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The SAC Classification in Implant Dentistry
SECOND EDITION
The SAC Classification in Implant Dentistry
SECOND EDITION
A. DAWSON, W. MARTIN, W. D. POLIDO
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ISBN 978-1-78698-110-3
The materials offered in The SAC Classification in Implant Dentistry are for educational purposes only and intended as a step-by-step guide to the treatment of a particular case and patient situation. These recommendations are in line with the ITI treatment philosophy. These recommendations, nevertheless, represent the opinions of the authors. Neither the ITI nor the authors, editors, or 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 SAC Classification in Implant Dentistry. The information contained in The SAC Classification in Implant Dentistry cannot replace an individual assessment by a clinician and its use for the treatment of patients is therefore 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 SAC Classification in Implant Dentistry 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 SAC Classification in Implant Dentistry are protected by copyright. Any reproduction, whether 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 The SAC Classification in Implant Dentistry is that of the FDI World Dental Federation.
Foreword
The SAC Classification in Implant Dentistry
Almost 20 years ago, the International Team for Implantology – ITI – formalized the SAC classification to categorize oral implant treatment procedures into three levels of difficulty: Straightforward, Advanced, and Complex. The SAC Classification in Implant Dentistry was published in 2009, and it immediately became clear that this approach to classifying treatment risk when planning patient treatment was a tool many dentists had been waiting for. Applying the SAC approach to the evaluation of patient-related risk factors and treatment modifiers has since become a standard procedure for many practitioners, contributing to a higher degree of predictability in the execution and outcome of proposed treatment. The SAC classification has been recognized by dental professionals as an objective, evidence-based framework, also making it an invaluable educational tool for both predoctoral and postgraduate training programs.
As dental materials, technology, and clinical techniques have evolved in the intervening years, the ITI decided to review the SAC classification and present it to clinicians in an updated form: a digital book that can be accessed from any device or computer as needed. With its mission to promote and disseminate knowledge covering all aspects of implant dentistry and related tissue regeneration, the ITI recommends this SAC Assessment Tool to all professionals in the field.
Acknowledgments
It may be trite, but it is true: projects such as this do not succeed without the commitment and hard work of a large team of people. Consequently, we would like to acknowledge the following people and groups.
The ITI Board of Directors trusted us to update one of the ITI’s crown jewels – the SAC Classification. This is a heady responsibility, as we know that the SAC Classification is widely used and respected by clinicians in implant dentistry. We thank the Board for their trust and support.
The staff at the ITI Headquarters have supported us throughout the project. From the events team that organized our meetings, to the Communications and Education teams for providing material, all have worked cheerfully and willingly to help us. Of special note: many thanks to Kati Benthaus and Katalina Cano, our project managers, who have guided us through the process.
Thanks must go to Stefan Keller and his fellow IT wizards at FERN who have turned our dreams of what we would like to do with the online tool into reality.
Thanks also to Änne Kappeler and the team at Quint-essence. Their professionalism and patience have allowed us to produce something that we can all be truly proud of.
Of course, we could not have done anything without the support of our colleagues on the Consensus Group who met in Zurich and Berlin and who toiled tirelessly to develop the framework for the new tool. Thanks also to the members of the ITI Education Committee and all the others who acted as our beta testers, and to those who have contributed material to this book. The quality of the group-achieved outcome is much, much more than the sum of the contributing parts.
And finally, but most importantly, we must thank our wives, children and families for their understanding and support. We could not have done this without you.
Editors / Authors
Anthony Dawson, BDS, MDS, FRACDS
Associate Professor in Prosthodontics
School of Dentistry and Medical Sciences
Charles Sturt University
346 Leeds Parade
Orange, New South Wales 2800
Australia
Email: tdawson@csu.edu.au
William C. Martin, DMD, MS, FACP
Clinical Professor and Director
Center for Implant Dentistry
Department of Oral and Maxillofacial Surgery
College of Dentistry
University of Florida
1395 Center Drive, Rm D7-6
Gainesville, Florida 32610
United States of America
Email: wmartin@dental.ufl.edu
Waldemar D. Polido, DDS, MS, PhD
Clinical Professor, Department of Oral and
Maxillofacial Surgery and Hospital Dentistry
Co-Director, Center for Implant, Esthetic and
Innovative Dentistry
Indiana University School of Dentistry
1121 W Michigan St, DS 109C
Indianapolis, Indiana 46202
United States of America
Email: wdpolido@iu.edu
Contributors
Daniel Buser, DMD, Dr med dent
Professor Emeritus
University of Bern
Buser & Frei Center for Implantology
Werkgasse 2
3018 Bern
Switzerland
Email: danbuser@mac.com
Paolo Casentini, DDS, DMD
Private practice
Studio Dr Paolo Casentini
(Implantology, Oral Surgery, Periodontology, Esthetic Dentistry)
