Dental Implant Complications in Israel

Transcription

1 A Survey Regarding the Nature and Type of Dental Implant Complications in Private Practices in the Province of Ontario by David Chvartszaid A thesis submitted in conformity with the requirements for the degree of Masters of Science Faculty of Dentistry University of Toronto Copyright by David Chvartszaid 2011

2 A survey regarding the nature and type of dental implant complications in the province of Ontario Abstract David Chvartszaid Masters of Science Faculty of Dentistry University of Toronto 2011 Aims and Objectives: To investigate the experience of implant complications and opinions on complications among dentists in private practices in Ontario. Methods: In 2010, a web-based anonymous survey was distributed to 2034 Ontario dentists with valid addresses. Results: 527 dentists replied to the survey, of which 469 utilized implants. Most complications were preventable. The most important cause of complications was poor planning. The most severe complication was permanent paraesthesia. Fewer than 5% of patients experienced a complication in There was little agreement among general dentists, oral surgeons, periodontists, and prosthodontists on the causes of complications, some agreement on preventive strategies to avoid complications, and significant agreement on severity of complications and their preventability. Conclusions: A significant proportion of dentists in Ontario had encountered an implant treatment complication in Since most complications are preventable, efforts at decreasing their prevalence and severity should be pursued. ii

3 Acknowledgments I would like to gratefully acknowledge the numerous individuals who contributed to the success of this project: my thesis supervisors Drs. Howard Tenenbaum and David Locker, my committee members Drs. Jim Lai and Leslie Laing-Gibbard, and my fantastic friend Dr. Amir Azarpazhooh. Without you this project would not have been possible. This thesis is dedicated to the memory of Dr. David Locker whose untimely passing earlier this year was a tremendous loss to everyone who knew him. iii

4 Table of Contents Page Abstract II Acknowledgements III Table of Contents IV List of Tables VI List of Appendices VIII Chapter 1: Introduction 1 Chapter 2: Definitions and Classifications 3 2.A: Terminology in the medical literature 3 2.B: Terminology in the dental implant literature 5 2.C: Classification of complications: introduction 6 2.D: Classification of complications in the medical literature 8 2.E: Classification of dental implant complications 10 Chapter 3: Literature Review on Implant Complications 15 3.A: Studies on implant complications study results 15 3.B: General study characteristics of reviews reporting implant treatment outcome and complication data 21 3.B.I: Thoroughness in reporting of complications 21 3.B.II: Study setting 22 3.B.III: Implant companies investigated in the literature 24 3.C: Geographic location survey of dentists 25 3.D: Treatment evolution and caution in interpretation of results from past reviews 27 3.E: Malpractice studies 30 3.F: Clinicians opinions on complications 32 3.G: Conclusion and rationale for further study 35 Chapter 4: Materials and Methods 36 4.A: Aims and objectives 36 4.B: Methods 36 4.C: Sample size calculations 40 4.D: Survey implementation 41 4.E: Data analysis 41 Chapter 5: Demographics 43 5.A: Results and tables 43 5.B: Discussion 50 Chapter 6: Complications and Corrective Actions 54 6.A: Surgical complications results 54 6.B: Prosthodontic complications results 58 6.C: Biological complications results 61 6.D: Patient-related complications results 63 6.E: Complications reported by each professional group results 66 6.F: Corrective actions taken in response to complications results 71 6.G: Complications and corrective actions discussion 74 iv

5 6.G.I: Surgical complications discussion 74 6.G.II: Prosthodontic complications discussion 75 6.G.III: Biological complications discussion 76 6.G.IV: Patient-related complications discussion 77 6.G.V: All complication types overall discussion 78 6.G.VI: Corrective actions discussion 81 Chapter 7: Opinions on Complications 82 7.A: Causes of complications results 82 7.B: Causes of complications discussion 84 7.C: Preventive strategies to decrease occurrence of complications results 89 7.D: Preventive strategies to decrease occurrence of complications discussion 91 7.E: Severity of complications results 95 7.F: Severity of complications discussion 97 7.G: Source of knowledge about complications results H: Source of knowledge about complications discussion I: Responsibility to keep dentists informed about potential implant complications results J: Responsibility to keep dentists informed about potential implant complications discussion K: Percentage of patients experiencing complications results L: Percentage of patients experiencing complications discussion 109 Chapter 8: Preventability of Complications A: Results B: Discussion 111 Chapter 9: Overall Discussion and Conclusions A: Study limitations B: Study strengths C: Implications and conclusions 117 Bibliography 119 Appendix 1 Survey 137 v

