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

ii

A survey regarding the nature and type of dental implant complications

in the province of Ontario

David Chvartszaid

Masters of Science

Faculty of Dentistry

University of Toronto

2011

Abstract

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 e-mail 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 2009. 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 2009. Since most complications are preventable, efforts at decreasing

their prevalence and severity should be pursued.

iii

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.

iv

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

v

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 102

7.H: Source of knowledge about complications – discussion 104

7.I: Responsibility to keep dentists informed about potential implant

complications – results 106

7.J: Responsibility to keep dentists informed about potential implant

complications – discussion 107

7.K: Percentage of patients experiencing complications – results 108

7.L: Percentage of patients experiencing complications – discussion 109

Chapter 8: Preventability of Complications 110

8.A: Results 110

8.B: Discussion 111

Chapter 9: Overall Discussion and Conclusions 114

9.A: Study limitations 114

9.B: Study strengths 115

9.C: Implications and conclusions 117

Bibliography 119

Appendix 1 – Survey 137

vi

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

number of studies included in the reviews

24

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 e-mail list, active

e-mail 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 2009 54

Table 6.2: Surgical complications reported by each professional group in 2009 56

Table 6.3: Prosthodontic complications reported by survey responders (N=435) in

2009 58

Table 6.4: Prosthodontic complications reported by each professional group in 2009 59

vii

Table 6.5: Biologic complications reported by survey responders (N=433) in 2009 61

Table 6.6: Biologic complications experienced by each professional group in 2009 62 Table 6.7: Patient-related complications reported by survey responders (N=397) in

2009 63

Table 6.8: Patient-related complications reported by each professional group in 2009 64

Table 6.9: Top 20 complications reported by the largest percentage of general dentists

in 2009 66

Table 6.10: Top 20 complications reported by the largest percentage of oral surgeons

in 2009 67

Table 6.11: Top 20 complications reported by the largest percentage of periodontists

in 2009 69

Table 6.12: Top 20 complications reported by the largest percentage of

prosthodontists in 2009 70

Table 6.13: Corrective actions taken by survey responders (N=424) in 2009 in

response to complications 71

Table 6.14: Corrective actions taken by each professional group in 2009 72 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

viii

List of Appendices

Appendix 1 – Survey

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.

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 2009. 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.

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 life-

threatening, 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)

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

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))

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

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

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 re-

operation 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

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).

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)

and Goodacre et al.

(1)

surgical

implant loss

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

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 semi-

optimal 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

implant, implant components and suprastructures

Aglietta et al.

(63)

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)

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

Greenstein et

al. (58)

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

12

Table 2.6: Other classifications of implant complications

aesthetic complications

(61)

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

(60)

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 screw-

retained 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

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

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.

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 post-

operative 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).

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

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

<10% of patients,

prostheses, or

implants

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

17

Several systematic reviews focused on complications associated with specific types of implant-

supported 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 suprastructure-

related complications) were also frequent (Table 3.3) (3). The authors concluded that significant

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 treatment-

specific (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.

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 – 0.1-0.3% 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 – 0.19-1.59% per patient during

the 5 year period depending on the type of restoration (highest incidence in implant-

supported overdentures)

technical complications related to suprastructures – 0.17-1.90% 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 implant-

supported 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

20

for the prosthetic components, which may lead to a higher risk of fractures (71). Higher failure

rates of implants supporting maxillary implant-supported overdentures have also been reported

occasionally, although this finding has not been observed in the majority of investigations (66,

71, 76). All reviews pointed out that the lack of uniform, standardized categorizations for

complications and significant variations in study design on implant-supported overdentures

preclude thorough analysis of certain complications and drawing firm conclusions.

Claims of superiority of one dental implant brand over another are made frequently by

manufacturers. A 2003 systematic review (77) evaluated evidence from controlled clinical trials

looking for a relationship between characteristics of dental implants and their clinical

performance. The study examined seven clinical outcomes, six of which represented various

aspects of complications: failure of osseointegration, unaesthetic outcomes, peri-implant

mucositis, marginal bone loss, mechanical problems at the interface, and mechanical failure of

the implant. It was concluded that, contrary to manufacturers’ claims, the existing scientific

literature does not generally support superiority in performance of some design characteristics

over others. Short-term marginal bone behavior was one of the only variables observed to differ

slightly among different implant brands based on non-randomized controlled clinical trials, but

the authors urged caution in result interpretation owing to the possibility of bias inherent in these

less rigorous study designs (77).

A 2008 systematic review (72) examined abutment screw loosening in single-implant

restorations. The results indicated that abutment screw loosening is a relatively rare event in

single implant restorations regardless of the geometry of the implant-abutment connection

(external or internal), provided that proper anti-rotational features and torque are employed.

Overall, the reviews concluded that while the survival of implants and prostheses was high,

complications were frequent (3), possibly underreported (1, 4), and may be treatment- or

prosthesis-specific (4). In particular, complications with implant-supported overdentures were

more frequent than those with fixed implant-supported prostheses (4) (albeit with notable

exceptions such as speech problems (78), where patients report fewer problems with phonetics

with implant-supported overdentures as compared to implant-supported fixed prostheses (79)).

Variability in definitions, classifications, reporting standards, and study methodologies are likely

21

responsible for the observed variability in complication reports and frequencies reported in

various studies.

3.B: General characteristics of reviews reporting implant treatment

outcome and complication data

3.B.I: Thoroughness in reporting of complications

The degree to which implant intervention studies judiciously report all specific complications

varies (4), and a 2003 review of over 200 clinical trials (1) found that not a single study

evaluated all of the known implant treatment complications simultaneously. Unfortunately,

many studies report implant or prosthesis success or survival as the only outcome variables

(Table 3.5) (2, 3). A 2002 systematic review (4) examined the incidence of biological and

technical implant complications reported in prospective studies at least 5 years in duration.

Several categories of complications were investigated within the included studies and the

percentage of studies that actually reported any given complication was reported (Table 3.6).

The percentage of studies that actually reported any given complication varied widely depending

on the specific complication and ranged from 100% of the studies reporting the complication of

implant failure to 20% of the studies reporting crestal bone loss of more than 2.5 mm (4). Of

course, many studies might not report specific complications, because they did not occur.

However, readers and reviewers cannot ascertain if the failure to mention a specific complication

was due to its non-occurrence or due to incomplete reporting (i.e., omission).

Table 3.5: Number of studies reporting on specific categories of complications in

comparison to the overall number of studies included in the reviews

review

total

number

of studies

number of studies reporting

success/

survival

biological

complications

aesthetic

complications

technical

complications

Jung et al. (2) 26 26 10 7 13

Pjetursson et al. (3) 21 21 9 * 11

* Aesthetic complications were not examined in this review.

22

Table 3.6: Percentage of studies that reported specific complications in a review by

Berglundh et al. (4)

type of complication

percent of studies reporting

this type of complication

(%)

implant loss 100

persistent sensory disturbance 41

soft tissue complications requiring therapy 50

peri-implantitis 40

crestal bone loss >2.5 mm 20

implant fracture 84

complications related to implant components 65

complications related to supra-structures 65

3.B.II: Study setting

The vast majority of data regarding complications comes from university centers and specialist

clinics (Table 3.7) (2). For example, a 2008 systematic review examining 5-year survival and

complication rates of implant-supported single crowns (2) included twenty-six studies, the

majority of which were based in the university centers. Only one study was based exclusively in

private practice, and three were based on a combined patient population seeking treatment at a

private (general) practice and a university or specialist clinic. A significant difference may exist

between university centers and specialist clinics on the one hand and private general practice on

the other. University centers and specialist clinics deal with more complex and difficult

treatments but also have the benefit of advanced education, training, experience, and equipment.

This may be particularly apparent in the area of implant complication prevention, identification,

and management. Treatment outcomes achieved in institutional environments might not be

generalizable to treatment outcomes achieved in private general practice.

23

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

review

total

number

of studies

university/

hospital

studies

specialist

practice

studies

general

practice

studies

combined

setting

studies

unknown

setting

studies

Theoharidou et al. (72) 27 17 8* - 2

Pjetursson et al. (3) 21 13 4 - 4 -

Jung et al. (2) 26 16 6 1 3 -

Aglietta et al. (63) 5 4 - 1 - -

Note: Theoharidou et al. (72) did not distinguish between specialist and private general practice.

Large university-based research centers (e.g., Gothenburg, Leuven, Malmo, Mayo, and Toronto)

represent the overwhelming majority of published implant treatment results, while a much

smaller number of studies document implant experience in private practice (80). Multi-center

studies reporting complication data are also relatively infrequent (2, 3) (Table 3.8). Population-

or region-wide implant complication data are available only from Finland (81), where the status

of all implanted medical and dental devices must be reported to the regulatory authorities. The

type of data collected in the Finish dental implant register, however, is very limited.