Via Anco Marzio 2
20123 Milano MI
Italy
Email: paolocasentini@fastwebnet.it
Vivianne Chappuis, PhD, DMD
Professor
Department of Oral Surgery and Stomatology
School of Dental Medicine
University of Bern
Freiburgstrasse 7
3010 Bern
Switzerland
Email: vivianne.chappuis@zmk.unibe.ch
Stephen Chen, MDSc, PhD
Faculty of Medicine, Dentistry and Health Sciences
Melbourne Dental School
The University of Melbourne
720 Swanston Street
Carlton, Victoria 3053
Australia
Email: schen@periomelbourne.com.au
Matteo Chiapasco, MD
Professor Unit of Oral Surgery
Department of Biomedical, Surgical, and Dental Sciences
University of Milan
Via della Commenda 10
20122 Milano MI
Italy
Email: matteo.chiapasco@unimi.it
Anthony J. Dickinson, OAM, BDSc, MSD, FRACDS
1564 Malvern Road
Glen Iris, Victoria 3146
Australia
Email: ajd1@i-pros.com.au
Luiz H. Gonzaga, DDS, MS
Clinical Associate Professor
Center for Implant Dentistry
Department of Oral and Maxillofacial Surgery
College of Dentistry
University of Florida
1395 Center Drive, Rm D7-6
Gainesville, Florida 32610-0434
United States of America
Email: lgonzaga@dental.ufl.edu
Stefan Keller Babotai, Dr sc nat
FERN Media Solutions GmbH
Weiherallee 11B
8610 Uster
Switzerland
Email: stefan.keller@fern.ch
Johannes Kleinheinz, MD, DDS Professor
Department of Cranio-Maxillofacial Surgery
University Hospital Münster
Albert-Schweitzer-Campus 1
48149 Münster
Germany
Email: johannes.kleinheinz@ukmuenster.de
Wei-Shao Lin, DDS, FACP, PhD
Associate Professor
Interim Chair, Department of Prosthodontics
Program Director, Advanced Education Program in Prosthodontics
Indiana University School of Dentistry
1121 W Michigan St, DS-S406
Indianapolis, Indiana 46202
United States of America
Email: weislin@iu.edu
Dean Morton, BDS, MS, FACP
Professor Department of Prosthodontics
Director, Center for Implant, Esthetic, and Innovative Dentistry
Indiana University School of Dentistry
1121 W Michigan St
Indianapolis, Indiana 46202
United States of America
Email: deamorto@iu.edu
Ali Murat Kökat, DDS, PhD
Prosthodontist
Private Practice
Valikonaǧı St 159/5
Nisantasi 34363 Sisli
Istanbul
Turkey
Email: alimurat@outlook.com
Mario Roccuzzo, DMD
Lecturer in Periodontology
Division of Maxillofacial Surgery
University of Turin
Corso Bramante 88
10126 Torino
Italy
and
Adjunct Clinical Assistant Professor
Department of Periodontics and Oral Medicine
University of Michigan
1011 N University Avenue
Ann Arbor, Michigan 48109-1078
United States of America
and
Private Practice Limited to Periodontology
Corso Tassoni 14
10143 Torino
Italy
Email: mroccuzzo@icloud.com
Charlotte Stilwell, DDS
Specialist Dental Services
94 Harley Street
London W1G 7HX
United Kingdom
Email: charlotte.stilwell@iti.org
Alejandro Treviño Santos, DDS, MSc
Postdoctoral and Research Division
Faculty of Dentistry
Department of Prosthodontics and Implantology
National Autonomous University of Mexico
Prolongación Reforma 1190
05349, Santa Fe
Ciudad de México
Mexico
Email: aletresan@hotmail.com
Daniel Wismeijer, PhD, DMD
Private Practice
Zutphensestraatweg 26
6955 AH Ellecom
Netherlands
Email: Danwismeijer@gmail.com
Table of Contents
Chapter 1: Introduction to the Updated SAC Classification
A. DAWSON, W. MARTIN, W. D. POLIDO
1.1 Introduction
1.2 Historical Background
1.3 The Review Team
1.4 Potential Roles for the SAC Classification
1.5 Using this Book
Chapter 2: The Rationale Behind the Updated SAC Classification
A. DAWSON, C. STILWELL
2.1 Definitions
2.2 Assumptions
2.3 Is the Clinician a Risk Factor?
2.3.1 Factors impacting the clinician as a risk factor
2.3.1.1 Experience
2.3.1.2 Training
2.3.1.3 Self-assessment of ability
2.3.1.4 Shared learning
2.3.1.5 Short training courses
2.3.1.6 Structured education and training
2.3.2 Reducing clinician-related risk
2.3.2.1 Recognizing “human factor” risks
2.3.2.2 Stress as a risk factor
2.3.2.3 Mitigating the human factor issues
2.3.2.4 Clinician risk factor in relation to other sources of risks
2.4 Classification Rationale
Chapter 3: Risks in Implant Dentistry
A. DAWSON, W. MARTIN, W. D. POLIDO
3.1 Principles of Risk Management
3.2 The SAC Classification as a Risk Management Tool
3.3 General Risks
A. DAWSON, J. KLEINHEINZ, A. MURAT KÖKAT, D. WISMEIJER
3.3.1 Patient medical factors
3.3.1.1 Medical fitness
3.3.1.2 Medications
3.3.1.3 Radiation
3.3.1.4 Growth status
3.3.2 Patient attitudes/behaviors
3.3.2.1 Smoking habit
3.3.2.2 Compliance
3.3.2.3 Oral hygiene
3.3.2.4 Patient expectations
3.3.3 Site-related factors
3.3.3.1 Periodontal status
3.3.3.2 Access
3.3.3.3 Previous surgeries in the planned implant site
3.3.3.4 Nearby pathology
3.4 Esthetic Risk
W. MARTIN, V. CHAPPUIS, D. MORTON, D. BUSER
3.4.1 Medical status and smoking habit
3.4.2 Gingival display at full smile
3.4.3 Width of the edentulous space
3.4.4 Shapes of tooth crowns
3.4.5 Restorative status of adjacent teeth
3.4.6 Gingival phenotype
3.4.7 Volume of surrounding tissues
3.4.8 Patient’s esthetic expectations
3.5 Edentulous Esthetic Risk Assessment (EERA)
L. GONZAGA, W. MARTIN, D. MORTON
3.5.1 Facial support
3.5.2 Labial support
3.5.3 Upper lip length
3.5.4 Buccal corridor
3.5.5 Smile line
3.5.6 Maxillomandibular relationship
3.6 Surgical Risks
W. D. POLIDO
3.6.1 Anatomy
3.6.1.1 Bone volume – Horizontal
3.6.1.2 Bone volume – Vertical
3.6.1.3 Presence of keratinized tissue
3.6.1.4 Quality of soft tissues
3.6.1.5 Proximity to vital anatomical structures
3.6.2 Adjacent teeth
3.6.2.1 Papilla
3.6.2.2 Recession
3.6.2.3 Interproximal attachment
3.6.3 Extractions
3.6.3.1 Radicular morphology / interradicular bone
3.6.3.2 Alveolar and basal bone morphology
3.6.3.3 Socket walls
3.6.3.4 Thickness of facial wall
3.6.3.5 Anticipated residual defect after implant placement
3.6.3.6 Quality and quantity of soft tissues
3.6.4 Surgical complexity
3.6.4.1 Timing of placement
3.6.4.2 Grafting procedures
3.6.4.3 Number of implants
3.7 Prosthetic Risks
C. STILWELL, W. MARTIN
3.7.1 Restorative site factors
3.7.1.1 Prosthetic volume
3.7.1.2 Interocclusal space
3.7.1.3 Volume and characteristics of the edentulous ridge
3.7.2 Occlusal factors
3.7.2.1 Occlusal scheme
3.7.2.2 Involvement in occlusion
3.7.2.3 Occlusal parafunction
3.7.3 Complexity of process
3.7.3.1 Access
3.7.3.2 Interim prosthesis
3.7.3.3 Implant-supported provisional restoration
3.7.3.4 Number and location of implants
3.7.3.5 Loading protocols
3.7.4 Complicating factors
3.7.4.1 Biologic
3.7.4.2 Mechanical and technical
3.7.4.3 Maintenance
Chapter 4: How Does the SAC Assessment Tool Derive a Classification?
