensive clinical studies and supported by long-term clinical results. The results of this commitment include, for instance, publications such as the ITI Treatment Guide and the ITI Consensus Papers.
The ITI organizes consensus conferences at five-year intervals to discuss relevant topics in implant dentistry. The first and second ITI Consensus Conferences in 1993 and 1997 (Proceedings of the ITI Consensus Conference 2000) primarily discussed basic surgical and prosthetic issues in implant dentistry.
The third ITI Consensus Conference was convened in 2003. For this conference, the ITI Education Committee decided to focus the discussion on four special topics that had received much attention in recent years, “Implants in Extraction Sockets” (current terminology: post-extraction sites) being one of them (Proceedings of the Third ITI Consensus Conference, International Journal of Oral and Maxillofacial Implants, 2004. Vol 19, Supplement).
The objectives of the ITI Consensus Conference were to review the current literature in peer-reviewed journals and to discuss where sufficient evidence was available for specific clinical procedures and where evidence was lacking.
A working group was elected for the exploration of each topic. Working Group 1,under the leadership of Professor Christoph H. F. Hämmerle, was asked to review relevant literature, focus on, and find consensus relating to implants in post-extraction sites.
The participants of Working Group 1 were:
Gil Alcoforado
Jay R. Beagle
Jean-Pierre Bernard
Stephen T. Chen
Anthony Dickinson
Paul Fugazzotto
Erik Hjørting-Hansen
Louis Antonio Lima
Jan Lindhe
Thomas Oates
Mario Roccuzzo
James Ruskin
Thomas von Arx
Gerhard Wahl
Thomas G. Wilson Jr.
The group was asked to develop evidence-based reviews on topics related to various placement protocols for dental implants. The following material was presented to the group for review and discussion:
Stephen T. Chen, Thomas G. Wilson Jr., and Christoph H. F. Hämmerle: “Immediate or Early Placement of Implants Following Tooth Extraction: Review of Biologic Basis, Clinical Procedures, and Outcomes” (Chen and coworkers, 2004)
The aim of this article was to review the current literature with regard to survival and success rates, along with the clinical procedures and outcomes associated with immediate and delayed implant placement.
The consensus statements and proposed clinical approaches defined by Working Group 1 on the topic of “Implants in Extraction Sockets”, as listed in Chapters 2.1.1 and 2.1.2 are intended to serve as a guide to clinicians in the diagnosis, treatment planning, and management of patients requiring dental implant therapy.
With the consensus statements as guidelines, it is hoped that clinicians will be better prepared to make informed surgical and prosthodontic treatment decisions to further enhance the quality of care and predictability of treatment outcome for their patients.
Socket Healing
Results of clinical, radiologic, and histologic studies indicate that bony healing of extraction sites proceeds with external resorption of the original socket walls and a varying degree of bone fill within the socket.
Bone Regeneration
Studies in humans and animals have demonstrated that at implant sites with a horizontal defect dimension (HDD; i.e. the peri-implant space) of 2 mm or less, spontaneous bone healing and osseointegration of implants with a rough titanium surface takes place.
In sites with HDDs larger than 2 mm and or non-intact socket walls, techniques utilizing barrier membranes and/or membrane-supporting materials have been shown to be effective in regenerating bone and allowing osseointegration.
Although scarce, the majority of the comparative data regarding the success of bone regeneration at peri-implant defects suggests no differences between Type 1, 2, and 3 procedures.
Further comparative analyses of different methods of bone augmentation with regard to successful bone formation and stability over time are required.
Long-term analysis of the stability of the regenerated bone is focused almost exclusively on radiographic assessments of the interproximal bone and implant survival. There is a need for studies to evaluate the fate of the buccal bone plate – whether regenerated or not – over time.
Adjunctive Medication
In most studies reviewed, broad-spectrum systemic antibiotics were used in conjunction with implant placement Type 1, 2, and 3. Controlled studies evaluating the effect of systemic antibiotics on treatment outcomes are needed.
Survival of Implants
The survival rate of immediately placed implants (Type 1) was reported in numerous studies to be similar to that of implants placed into healed ridges (Type 4).
In the few studies available, short-term survival rates of implants placed in conjunction with Type 2 and 3 procedures appear similar to those placed in Type 1 and 4 approaches.
There have been relatively few reports on the subject of Type 2 and 3 implant procedures, and only 2 of them were randomized with respect to timing of placement and augmentation methods used. Longitudinal studies of greater than 3 years’ duration were limited to 2 reports.
There is evidence to suggest that the survival rate for implants placed immediately following extraction of teeth associated with local pathology is similar to that of implants placed into healed ridges. Further controlled studies are required to provide definitive information about the management of these situations.