Table 3.8: Number of multi-centre studies relative to the total number of studies included

in the reviews

reviews total number

of studies

multi-center

studies

Jung et al. (2) 26 2

Pjetursson et al. (3) 21 5

24

3.B.III: Implant companies investigated in the literature

A large and ever-increasing number of companies are involved in the manufacture and

distribution of dental implants. A 2003 assessment revealed that approximately 80

manufacturers marketed more than 220 different implant brands around the world (77). Only a

small minority of these could provide extensive clinical documentation, and some manufacturers

appeared to market dental implants without any clinical research documentation (77). An

evaluation of several systematic reviews on implant complications (2-4, 72, 82) clearly

demonstrates that implants made by four implant manufacturers – NobelBiocare/Branemark,

ITI/Straumann, Astra, and 3i – are the focus of the vast majority of implant outcome data (Table

3.9). Moreover, in some parts of the world implants are manufactured and sold with no

demonstration of adherence to international standards (such as ISO 9001, EN46001, and FDA

510K) (77).

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

number of studies included in the reviews

reviews

Total

number

of studies

implant companies

Nobel

Biocare ITI Astra 3i Other

Not

reported

Aglietta et al. (63) 5 1 2 1 1 - -

Berglundh et al. (4) 51 28 8 6 1 8 -

Jung et al. (2) 26 10* 9 3 3* 1 1

Payne et al. (45) 35^ 25 4 4 1 8 -

Pjetursson et al. (3) 21 15 3 1 - 2 -

Theoharidiou et al. (72) 27 9 6 5 2 5 -

Zurdo et al. (82) 3 - 1 1 1 - -

* One trial involved both NobelBiocare and 3i implant brands.

^ Eight trials involved more than one implant brand.

The use of different brands of osseointegrated implants varies dramatically around the world and

over time (Table 3.10). Several reviews (84) suggested that the incidence of some technical

complications may be specific to certain implant systems and designs. Overall complication

types and frequencies experienced by different geographic regions may differ based on the most

common implant products utilized in that geographic region. Dramatic inter-country differences

25

in the relative utilization of specific implant-supported prostheses have been reported (85). In

particular, a 2004 survey on the use of mandibular implant-supported overdentures relative to the

use of fixed implant-supported prostheses in the treatment of completely edentulous arches noted

that some countries (e.g., Sweden) utilized fixed implant-supported prostheses almost

exclusively, while others (e.g., Netherlands) utilized implant-supported overdentures almost

exclusively (85).

Table 3.10: The 5 most common implant manufacturers utilized in different countries or

geographic regions

country/geographic region, year

top 5 implant manufacturers

(percentage of the market belonging to the

specific manufacturers, if available)

UK, 1999 (86) Branemark (68.5%), Straumann (16.7%), Flialit

(5.5%), Astra (3.7%), others (5.5%)

Japan, 2002 (87) Nobel, Straumann, Kyocera, Centerpulse, Astra

US, 2002 (88) Nobel, 3i, Centerpulse, Straumann, BioHorizons

Europe, 2004 (89) Straumann, Nobel, 3i, Zimmer, Dentsply/Friadent

New Zealand, 2004 (90) Branemark (73.0%), Renew Biocare (13.9%),

Straumann (12.1%), Southern (6.2%), 3i (0.8%)

Finland, 2006 (81) Straumann (46.7%), Astra (20.4%), Xive (9.8%),

Replace Select (5.4%), Branemark (4.6%)

Switzerland, 2006 (91) Straumann (53.2%), Nobel Biocare (15.2%), 3i

(7.7%), SPI (7.4%), Frialit (3.7%) Note: The names of implant manufacturers in this table are exactly as they appeared in the original

publications. Hence, they may not be exactly comparable owing to differences in years of original study

publication and differences in specific brands marketed by the same manufacturers in different

geographic locations.

3.C: Geographic location – survey of dentists

Very limited implant-related data are available from surveys of dentists bound by a geographic

or professional association. National year-specific implant-related information is available from

Finland (for 2006) (81), Israel (for 1988) (92), New Zealand (for 2004) (90), Switzerland (for

2006) (91), and the U.S. (for 2006) (93). Hospital-based provision of implant services has been

documented in year-specific surveys of Beijing, China (for 1992) (94), Nigeria (for 2004) (95),

26

and United Kingdom (for 1999) (86, 96). Most of the available information deals with implant

service utilization and barriers to implant service utilization.

Implant utilization rates and patterns of implant practice with respect to degree of involvement in

the surgical or prosthodontic phases vary widely among countries and professional groups. In

the U.S., only 12.3% of general dentists, but 98.8% of oral surgeons and 80.4% of periodontists

surgically placed an implant in 2006 (93). In Switzerland in 2006 (91), four groups of dentists

were identified with respect to the types of implant-related services they provided to patients –

52.0% were involved in both surgical and prosthodontic phases, 1.8% were involved only in the

surgical phase, 28.3% were involved only in the prosthodontic phase, and 17.8% were not

involved in implant treatment at all. A 2004 survey of New Zealand dentists (90) revealed that

only 49.5% of the dentists were providing implant services to their patients. Among those who

provided implant therapy, less than 15% carried out both surgical and prosthodontic phases. A

1999 survey of implant treatment provided by consultants in restorative dentistry within National

Health Service Hospital service in the U.K. (86) revealed that 11% were involved in both the

surgical and prosthodontic phases, 35% were primarily involved in the prosthodontic phase with

limited surgical involvement, and 56% were involved exclusively in the prosthodontic phase. By

contrast, only 3% of general dental practitioners in the U.K. had experience with dental implants

as of 2006 (96). Similarly, year-specific surveys of certain geographic regions (namely, China in

1992 and Nigeria in 2004 (94, 95)) indicated very low implant service utilization.

Several professional groups bound by national boundaries (namely, U.S. prosthodontists in 2001

(97) and members of the U.K. Association of Dental Implantology in 1998 (98)) have published

year-specific implant-related surveys of their members, focusing on the utilization of implant

services and barriers that prevent their utilization. A 2001 survey of U.S. prosthodontists

revealed that 82.2% were involved in the prosthodontic phase of implant therapy, while only

12.2% were also involved in the surgical phase of therapy (97).

27

3.D: Treatment evolution and caution in interpretation of results from

past reviews

The experience of complications arising from implant treatment is an evolving problem.

Complications experienced and reported by some clinicians or in one time period become a part

of general implant knowledge and come to guide the treatment planning and execution by other

clinicians at a later time. These negative experiences lead to the development of guidelines for

avoiding complications and strategies for their management (58-61, 99, 100). Similarly, many of

the changes and attempted improvements in implant materials, designs and treatment techniques

are made in direct response to the prior experience of complications (101, 102). Ironically,

although technological improvement are often designed to specifically diminish or eliminate the

occurrence of certain complications or to simplify their management, these new technologies and

techniques might also inadvertently introduce new unforeseen complications. For example, the

negative experiences with certain aspects of screw-retained restorations (such as the loss of

access hole restorations and the difficulty in achieving passivity of fit) led to the introduction of

cemented restorations. While cemented restorations eliminated or reduced some of these

challenges, they introduced new types of complications such as cement extrusion into peri-

implant tissues and difficulty in seating of the final restoration (103). Thus, the constant

advancement of implant technologies and techniques changes both the types of complications

and their frequencies.

The duration of the study follow-up and its date of publication are important parameters in the

interpretation of the study results. The length of follow-up in a trial has an impact on the

apparent cumulative incidence of complications. Many complications take time to manifest and

will not be noted in studies of short duration. For example, implant failures typically occur

within the first 2 years following implant placement (20). Therefore, studies less than 2 years in

duration will effectively under-report the occurrence of implant failure and provide a falsely high

success rate. Similarly, some prosthetic complications (e.g., implant or framework fracture,

screw loosening, and material wear) are the result of a lengthy period of repeated loading (104)

and, hence, can take years or decades to manifest themselves. These prosthetic complications

might not be detected in studies with relatively short follow-up periods. Therefore, studies with

28

short follow-up periods will effectively under-report the occurrence of many prosthodontic

complications and will provide an overly optimistic success rate.