6 List of Tables Table Page Table 2.1: Examples of terms and definitions used in the medical literature related to complications 3 Table 2.2: Examples of the definitions of the term complications used in the dental implant literature 5 Table 2.3: Classifications focusing on all complications 10 Table 2.4: Classifications of prosthodontic complications 11 Table 2.5: Classifications of surgical complications 11 Table 2.6: Other classifications of implant complications 12 Table 3.1: The most common complications according to Goodacre et al. (1) 16 Table 3.2: Complication data reported for implant-supported single crowns after an observation period of 5 years by Jung et al. (2) 17 Table 3.3: The most common technical complications for implant-supported FPDs after an observation period of 5 years according to Pjetursson et al. (3) 18 Table 3.4: Complications data from Berglundh et al. (4) 19 Table 3.5: Number of studies reporting on specific categories of complications in comparison to the overall number of studies included in the reviews 21 Table 3.6: Percentage of studies that reported specific complications in a review by Berglundh et al. (4) 22 Table 3.7: Number of studies conducted in a university, specialist, or general practice setting in comparison to the overall number of studies included in the reviews 23 Table 3.8: Number of multi-centre studies relative to the total number of studies included in the reviews 23 Table 3.9: Certain implant companies are over-represented in the implant literature number of studies utilizing implants of specific companies in comparison to the total 24 number of studies included in the reviews Table 3.10: The 5 most common implant brands utilized in different countries or geographic regions 25 Table 3.11: Classification of complications according to Givol et al. (5) 32 Table 3.12: Clinical performance scale for implants according to Van Waas et al. (6) 34 Table 3.13: Clinical performance scale score for a range of complications according to Van Waas et al. (6) 34 Table 5.1: Survey flow 43 Table 5.2: Comparison between Ontario dentist population, survey list, active list, and survey responders 43 Table 5.3: Demographic characteristics surgical/prosthodontic expertise, practice focus 44 Table 5.4: Demographic characteristics year of graduation, number of patients/implants treated 45 Table 6.1: Surgical complications reported by survey responders (N=419) in Table 6.2: Surgical complications reported by each professional group in Table 6.3: Prosthodontic complications reported by survey responders (N=435) in Table 6.4: Prosthodontic complications reported by each professional group in vi

7 Table 6.5: Biologic complications reported by survey responders (N=433) in Table 6.6: Biologic complications experienced by each professional group in Table 6.7: Patient-related complications reported by survey responders (N=397) in Table 6.8: Patient-related complications reported by each professional group in Table 6.9: Top 20 complications reported by the largest percentage of general dentists in Table 6.10: Top 20 complications reported by the largest percentage of oral surgeons in Table 6.11: Top 20 complications reported by the largest percentage of periodontists in Table 6.12: Top 20 complications reported by the largest percentage of prosthodontists in Table 6.13: Corrective actions taken by survey responders (N=424) in 2009 in 71 response to complications Table 6.14: Corrective actions taken by each professional group in Table 7.1: Causes of complications chosen by survey responders (N=397) 82 Table 7.2: Causes of complications chosen by each professional group 83 Table 7.3: Strategies to prevent occurrence of complications chosen by survey responders (N=405) 89 Table 7.4: Strategies to prevent occurrence of complications chosen by each professional group 90 Table 7.5: Most severe complications chosen by survey responders (N=403) 95 Table 7.6: Most severe complications chosen by each professional group 96 Table 7.7: Sources of knowledge about complications identified by survey responders (N=418) 102 Table 7.7b: Sources of knowledge about complications identified by survey responders who graduated in the last 10 years (N=50) 102 Table 7.8: Sources of knowledge about complications identified by each professional group 103 Table 7.9: Responsibility for informing dentists about potential implant complications as chosen by all responders (n=418) 106 Table 7.10: Responsibility for informing dentists about potential implant complications as chosen by each professional group 106 Table 7.11: Cross-tabulation of opinions about the responsibility to keep dentists informed about implant complications as chosen by each professional group against every other professional group (0.008 level of statistical significance) 106 Table 7.12: Percentage of patients experiencing complications reported by each professional group and by all survey responders (n=428) 108 Table 7.13: Cross-tabulation of percentage of patients experiencing complications reported by each professional group against every other professional group (0.008 level of statistical significance) 108 Table 8.1: Preventability of complications 110 vii

8 List of Appendices Appendix 1 Survey viii

9 1 Chapter 1 Introduction Patients come into contact with healthcare providers, including dentists, to address a range of physical and emotional ailments and conditions. Many of these interactions are positive, freeing patients from the burden of disease that limited their well-being and leading to improvements in their health status or quality of life. However, complications can occur in the process or outcome of care that do not allow patients to reach the full benefit of the therapeutic interventions intended for them. Although Socrates first, do no harm has always been at the center of medical practice, the issue of treatment complications is being increasingly recognized and addressed as a serious health care problem by government agencies (7, 8), non-governmental organizations (9), in popular culture (10-13), and in scientific literature (14, 15). Many medical errors and complications are suspected to be preventable (16, 17), and, hence, substantial research efforts, educational initiatives, and government policies are being directed at prevention of complications (8). Implant therapy is a commonly utilized and highly successful treatment modality for the management of missing teeth (18, 19). However, numerous complications may be encountered during the various phases of therapy (3, 4, 20, 21). While the types of complications that can be encountered are well known, the degree to which they are actually encountered in contemporary private practices is uncertain. In particular, the experience of implant complications in the province of Ontario and the opinions of dentists regarding implant complications are unknown. In light of these observations, the primary objective of this study was to determine the nature and the types of complications arising from dental implant therapy carried out in private practices in the province of Ontario and as reported by the treatment providers. Other specific objectives were: 1) to determine the causes of complications as perceived by the treatment providers; 2) to determine if the types of complications experienced in private practices differ based on educational background of the treating dentist; 3) to determine the relative severity ranking of complications as perceived by the treatment providers.