A. DAWSON, S. KELLER
4.1 Introduction
4.2 Definitions
4.3 Workflow
4.3.1 General risk assessment (GRA)
4.3.2 Esthetic risk assessment (ERA)
4.3.2.1 ERA
4.3.2.2 EERA
4.3.3 Surgical risk assessment (SRA) and surgical classification
4.3.4 Prosthodontic risk assessment (PRA) and prosthodontic classification
4.4 Calculating a Classification
4.4.1 Calculation mechanism
4.5 Testing the Algorithm
4.6 Presenting the Results
Chapter 5: Practical Application of the SAC Assessment Tool
W. MARTIN, A. DAWSON, W. D. POLIDO
5.1 Introduction
5.2 Implants for Restoration of Single-Tooth Spaces: Areas of Low Esthetic Risk
5.2.1 Mandibular molar
M. ROCCUZZO
5.2.2 Mandibular molar
L. GONZAGA
5.3 Implants for Restoration of Single-Tooth Spaces: Areas of High Esthetic Risk
5.3.1 Maxillary central incisor
L. GONZAGA, W. MARTIN
5.3.2 Maxillary lateral incisor
A. TREVIÑO SANTOS
5.4 Implants in Extraction Sockets: Single-Rooted Teeth
5.4.1 Maxillary central incisor
W. MARTIN, L. GONZAGA
5.4.2 Maxillary premolar
L. GONZAGA
5.5 Implants in Extraction Sockets: Multirooted Teeth
5.5.1 Maxillary first molar
P. CASENTINI
5.6 Implants for Restoration of Short Edentulous Spaces: Areas of Low Esthetic Risk
5.6.1 Adjacent maxillary premolars
S. CHEN, A. DICKINSON
5.7 Implants for Restoration of Short Edentulous Spaces: Areas of High Esthetic Risk
5.7.1 Adjacent maxillary incisors
P. CASENTINI, M. CHIAPASCO
5.8 Implants for Restoration of Long Edentulous Spaces: Areas of High Esthetic Risk
5.8.1 Maxillary lateral and central incisors
A. TREVIÑO SANTOS
5.9 Implants for Restoration of Long Edentulous Spaces: Removable Prostheses
5.9.1 Maxilla
C. STILWELL
5.10 Implants for Restoration of the Full Arch: Removable
5.10.1 Edentulous maxilla: Bar-supported overdenture:
WS. LIN, D. MORTON
5.10.2 Edentulous maxilla: Zygomatic implant bar-supported overdenture
W. D. POLIDO, WS. LIN
5.11 Implants for Restoration of the Full Arch: Fixed
5.11.1 Edentulous mandible: Fixed dental prosthesis
P. CASENTINI
5.11.2 Edentulous maxilla and mandible: Implant-supported all-ceramic fixed complete dentures
D. MORTON, WS. LIN, W. D. POLIDO
Chapter 6: Conclusion
A. DAWSON, W. MARTIN, W. D. POLIDO
Chapter 7: References
CHAPTER 1: Introduction to the Updated SAC Classification
A. DAWSON, W. MARTIN, W. D. POLIDO
1.1 Introduction
Implant dentistry is an integral part of modern dental practice, providing a strong evidence-based option for the rehabilitation of partially and completely edentulous patients. Clinical and technologic advancements in this field have increased the level of confidence that clinicians have in this form of therapy and have also led to a broader base of incorporation into daily practice. What was once the domain of specialist practice is now a common treatment modality in many, if not most, general practices. This has increased the need for all clinicians involved with the field of implant dentistry, irrespective of specialty, to be able to provide therapy at an appropriate level of care.
It has long been recognized that clinical situations present with different levels of difficulty and with different degrees of risk for esthetic, restorative, and surgical complications. Despite the advances in knowledge and improved techniques, implant dentistry is not free from risks of complications or suboptimal outcomes. Over the last decade, research in this field has increasingly provided information regarding the risks associated with this treatment option. The successful osseointegration of an implant is no longer the primary focus of treatment. Rather, the range of potential problems with implants and their related prostheses has come into sharper focus. It is in this environment that the SAC classification has evolved to assist practitioners in recognizing risk factors and providing appropriate levels of care.
1.2 Historical Background
The concept of assessing risk factors in implant dentistry has attracted considerable attention since the early 1990s, when the number of clinicians placing and restoring implants increased significantly. With this increase in use, the number of associated complications also increased.
Renouard and Rangert (1999) published a classification system that addressed the risk factors involved with the surgical and restorative phases of implant rehabilitation. At that time, they affirmed that some risk factors are relative, while others are absolute. The distinction between the two is not as clear as it might appear. However, several relative contraindications or one absolute contraindication should lead to a reevaluation of the original treatment plan. Although they were using terms like “OK,” “Caution,” and “Danger,” and using the green, yellow, and red colors associated with increased risk factors, an integrated decision tree was not present.
The term SAC, with the associated risk factor classification and color scheme, was first used by its two creators, Sailer and Pajarola (1999), in an atlas of oral surgery, with the intent to classify risk factors for general dentists practicing dentoalveolar surgery. The authors described in detail various clinical situations for procedures in oral surgery, such as the removal of third molars, and proposed the classification S = Simple, A = Advanced, and C = Complex. This concept was then adopted in 1999 by the Swiss Society of Oral Implantology (SSOI) during a 1-week congress on quality guidelines in dentistry. The working group of the SSOI developed this SAC classification from a surgical and prosthetic point of view for various clinical situations in implant dentistry. This SAC classification was then adopted by the International Team for Implantology (ITI) in 2003 during the ITI Consensus Conference in Gstaad, Switzerland. The surgical SAC classification was presented in the proceedings of this conference (Buser et al, 2004). The ITI Education Core Group decided in 2006 to slightly modify the original classification by changing the term Simple to Straightforward.
Fig 1. The participants of the SAC Consensus Conference held by the ITI in Palma de Mallorca in March 2007. (Source: The SAC Classification in Implant Dentistry, 2009).
In March 2007, the ITI held a consensus conference in Palma de Mallorca in Mallorca, Spain aimed at improving on the SAC classification (Figure 1). In its initial form, the SAC classification tended to be subjective, as it related the perceived difficulty of the treatment to the individual practitioner. The Mallorca meeting sought to develop a classification scheme that was more structured and objective. The results of this conference were published in an adjunct to the ITI Treatment Guide series in 2009 (Dawson & Chen, 2009). Later in 2009, the ITI developed an SAC Assessment Tool that clinicians could use to determine the normative classification for a case type that they were treating and identify any additional modifying factors that might apply to their own patient’s clinical situation.
The participants in the first SAC Conference were as follows: Urs Belser (Switzerland), Daniel Botticelli (Italy), Daniel Buser (Switzerland), Stephen Chen (Australia), Luca Cordaro (Italy), Anthony Dawson (Australia), Anthony Dickinson (Australia), Javier G. Fabrega (Spain), Andreas Feloutzis (Greece), Kerstin Fischer (Sweden), Christoph Hämmerle (Switzerland), Timothy Head (Canada), Frank Higginbottom (USA), Haldun Iplikcioglu (Turkey), Alessandro Januario (Brazil), Simon Jensen (Denmark), Hideaki Katsuyama (Japan), Christian Krenkel (Austria), Richard Leesungbok (South Korea), Will Martin (USA), Lisa Heitz-Mayfield (Australia), Dean Morton (USA), Helena Rebelo (Portugal), Paul Rousseau (France), Bruno Schmid (Switzerland), Hendrik Terheyden (Germany), Adrian Watkinson (UK), and Daniel Wismeijer (Netherlands).
The 2009 version of the SAC classification scheme has received widespread acceptance in the dental profession and in the realm of dental education (Mattheos et al, 2014), where it has formed the basis of implant dentistry teaching in many predoctoral and postgraduate dental programs.
From its initial release in 2009, clinical techniques, materials, and technology have continued to evolve and, in early 2017, the ITI recognized that there was a need to review the SAC classification to ensure that it was still consistent with contemporary implant practice. A review group met in Zurich in October 2018, and again in Berlin in April 2019, to develop an updated SAC classification scheme. The primary aim of this review was to develop an updated SAC Assessment Tool, as this had been found to be clinicians’ favored way of determining the classification of their patients’ treatment needs. The publication of this book satisfies the secondary goal of the review: to document the rationale for this SAC Assessment Tool and the evolution of the SAC classification.
1.3 The Review Team
This text documents the proceedings of consensus meetings held by the ITI in 2018 and 2019. The following individuals contributed to the findings of this conference and the content of this publication (Figure 2):
Fig 2. Review team members.
| Paolo Casentini | Italy |
| David Cochran | USA |
| Anthony Dawson | Australia |
| Luiz Gonzaga | USA |
| Stefan Keller | Switzerland |
| Thomas Kiss | Switzerland |
| Johannes Kleinheinz | Germany |
| Ali Kökat | Turkey |
| William Martin | USA |
| Dean Morton | USA |
| Waldemar Polido | USA |
| Lira Rahman | Switzerland |
| Mario Roccuzzo | Italy |
| Irena Sailer | Switzerland |
| Charlotte Stilwell | UK |
| Mauro Tosta | Brazil |
| Alejandro Treviño Santos | Mexico |
| Daniel Wismeijer | Netherlands |
1.4 Potential Roles for the SAC Classification
On its surface, the SAC classification provides an assessment of the potential difficulty and risk of an implant-related treatment for a given clinical situation and serves as a guide for clinicians in both patient selection and treatment planning. In addition, it can also fulfill several additional roles.