The above notwithstanding, and despite clear advantages of long-term follow-up studies,

contemporary short-term follow-up studies have a number of positive attributes. First, several

complications (including post-operative paraesthesia (105) and phonetic difficulties subsequent

to insertion of a new prosthesis (34-36)) can be temporary in nature and are likely to diminish or

disappear over time. Hence, these complications may not be detected in studies reporting only

long-term end-point data (rather than cumulative data). Second, the constant innovation and

evolution of implant treatment protocols, materials, and techniques (101, 106, 107) has an impact

on the interpretation and contemporary relevance of studies with a long-term follow-up. The

treatment protocols of a prospective trial are rigidly set, and, in effect, it becomes a glimpse

“back in time” at what complications would be experienced, if the protocols utilized at the

inception of the trial were still utilized. For example, a prospective study reporting 10-year data

and published ten years ago was initiated twenty years ago – a time period during which many

innovations would have occurred limiting the clinical relevance of the protocols under

investigation to the contemporary clinical practice. Furthermore, long-term outcome studies that

were initiated 10-15 years ago will not be able to report on new types of complications arising

from more recent technologies and techniques. Similarly, complications related to recently

introduced changes in materials or techniques will not be detected in reviews that exclude

recently published short-term follow-up studies. Hence, several complications related to recent

developments in treatment modalities are known to occur (e.g., fracture of the narrow diameter

internal connection implant during the surgical placement) but are not described in the literature

in great detail or at all. This leaves the interpretation of the long-term study results challenging

from the stand point of accurately reflecting the contemporary clinical reality. Similarly, the

publication date of the studies must always be taken into account when deciding if the data

contained therein is applicable to guiding current decision making.

As alluded to above, the composition and design of implants and components have changed

dramatically over time (101, 106, 107). For example, machined surface implants have declined

substantially in popularity and are no longer manufactured by many of the industry leaders. The

degree to which prior reports of complications experienced with a particular implant brand are

29

representative of the current complications likely to be experienced with that brand is uncertain.

Several implant designs or techniques were found to have a particularly high incidence of

implant complications and failures and their use has been abandoned or modified significantly.

Examples of such abandoned designs include IMZ implants employing mobile elements (108),

implants with very rough surfaces (e.g., titanium-plasma-sprayed [TPS]) (74), implants coated

with very thick hydroxyapatite surface coatings (74), and hollow implant designs (74). These

implant designs are no longer used, but reviews continue to incorporate data from the studies

utilizing these abandoned designs in the assessment of aggregate complication rates (63). No

review or systematic review had explicitly attempted to limit its analysis only to the designs that

are currently in use.

There are several examples of specific complications arising from implant treatment whose

frequency of occurrence appears to have diminished over time (including implant fracture,

cantilever fracture, resin fracture, and screw loosening) owing to technological improvements in

materials, techniques, and designs and owing to changes in the relative frequency of utilization

of specific prosthesis types. Improvements in material composition (specifically, the change in

the grade of titanium used) have caused implant fracture after loading (109-111) to diminish

substantially in the frequency of occurrence (102). Guidelines for dimensions of cantilevers

were introduced successfully to decrease the occurrence of cantilever fractures in fixed full-arch

prostheses (112). At one time, acrylic resin fracture was a very common prosthodontic

complication encountered with the use of single piece full-arch prostheses (44), representing

60% of all complications observed in one multi-centre study of prosthodontic specialist clinics in

Sweden in 1991 (113). While acrylic resin is still widely used in the treatment of edentulous

full-arch prostheses, it is almost never used the treatment of partially edentulous patients, who

now constitute the overwhelming majority of patients receiving implant treatment (93). Hence,

acrylic resin fractures now constitute a much smaller percentage of the total number of

complications partly due to the relatively low utilization of metal-acrylic prostheses in favour of

metal-ceramic and all-ceramic prostheses.

Screw loosening is another example of how changes in technology and design have significantly

altered the experience of this complication. Prosthetic and abutment screw loosening is a well-

known complication of implant treatment (72), and at one time the frequent occurrence of screw

30

loosening was a major impediment to the utilization of cemented restorations (103) and single

implant-supported crowns (57). Significant technological efforts were directed at improvement

of screw design and joint stability (102), and recent reviews (2) appear to indicate lower

frequencies of occurrence of screw loosening than were reported in the past. The most recent

systematic review on this topic concluded that abutment screw loosening in single-implant

restoration is a rare event regardless of the geometry of the implant-abutment connection

(external or internal), provided that proper anti-rotational features and torque are employed (72).

Taken together, the discussion above highlights the need for ongoing re-evaluation of

complications both in long- and short-term studies. Although it is common practice for reviews

on implant-related complications to exclude trials that report clinical outcomes up to five years

of prosthesis function (2-4), this may have inadvertently biased results and conclusions of these

reviews in favour of possibly outdated materials, techniques and designs, while ignoring the

contemporary clinical reality.

3.E: Malpractice studies

A unique perspective on severe implant complications is offered by studies examining legal

malpractice cases involving implant dentistry (5, 114). While the legal systems differ

dramatically across countries, useful information can nonetheless be gleaned by examining the

complications reported and their analysis. One research group (114) evaluated court decisions

and expert reports related to on-going court cases in Germany from 1984 to 2004. This group

examined inadequacies in the delivery of care in terms of the four stages of therapy (namely,

diagnosis, planning, treatment, and aftercare) during which these inadequacies occurred.

Diagnosis and planning accounted for the majority of inadequacies in delivery of care (36% and

53% respectively), while treatment (23%) and aftercare (8%) accounted for the minority of

inadequacies. Hence, the preparatory phase (diagnosis and planning) is of crucial importance

with respect to satisfactory treatment delivery. Although it is often assumed that the direct cause

of complications is “intra-operative malpractice,” deficits in the preparation and planning clearly

represent a critical underlying theme in serious complications (114). The authors also observed

31

that most cases (90%) involved more than one problem area, while cases involving a single

inadequacy in delivery of care were a clear minority (10%). Hence, serious complications are

likely the cumulative result of numerous mis-judgments – a view that is also supported in the

medical literature (24).

The observation that most complications resulting in legal proceedings (i.e., serious

complications) were the result of a series of mis-steps (114) echoes the Swiss Cheese model of

system failure (115). This model postulates that partially effective barriers exist to prevent

complications. These barriers are visualized as slices of cheese perforated with holes (which

represent errors that may allow the complication to pass unobtrusively through the barrier).

While any given barrier may fail to catch an error, the presence of many barriers makes it likely

that the error will be caught at some point in the process of care and remedied before it manifests

as a frank complication. This suggests that for a complication to occur, an error must occur in

each of the “barriers” – i.e., a series of errors. This is often represented pictorially by the perfect

alignment of the holes of all the cheese slices (115).

The importance of preoperative assessment seen above (114) is also highlighted by a study that

examined cases reported to the professional liability insurance carrier in Israel between the years

1992 and 1999 (5). Patients paying their own bills without third-party involvement filed all the

legal claims. Complications resulting in legal action were divided into immediate and late

groups (Table 3.11). Immediate complications were those occurring between the first- and

second-stage surgeries. Late complications were defined as those occurring following stage 2

surgery. According to the authors, all but 2 cases (59/61) were ultimately the result of

preoperative error (5). Consultants for the insurance carrier acknowledged liability in the

majority of cases (67%). In particular, liability was acknowledged in 100% of cases of loss of

sensation and implant malposition, and, in general, liability was acknowledged in a higher

percentage of immediate complications (77%) (5).

32

Table 3.11: Classification of complications according to Givol et al. (5)

category of complications

specific complications

(number of specific complications out of the total of 61

cases)

immediate complications permanent altered sensation (16/61)

implant failure (10/61)

unfavourable implant location compromising the

prosthetic rehabilitation (7/61)

postoperative infection (3/61)

invasion of maxillary sinus (2/61)

life-threatening hemorrhage (1/61)

late complications loss of prosthetic rehabilitation (16/61)

implant loss not resulting in the loss of the prosthetic

rehabilitation (4/61)

massive bone loss related to implant failure (2/61)

The facts that most serious complications can be traced to errors in judgment during the

preoperative phase (5, 114) and that liability was acknowledged in most cases (5, 116) lead to

two conclusions. First, they reinforce the contention that implant complications may be largely

preventable (62, 117) (similarly to the manner in which many treatment complications in the

medical field are suspected to be preventable (16, 17)). Second, they highlight the need to focus

on improvements in operator education, skill and judgment rather than improvements in implant

technology (5). The focus on these human elements is likely to lead to further reductions in

implant complications. Further technological improvements should be sought only in so far as

they facilitate acquisition of operator knowledge and skill or improve operator judgment.