10 2 This thesis will proceed in the following manner. The thesis is divided into 9 chapters. Sections within chapters are identified by capital letters, and, where necessary, subsections are identified by roman numerals. Chapters 2 and 3 will review the pertinent literature on complications. Chapter 2 will focus on the nomenclature related to complications, while chapter 3 will focus on the specific reports regarding complications in the dental implant literature. Chapter 4 will outline the materials and methods used in the thesis. Chapters 5 through 8 will report the data gathered in the survey and discuss the results. Chapter 5 will report and discuss the basic demographic attributes of the survey responders. Chapter 6 will report and discuss the dentists experience of complications in Chapters 7 and 8 will report and discuss dentists opinions on various topics related to complications including the causes of complications, possible strategies for preventing complications, severity of complications, and preventability of complications. Chapter 9 will discuss the overall findings focusing on the strengths and limitations of the project as well as the conclusions.

11 3 Chapter 2 Definitions and Classifications 2.A: Terminology in the medical literature Terms, definitions, and classifications vary widely in the medical and dental literature related to complications. Several terms have been used in the medical literature to refer to the negative occurrences arising in the process of patient care or to events elevating the risk of these negative occurrences (Table 2.1). Definitions of these terms tend to overlap (22), and the use of these terms is not consistent across studies (Table 2.1). Some authors define the terms by actually providing their definitions, while others implicitly define the terms by providing examples and letting the reader infer their meaning. A 2002 review of over 100 studies (including 42 randomized controlled trials (RCTs)) in the surgical literature (23) revealed that only 34% of the studies provided definitions of complications. Similarly, the term preventability is often used but is rarely defined. Table 2.1: Examples of terms and definitions used in the medical literature related to complications adverse medical event an injury to the patient that may have been the result of medical or surgical intervention that may prolong hospitalization, produce disability, death or both (24) adverse event Serious adverse event is defined as an event that results in death, is lifethreatening, requires inpatient hospitalization or prolongation of existing hospitalizations, results in persistent or significant disability/incapacity, or necessitates surgical re-intervention. [Food and Drug Administration (FDA) as quoted in Dekutoski et al. (25)] an unintended harm, injury, or loss that is more likely associated with the patient s interaction with the health care delivery system than from an attendant disease process [Medicare as quoted in Dekutoski et al. (25)] unanticipated problem involving risks to study participants or others [National Institute of Health (NIH) as quoted in Dekutoski et al. (25)] an injury that was caused by medical management (rather than the underlying disease) and that prolonged the hospitalization, produced a disability at the time of discharge, or both (26) any unexpected or undesirable event occurring as a result of surgery (27) an injury that was caused by medical management and that results in measurable disability (8)

12 4 unpreventable adverse event an adverse event resulting from a complication that cannot be prevented given the current state of knowledge (8) adverse occurrence Adverse occurrence is any medical event in the course of patient s treatment that had the potential for causing harm to patient. This term (adverse occurrence) was selected to avoid connotations of blame often associated with the term complication. (28) complication undesirable development arising during or out of the delivery of patient care Institute of Medicine (29) Complications are unintended and undesirable diagnostic or therapeutic events that may impact the patient s care. Complications should be recoded and analysed relative to disease severity, patient co-morbidities, and ultimately their effect on patient outcomes. (25) disease or disorder, which, as a consequence of a surgical procedure, will negatively affect the outcome of a patient (27) errors or adverse events Errors are events in your practice that made you conclude, That was a threat to patient well-being and should not happen. I don t want it to happen again. Such an event affects or could affect the quality of care you give to patients. Errors can be large or small, administrative or clinical, or actions taken or not taken. Errors might or might not have discernable effects. Errors are anything you identify as something wrong, to be avoided in the future. (30) harm impairment of the physical, emotional, or psychological function or structure of the body and/or pain resulting therefrom (31) medical error failure of the planned action to be completed as intended or the use of a wrong plan to achieve an aim [including] problems in practice, products, procedures, and systems (7) an adverse event or near miss that is preventable with the current state of medical knowledge (8) medical mistake Some examples of medical mistakes are when a wrong dose of medicine is given; an operation is performed other than what was intended for the patient; or results of a medical test are lost of overlooked. (32) near miss an event or situation that could have resulted in an accident, injury or illness, but did not, either by chance or through timely intervention (8) negligence care that fell below the standard expected of physicians in their community (26) patient safety freedom from accidental injury due to medical care, or medical error (7) sentinel event A sentinel event is an unexpected occurrence involving death or serious