Primarily, the classification scheme is aimed at providing clinicians with an objective and evidence-based framework against which they can assess clinical cases regarding the complexity of the planned treatment. This can then be used to assist them in deciding if they possess the necessary skills and knowledge to complete the treatment themselves, or whether referral to a more experienced clinician is indicated. With this capacity, they can build their experience in implant dentistry incrementally and minimize potential risk to their patients. Recently, the current SAC Assessment Tool validity was tested in regard to the agreement level between users, confirming its role as a clinical decision-making tool, as well as a valuable tool for the education of less experienced clinicians (Correia et al, 2020).
The SAC classification can also act as a checklist for more experienced clinicians to help them ensure that all relevant risks have been considered in the patient assessment and treatment planning phases of care.
Communication is a vital part of any step of patient management. In this regard, the SAC classification can aid in communication between clinicians as well as between them and their patients. The classification facilitates communication between colleagues by providing a known framework to exchange information: a shorthand that all involved clinicians are familiar with. When dealing with patients, clinicians can use the SAC classification of their situation to illustrate to patients the complexity and risks associated with their care. As such, it becomes an important tool not only in treatment planning but in the informed consent process as well.
Finally, the SAC classification can aid educators in developing training programs that gradually introduce increasingly more complex cases to their students, allowing an incremental development of knowledge and skill.
1.5 Using this Book
This book is intended to support your use of the SAC Assessment Tool that can be found at www.iti.org. Many sections of this publication are also supported by additional online information from the ITI Academy, the ITI’s e-learning platform, including learning modules and assessments, congress lectures, clinical cases, and Consensus Conference papers.
To view this additional material in full and for free, you need to be an ITI Member and logged in at www.iti.org.
Are you an ITI Member?
Please click here to log in to the ITI Academy or scan the QR code below:
Would you like to sign up for ITI membership?
Please click here or scan the QR code below:
Would you like to create a free ITI Academy account?
Please click here or scan the QR code below. Please note that only selected items featured in this publication will be available to view on the ITI Academy free of charge.
As soon as you have logged in or have created your free ITI Academy account, and if you are reading the print version of this publication, you can scan QR codes like the one below and will be taken to the corresponding item in the ITI Academy.
If you are an ITI Member and reading the online version of the book on the ITI Academy, you can also click on the link in the text that accompanies each QR code:
 | The SAC Assessment Tool distills the content of this book in an easy-to-use process that takes you through each step necessary to identify the degree of complexity and potential risk involved in individual clinical cases. To start your assessment, scan the QR code to the left or click on the link. |
CHAPTER 2: The Rationale Behind the Updated SAC Classification
A. DAWSON, C. STILWELL
Please refer to chapter 1, section 1.5 for information on the prerequisites for accessing the additional online information from the ITI Academy via the QR-codes and links provided in this chapter.
Please note that to view this additional material in full and for free, you need to be an ITI Member and logged in at www.iti.org.
2.1 Definitions
Case type A class of implant-supported prostheses that share similar defining characteristics. For example, implant-supported crowns for single-tooth replacements, or short-span implant-supported fixed dental prostheses replacing three or four teeth and supported by two implants.
Process: The implant dentistry “process” is defined as the full range of issues pertaining to assessment, planning, management of treatment, and subsequent maintenance of the implant and prosthetic reconstruction; it does not merely refer to the clinical treatment procedures that are involved.
Normative classification In this context, “normative” relates to the classification that conforms to the norm, or standard, for a given clinical situation in implant dentistry. The normative classification relates to the most likely classification of a case type. The final classification of a specific case may differ from the normative classification for the case type as a result of individual risk factors.
Timing of implant placement and loading: Loading and placement protocols have been investigated by the ITI at its last four Consensus Conferences. Hämmerle and coworkers (Hämmerle et al, 2004) defined the timing of implant placement relative to the event of tooth removal in a site, relating this to healing events rather than a specific time frame. This classification is detailed in Table 1.
Table 1 Implant placement protocols (Hämmerle et al, 2004).
| Classification | Definition |
| Type 1 | Implant placement immediately following tooth extraction and as part of the same surgical procedure |
| Type 2 | Complete soft tissue coverage of the socket (typically 4 to 8 weeks) |
| Type 3 | Substantial clinical and/or radiographic bone fill of the socket (typically 12 to 16 weeks) |
| Type 4 | Healed site (typically more than 16 weeks) |
 | Review article from the 3rd ITI Consensus Conference on the Placement of Implants in Extraction Sockets by Hämmerle and coworkers (2004). |
Implant loading protocols were also the subject of consensus conference reviews. At the Fourth ITI Consensus Conference, Weber and coworkers (Weber et al, 2009) defined the timing of implant loading relative to its placement. These descriptions are summarized in Table 2.
Table 2 Implant loading protocols (Weber et al, 2009).
| Classification | Definition |
| Conventional loading | Greater than 2 months subsequent to implant placement |
| Early loading | Between 1 week and 2 months subsequent to implant placement |
| Immediate loading | Earlier than 1 week subsequent to implant placement |
 | Review article from the 4th ITI Consensus Conference on Loading Protocols by Weber and coworkers (2009). |
Most recently, the relationships between the timing of implant placement (relative to the time that the tooth in the placement site was extracted) and the timing of loading of the implant with a provisional or definitive prosthesis in partially dentate patients were addressed by Gallucci et al (Gallucci et al, 2018). The outcomes of this review, correlating the evidence for the various combinations of placement and loading protocol, are summarized in Table 3. Protocols that had multiple high-quality studies were deemed scientifically and clinically validated (SCV) and could be seen as suitable for routine use by appropriately trained and experienced clinicians. Clinically documented (CD) approaches had less support in the published literature but did possess reasonable long-term clinical documentation to allow their use in specific situations. Finally, clinically insufficiently documented (CID) protocols lacked sufficient scientific evidence and clinical documentation to be recommended for use. This review built on previous consensus meetings where definitions of the placement and loading protocols were developed.
Table 3 Summary of placement and loading protocols (Gallucci et al, 2018).
| Loading protocol | |||
| Immediate restoration/loading (Type A) | Early loading (Type B) | Conventional loading (Type C) | |
| Implant placement protocol | |||
| Immediate placement (Type 1) | Type 1A CD | Type 1B CD | Type 1C SCV |
| Early placement (Type 2–3) | Type 2–3A CID | Type 2–3B CID | Type 2–3C SCV |
| Late placement (Type 4) | Type 4A CD | Type 4B SCV | Type 4C SCV |
 | Review article from the 6th ITI Consensus Conference on Implant Placement and Loading Protocols in Partially Edentulous Patients by Gallucci and coworkers (2018). |
Risk factors This term refers to any preexisting condition, treatment option, or material choice that may have an adverse effect on the outcome of treatment. These factors have the potential to influence the final SAC classification of a clinical situation.