3.F: Clinicians’ opinions on complications

Extremely limited information exists with respect to clinicians’ opinions on complications. Two

surveys on implant treatment outcomes in the U.K. (118) and Israel (92) asked dentists’ opinions

on primary determinants of treatment outcomes. In a 1999 survey in the U.K. (118), clinicians

stated that the most important reasons for implant failure were (in a decreasing order of

importance) poor bone quality, unsuitable loading, poor oral hygiene, smoking, poor surgical

technique, poor patient selection, implant type, and use of bone grafts. The importance given by

responders to poor bone quality is in agreement with comprehensive reviews on this topic (20,

33

74). In a 1988 survey of Israeli dentists (92), the most commonly cited reasons for success of

dental implants were (in a decreasing order of frequency) surgical phase, case selection,

prosthodontic phase, following manufacturer’s instruction, skills and knowledge, oral hygiene,

occlusal adjustments, and osseous factors. The first three reasons (surgical phase, case selection,

and prosthodontic phase) were far more commonly cited than the rest. While the information

from these two surveys is interesting, differences in study methodologies make these results hard

to reconcile with each other. Furthermore, the results of the survey from Israel (92) must be

considered in light of the year when the information was collected (i.e., 1988), since substantial

progress has been made in the field of implant dentistry since that time (101, 106, 107). This is

well-illustrated by the fact that the third most commonly used implant product on the market in

Israel at the time was blade implants – a non-osseointegrated implant type that is no longer used

and bears little resemblance in method of anchorage or in surgical or prosthetic protocols to

osseointegrated screw-shaped implants.

Very little is known about severity ranking of complications by the dentists or about inter-

personal agreement with respect to such rankings. A 5-point ordinal scale relating to the severity

of implant-related complications – “clinical performance scale for implants” (Table 3.12) – has

been proposed (6), with implant failure intrinsically defined in this scale as the most severe

complication. In this study (6), a panel of six specialists (two oral surgeons and four

prosthodontists) was used to rank complications that had occurred in a group of patients treated

with implant-supported mandibular overdentures (Table 3.13). Most complications received a

score of 1 or 2 (out of 4). Not surprisingly, implant failure and implant fracture received a score

of 4 (out of 4). Bone loss could not be assigned a single score due to a wide range of clinical and

radiographic circumstances. Full consensus in the ranking was sought by the authors from the

six person panel but was obtained only for 65% of the specific complications. For 87% of the

complications at least five of the six experts gave the same score (6).

A significant disadvantage of the Clinical performance scale (6) (Table 3.12) is that it

intrinsically regards implant loss as the ultimate (most severe) complication and ranks other

complications based largely on their likelihood of leading to implant loss. No support exists to

justify the ordering of options in this scale. Although loss of a unit of anchorage can be a serious

event, a number of other complications (including permanent paraesthesia, very poor aesthetic or

34

functional prosthetic outcome, very poor implant placement, jaw fracture, significant damage to

an adjacent tooth, and severe life-threatening post-operative infection) may also produce very

debilitating effects on the patient. Moreover, in some situations – such as loss of an implant

under a screw-retained full-arch prosthesis – loss of an implant may not have much of a

significant impact at all, because some prostheses are over-engineered/designed precisely to

allow for such a possibility. In this situation, the loss of a single implant might not affect the

stability and retention of the prosthesis, permitting its function to continue uninterrupted.

Ultimately, the impact that the complication has on the patient is an important determinant of the

severity of a complication (64). This patient-relevant aspect is absent from the Clinical

performance scale and the results of the study utilizing this scale (6) must be interpreted with

caution.

Table 3.12: Clinical performance scale for implants according to Van Waas et al. (6)

0 – no complication or need for replacement

1 – minor complication that does not need intervention or is easily treated

2 – complication with a reasonable chance of recovery or stabilization of the situation

3 – serious complication or treatment procedure that may lead to failure of the implant

4 – complete failure of the implant

Table 3.13: Clinical performance scale score for a range of complications according to Van

Waas et al. (6)

Complication Clinical performance scale score (6)

- broken abutment

- hyperplastic mucosa

- incorrect occlusion or articulation

- loosening of suprastructure screws

- denture relining necessary

- minor disturbance of mental nerve

1

- suprastructure not fitting

- broken suprastructure

- severe disturbance of mental nerve

2

- 3

- bone loss

could be assigned a score from 0 to 3

depending on the extend of radiographic bone

loss and clinical presentation

- implant loss

- implant fracture 4

35

3.G: Conclusion and rationale for further study

All reviews referred to previously (2-4) found that while survival of implants and implant-

supported restorations was high, a notable percentage of patients experienced complications.

Although much knowledge has been accumulated with respect to osseointegrated implants and

complications associated with their use, much information remains unknown or is out of date.

The constant evolution of treatment strategies, technologies, and patient expectations (101, 106,

107) creates a constant need to update the existing information. In particular, current

information regarding dentists’ experience of implant treatment-related complications in specific

geographic locations is largely unknown. Furthermore, the nature and the types of implant

complications experienced in private practice may be different from those commonly reported in

the literature based on experience in academic centres. Opinions of dentists regarding the

causes, preventability, preventive strategies, and severity of complications are also unknown.

Hence, there is a growing and ever-present need to investigate location-specific experience with

complications in contemporary private practices.

36

Chapter 4

Materials and Methods

4.A: Aims and objectives

The aims and objectives of this research were already stated at the very beginning of this thesis

(Chapter 1). However, they are restated here again so that subsequent sections of this study can

be interpreted more easily.

The primary objective of the study was to determine the nature and the types of complications

arising from dental implant therapy in private practices in the province of Ontario as reported by

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; and

3) to determine the relative severity ranking of complications as perceived by the treatment

providers.

It should be understood that although research is generally hypothesis driven, this is not always

possible with a survey. However, insights generated from survey analysis and interpretation may

give rise to post-hoc hypotheses that could be tested in future investigations.

4.B: Methods

This research was carried out as a survey (see Appendix 1). The survey tool was developed

based on complications arising from implant therapy that have been reported in the literature (1-

4, 20, 38, 42, 43, 45, 57-59, 61, 63, 71, 72, 82, 84, 99, 119). This information was supplemented

by several additional sources including: 1) implant-related complications reported to the

malpractice carrier for the dentists of Ontario (Professional Liability Program – PLP), 2)

personal interviews with a convenience sample of 10 dentists, and 3) a preliminary survey of a

37

convenience sample of 30 general dentists and specialists participating in clinical teaching at the

Faculty of Dentistry, University of Toronto. Legal cases involving implants that have resulted in

Canadian court judgments or in decisions by Ontario disciplinary bodies (i.e., The Royal College

of Dental Surgeons of Ontario) were also examined. The survey tool was pre-tested for length

and comprehensibility by 20 specialty graduate students at the University of Toronto. The

survey tool was revised on the basis of this test. To reiterate, although the survey tool was

developed partly on the basis of information obtained from the PLP, data from the PLP were not

included in any of the data sets nor used in any of the subsequent analyses of the survey results.

The survey tool contained two sections: basic demographic questions and questions about

implant complications. Basic demographic questions focused on the dentists’ level of expertise

and education with respect to surgical and prosthodontic aspects of implant therapy. No personal

identifying information was collected, and all questionnaires were anonymous and confidential.

Questions about implant complications pertained to the actual complications that the dentists had

experienced in 2009, the factors associated with those complications, and the dentists’ general

opinions regarding complications. Four different categories of complications related to implant

therapy were investigated – surgical, prosthodontic, biological, and patient-related. The dentists

were also asked about the corrective actions they took in response to complications in 2009.

Opinions were sought with respect to preventability of complications, causes of complications,

ways to prevent complications, and severity of complications.

As just mentioned above, this study (and survey) divided implant treatment complications into

four categories – surgery-related, prosthodontic, biological, and patient-related. This

classification system builds upon a classification described previously by Esposito et al. (20). In

the original iteration of this classification system (20), complications were divided into four

categories – biological (e.g., implant failure), mechanical (e.g., fracture of implants, connecting

screws, bridge frameworks etc.), iatrogenic (e.g., nerve damage, wrong alignment of the implants

etc.), and inadequate patient adaptation (e.g., phonetic, aesthetic, psychological problems etc.)

(Table 2.3). In this study, the following superficial modifications were made:

1) the category of “mechanical complications” was renamed to “prosthodontic

complications”,

38

2) the category of “iatrogenic complications” was renamed to “surgical complications”, and

3) the category of “inadequate patient adaptation” was renamed to “patient-related

complications”.

The rationale for renaming “mechanical complications” into “prosthodontic complications” was

based on the idea that the term “mechanical” did not appear to embrace the full scope of

prosthodontic complications, such as complications that might arise even before prosthesis

fabrication (e.g., inability to take an impression). The category of “iatrogenic complications”

was changed to “surgical complications”, because most complications that fall under that

category arise as a direct result of a surgical procedure. At the same time, most implant

complications are probably iatrogenic in nature (114, 116, 117), and, hence, using the term

“iatrogenic” to refer only to one category of complications would appear to be inaccurate.