13 5 physical or psychological injury, or the risk thereof. Serious injury specifically includes loss of limb or function. The phrase risk thereof includes any process variation which would carry a significant chance of a serious adverse outcome. (33) 2.B: Terminology in the dental implant literature Although the medical literature appears to use a range of terms to refer to untoward events or risks thereof (Table 2.1), the term complication is used most frequently in the dental implant literature. Interestingly, almost none of the studies and reviews actually defined the term complication. Where definitions of the term were provided, they were usually inconsistent (Table 2.2). This thesis maintained the use of the term complication in the interests of consistency and used it in a broad context. In this thesis, an implant complication was defined as an event that requires (or may require) corrective action that, if not taken, may compromise the outcome of treatment with osseointegrated dental implants. The use of the term complication does not automatically imply that an error was made during the treatment planning, execution, or follow up, or that there was necessarily a direct negative impact on the patient (although both of these conditions are frequently true). Occasionally, a negative impact on the patient is avoided due to the subsequent skilful efforts of the members of the dental team (including the laboratory technician), as well as the patients frequent ability to adapt to or to accept slight departures from ideal appearance, form, or function (34-36). Table 2.2: Examples of the definitions of the term complications used in the dental implant literature unexpected deviations from the normal treatment outcome (37) may represent an increased risk of failure but are either of temporary significance or are amendable to correction (38) chair time is required after incorporation of the prosthesis (39) a reversible or irreversible unfavourable condition (40) causes annoyance or inconvenience to the patient and the practitioner, can be financially burdensome if it occurs frequently, and may be a sign of impeding failure (modified after Taylor 1998 (41))

14 6 Two other terms failure and maintenance are occasionally used by some authors in specific circumstances in the context of implant complications. Failure is most commonly used to refer to implant failure (i.e., complete loss of osseointegration). However, some authors use this term more broadly to indicate not only loss of osseointegration but also substantial departures from health or severe positional or structural problems that prevent a successful prosthesis fabrication (20, 42). To avoid confusion and lack of clarity, this study used the term failure to refer strictly to implant failure (i.e., complete loss of osseointegration) keeping in line with the most frequent use of this term. Making the distinction between discussions of failure and complication has also been advocated by others (38). Some authors refer to the time-dependent process of upkeep of implant-supported prostheses (especially, implant-supported overdentures) as maintenance (43-45). The utilization of implant-supported overdentures presents unique challenges related to the use of mucosal surface for support and the use of resin acrylic materials in the fabrication of the prostheses. The shape and form of denture-bearing mucosal surfaces can change with time, acrylic can wear at the occlusal interface, and the attachments holding the overdenture to the implants may lose their retentive qualities. As a result, regular re-evaluation of the patient, minor denture base and occlusal surface adjustments, as well as modification and replacement of retentive elements may be required. This study did not use the term maintenance in keeping with the desire to avoid (wherever possible) procedure- or prosthesis-specific terminology. Hence, these adverse events (e.g., overdenture clip loosening or acrylic fracture) were referred to as complications. 2.C: Classification of complications: introduction No universal system for classifying complications exists. Classifications of complications may focus on the errors (e.g., a patient receiving a medication that the patient is known to be allergic to), the complications or outcomes of complications (e.g., the patient experiencing an anaphylactic shock), or the steps taken to address the complication (e.g., medical treatment given to treat the anaphylactic shock). A simple example of endosseous implant placement in a poor position can also be used to illustrate the distinction among these ideas. A treatment provider

15 7 might neglect to consider the final restorative outcome during treatment planning and execution ( an error ). This error may initiate a sequence of untoward events starting with poor implant position ( a complication ) and leading to a poor restorative outcome and an unhappy patient ( an outcome of the complication ). To remedy this situation, the poorly positioned implant may be removed and replaced with a new implant in a more optimal position permitting a satisfactory restoration to be fabricated for the patient ( steps taken to address the complication ). Clearly, not all errors lead to complications because some errors are recognized and remedied before they produce a frank negative outcome. These are occasionally referred to as silent errors, near misses or close calls (8). Similarly, not all complications actually produce a patient-perceived negative outcome, since some negative outcomes may be managed to seamlessly produce an adequate result at the end of treatment. For example, a poorly positioned implant may occasionally be restored with extra effort to produce an acceptable result despite the poor implant position. In this manner, the patient is not the only potential injured party resulting from a complication. In a multi-disciplinary treatment scenario, other members of the treatment team may also be victims of a complication insofar as they may need to take actions to address the complication and prevent it from having an adverse impact on the patient. Some classification systems of complications focus on errors made in the process of care. For example, six categories of errors have been identified (30) in a family practice setting and included administrative, communication, diagnostic, documentation, medication, and surgical (or procedural) errors. Classifications focusing on errors permit attention to be zeroed in on specific aspects or processes of care where errors are being made. They may facilitate identification of adverse issues and allow for those issues to be addressed and corrected before frank complications arise. However, although complication classifications focusing on errors have an intuitive appeal, they may have a strong subjective component and may not account for the fact that an error may be silent (i.e., may not lead to an actual complication). Some authors have argued strongly against examining errors solely in terms of failed processes and without any link to subsequent patient harm (22). To address this issue, some classifications attempt to take both the errors and their outcomes into account by drawing a distinction between errors that do and do not negatively impact on the patient. For example, the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) Index for Categorizing Medication