2.2 Assumptions
This classification assumes that appropriate training, preparation, and care are devoted to the planning and implementation of treatment plans. No classification can adequately address cases or outcomes that deviate significantly from the norm. In addition, it is assumed that clinicians will be practicing within the bounds of their clinical competence and abilities. Thus, within each classification, the following general and specific assumptions are implied:
• Treatment will be provided in an appropriately equipped dental office with an appropriate aseptic technique.
• Adequate clinical and laboratory support is available.
• Patients’ medical conditions are appropriately addressed.
• The surgical procedures are planned and provided following recognized protocols.
• The prosthesis is designed, manufactured, and managed correctly.
 | ITI Learning Module Surgical Setup for Office-Based Implant Surgery by Waldemar Daudt Polido. |
2.3 Is the Clinician a Risk Factor?
With the increasing popularity of dental implant treatments with both patients and dental practitioners, the risks associated with the clinician are often overlooked. Derks and coworkers (Derks et al, 2016) described a situation where implant complications from peri-implantitis were significantly correlated with the level of experience of the dentist who was completing the restorative part of the treatment. In this study of real-world treatments, general dentists were 4.3 times more likely to be associated with a peri-implantitis problem than were restorative specialists. While this result may relate to confounding biases in the data set used in this study, which could not be controlled due to the nature of the data, it is still a somewhat disconcerting statistic.
It is also a concern in connection with the incidence of complaints and medicolegal claims relating to implant treatments that are increasing in many jurisdictions. In some regions, professional indemnity insurers are charging additional premiums for particular groups of practitioners who are participating in implant dentistry. These insurance companies do so on the basis of their own actuarial research, which indicates additional risk associated with these treatments in the hands of specific cohorts of practitioners.
2.3.1 Factors impacting the clinician as a risk factor
2.3.1.1 EXPERIENCE
It is a widely held truism in the surgical disciplines in medicine that a surgeon needs to complete between 50 and 100 procedures to be considered competent. The real evidence for this is somewhat less clear. Jerjes and Hopper (2018) described a number of investigations into the relationship between experience and postoperative outcomes in both medical and dental surgical disciplines. Their review found no consistent relationship between these factors. However, it did find evidence that there was often a threshold level of experience below which surgeons could be expected to have greater incidence of problems, indicating that there was a “learning curve” related to most surgical procedures. This threshold value varied between disciplines and studies.
In a systematic review of the relationship between surgeon experience and implant failure rates, Sendyk and others (Sendyk et al, 2017) noted that this relationship did not correlate with the surgeon’s specialty but was significantly related to the number of implants that the surgeon had placed. In an earlier study, Lambert and coworkers (Lambert et al, 1997) found similar outcomes, noting that implant failure rates were two times higher for inexperienced surgeons (ie, who had placed less than 50 implants) compared to those of surgeons who had placed 50 or more implants. They also noted that the first nine implants placed by a surgeon under training where at the greatest risk of failure. These findings could be reasonably accepted as showing a relationship between experience and outcomes in implant treatments.
2.3.1.2 TRAINING
Training is another area of consideration. The Conscious Competence Learning Model (Curtiss & Warren, 1973) is an accepted description of how people learn new skills. In this model (Figure 1), four stages of learning are described:
1. Unconsciously incompetent: Here
2. Unconsciously incompetent: Here the person knows little about what they are doing. They cannot comprehend the potential difficulties involved in a process, and they often feel that they are performing the task to a high standard. They do not know what they do not know, and this is a major impediment to learning.
3. Consciously incompetent The learner comprehends that they fall short of ideal performance and understands their knowledge deficit. Making mistakes at this stage is often a key part of learning.
4. Consciously competent: The person at this level of learning can perform the task to an acceptable standard, but this requires concentration and attention to detail.
5. Unconsciously competent The individual at this level has had so much practice that they can perform this task without conscious effort. These people can be good teachers in the technique but can also make the task appear “too easy” to casual observers.
 | Congress lecture Surgical Treatment of Esthetic Disasters by Waldemar Daudt Polido. |
Fig 1. The Conscious Competence Learning Model.
Training in implant dentistry needs to address each of these learner levels. For the unconsciously incompetent, clinical training must address their knowledge deficit and stress best-practice approaches to treatment provision. Simulations of treatment provision, and mentoring by more experienced clinicians, can assist the consciously incompetent practitioner to pass through this level without endangering patients under their care. Mentoring will also benefit the consciously competent clinician by supporting their incremental development of skills. Finally, for the unconsciously competent clinician, training must support their focus on practicing in a reflective and consistent manner. The unconsciously competent clinician is at some risk of complacency and overconfidence and must make a conscious effort to remain focused on current best practices and the evolution of techniques in implant dentistry. They are also something of a risk to less knowledgeable and less skillful colleagues who might observe them providing patient care and conclude that these treatments are more straightforward than they really are.
2.3.1.3 SELF-ASSESSMENT OF ABILITY
Another way of considering this journey of skill development is the so-called “Dunning-Kruger Effect” (Kruger & Dunning, 1999). This describes a form of cognitive bias that leads to individuals overestimating their own ability because they lack sufficient knowledge and understanding of what they are doing to realistically measure their level of skill. It is only through painful discovery of the limitations of their ability that they can begin to learn. This correlates well with the unconsciously incompetent level described above. It is also a potentially dangerous issue with a novice clinician involved in providing a potentially complex treatment to a patient.
2.3.1.4 SHARED LEARNING
Training in implant dentistry is provided at a number of levels. At its simplest, clinicians learn from each other as they progress along the learning curve. This is the process by which most of today’s acknowledged “experts” learned these skills in the period during which implant treatments were evolving.
With implant dentistry now an established discipline, learning from shared experience is valuable for clinicians who have a sound understanding of implant treatments. Here, the consciously and unconsciously competent clinicians can benchmark their understanding against that of others.
However, this approach is unlikely to be effective if the individuals (eg, those in the unconsciously incompetent group) sharing their experiences do not fully understand the significance of what these experiences represent. This model is often popular today with younger practitioners who learn from colleagues via online forums, but this represents a real risk of being “the blind leading the blind.”
2.3.1.5 SHORT TRAINING COURSES
Similar observations might be made about the short, companyled programs. Often the aim of this training is to make practitioners aware of the processes needed to handle that company’s componentry, and thus these programs often focus on the “how” rather than the “why” or “why not.” Also, due to the brevity of these courses, the biologic and biomechanical principles involved in implant treatments must be greatly abbreviated or are simply not covered at all. Unfortunately, this method can be fraught with danger to patients and cannot allow for a focus on best-practice protocols, as these concepts may be unknown to those learning.
2.3.1.6 STRUCTURED EDUCATION AND TRAINING
The most effective training comes from structured programs that provide a sound basis for patient selection and treatment. These courses address the basic sciences that underpin successful treatment, introduce protocols for patient assessment and selection and treatment planning, and then provide candidates with the opportunity to perform actual treatment and patient maintenance with assistance and guidance from more experienced mentors. Given the breadth of the topics to be covered, these programs must extend over longer periods compared with other approaches. Thus, these programs can be expensive in terms of time and money and difficult to fit in alongside daily practice, leading to under-utilization of this type of education and training.
Intuitively, one might expect that better-quality training would result in fewer complications or failure. While this is generally accepted in health care, little evidence is available to support these conclusions. Certainly, patients and regulators see this connection as true, and this forms that basic assumption that underpins mandated continuing professional development requirements.