Esthetic Outcomes
Esthetically pleasing treatment outcomes have received considerable attention in recent years; however, there are no controlled studies available on esthetic treatment outcomes in Type 1, 2, and 3 procedures.
Patient Assessment
All candidates for extraction-site implants should meet the same general screening criteria as regular implant patients, regardless of the timing of implant placement.
Antibiotics
The literature is inconclusive regarding antibiotic use in conjunction with implant therapy. There is general agreement that the use of antibiotics is advantageous when augmentation procedures are performed.
Tooth Extraction
Extraction techniques that result in minimal trauma to hard and soft tissue should be used. The sectioning of multi-rooted teeth is advised. All granulation tissue should be removed from the socket.
Site Evaluation
Site evaluation is critical to the determination of appropriate treatment modalities. Factors of concern include:
Overall patient treatment plan
Esthetic expectations of the patient
Soft tissue quality, quantity, and morphology
Bone quality, quantity, and morphology
Presence of pathology
Condition of adjacent teeth and supporting structures
Primary Implant Stability
The implant should not be placed at the time of tooth removal if the residual ridge morphology precludes attainment of primary stability of an appropriately sized implant in an ideal restorative position.
Thin Biotype
When treating patients with a thin, scalloped tissue biotype – even those with an intact buccal plate – concomitant augmentation therapies at the time of implant placement (Type 1) are recommended because of the high risk of buccal plate resorption and marginal tissue recession.
If buccal plate integrity is lost, implant placement is not recommended at the time of tooth removal. Rather, augmentation therapy is performed, and a Type 3 or 4 approach is utilized.
Thick Biotype
In cases involving a thicker, less scalloped tissue bio-type with an intact buccal plate, the need for concomitant augmentation therapies at the time of implant placement (Type 1) may be reduced, since thick bio-types have a decreased risk of buccal-plate resorption in comparison with thinner biotypes. As buccal-plate integrity is lost, the need for augmentation therapies increases.
When the buccal plate is compromised, negatively impacting the predictability of treatment outcomes, immediate (Type 1) implant placement is not indicated; rather, a Type 2, 3 or 4 procedure is carried out. When the HDD is greater than 2 mm, concomitant augmentation therapy needs to be performed.
Adjunctive augmentation therapies may be indicated in any of the above situations to optimize esthetic treatment outcome.
Implant Placement
The three-dimensional positioning of the implant should be restoratively driven.
The Third ITI Consensus Conference took place in August 2003. The Consensus Statements phrased by Working Group 1 explored the topic of “Implants in Extraction Sockets” and were based on the body of literature available at that time.
Meanwhile, the topic of “Implants in Extraction Sockets” has been further researched, and additional literature has been published. In addition, new implant surface technologies and their influence on immediate and early placement protocols have been investigated.
Chapter 2.2, “Implants in Post-Extraction Sites – A Literature Update,” and Chapter 3.2, “Advantages and Disadvantages of Treatment Options for Implant Placement in Post-Extraction Sites” recognize the evolution of implant placement protocols, including recent data and literature, in order to give a state-of-the-art overview of implant placement protocols in connection with the clinical implications and applications to be derived from them.
Since the Third ITI Consensus Conference in August 2003, there has been a sustained interest in techniques for placing implants in post-extraction sites. Several randomized controlled clinical studies and a number of prospective and retrospective case series studies have been published to provide additional information regarding the clinical outcomes of this mode of treatment.
A number of descriptive terms have been used to indicate the timing of implant placement after the extraction of teeth. Wilson and Weber (1993) proposed the terms “immediate,” “recent,” “delayed,” and “mature” to describe the timing of implant placement in relation to soft-tissue healing and the predictability of guided bone-regenerative procedures using barrier membranes. In 1999, the terms “delayed” and “late” were used to describe time intervals of 6 to 10 weeks and 6 months or more after extraction, respectively (Mayfield, 1999). More recently, the term “early” implant placement has been used to describe implant placement after initial soft- and hard-tissue healing, but before complete healing of the socket has occurred (Chen and coworkers, 2004).