16 8 Errors (31) is a classification that focuses on presence of three factors error, harm, and death. These three factors combine to create a 5-category classification that includes the subheadings of no error, error but no harm, error and temporary harm, error and permanent harm, and error and death (31). Classifications focusing on the actual complications are more objective since no attempt is made to second-guess why the complication arose (i.e., what the error was). However, each complication may have a multitude of causes and may have a multitude of severity outcomes depending on other details of the situation. Hence, classifications focusing exclusively on complications themselves do not necessarily provide the best estimate of the ultimate treatment burden that the patient will need to endure to remedy the complication. Classifications focusing on steps needed to address the complication tend to be most objective and permit a quick appraisal of treatment burden on the patient. They also intrinsically permit an evaluation of severity of underlying complication not by attempting to ascertain the burden of complication on the patient, but by assessing invasiveness or financial burden of steps taken to address the complication. For example, the T92 complication classification system for in-patient surgical outcomes (46) grades severity of complications by relying heavily on the type of intervention used to manage the complication and whether there was permanent disability or death. Variables were selected as indicators of severity based on their objectivity and ready retrospective availability from chart entries (47). In this regard, some studies consider reoperation as an important marker of poor surgical outcome because of its objectivity (25). However, these classification systems do not address the causes of complications and are of limited value in formulating and executing approaches to complication prevention. 2.D: Classification of complications in the medical literature Several classifications of errors, adverse events, and complications have been proposed for a number of health care settings (e.g., intensive care units (48) and hospital administration (49)), medical procedures, service providers, and service recipients (i.e., patients (50)). These

17 9 classifications have been developed for use in a number of medical disciplines including family medicine (30), pharmacology (31), oncology (51), general surgery (14, 52-54), and several surgical subspecialties such as spine surgery (25). Moreover, many individual adverse events themselves have numerous definitions and measurement scales. For example, a 2001 systematic review (55) identified 41 different definitions and 13 grading scales of surgical wound infections from an evaluation of 82 studies. Although a number of attempts have been made to classify errors and complications, none of the classification systems have gained wide-spread acceptance even within the individual sub-disciplines or for specific procedures (56).

18 10 2.E: Classification of dental implant complications Similarly to the observations from the medical literature (55, 56), no single universally accepted classification system for implant-related complications exists. Several approaches to classifying all or some implant complications have been suggested (1-4, 20, 57, 58). Two general approaches appear to have been used by authors in classifying implant complications. Some authors attempted to classify all types of implant complications (1, 57). Other authors attempted to classify only some implant complications united either by the particular phase of therapy during which they tend to occur (such as surgical (58, 59) or prosthodontic complications (2, 4)) or by some other feature in the process (e.g., reversible complications (60)) or outcome of care (e.g., aesthetic complications (61)). All the above-mentioned classifications are summarized in Tables 2.3 through 2.6. Table 2.3: Classifications focusing on all complications Esposito et al. (20) biological complications implant failure (failure to achieve or maintain osseointegration) mechanical complications fracture of implants, connecting screws, bridge frameworks etc. iatrogenic complications nerve damage, wrong alignment of the implants etc. inadequate patient adaptation phonetic, aesthetic, psychological problems etc. Goodacre et al. (57) surgical and Goodacre et al. implant loss (1) bone loss peri-implant soft tissue mechanical aesthetic/phonetic Zarb & Schmit (62) surgical complications at stage I surgery following stage I surgery at stage II surgery following prosthodontic treatment (e.g., soft tissue complications) prosthodontic complications structural cosmetic functional delayed complications maintenance requirements