Moreover, for the purposes of this study, it was felt that the term “iatrogenic” might not be

understood fully by all dentists who might participate in the survey. Lastly, the category of

“inadequate patient adaptation” was renamed to “patient-related complications” to avoid the

inadvertent connotation that the patient is responsible for the complication. Most specific

complications in this category have direct causes in treatment execution. Poor patient response

(e.g., poor speech or poor comfort) is often a direct or indirect manifestation of other underlying

complications (e.g., poor implant position). The term “patient-related complications” was used,

because complications in this category often have an element of patient response or evaluation of

therapy (e.g., aesthetics, phonetics, comfort, and overall satisfaction).

This study investigated a large number of specific complications spanning all phases of implant

therapy. It simultaneously assessed more specific complications on a single dentist population

than almost any other study in this field, including some specific complications that appear to be

examined here for the first time. However, not all conceivable complications were included on

the list of specific complications investigated in this research. The selection of complications for

inclusion in this survey was based on complications reported in the literature (1-4, 20, 38, 42, 43,

45, 57-59, 61, 63, 71, 72, 82, 84, 99, 119), complications mentioned by dentists during informal

interviews, and complications mentioned by dentists during preliminary open-answer surveys,

while keeping the limitations of survey space in mind. The need to keep the survey length as

small as possible to maximize response rates was the primary constraining factor.

39

Furthermore, implant-related procedures (and complications associated with them) were not

included/addressed in this survey if they were understood to be done too infrequently, mostly by

specialists, or primarily in a hospital setting (e.g., block grafting, zygomatic implants, distraction

osteogenesis, inferior alveolar nerve transposition, and maxillofacial prostheses). Complications

associated exclusively with grafting procedures were not included (with the exception of sinus

membrane perforation), because grafting procedures have a very large number of procedure-,

material-, and technique-specific complications, and their inclusion would have tremendously

increased the number of surgical complications. (Sinus membrane perforation was included in

the survey because it is a very well-researched, frequently mentioned, and objective complication

(65).) However, certain basic complications (such as severe bleeding, severe infection, and

incision line opening, for example) and corrective actions (such as performing additional surgical

procedures and increasing the length of treatment) would apply to complications associated with

all surgical procedures, including grafting procedures, and these were included in this study.

Wherever possible, this study attempted to state specific complications in a procedure- or

prosthesis-independent fashion. Specific procedures or prostheses were mention only to increase

clarity.

Functional and phonetic adaptation takes place with the insertion of all dental prostheses (34-36).

This survey did not specify how long after prosthesis insertion a particular patient complaint of

speech defect or poor comfort should be regarded as a complication. Instead, the survey left it to

the discretion of the individual dentists to judge if the experiences of their patients constituted a

complication. The challenges of establishing time horizons and thresholds for complications

have been discusses earlier in section 2.E.

The survey was administered to the dentists most likely to be involved in the treatment of dental

implants – general dentists, oral and maxillofacial surgeons, periodontists, and prosthodontists

(93). (“Oral and maxillofacial surgeons” will be shortened to “oral surgeons” in the rest of the

thesis.) The survey tool was administered using the QuestionPro web program

(http://www.questionpro.com/). Surveys were e-mailed to all general dentists and specialists

with available e-mails. The survey was conducted based on Dillman’s Tailored Design Method

(120) as it applies to web-based surveys (121, 122). This approach focuses on optimizing survey

response by virtue of survey instrument design and survey implementation. In particular,

40

Dillman’s Tailored Design Method for survey design utilizes Social Exchange concepts that

postulate that people’s actions are motivated by the return these actions are expected to bring.

Hence, survey design should built respondent trust and make it as easy as possible to complete

the survey while making the expected benefits (to society) clearly apparent (120).

4.C: Sample size calculations

To ensure that our sample was representative of the overall dentist population of Ontario, the

sample size calculations were based on the following four assumptions (120):

1) 5% margin of error.

2) 95% confidence interval.

3) The population size from which the sample was selected.

4) 50% response distribution rate: The response rate was essentially unpredictable with regard

to the survey in toto as well as specific questions therein. In order to assure a good response,

a conservative response rate of only 50% was presumed a priori.

Therefore, the calculation of the sample size (n) was based on the size of the population (N), the

proportion of the population expected to choose one of two responses (P= 0.5 to allow for the

maximum variance), the assumed sampling error (C= 0.05), and the Z-statistic of the confidence

interval (Z = 1.96 for 95% confidence level) (123):

n = ((N)(P)(1-P)) / ((N-1)(C/Z)2 + (P)(1-P))

The dentist population target sample was made up of four professional groups of subjects as

outlined previously. The sample size calculations were based on the total numbers of subjects in

those groups within the province of Ontario:

Oral Surgeons: Based on the total of 194 in Ontario, the sample size required was 128.

Periodontists: Based on the total of 186 in Ontario, the sample size required was 124.

Prosthodontists: Based on the total of 68 in Ontario, the sample size required was 58.

General Dentists: Based on the total of 7,154 in Ontario, the sample size required was 366.

41

Therefore, the preliminary sample size for professionals would have been 676

(=128+124+58+366). However, response rates from professional surveys are notorious for being

low. (A recent survey utilizing similar methodology at Faculty of Dentistry, University of

Toronto reported a response rate of 15% (personal communication, Dr. Amir Azarpazhooh).)

Moreover, it was anticipated that it would not be possible to obtain e-mail addresses of all

Ontario dentists to allow a random sample to be drawn, and furthermore, it was also expected

that some e-mail addresses would be invalid. Therefore, in order to account for these

shortcomings, a sample of 2621 dentists with available e-mail addresses was selected from the

total pool of 7602 dentists currently practicing in Ontario. This project was approved by the

Ethics Committee of the University of Toronto (#24931).

4.D: Survey implementation

The anonymous web-based survey was implemented between April and May 2010. A

personalized e-mail was sent to all dentists with available e-mail addresses (2621). The e-mail

described the research design and purpose of the investigation and contained a link to the actual

survey. Potential respondents were informed that completion of the survey signified their

consent. Clicking on the link to the survey took the potential respondents to the actual

anonymous web-based survey. On average, it took approximately 15 minutes to complete the

survey. Wherever possible, the order of options within the questions was randomized so that

each respondent saw the options in a different sequence. This was particularly important for the

questions with a long list of options to prevent certain options from being preferentially selected

by virtue of their preferred sequence order. Three reminders were sent 1-2 weeks apart. Each

reminder e-mail contained a slightly modified text of the original e-mail. In particular, a section

of answers to commonly asked questions about the survey was included with the reminder e-

mails. Each subsequent reminder generated fewer additional responders. Data security and

privacy were addressed at all levels starting with survey delivery all the way through to

protecting the integrity of survey results and user data. Respondents were not given a financial

incentive to participate.

42

4.E: Data analysis

The data that were collected on-line were downloaded from the QuestionProTM

website into a

Microsoft Excel file. The data were cleaned, recoded, and imported to the Statistical Package for

Social Sciences software 18.0 (SPSS, Chicago, Ill, USA) for data management and analysis. The

data underwent quantitative analysis. Summary statistics were compiled from completed surveys

to address each of the objectives. Associations among variables such as level of dental implant

experience (i.e., expertise in this field), specialty status, and types of complications were

assessed using the Chi-squared statistics with a threshold of significance set at a p-value of 0.05.

Descriptive analyses of data, including tables, frequency distributions and graphic displays were

performed. Descriptive analyses of the data were undertaken for the sample as a whole and

separately for the four professional groups (general dentists, oral surgeons, periodontists, and

prosthodontists). Experience with complication and opinions about complications were

subjected to the Chi-squared test using the Bonferroni correction, adjusting for multiple

comparisons and the possibility of increased Type II error. For several cross-tabulations, six

comparisons were made between the four groups of professionals. Consequently, the threshold

for significance was corrected to a p-value of 0.008 (derived by dividing 0.05 by 6 to account for

multiple comparisons). Non-parametric techniques constituted the bulk of tools for analysis of

this survey.