2.3.2 Reducing clinician-related risk
2.3.2.1 RECOGNIZING “HUMAN FACTOR” RISKS
What have been described as “human factors” are becoming recognized as sources of error in health care provision. Much of the research in this area comes from the commercial aviation industry, but these findings are beginning to permeate into health care safety considerations.
A second edition of Renouard and Rangert’s book about risk factors was published in 2008 (Renouard & Rangert, 2008) and brought the topic of experience and human factors to the discussion.
In a recent review of these factors and their influence in dental implantology, Renouard and coworkers (Renouard et al, 2017) described five hazardous attitudes or behaviors that are potentially detrimental to safe practice. Originally identified in aviation, these types are:
1. Impulsiveness The urge to get things done quickly, without necessarily considering potential dangers.
2. Anti-authority The attitude held by some practitioners that rules, regulations, and protocols are for others, and do not pertain to them.
3. Invulnerability Practitioners who believe that adverse outcomes only happen to others, and not to them.
4. Macho The belief that a practitioner must be constantly demonstrating their superiority over others. While this is mostly a male trait, it can affect women as well.
5. Resignation The belief that no matter what a practitioner does, it will not have any effect on the outcome.
2.3.2.2 STRESS AS A RISK FACTOR
Renouard and coworkers also discuss stress as a potential problem. While the stress response is adaptive (ie, it is protective against external threats), it can have negative effects in a health care setting where the stress is mostly self-induced. Stress factors such as time pressures, staff problems, and interpersonal frictions between the dentist and the patient can all have a negative effect on performance. Stress tends to reduce the practitioner’s ability to rationally think through a problem and rather promotes the use of automatic responses, which may be incorrect or unhelpful. These factors are well studied in the medical literature as well, as it relates to many daily issues, like less sleep, financial problems, and health or family issues (West et al, 2006).
2.3.2.3 MITIGATING THE HUMAN FACTOR ISSUES
To counter these “human factor” issues, Renouard recommends using techniques that have been developed for the airline industry to address safety problems: so-called “crew resource management.” The concept of the “sterile cockpit” where all extraneous activity is banned during high-risk periods, such as take-off and landing, can be transferred to the dental implantology setting for use during critical periods of treatment provision. Strict division of responsibilities between team members also reduces stress and “information overload.” Additionally, checklists can be very useful in concentrating attention on critical steps, especially in highly procedural tasks such as those seen in medicine and dentistry. This approach has also been promoted by other authors (Gawande, 2009; Pinsky et al, 2010). Here the SAC classification can be used as a checklist to ensure that all factors relevant to the patient’s presentation are assessed and incorporated into treatment plans.
2.3.2.4 CLINICIAN RISK FACTOR IN RELATION TO OTHER SOURCES OF risks
The clinician is central to most decisions and their practical application in implant treatment. Risks in implant dentistry can be attributed to four main sources: the patient, the treatment approach, the biomaterials, and the clinician. This relationship between the clinician, the materials, and the patient factors was first described by Chen and Schärer in 1993 (Chen & Schärer, 1993). Further, Buser and Chen (Buser & Chen, 2008), published on a model that also illustrates the potential interactions between these factors, as shown in Figure 2.
Fig 2. Potential sources of risk (Source: ITI Treatment Guide Vol. 3 “Implant Placement in Post-Extraction Sites”)
In this model, the clinician has a potentially disproportionate influence: they select the patient, the treatment approach, and the biomaterials, and they subsequently carry out the treatment on the patient. Thus, a flaw or shortcoming in their knowledge or skills will put their patient at greater risk of adverse outcomes. Therefore, in answer to the question posed earlier, we must conclude that the clinician has the potential to be a significant risk factor.
Can the SAC classification assist in reducing risk? By focusing the attention of the clinician on potential risk factors, it should ensure that the clinician-related risk is mitigated. However, the review group did not believe that the clinician could be considered as a factor in determining the SAC classification for a case, as they were not confident that all clinicians could accurately self-assess their ability. Nonetheless, discussions such as this may assist individuals in progressing along their own learning journey and improve their ability to control this potential risk.
2.4 Classification Rationale
In the 2009 version of the SAC classification (Dawson & Chen, 2009) the main determinants of the classification were:
• The esthetic risk
• The complexity of the process
• The risks of complications
These factors were considered for each of the treatments considered in this publication, and a normative SAC classification was derived for each of these case types. Further modifiers were considered that might increase or decrease the level of complexity or risk, but these did not change the normative classification for the case type.
In this update, the normative classifications have been reviewed, but they have not altered greatly. These are still based on the factors above, with an increased emphasis on the SAC classification as a risk management instrument.
The updated SAC Assessment Tool now allows users to derive a SAC classification for their specific case based on the pattern of risk factors that they report. Risks are considered in four broad areas:
• General risks These are the issues normally identified during anamnesis and the initial clinical assessment and are mostly patient related.
• Esthetic risk Esthetic issues are often the patient’s only way of measuring the treatment outcome. This is more than a consideration of “is the treatment site visible during function and/or smiling, and are the peri-implant mucosal tissues visible?” but also includes other factors described by Martin and coworkers (Martin et al, 2017) in their discussion of the esthetic risk assessment for single-tooth implant prostheses. Esthetic risk assessment for more extensive tooth replacement situations have also been considered.
• Edentulous esthetic risk When patients undergo complete loss of teeth, several unique clinical factors specific to this patient subset can have a significant influence on esthetic outcomes. The edentulous esthetic risk assessment will highlight these factors as they influence particular case types.
• Surgical risk Factors influencing the complexity and risk of the surgical phase of treatment.
• Prosthetic risks Factors relating the implant-supported prosthesis; for example, the clinical processes involved, the mode of manufacture, the materials used, and the design employed.
Each of these areas will be considered in more detail later in this book.
CHAPTER 3: Risks in Implant Dentistry
A. DAWSON, W. MARTIN, W. D. POLIDO
Please refer to chapter 1, section 1.5 for information on the prerequisites for accessing the additional online information from the ITI Academy via the QR codes and links provided in this chapter.
Please note that to view this additional material in full and for free, you need to be an ITI Member and logged in at www.iti.org.
3.1 Principles of Risk Management
All interventions in health care carry some risk of failure, complications, or other suboptimal outcomes. Implant treatments are no different.
The risk management cycle is a term used to define a process aimed at limiting the incidence of adverse outcomes, and their impact.
Fig 1. The risk management cycle.
In general, this cycle aims to:
• Identify potential problems
• Measure the incidence of these adverse outcomes and the impact that they have
• Educate users about these potential problems
• Develop strategies to mitigate the incidence or effect of these problems
• Review the effectiveness of these mitigation strategies
As indicated in Figure 1, this is a continuous process where outcomes are monitored, and refinements are made to mitigation strategies to incrementally improve process outcomes.
In implant dentistry, the users refer to patients and clinicians. However, the process remains the same. Although it is not usually referenced in such terms, effective practice in most areas of health care, including implant dentistry, follow the basic principles of risk management. A common dental practice example of this might be the management of dental caries. Here, our modern preventive approach to caries management centers on identifying risk factors (eg, patient behavior/diet, salivary function, oral microflora, plaque retentive restorations, etc) and measuring their impact. We then can focus on reducing risk by attempting to mitigate these risks through patient education and risk-reduction focused treatments. We then continue to monitor our patient’s progress and the success of our interventions.
The importance or severity of a risk can be considered in terms of the likelihood of that risk being realized and the impact or significance associated with the outcome that follows. These situations are often tabulated in a risk matrix, an example of which can be seen in Table 1.