19 11 Table 2.4: Classifications of prosthodontic complications Jung et al. (2) biological complications disturbances in the function of the implant characterized by a biological process affecting the supporting tissues e.g., peri-implantitis and soft tissue complications aesthetic complications appearance classified as unacceptable or semioptimal by dental professionals or patients technical complications mechanical damage of implants, implant components and /or supra-structures e.g., fractures of implants, screws, or abutments; fractures of luting cement (loss of retention); fractures or deformation of the framework or veneers; loss of the screw access hole restoration; screw or abutment loosening Berglundh et al. (4) biological complications disturbances in the function of the implant characterized by biological processes that affect the tissues supporting the implant e.g., implant loss and reactions in the peri-implant hard and soft tissues technical complications collective term for mechanical damage of the Aglietta et al. (63) implant, implant components and suprastructures biological complications not defined e.g., peri-implantitis and soft tissue complications technical complications damage to the integrity of the implants or of the meso- and supra-structures e.g., implant fractures, veneer fractures, framework fractures, abutment or screw fractures, loss of retention and screw loosening Table 2.5: Classifications of surgical complications Misch & Wang (59) Greenstein et al. (58) treatment plan-related e.g., wrong angulation, improper implant location, lack of communication anatomy-related e.g., nerve injury, bleeding, cortical plate perforation, sinus membrane complication, devitalization of adjacent teeth procedure-related e.g., mechanical complications (overheating the bone, not tapping dense bone, over-preparation of the osteotomy), lack of primary stability, mandibular fracture, ingestion and aspiration other e.g., iatrogenic damage and human error oral soft tissue complications e.g., hemorrhage, nerve injury, tissue emphysema, infections, wound dehiscence, aspiration or ingestion, pain control hard tissue complications e.g., periapical implant pathosis, mandibular jaw fracture, lack of implant primary stability, inadvertent penetration into maxillary sinus or nasal fossa, complications associated with sinus elevation

20 12 Table 2.6: Other classifications of implant complications aesthetic complications (61) reversible complications (60) aesthetic complications not defined loss of interdental papilla gingival recession exposure of implant margin restoration too buccal or too palatal poor emergence profile chronic inflammation reversible complications complications whose negative impact is either temporary or is easily corrected intraoperative complications immediate/early postoperative complications late postoperative complications prosthetic-related (mechanical/biologic) complications aesthetic/soft tissue-related complications Several challenges occur in attempting to classify dental implant complications, to ascertain their frequency of occurrence, or to interpret the findings of the reviews on this subject. First, the same adverse occurrence for example, a loose prosthetic screw may have several outcomes ranging in severity from trivial to severe (64). A loose screw that occurred under a screwretained fixed restoration may be accessed and managed simply and uneventfully; a loose screw under a cemented fixed restoration may be much more difficult to access and manage. The most significant negative impact might occur if the restoration is destroyed in the process of gaining access to the screw, requiring fabrication of a new prosthesis. In other words, looking at a complication in isolation and without regard for the steps that are needed to remedy the complication does not tell the whole story (as alluded to earlier in Section 2.C). Second, many specific complications occur on a continuum with healthy states or inconsequential departures from the ideal. Hence, it is not always easy to determine that a complication has actually occurred. Two examples will be used to illustrate this point. All new prostheses (especially those involving treatment of large edentulous spans) are likely to produce some temporary degree of speech deficit and discomfort, and, hence, require a period of adaptation or learning by the patient (34-36). At what time point after prosthesis insertion, should continued presence of a speech deficit or inability to become accustomed to the feel of the

21 13 prosthesis be classified as a complication? At the same time, many biological tissues undergo changes over time, while the prostheses undergo wear and tear. Soft tissue form is likely to change causing instability to the removable tissue-borne prosthesis; acrylic is likely to wear causing changes to the appearance and function of the prosthesis; the color of a metal-ceramic prosthesis may begin to depart from that of adjacent teeth as the enamel and porcelain do not undergo color changes in the mouth to the same degree. All these time-dependent changes may require prosthesis modification or even replacement. Do these changes constitute a complication? At what point (if ever) after successful prosthesis wear, can an adverse experience (for example, a need to replace a prosthesis) be regarded simply as a consequence of natural phenomena, or should such events always be regarded as a complication? The issues of establishing time horizons and thresholds for identification of complications have also been widely acknowledged in the medical literature (47). Third, since no uniform definitions for implant complications exist, inter-study comparisons of different complications must be interpreted with caution (57). This is particularly true for biological complications, where different criteria for soft tissue complications were used in various studies (3). Fourth, no universal agreement exists on how best to calculate and report complication rates of occurrence. Occurrence of complications may be reported per number of units (implants, restorations, or patients) treated or per unit of time (1, 57). Without access to the underlying data, it is often impossible to compare results obtained in various studies (57). The issues of inconsistency of reporting and the lack of accepted principles of accrual, display, and analysis of complication data have also been raised in the medical context (23). Fifth, most implant complications are procedure-dependent in terms of type, frequency, or both. For example, sinus membrane perforation as a clinically significant complication occurs most prominently in cases of sinus elevation (65). Implant loss, on the other hand, occurs with all types of implant therapies. However, the frequency of implant failure reported in some studies is higher with some prosthetic procedures (e.g., unplanned maxillary overdentures (66)) and with some surgical procedures (e.g., simultaneous implant placement combined with grafting (4)). For example, a 2002 systematic review (4) found that the early failure of implants used for replacement of single missing teeth was 0.76%. However, this increased to 3.35% (an increase of almost 400%) when implants were inserted immediately following tooth extraction or in early

22 14 loading situations. Hence, the range of procedures undertaken by a dentist or group of dentists would have a significant impact on the types of complications that might be encountered. Similarly, the range of complications reported in any given trial is determined partly by the interventions undertaken within the trial. Lastly, caution must be exercised in interpreting average results. Each implant treatment involves the interplay of numerous patient, provider and procedural factors. Focusing on only one of these factors for example, survival of implant-supported single crowns betrays the fact that each factor operates within a large sea of semi-dependent and independent variables many of which might have a direct or indirect impact on the main factor in question. Thus, while it is possible to calculate the numerical average survival of implant-supported crowns, this value may not be applicable to all clinical situations or to all operators. In particular, novice clinicians are known to be more likely to make errors and to have complications both in the medical (67-69) and the dental implant (70) fields.