43

Chapter 5

Demographics

5.A: Results and tables

Table 5.1: Survey flow

2621 e-mails sent out

- 559 bounced, - 28 unsubscribed

2034 active

537 completed the

survey

- 68 who were not involved in implant dentistry

(60 general dentists + 2 oral surgeons + 4 periodontists + 2 prosthodontists)

469 performed implant

treatments

Table 5.2: Comparison between Ontario dentist population, survey e-mail list, active e-mail

list, and survey responders

*Note: All subsequent tables in this thesis present data referring strictly to the 469 dentists who responded

to the survey and were involved in implant dentistry. This is further clarified on page 46.

general dentists oral surgeons periodontists prostho

dontists total

Ontario n 7154 194 186 68 7602

% 94.1 2.6 2.4 0.9 100.0

survey mailed out

n 2353

-527 bounced

-25 unsubscribed

125

-18 bounced

-1 unsubscribed

93

-9 bounced

-2 unsubscribed

50

-5 bounced

2621

% 89.8 4.8 3.5 1.9 100.0

active survey list

(w/o bounced and

w/o unsubscribed)

n 1801 106 82 45 2034

% 88.6 5.2 4.0 2.2 100.0

all survey

responders

n 443 33 41 20 537

%

survey

responders who

performed implant

treatments*

n 383 31 37 18 469

% 81.7 6.6 7.9 3.8 100.0

44

Table 5.3: Demographic characteristics – surgical/prosthodontic expertise, practice focus

general

dentists

oral

surgeons

periodon

tists

prosthod

ontists

total 2 P-

Value

all responders who perform

implant treatments

n 383 31 37 18 469

% 81.7 6.6 7.9 3.8 100.0

Surgical Expertise

advanced/average % 39.4 100.0 100.0 72.2 49.5 <0.001

basic knowledge/none % 60.6 0.0 0.0 27.8 50.5

total n 383 31 37 18 469

Prosthodontic Expertise

advanced/average % 89.4 51.7 57.1 100.0 85.0 <0.001

basic knowledge/none % 10.6 48.3 42.9 0.0 15.0

total n 379 29 35 18 461

Practice focus

exclusively prosthodontic

implant treatment % 61.4 0.0 0.0 33.3 51.4

<0.001

primarily prosthodontic

implant treatment and

limited surgical treatment

% 14.1 0.0 0.0 33.3 12.8

both surgical and

prosthodontic implant

treatment

% 24.3 0.0 8.1 33.3 21.7

exclusively surgical implant

treatment % 0.0 87.1 70.3 0.0 11.3

primarily surgical implant

treatment and limited

prosthodontic treatment

% 0.3 12.9 21.6 0.0 2.8

Total n 383 31 37 18 469

Practice focus

exclusively prosthodontic

implant treatment % 61.4 0.0 0.0 33.3 51.4

<0.001

both surgical and

prosthodontic implant

treatment

% 38.6 12.9 29.7 66.7 37.3

exclusively surgical implant

treatment % 0.0 87.1 70.3 0.0 11.3

Total n 383 31 37 18 469

45

Table 5.4: Demographic characteristics – year of graduation, number of patients/implants

treated

general

dentists

oral

surgeons

periodon

tists

prosthod

ontists

total 2 P-

Value

Years in practice

(Year of graduation from

DDS program)

>40 (<1970) % 8.3 9.7 2.9 18.8 8.4

0.104

31-40 (1970-1979) % 24.9 22.6 26.5 12.5 24.3

21-30 (1980-1989) % 27.5 29.0 26.5 43.8 28.2

11-20 (1990-1999) % 28.1 32.3 17.6 12.5 27.0

0-10 (2000-2009) % 11.2 6.5 26.5 12.5 12.2

total n 338 31 34 16 419

Years in specialist practice

(Year of graduation from

specialty program)

>30 (<1980) % 0.0 9.7 11.5 25.0 13.1

0.872 21-30 (1980-1989) % 50.0 35.5 31.4 25.0 32.1

11-20 (1990-1999) % 50.0 22.6 20.0 18.8 21.4

0-10 (2000-2009) % 0.0 32.3 37.1 31.3 33.3

total n 2 31 35 16 84

Years in implant dentistry

0-10 % 53.3 22.6 39.4 25.0 48.8

<0.001 11-20 % 37.1 32.3 39.4 25.0 36.5

>20 % 9.6 45.2 21.2 50.0 14.7

total n 334 31 33 16 414

Patients treated

0-10 % 96.7 60.0 52.9 73.3 89.5 <0.001

>10 % 3.3 40.0 47.1 26.7 10.5

total n 332 30 34 15 411

Implants placed

0 % 63.5 0.0 3.0 46.7 52.7

<0.001 1-10 % 33.3 35.5 51.5 40.0 35.3

>10 % 3.2 64.5 45.5 13.3 12.0

total n 312 31 33 15 391

Implants placed

(among those who placed

implants)

1-10 % 91.2 35.5 53.1 75.0 74.6 <0.001

>10 % 8.8 64.5 46.9 25.0 25.4

total n 114 31 32 8 185

Implants restored

0 % 7.5 84.0 69.0 0.0 16.4

<0.001 1-10 % 87.8 12.0 24.1 64.3 77.7

>10 % 4.8 4.0 6.9 35.7 6.0

total n 335 25 29 14 403

Implants restored

(among those who

restored implants)

46

1-10 % 94.8 75.0 77.8 64.3 92.9 <0.001

>10 % 5.2 25.0 22.2 35.7 7.1

total n 310 4 9 14 337

The survey was mailed out to 2621 dentists in Ontario with available e-mail addresses (Tables

5.1 and 5.2). Contact information was available for a greater percentage of specialists, and hence

specialists made up a greater percentage in the sample population than in the Ontario dentist

population in general (11.2% vs. 5.9%). There were 559 invalid e-mail addresses, and 28

dentists unsubscribed from the survey (i.e., they informed the investigators that they did not wish

to be contacted or did not wish to participate in the survey). The active list of responders

consisted of 2034 dentists. A total of 537 dentists replied to the survey after 3 reminders had

been sent. Among these were 68 dentists who were not involved in implant dentistry. These 68

dentists did not complete the survey, and they were not included in the survey analysis. Hence,

the final count of responders was 469. The rest of the survey results reported below will apply to

these 469 dentists, and they will be referred to as “the responders.” Not all responders answered

every question. Hence, for every question the total number of dentists who answered it will also

appear. The response rates (obtained by comparing the active survey list and the survey

responders involved in implant dentistry) were 23.1% for the dentists as a group and 21.3%,

29.3%, 45.1%, and 40.0% for general dentists, oral surgeons, periodontists, and prosthodontists

respectively. Survey response rates for specialists (especially, for periodontists and

prosthodontists) were higher than the response rate for general dentists. However, general

dentists made up the majority of survey responders (81.7%), with specialists making up the

remaining 18.3%. Specialists (oral surgeons, periodontists, and prosthodontists) made up 6.6%,

7.9%, and 3.8% of the responders respectively (Table 5.3).

Among the survey responders, roughly half the dentists possessed advanced or average surgical

expertise, and half possessed basic or no surgical expertise (Table 5.3). All oral surgeons and

periodontists, the majority of prosthodontists (72.2%), and 39.4% of general dentists had average

or advanced level of surgical expertise. These differences in surgical expertise among the four

professional groups were statistically significant (2 p-value<0.001).

47

Among the survey responders, the vast majority of dentists (85.0%) had advanced or average

level of prosthodontic expertise (Table 5.3). All prosthodontists, the vast majority of general

dentists (89.4%), and 50-60% of surgical specialists (oral surgeons and periodontists) had

advanced level of prosthodontic expertise. These differences in prosthodontic expertise among

the four professional groups were statistically significant (2 p-value<0.001).

Among the survey responders, with respect to performance of implant-related treatments most

dentists (51.4%) were involved exclusively in prosthodontic implant treatment, and another

12.8% were involved primarily in prosthodontic phase with limited surgical involvement (Table

5.3). Only 11.3% were involved exclusively in the surgical phase of implant therapy, and

another 2.8% were involved primarily in the surgical phase with limited prosthodontic

involvement. Approximately 21% were actively involved in both surgical and prosthodontic

phases of implant therapy. Another way to look at the same data is to consider that the vast

majority of dentists (88.7%) were involved, in some capacity, in the prosthodontic phase of

therapy, while only 48.6% were involved in some capacity in the surgical phase of implant

therapy. In other words, among the survey responders involvement in the prosthodontic phase of

implant therapy was far more common compared to involvement in the surgical phase of implant

therapy.

All general dentists reported that they were involved in the prosthodontic phase of implant

therapy, and 61.4% of them were involved exclusively in the prosthodontic phase of treatment

(Table 5.3). All prosthodontists were involved in the prosthodontic phase of implant therapy, but

only 33.3% of them were involved in the prosthodontic phase exclusively. Those involved only

in the prosthodontic phase of implant therapy were exclusively general dentists or

prosthodontists. All oral surgeons and periodontists were involved in the surgical phase of

implant therapy, and most oral surgeons (87.1%) and periodontists (70.3%) were involved in the

surgical phase exclusively. Those involved only in the surgical phase of implant therapy were

exclusively oral surgeons or periodontists.