While we often concentrate our efforts on mitigating the risks of high-impact outcomes, like implant failure, it must also be noted that less dire outcomes that are more common, such as peri-implant disease, may be more important.
Table 1 An example of a risk matrix.
3.2 The SAC Classification as a Risk Management Tool
The SAC classification is essentially a tool that assists practitioners to identify risks so that they can educate their patients about these potential problems as part of the informed consent process. Clinicians then use their understanding of these risks to plan treatments that minimize risk. Patients are then monitored after the completion of treatment to identify problems that might arise as early as possible, thus allowing intervention to minimize the impact of the problem on the ongoing quality of treatment outcomes.
This review of the SAC classification system incorporated this risk-management focus on risk identification, the likelihood of this problem arising, and the potential impacts of these risks on treatment outcome. Three subgroups in the review team each looked at one major area of risk factors. A “Systems” group reviewed general patient-related risk factors and worked to develop concepts in the SAC Assessment Tool workflow and algorithm. The “Surgical” and “Prosthetic” groups looked at surgical and restorative risk factors respectively, concentrating on risks associated with the treatment approach and technologies. The results from the deliberations of these groups represent a consensus opinion of the risk factors most likely to influence dental implant treatments.
3.3 General Risks
A. DAWSON, J. KLEINHEINZ, A. MURAT KÖKAT, D. WISMEIJER
A structured approach to patient assessment and treatment planning aims to identify all factors that have the potential to have some impact or influence on our treatment. Such a structured approach has been promoted by the ITI in its Academy Learning Module “Structured Assessment and Treatment Planning” (Weber, 2015), and the sequence and steps in this process are illustrated in Figure 2.
 | ITI Learning Module Structured Assessment and Treatment Planning by Hans-Peter Weber. |
Identification of potential risk factors occurs relatively early in this process—during the information-gathering phase that incorporates anamnesis, clinical examination, imaging, and other investigations.
Identification of general risk factors is almost always done in the anamnesis and clinical examination. These factors relate to potential problems arising out of the patient’s medical and dental history and their presenting condition. These general factors fall into three main clusters:
• Patient medical factors
• Patient-related attitudinal/behavioral factors
• Site-related factors
3.3.1 Patient medical factors
Most implant patients present with a range of historical and ongoing medical issues that may have an impact on implant treatment. The following were considered the most significant.
3.3.1.1 MEDICAL FITNESS
A patient’s current health status has the potential to influence their fitness to undergo treatment, and also how well they will heal after implant surgery.
The American Society of Anesthesiologists (ASA) has developed a physical status classification and risk management tool that is widely used to assess patients’ fitness for surgical interventions. The ASA Physical Status classification system (Doyle et al, 2019) is detailed in Table 2.
Fig 2. A structured approach to patient assessment and treatment planning.
Table 2 The ASA Physical Status Classification.
| ASA PS Classiciation | Definition |
| ASA I | A normal healthy patient |
| ASA II | A patient with mild systemic disease |
| ASA III | A patient with severe systemic disease |
| ASA IV | A patient with severe systemic disease that is a constant threat to life |
| ASA V | A moribund patient who is not expected to survive without the operation |
| ASA VI | A declared brain-dead patient whose organs are being removed for donor purposes |
Healthy patients (ASA I) and those with mild, well-controlled systemic disease (ASA II) are generally good candidates for implant surgery. Some patients identified as ASA III (severe systemic disease that may or may not be well controlled) can be treated with care but have higher risk and might best be managed by highly trained and experienced clinicians. While there may be some occasional indications for implant treatment in ASA IV cases, these treatments are high risk and should be restricted to specialist facilities where emergency medical care is readily available, and by highly experienced surgical teams.
 | ITI Learning Module Patient Medical Factors by Simon Storgård Jensen |
Medical status may also impact the speed of implant healing (usually a slowdown) and the esthetic outcome of treatments. For example, conditions associated with abnormal scarring after surgery, such as the development of keloid scars, may impact esthetic outcomes.
3.3.1.2 MEDICATIONS
Pharmaceutically active substances include prescription medications, over-the-counter medicines, herbal remedies, dietary supplements, and recreational substances. All of these may have an influence on implant treatment either directly through their influence on implant healing and/or peri-implant tissue health, or indirectly through their effects on the patient’s behavior.
 | Review article from the 6th ITI Consensus Conference on Medication-Related Dental Implant Failure by Vivianne Chappuis and coworkers (2017). |
 | ITI Learning Module Pharmacology with Relevance to Dental Implant Therapy by Stephen Barter. |
Possibly of most importance relating to implant surgery are the antiresorptive drugs used to manage osteoporosis. These medications have been linked to a condition known as medication-related osteonecrosis of the jaws (MRONJ) that can also arise following surgical interventions involving the facial skeleton (Figure 3). The risk of MRONJ arising is related to the type of medication (usually biphosphonates), the dosage used and the duration of therapy (as some types of antiresorptives accumulate in facial bones). Antiresorptives with higher potency are usually administered via intravenous route, and hence they are associated with greater risk. This condition can be very difficult to treat and is usually associated with significant discomfort and disfigurement. In cases where there is a history of intravenous treatment, such as in patients with metastatic bone disease or Paget’s Disease, the risks are such that implant treatment would normally be contraindicated.
Fig 3. MRONJ associated with an implant in the mandibular left molar region.
3.3.1.3 RADIATION
Radiotherapy can have a dramatically adverse effect on bone healing. Osteoradionecrosis can arise following surgery in irradiated bone due to the reduction in blood supply to affected bone. This effect is dose related. The dosage to the area where implant placement is planned is the significant consideration, rather than the dosage used to treat the cancer. Doses of less than 50 Gray may allow implant placement with care. Doses of greater than 50 Gray to the area of interest would likely contraindicate implant placement. Time after radiation therapy, and presence of other coadjutant factors, such as smoking and oral hygiene can also impact the rate of occurrence of osteoradionecrosis of the jaws (Aarup-Kristensen et al, 2019).
3.3.1.4 GROWTH STATUS
Implants act in a similar way to ankylosed teeth to retard the development of surrounding bone. As such, placement of implants in growing individuals is normally contraindicated. These implant-supported prostheses can become unesthetic and/or nonfunctional due to apparent infraocclusion as a result of the continued growth of the alveolar bone supporting adjacent teeth. This issue can also arise in older patients, as facial growth can continue—albeit at a very slow rate—well into maturity. The following case demonstrates the esthetic issues that can arise. An implant-supported crown replacing the maxillary right central incisor 5 years after placement in a 24-year-old male patient is seen in Figure 4. Ten years later, there is a significant difference in incisal edge position between the implant-supported crown and the adjacent natural teeth, due to continuous growth and extrusion of natural teeth. The implant crown remained stable (Figure 5).
Fig 4. Five-year follow-up of an implant-supported crown replacing the maxillary right central incisor.