23 15 Chapter 3 Literature Review on Implant Complications 3.A: Studies on implant complications study results As discussed previously, several reviews and systematic reviews have attempted to identify and quantify the occurrence of complications related to treatment with endosseous dental implants (Section 2.E). The most comprehensive reviews (1, 57) have examined the entire scope of complications beginning with the surgical appointment until the latest follow up. Other reviews have limited themselves to specific phases of therapy such as the surgical or immediate postoperative complications (58, 59) or complications that might occur over the maintenance period (43, 71). Implant complications associated with specific types of prostheses have also been evaluated (2, 3, 43, 63, 71). Several reviews have focused on the evaluation of specific complications, such as abutment screw loosening in single-implant restorations (72), severe intra-operative hemorrhage (73), or implant failure (20, 38). The issues of complication prevention and management have also been addressed (58, 59). By far the most well-researched implant treatment complication is implant failure (i.e., loss of osseointegration) (20, 38, 74). Overall, the failure rate of implants was 7.7% (20). Implant failures are usually categorized according to chronological criteria into early and late failures. Early failure signifies failure to establish osseointegration and occurs within the first few months after surgical implant surgical placement and prior to insertion of the implant-supported prosthesis. Hence, surgically-mediated factors (e.g., surgical trauma and local anatomic conditions) and host-healing factors are usually thought to be important (20). Approximately half of all failures (3.6%) fall into the early failure category (20). Late failure signifies breakdown of established osseointegration phenomena and occurs after prosthesis insertion and typically within the first two years of loading (18, 75). Bone quality, bone quantity and overloading are felt to be the leading causes of late implant failures (20). The importance of peri-implant inflammation and infection as a significant cause of implant failures is controversial and may not be applicable to all implant systems (74).

24 16 One research group (57) examined 216 studies covering the years 1981 to 2001 and catalogued complications occurring during both the surgical and the prosthodontic phases (Table 3.1). Complications were divided into six categories: surgical, implant loss, bone loss, peri-implant soft tissue, mechanical and aesthetic/phonetic. The estimates of complication rates ranged widely across the studies from which the average estimates were derived. The total sample sizes of the studies on the basis of which the average complication rates were calculated also varied widely, reflecting the paucity with which some complications have been reported in the literature. Some complications were mentioned in most studies, and their prevalence data was based on a large total sample size. For example, the prevalence of gingival inflammation and proliferation was reported in 13 studies having the combined sample size of 17,565 implants. Other complications were not mentioned frequently (e.g., opposing prosthesis fracture), and the total sample size of the studies reporting them was much smaller. None of the studies examined in these reviews evaluated all of the complications simultaneously. The authors concluded that implant complications were frequently encountered and suggested that implant-supported prostheses tend to have a greater incidence of complications compared to other types of dental prostheses (e.g., single crowns, FPDs etc.) (1). Table 3.1: The most common complications according to Goodacre et al. (1) >10% of patients, prostheses, or implants <10% of patients, prostheses, or implants overdenture clip/attachment loosening 30% of prostheses hemorrhage-related complications 24% of patients resin veneer fracture (FPD) 22% of prostheses overdenture reline needed 19% of prostheses overdenture clip/attachment fracture 17% of prostheses porcelain veneer fracture (FPD) 14% of prostheses overdenture fracture 12% of prostheses opposing prosthesis fracture 12% of prostheses aesthetic complications with prostheses 10% of prostheses acrylic resin base fracture 7% of prostheses neuro-sensory disturbance 7% of patients prosthesis screw loosening 7% of screws fenestration/dehiscence prior to stage 2 surgery 7% of implants phonetic complications 7% of prostheses abutment screw loosening 6% of screws gingival inflammation/proliferation 6% of implants prosthesis screw fracture 4% of screws metal framework fractures 3% of prostheses abutment screw fractures 2% of screws fistulas 1% of implants implant fractures 1% of implants mandibular fractures 0.3% of patients