The variation in descriptive terminology in the dental literature was discussed at the Third ITI Consensus Conference, and a new classification system for the timing of implant placement after tooth extraction was proposed (Hämmerle and coworkers, 2004). This classification system is based on the desired clinical outcome of the wound-healing process, rather than on descriptive terms or rigid time frames following extraction. Thus, Type 1 placement refers to the placement of an implant on the day of tooth extraction and within the same surgical procedure. Type 2 refers to implant placement after soft-tissue healing, but before any clinically significant bone fill occurs within the socket. In contrast, Type 3 placement describes implant placement following significant clinical and/or radiographic bone fill of the socket. Type 4 placement refers to the insertion of an implant in a fully healed site. For the purpose of this review, the post-extraction period will include Type 1, 2, and 3 placement protocols. Table 1 summarizes the terminology that will be adopted in this Treatment Guide. Typically, between 4 and 8 weeks of healing is required for adequate soft tissue healing for early placement (Type 2). For early placement with partial bone healing (Type 3), a healing period of 12 to 16 weeks is usually needed. The time for healing and for achieving the desired clinical outcome for Type 2 and Type 3 placement depends upon the initial condition of the extraction site and the dimensions of the socket. For late placement (Type 4) healing, 6 months or longer are usually required for the complete healing of the bone.
| Classification | Descriptive terminology | Period after tooth extraction | Desired clinical situation at implant placement |
| Type 1 | Immediate placement | 0 | Post-extraction site with no healing of bone or soft tissues |
| Type 2 | Early placement with soft-tissue healing | Typically 4 to 8 weeks | Post-extraction site with healed soft tissue but without significant bone healing |
| Type 3 | Early placement with partial bone healing | Typically 12 to 16 weeks | Post-extraction site with healed soft tissues and with significant bone healing |
| Type 4 | Late placement | Typically 6 months or longer | Fully healed post-extraction site |
An update of the relevant literature pertaining to implants in post-extraction sites is presented below. The majority of the studies discussed in the following chapter were published after the Third ITI Consensus Conference. The proceedings of Group 1 of the Consensus Conference provide details of studies published before that time (Chen and coworkers, 2004; Hämmerle and coworkers, 2004).
The histological events that take place during the healing of extraction sockets have been presented mainly in experimental studies and in a limited number of clinical studies.
Recently, a comprehensive histological study in a canine model over a 6-month period was published (Cardaropoli and coworkers,2003).Healing was examined histologically in mandibular premolar sites at intervals of 1, 3, 7, 14, 30, 60, 90, 120, and 180 days after extraction in nine mongrel dogs. An initial blood clot that occupied most of the socket was gradually replaced with a provisional matrix between 3 and 7 days after tooth extraction. This matrix consisted of newly forming blood vessels, immature mesenchymal cells, leukocytes, and collagen fibers. The bundle bone lining the socket walls showed intense osteoclastic activity leading to the formation of Volkmann’s canals that formed channels between the healing socket and surrounding bone. At 14 days, the socket was filled with well-organized connective tissue rich in blood vessels and inflammatory cells. The lateral and apical regions of the socket were lined with immature woven bone. By 30 days, newly formed bone had completely filled the socket, with early signs of modeling and remodeling taking place. By 60 days, a mineralized bridge had formed at the socket entrance, which gradually corticalized and became indistinguishable from the surrounding cortical bone after 180 days.
A limited number of human studies are available with histological data on the healing of extraction sockets (Mangos, 1941; Amler and coworkers, 1960; Boyne, 1966; Amler, 1969; Evian and coworkers, 1982). Osteoid was first seen between 7 and 10 days with initial calcification evident approximately 3 weeks after extraction (Mangos, 1941; Amler and coworkers, 1960; Boyne, 1966; Amler, 1969). Substantial bone fill of the socket occurred between 5 and 10 weeks (Amler and coworkers, 1960; Amler, 1969). Maximum osteoblastic activity occurred between 4 and 6 weeks after extraction, and at 8 weeks the osteogenic process appeared to slow down until bone formation was complete at 16 weeks (Evian and coworkers, 1982).
Very little data is available on the healing of sockets with damage to one or more of the socket walls (Adriaens, 1999). In a randomized controlled study investigating the efficacy of recombinant bone morphogenetic protein-2 for bone augmentation in extraction sockets, sites with more than 50% loss of the facial bone wall showed less regenerative capacity than sites with intact bone walls (Fiorellini and coworkers, 2005). This finding supports the views expressed by a number of authors on the importance of the integrity of the socket walls in the regenerative potential of extraction sockets (Becker and coworkers, 1994a; Zitzmann and coworkers, 1999; Schropp and coworkers, 2003a).
The external dimensions of the alveolar ridge are reduced following tooth extraction (Johnson, 1963; Carlsson and Ericson, 1967). In a prospective clinical study, about 50% of the width of the ridge in posterior sites was lost after a healing period of 12 months (Schropp and coworkers, 2003b). Of note was the observation that two-thirds of this loss occurred within the first 3 months. The authors reported that the only dimensional gain was in the height of the mucosa, about 0.5 mm on the buccal aspect. The majority of the patients did not wear prostheses during the 12-month observation period.