3.3.2 Patient attitudes/behaviors
3.3.2.1 SMOKING HABIT
Tobacco smoking is related to increased risks of implant failure and peri-implant disease (Heitz-Mayfield & Huynh-Ba, 2009). There is some evidence of a dose-related effect, and that this is mediated by nicotine and other tobacco-derived chemicals that compromise wound healing, the immune response, and increase the risk of scarring. Ideally, patients should cease smoking prior to implant placement, as there is evidence that reducing their smoking habit acts to reduce risk. There is a paucity of evidence relating cannabis use or vaping (electronic cigarettes) to implant failure, but caution is advised when treating patients practicing these habits.
 | Review article from the 4th ITI Consensus Conference on History of Treated Periodontitis and Smoking as Risks for Implant Therapy by Lisa J. A. Heitz-Mayfield and Guy Huynh-Ba (2009). |
3.3.2.2 COMPLIANCE
A patient’s willingness and/or ability to comply with instructions is an important factor in any complex treatment where maintenance is vital to long-term success, and where following instructions is essential for optimal treatment outcomes in the short term. Noncompliant patients are more likely to experience problems with treatment and are less likely to follow the necessary steps to overcome these issues. Poor compliance might best be considered relative contraindication for implant therapy until the patient can become motivated to support their treatment.
Fig 5. 15-year follow-up. Note the difference in incisal edge between implant-supported crown and adjacent natural teeth, due to continuous growth and extrusion of natural teeth.
3.3.2.3 ORAL HYGIENE
Bacterial biofilm accumulation has been associated with the development of peri-implant mucositis and peri-implantitis (Salvi & Zitzmann, 2014), and measures to regularly remove these deposits are the prime strategy for preventing the development of these biologic complications. If patients are unwilling or unable to perform these oral hygiene procedures, implant therapy should be delayed until they can do so. Alternatively, other forms of prosthetic reconstruction might best be considered.
 | Review article from the 5th ITI Consensus Conference on the Effects of Anti-infective Preventive Measures on the Occurrence of Biologic Implant Complications and Implant Loss by Giovanni E. Salvi and Nicola U. Zitzmann (2014). |
3.3.2.4 PATIENT EXPECTATIONS
Unrealized expectations are often the trigger of patient complaints to statutory bodies, or to initiation of legal proceedings against treating practitioners. This risk is only amplified by the expense and invasiveness of implant treatment.
Communicating realistic expectations to patients, and managing their desired outcomes, is an important part of the ongoing consent process. A patient may have high and realistic expectations due to their social position or employment, and managing these situations can be challenging. Patients may also have unrealistic expectations, and managing these can often be virtually impossible. An extreme example of such a situation might involve a patient with body dysmorphic disorder. Unless these expectations can be managed, it is best not to proceed with implant rehabilitation.
3.3.3 Site-related factors
3.3.3.1 PERIODONTAL STATUS
A history of treated periodontal disease has been associated with an increased risk of biologic complications (Heitz-Mayfield & Huynh-Ba, 2009), as has the presence of active periodontal disease with periodontal pockets greater than 5 mm in depth. As an elective rehabilitative treatment, an implant-supported prostheses should not be considered until all active oral diseases are under control. Where implant treatment is planned, treatment to manage the periodontal disease prior to implant placement is mandatory.
 | Review article from the 4th ITI Consensus Conference on the History of Treated Periodontitis and Smoking as Risks for Implant Therapy by Lisa J. A. Heitz-Mayfield and Guy Huynh-Ba (2009). |
3.3.3.2 ACCESS
Implant treatment involves the use of instruments that can occupy more physical space than conventional handpieces. During surgical procedures, the use of templates in conjunction with the surgical handpiece, twist drills, and drivers can consume more vertical space, requiring a large mouth opening by the patient. If there is insufficient space, treatment cannot proceed without changes to instrumentation. Limited (but adequate) space can make treatment more difficult, but insufficient space will need adjunctive treatment to make more space if implant placement and restoration is still desired. The use of a measuring device (such as the Straumann Diagnostic-T; Figure 6) during the consultation visit can assist in identifying situations where access will be difficult. This device identifies the amount of space needed to fit the head of the handpiece with the shortest Straumann kit twist drill (33 mm) at the site of planned implant placement.
3.3.3.3 PREVIOUS SURGERIES IN THE PLANNED IMPLANT SITE
Previous surgeries in the site of a planned implant can result in hard and soft tissue changes that may complicate implant placement and healing. Scarring from these surgeries (Figures 7 and 8) is also often associated with reduced vascularity that may have a negative influence on healing. While a single previous surgical treatment in a site may only have a small impact, multiple surgeries are likely to significantly increase the risk of problems.
Fig 6. Clinical use of a Diagnostic-T (Straumann, Basel, Switzerland) to assess available space for surgical instrumentation.
Fig 7. Clinical evaluation of patient missing maxillary central and lateral incisors with evidence of previous surgical procedures.
Fig 8. Clinical evaluation of patient missing tooth 21 with evidence of previous surgical procedures.
Fig 9. An apical infection adjacent to a recently placed implant can infect this site as well.
3.3.3.4 NEARBY PATHOLOGY
As a general rule, elective treatments such as implant therapy are only provided once all other pathologic conditions have been managed. However, there are situations where this may not be either possible or practical. Notwithstanding this, pathologies that may have an adverse effect on implant healing, or the risk of biologic complications, must be managed before implants are placed. For example, apical periodontitis affecting a tooth in another quadrant might be managed simultaneously with implant treatment. However, apical periodontitis related to a nonvital tooth adjacent to the planned implant site (Figure 9) must be managed prior to implant placement.
3.4 Esthetic Risk
W. MARTIN, V. CHAPPUIS, D. MORTON, D. BUSER
Esthetic issues apply where the implant restoration and the surrounding mucosal margin will be visible during normal functional activity or when the patient smiles. Smiles are as unique to individuals as the treatment necessary to maintain their natural appearance. Implant therapy in the esthetic zone can be a challenging process, as patient demands on esthetics coupled with preexisting deficiencies in the anatomy can present obstacles to obtain ideal results. Failure to achieve esthetic and functional results with dental implants could lead to disastrous situations that would require additional surgical and restorative procedures in an attempt to correct the compromise (Buser et al, 2004; Levine et al, 2014).
Consequently, not all implant treatments will have associated esthetic risk. It is therefore important for clinicians to understand their patient’s desires and to perform a thorough initial clinical examination to highlight any potential obstacles that may present as a challenge in achieving an ideal esthetic outcome. Clinicians performing a rehabilitation must have a thorough understanding of tissue biology and the knowledge of all treatment modalities for a given clinical situation, as dental implants may not always be the primary choice. This series of modifiers has been discussed in detail in Chapter 3: “Preoperative Risk Assessment and Treatment Planning for Optimal Esthetic Outcomes” (W. Martin, V. Chappuis, D. Morton, D. Buser) found in “The ITI Treatment Guide, Volume 10: Implant Therapy in the Esthetic Zone: Current Treatment Modalities and Materials for Single-tooth Replacements” (Chappuis & Martin, 2017).
 | ITI Treatment Guide Vol. 10 Extended Edentulous Spaces in the Esthetic Zone: Current Treatment Modalities and Materials for Single-tooth Replacements by Vivianne Chappuis and Will Martin. |
 | ITI Learning Module Esthetic Risk Assessment by William Christopher Martin. |
Table 3 lists the factors that determine esthetic risk in the partially edentulous patient. The esthetic risk assessment (ERA) table was developed to assist clinicians in the diagnosis and planning of treatment in the esthetic zone and to identify clinical situations that could contribute to an esthetic compromise, thus assisting the clinician in determining the SAC classification of the case. It should be noted that, by definition, a case for which there is some esthetic risk (ie, the restoration margin is visible) would have a classification of at least Advanced.
 | Congress Lecture Pre-treatment Analytics to Maximize Longevity of Treatment Outcomes in the Esthetic Zone by William Christopher Martin. |
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