25 17 Several systematic reviews focused on complications associated with specific types of implantsupported prostheses such as single crowns (2), fixed dental prostheses (3), fixed dental prostheses with cantilever extensions (63), and overdentures (43, 45, 71). A systematic review and meta-analysis of the 5-year survival and complication rates of implant-supported single crowns (2) concluded that after an observation period of 5 years, high survival rates for implants and implant-supported single crowns can be expected. However, biological and particularly technical complications were reported to occur frequently (Table 3.2) (2). Table 3.2: Complication data reported for implant-supported single crowns after an observation period of 5 years by Jung et al. (2) survival rate of implants (supporting single crowns) 96.8% after 5 years survival rate of single crowns (supported by implants) 94.5% after 5 years of function survival rate of metal-ceramic crowns (95.4%) was better than the survival rate of all-ceramic crowns (91.5%) peri-implantitis and soft tissue complications occurred adjacent to 9.7% of single crowns 6.3% of implants had bone loss exceeding 2 mm over the 5-year observation period cumulative incidence of crowns having unacceptable or semi-optimal aesthetic appearance 8.7% cumulative incidence of implant fractures 0.14% after 5 years cumulative incidence of screw or abutment loosening 12.7% after 5 years cumulative incidence of screw or abutment fracture 0.35% after 5 years cumulative incidence of ceramic or veneer fractures 4.5% complications based on crown composition: metal-ceramic 75% all-ceramic 18% metal-acrylic 7% complications based on method of crown retention: screw-retained 12% cemented 88% A systematic review examining the incidence of complications of implant-supported fixed partial dentures (FPDs) after an observation period of 5 years (3) reported high survival of FPDs. The overall survival of implant-supported fixed partial dentures (with or without modification) was 95% after 5 years and 86.7% after 10 years of function. However, only 61.3% of patients were free of any complications after 5 years. Soft tissue complications occurred in 8.6% of FPDs after 5 years. Technical complications (e.g., implant fractures, connection-related and suprastructurerelated complications) were also frequent (Table 3.3) (3). The authors concluded that significant

26 18 amount of chair time may be required during the maintenance period following conclusion of treatment (3). Table 3.3: The most common technical complications for implant-supported FPDs after an observation period of 5 years according to Pjetursson et al. (3) veneer fracture (acrylic, ceramic or composite) 13.2% after 5 years loss of screw access hole restoration 8.2% after 5 years screw loosening 5.8% after 5 years loss of retention of cemented restoration 2.9% after 5 years and 16% after 10 years screw fracture 1.5% after 5 years and 2.5% after 10 years implant fracture 0.4% after 5 years and 1.8% after 10 years A 2002 systematic review (4) examined the incidence of biological and technical implant complications reported in prospective studies at least 5 years in duration. The complication data were categorized according to the type of implant therapy the patients were undergoing, underscoring the fact that the type and frequency of implant complications may be treatmentspecific (Table 3.4) (4). It was observed that the number of studies examining treatments with overdentures (15 studies), fixed complete dentures (14 studies) and fixed partial dentures (14 studies) was significantly higher than the number of studies reporting on single-tooth replacements (8 studies). The number of studies reporting complications with immediate placement/early loading (3 studies) and augmentation procedures (2 studies) was particularly small (4). This highlights the fact that novel treatment concepts are likely to have few long-term studies to give guidance as to the types of complications (and their frequency) that may be experienced with these novel treatment concepts.

27 19 Table 3.4: Complications data from Berglundh et al. (4) implant loss prior to loading 2.5% of implants after loading 2-3% of implants (failure is higher in implant-supported overdentures) sensory disturbance absence or low incidence (1-2%) after 1 year post-surgery soft tissue complications % per patient during the 5 year period (higher incidence in implant-supported overdentures) peri-implantitis limited information crestal bone loss limited information implant fracture <1% of implants during 5 year period technical complications related to implant components % per patient during the 5 year period depending on the type of restoration (highest incidence in implantsupported overdentures) technical complications related to suprastructures % per patient during the 5 year period depending on the type of restoration (the highest incidence observed with implant-supported overdentures) Several reviews and systematic reviews addressed the occurrence of complications with implantsupported overdentures (43, 45, 71). Several complications specific to implant-supported overdentures (rather than being specific to removable prostheses, in general) have been identified including anchorage system maintenance and replacement (i.e., matrix and patrix replacements and adjustments), soft tissue reactions, and prosthesis fractures. Some research indicates that the occurrence of technical and soft tissue complications is higher with implant-supported overdentures compared to fixed implant-supported prostheses (4). There is a long history of debate as to the best anchorage system for implant-supported overdentures, including the impact of the anchorage system on the occurrence of complications (43, 71). Although conflicting reports have been presented, recent analyses of the available research appear to indicate that complications involving anchorage system (e.g., matrix replacement, bar fracture, clip loosening etc.) were the most common complications involving implants-supported overdentures, and that the method of anchorage appears to have a limited influence of the prosthetic outcome (43, 71). Conflicting conclusions have been drawn with respect to the difference in the occurrence of complications between maxillary and mandibular implant-supported overdentures, with some researchers finding higher rates of complications with maxillary implant-supported overdentures (71) and others finding no such difference (43). The possible higher occurrence of complications with maxillary implant-supported overdentures has been attributed to limitations in vertical space