The external changes to the mucosa appear to be mirrored by modeling changes of the socket walls. These changes result in a loss of vertical (0.7 to 1.8 mm) and horizontal (2.6 to 4.6 mm) dimension (Lekovic and coworkers, 1997; Lekovic and coworkers, 1998; Camargo and coworkers, 2000; Iasella and coworkers, 2003; Serino and coworkers, 2003). In a recent study, the reported dimensional changes were small (1.2 mm vertical loss and 0.6 mm horizontal gain), as the sites under investigation were already damaged and had more than 50% loss of the facial bone wall at the beginning of the study (Fiorellini and coworkers, 2005).
These dimensional changes may commence soon after tooth extraction. In a study comparing immediate and early implant placement, the orofacial dimension of the sockets was almost 2 mm less at “early” sites 6 to 8 weeks after extraction as compared to fresh extraction sockets (Covani and coworkers, 2004). This represented a loss to the horizontal dimension of 15% within 6 to 8 weeks of extraction.
The dimensional changes after tooth extraction reported in the preceding clinical studies occur as a result of bone modeling. In a recent histological study using a canine model, the authors reported that following tooth extraction, resorption of the bundle bone that lines the extraction socket takes place during the first 8 weeks of healing (Araújo and Lindhe, 2005a). The facial bone wall is thinner than the lingual bone wall and is comprised almost entirely of bundle bone in the coronal region. Thus, resorption of the bundle bone leads to a marked reduction in the height of the facial bone wall compared to the lingual bone wall. At the same time, intense osteoclastic activity on the external surface of the facial and lingual bone causes a reduction in the horizontal dimension of the ridge, predominantly from the facial aspect.
Several studies assessing ridge-preservation techniques for maintaining the dimensions of the bone after tooth extraction showed that despite the use of barrier membranes or bone grafts with low substitution rates, horizontal resorption of 13% to 25% still occurred (Lekovic and coworkers, 1997; Lekovic and coworkers, 1998; Iasella and coworkers, 2003). It may thus be concluded that resorption and modeling processes leading to dimensional changes still take place even in the presence of bone grafts within the socket. These processes, however, may be influenced by the substitution rate of applied bone fillers. In contrast, where both the socket and the external surface of the facial socket wall were grafted with demineralized freeze-dried bone allograft (DFDBA) and covered with a resorbable membrane, the horizontal dimension was increased by 24% (Simon and coworkers, 2000). Although the graft initially increased the horizontal dimension by 42%, half of the grafted dimension was lost after 4 months of healing, probably through the settling of the particulate graft and the resorption of the DFDBA, which has a high substitution rate during remodeling (Buser and coworkers, 1998).
Since the Third ITI Consensus Conference in 2003, a number of studies have been published that present further data on socket healing in conjunction with implant placement. In a prospective clinical study, 18 patients received 21 implants that were placed at the time of extraction. No bone fillers or barrier membranes were used. Following 4 months of submerged healing, the implant sites were reentered for the connection of transmucosal abutments. The majority of marginal defects with initial horizontal marginal gaps of up to 3 mm healed with bone fill and defect resolution (Botticelli and coworkers, 2004). The observation that, after 4 to 6 months, marginal defects adjacent to implants in post-extraction sites can heal with spontaneous bone fill and defect resolution has been confirmed in a number of recent clinical studies (Covani and cowork-ers,2003; Covani and coworkers,2004; Chen and coworkers, 2005; Chen and coworkers, 2007). However, regeneration within the socket was accompanied by external resorption and modeling of the facial bone wall, leading to flattening of the alveolar ridge on the facial aspect. Botticelli and coworkers observed that 56% horizontal resorption and 0.3 ± 0.6 mm vertical crestal resorption of the facial bone wall occurred (Botticelli and coworkers, 2004). Other studies of non-grafted marginal defects adjacent to immediate implants showed similar dimensional changes (Covani and coworkers, 2003; Chen and coworkers, 2005; Chen and coworkers, 2007). A recent study compared immediate (Type 1) vs. early (Type 2) placement in 33 patients who did not receive bone grafts (Covani and coworkers, 2004). Both treatment approaches were associated with similar horizontal dimensional changes following 4 to 6 months of healing. For immediate implants, the ridge changed from 10.5 ± 1.5 mm to 8.1 ± 1.3 mm in orofacial width. The corresponding change for early placement was 8.9 ± 2.4 mm to 5.8 ± 1.3 mm.