Due to the relatively small number of survey participants belonging to certain subgroups in the

“practice focus” question, the five groups were recoded into three groups with respect to

provision of implant therapy – “prosthodontics only,” “both prosthodontics and surgery,” and

48

“surgery only” (Table 5.3). Those who performed prosthodontic implant treatment exclusively

were recoded as the “prosthodontics only” group. This was the largest group with 51.4% of

responders. It was made up primarily of general dentists (97.5%). Those who performed both

prosthodontic and surgical phases of implant therapy were recoded as the “both prosthodontics

and surgery” group. This was the second largest group with 37.3% of responders. It was made

up predominantly of general dentists (84.6%) with small percentages of oral surgeons,

periodontists, and prosthodontists. Those who performed surgical implant treatment exclusively

were recoded as the “surgery only” group. This was the smallest group with 11.3% of the

responders and was made up of oral surgeons and periodontists. Hence, this was the only group

made up exclusively of specialists.

Approximately 2/3 of general dentists were involved with prosthodontic treatment only, while

1/3 were involved with both the prosthodontic and surgical phases of therapy (Table 5.3). The

reverse was true for prosthodontists where approximately 2/3 were involved in both the

prosthodontic and surgical phases of treatment, while 1/3 were involved with the prosthodontic

phase only. The majority of oral surgeons and 2/3 of periodontists were involved only with the

surgical phase of therapy. Only oral surgeons and periodontists were involved exclusively in the

surgical phase of implant therapy.

The date of graduation for the dentists or dental specialists did not affect participation in the

survey (2 p-value=0.104 and 0.872 respectively) (Table 5.4).

With respect to duration of involvement in implant dentistry, specialists (oral surgeons,

periodontists, and prosthodontists) were likely to be involved in implant dentistry for a longer

period of time compared to general dentists (Table 5.4). Specifically, 53.3% of general dentists

were involved in implant dentistry less than 10 years, and only 9.6% of general dentists were

involved in implant dentistry longer than 20 years. By contrast, 77.4% of oral surgeons, 60.6%

of periodontists, and 51.2% of prosthodontists were involved in implant dentistry more than 10

years. The differences were particularly pronounced when examining specialist involvement in

implant dentistry over a period longer than 20 years. Almost half of the oral surgeons and

prosthodontists have been involved in implant dentistry for more than 20 years. These

49

differences in the duration of involvement in implant dentistry among the four professional

groups were statistically significant (2 p-value<0.001).

Among the survey responders, most dentists treated a relatively small number of patients with

implant therapy (Table 5.4). In fact, 89.5% of dentists treated 10 or fewer patients with implant

therapy per month in 2009. Clear differences emerged when examining the number of patients

treated relative to the educational status. The overwhelming majority of general dentists (96.7%)

treated 10 or fewer implant-related patients per month. In other words, only a tiny percentage of

general dentists (3.3%) treated more than 10 implant-related patients per month, while a

significant percentage of oral surgeons (40.0%), periodontists (47.1%), and prosthodontists

(26.7%) treated more than 10 implant-related patients per month in 2009. These differences in

the number of patients treated with implant therapy among the four professional groups were

statistically significant (2 p-value<0.001).

Among the survey responders, most dentists (52.7%) did not provide surgical implant treatment,

while 35.3% placed between 1 and 10 implants per month in 2009 (Table 5.4). Hence, only a

minority of dentists (12.0%) placed more than 10 implants per month. Another way to look at

the same information is to consider that among those who performed surgical implant placement,

74.6% placed 10 or fewer implants, and 25.4% placed more than 10 implants per month in 2009.

Among dentists who placed implants, the vast majority of general dentists (91.2%) and the

majority of prosthodontists (74.6%) placed 10 implants or fewer per month in 2009. The

majority of oral surgeons (64.5%) and approximately half the periodontists (46.9%) placed more

than 10 implants per month. These differences in the provision of implant-related treatments

among the four professional groups were statistically significant (2 p-value<0.001).

Among the survey responders, the majority of dentists restored (more precisely, finished

restoring) between 1 and 10 implants per month in 2009 (Table 5.4). At the same time, 16.4%

did not restore any implants, and 6.0% restored more than 10 implants per month. Another way

to look at the same information is to consider that among those dentists who restored implants,

92.9% restored 10 or fewer implants per month in 2009, while only 7.1% restored more than 10

implants per month.

50

When examining only those dentists who restored dental implants in 2009, the majority of

general dentists (94.8%) and prosthodontists (64.3%) restored fewer than 10 implants per month

(Table 5.4). However, the proportion of prosthodontists who restored more than 10 implants per

month (35.7%) was much greater than the proportion of general dentists who restored more than

10 implants per month (5.2%). Among the small number of oral surgeons and periodontists who

restored implants, the majority (approximately 75%) restored fewer than 10 implants per month

in 2009. Hence, specialists (and especially prosthodontists) who restored implants in 2009 were

more heavily involved in the prosthodontic phase of implant therapy compared to general

dentists (2 p-value<0.001).

5.B: Discussion

E-mail addresses were available for only a non-random subset of dentists in Ontario. A slightly

greater percentage of specialists had e-mail addresses that were publicly available compared to

the percentage of specialists in the Ontario dentist population. This might be a reflection of the

referral nature of specialist practices, where the ability to be readily accessible to other

professionals is important. Response rates of specialists to this survey were also slightly higher

than those of general dentists. These two factors caused a slight imbalance in the final mix of

survey responders with a greater percentage of specialists among the survey responders

compared to the Ontario dentist population.

The population of responders consisted of 383 general dentists, 31 oral surgeons, 37

periodontists, and 18 prosthodontists. The sample size calculations called for 366 general

dentists, 128 oral surgeons, 124 periodontists, and 58 prosthodontists. The survey exceeded the

desired sample size for general dentists. Although high response rates were achieved from the

specialists (e.g., 45.1% response rate for periodontists and 40.0% response rate for

prosthodontists), the ability to reach the sample size for specialists was significantly hampered

by the limited number of valid e-mail addresses available and by the fact that not all dentists

were involved in implant therapy. In particular, 68 dentists (12.7%) were not involved in

implant dentistry and, hence, did not participate in the full survey. Difficulties in achieving a

51

sufficient number of responders among certain dental specialties with relatively small

constituencies (e.g., prosthodontists) to allow for reliable statistical analysis to be carried out

have been reported in previous surveys (93). The differential response rates between specialists

and general dentists could be important since this might have an impact on interpretation of the

data, but overall it was decided that a more than adequate sample size had been attained for

analysis. The small percentage of dentists among the survey responders who were not involved

in implant dentistry (12.7%) is comparable to the 17.8% of Swiss dentists who were not involved

in implant treatment in 2006 (91), but is much lower than the 50.5% of New Zealand dentists

who were not providing implant services to their patients in 2004 (90). Although these

comparative observations among these three populations are interesting, they are difficult to

explain precisely. Differences in patterns of disease in the treatment population, dentists’

educational experiences and opportunities, economic structure of provision of dental services and

preferences of providers and patients for specific treatments (85) or treatment decisions may

account for the differences observed in the utilization of implant therapy.

Clear differences emerged regarding dentists’ treatment expertise with respect to the provision of

surgical and prosthodontic implant treatment phases. A clear majority of dentists (85.0%) had

advanced or average level of prosthodontic expertise with respect to the provision of implant

therapy, but only approximately half the dentists (49.5%) had advanced or average level of

surgical expertise. Hence, among dentists, the level of prosthodontic expertise is significantly

higher than the level of surgical expertise. This is reflected in the finding that 51.4% of the

responders focused exclusively on prosthodontic implant treatment, while only 11.3% focused

exclusively on surgical implant treatment. The dentists’ greater focus on the provision of

prosthodontic rather than surgical phases of implant therapy has been documented also in other

countries (90, 91). Among general dentists, 89.0% had advanced or average prosthodontic

expertise with respect to provision of implant therapy, but only 39.4% had advanced or average

surgical expertise. This finding parallels the data showing that with respect to provision of

implant therapy, the majority of general dentists (61.4%) focused exclusively on prosthodontic

treatment.

The finding of stronger knowledge base in prosthodontic phase of implant therapy compared to

the surgical phase of implant therapy among the survey responders correlates with the

52

preferential emphasis that dental Faculties in Europe (124) and North America (125) have been

placing on the prosthodontic implant experience compared to the surgical implant experience. A

2004 survey (125) of deans of 56 US and Canadian Dental Schools (39 of whom actually replied

to the survey) revealed that the vast majority of the Dental Schools (97%) provided didactic

instruction relating to implant therapy in the undergraduate curriculum. However, actual clinical

experience with dental implants was not as frequently available especially with respect to

surgical experience. While 86% of the Dental Schools reported that some of their students

received clinical experience in restoring implants, only 51% of the students actually received

clinical experience, and only 11.5% of the Dental Schools had a competency requirement. With

respect to clinical surgical experience, while 74% of the Dental Schools reported that some of

their students received this experience, only 28% of the students actually received this

experience, and only 2.8% of the Dental Schools had a competency requirement (125). A 2009

survey (124) of participants in the Association for Dental Education in Europe (ADEE)

workshop on implant dentistry reported similar findings. While all European Dental Schools

provided didactic implant education, only 70% of Dental Schools reported that their students

received clinical experience with implant prosthodontics by treating patients or by assisting

others. In comparison, an even smaller percentage of Dental Schools (53%) reported that their

students received clinical experience with implant surgical placement, and even then it was

largely in the capacity of a surgical assistant. The two leading barriers to the inclusion of

implant prosthodontics or implant surgery in the undergraduate curriculum included “limited

time in the curriculum” and “limited staff” (124).

An interesting and somewhat unexpected observation was that there was a high level of

prosthodontic expertise among surgical specialists and a similarly high level of surgical expertise

among prosthodontists. This observation was surprising since only two thirds of the

prosthodontists were actually involved in the provision of surgical implant services and less than

a third of the surgical specialists were actually involved in the provision of prosthodontic

services. This observation might be a reflection of the specialists’ advanced cross-training in the

complementary fields (126-128), which itself might have its origin in the need for insight into

both surgical and prosthodontic aspects during the management of complex cases likely treated

by the specialists.

53

Specialists (oral surgeons, periodontists, and prosthodontists) were involved in implant dentistry

for a longer period of time compared to general dentists. The differences were particularly

pronounced when examining specialists’ involvement in implant dentistry over a period of

greater than 20 years. In fact, almost half of oral surgeons and prosthodontists, one fifth of

periodontists, but only one tenth of general dentists had been involved in implant dentistry for

over 20 years. This is likely a reflection of the evolution of implant dentistry as it passed from

being principally within the realm of the specialist practice to the general practice. While oral

surgeons and prosthodontist were the first clinicians to become involved heavily in implant

dentistry (129), general dentists now provide an increasingly large portion of dental implant

services.

Not only did specialists tend to be involved in implant dentistry for a longer period of time, but

the individual specialists also tended to treat more implant-related patients. Only 3.3% of

general dentists treated more than 10 implant-related patients in a typical month of 2009. At the

same time, 40.0% of oral surgeons, 47.1% of periodontists, and 26.7% of prosthodontists treated

more than 10 implant-related patients per month. Among dentists who performed surgical

implant placement, the individual specialists also tended to place many more implants than the

general dentists. In fact, only 8.8% of general dentists placed more than 10 implants in a typical

month of 2009. At the same time, 64.5% of oral surgeons, 46.9% of periodontists, and 25.0% of

prosthodontists placed more than 10 implants per month. Greater involvement of specialists in

surgical implant placement in this survey is in agreement with a 2006 survey of US dentists,

which reported that annually the specialists placed an average of 99 implants and the general

dentists placed only 32 (93). Among dentists who restored implants, specialists (and especially

prosthodontists) tended to be more heavily involved in the restoration of implants. Only 5.2% of

general dentists but 35.7% of prosthodontists restored more than 10 implants in a typical month

of 2009. However, overall the size of implant-related practices was small in 2009. Most dentists

saw 10 or fewer implant-related patients per month (89.5% of dentists), surgically placed 10 or

fewer implants per month (88.0% of dentists), and restored 10 or fewer implants per month

(94.0% of dentists).

54

Chapter 6

Complications and Corrective Actions

6.A: Surgical complications – results

Table 6.1: Surgical complications reported by survey responders (N=419) in 2009

Surgical complications n Percentage of cases (N=419)

(%)

lack of primary implant stability 116 27.7

aborted surgical site 77 18.4

sinus membrane perforation (during a direct sinus lift procedure)

69 16.5

surgical stent unusable 63 15.0

significant thread exposure 63 15.0

incision line opening 54 12.9

temporary paraesthesia 48 11.5

limited patient opening 47 11.2

cover screw or healing abutment not fully seated

47 11.2

treatment not prosthetically driven 44 10.5

significant bleeding 25 6.0

wrong brand used (other than what was requested by the referring dentist)

22 5.3

severe post-operative infection 12 2.9

implant fracture during placement 11 2.6

damage to adjacent tooth 10 2.4

permanent paraesthesia 8 1.9

implant dislodged into the sinus 6 1.4

no complications 196 46.8

other (specify) 46 11.0

Total* 964 230.1

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Among survey responders, 53.2% encountered a surgical complication in 2009 (Table 6.1). The

following surgical complications were reported by the largest number of dentists (the number in

brackets is the percentage of dentists who reported this complication) – lack of primary implant

stability (27.7%), need to abort the surgical site (18.4%), and sinus perforation (16.5%). The

following surgical complications were reported by the smallest number of dentists – damage to

adjacent tooth (2.4%), permanent paraesthesia (1.9%), and implant dislodgement into the sinus

(1.4%). (Note that in the actual survey the participants were asked if they “experienced,

55

managed, or treated” complications, alluding to the fact that in addition to experiencing

complications as a consequence of the treatment they provided, dentists may also be dealing with

complications that were referred to them for treatment or management. In the interests of

brevity, the verbs “experienced,” “encountered,” or “reported” will be used singly in this thesis

to describe complications that participants “experienced, managed, or treated.”) Dentists who

experienced surgical complications (419-196=223) checked off a total of 768 responses (964-

196=768) to this multiple-response question. Hence, on average, dentists who actually

experienced surgical complications experienced 3.4 different types of surgical complications in

2009.

56

Table 6.2: Surgical complications reported by each professional group in 2009

surgical complications general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

lack of primary implant stability n 61 22 26 7 116

<0.001* % 18.3^ 71.0^ 70.3^ 41.2^

aborted surgical site n 43 10 21 3 77

<0.001* % 12.9^ 32.3 56.8 17.6

sinus membrane perforation (during a

direct sinus lift procedure)

n 19 25 23 2 69 <0.001*

% 5.7 80.6^ 62.2^ 11.8

surgical stent unusable n 21 19 22 1 63 <0.001*

% 6.3 61.3 59.5^ 5.9

significant thread exposure n 23 23 13 4 63 <0.001*

% 6.9 74.2^ 35.1 23.5

incision line opening n 22 13 12 7 54 <0.001*

% 6.6 41.9 32.4 41.2^

temporary paraesthesia n 19 14 12 3 48 <0.001*

% 5.7 45.2 32.4 17.6

limited patient opening n 22 11 13 1 47 <0.001*

% 6.6 35.5 35.1 5.9

cover screw/healing abutment not fully

seated

n 27 12 6 2 47 <0.001*

% 8.1 38.7 16.2 11.8

treatment not prosthetically driven n 31 4 4 5 44

0.066 % 9.3^ 12.9 10.8 29.4^

significant bleeding n 12 6 7 0 25

<0.001* % 3.6 19.4 18.9 0.0

wrong brand used (other than what was

requested by the referring dentist)

n 12 3 5 2 22 0.022*

% 3.6 9.7 13.5 11.8

severe post-operative infection n 6 3 2 1 12

0.047* % 1.8 9.7 5.4 5.9

implant fracture during placement n 2 6 2 1 11

<0.001* % 0.6 19.4 5.4 5.9

damage to adjacent tooth n 5 1 3 1 10

0.062 % 1.5 3.2 8.1 5.9

permanent paraesthesia n 4 3 0 1 8

0.005* % 1.2 9.7 0.0 5.9

implant dislodged into the sinus n 2 0 1 3 6

<0.001* % 0.6 0.0 2.7 17.6

no complications n 184 2 3 7 196

<0.001* % 55.1 6.5 8.1 41.2

other (specify) n 37 4 2 3 46

0.558 % 11.1 12.9 5.4 17.6

total n 334 31 37 17 419

%

Note: 1) * indicates statistical significance among the four professional groups for a specific option.

2) ^ indicates the top three reported complications within each professional group.

57

A significant percentage of general dentists (55.1%) and prosthodontists (41.2%) did not

experience any surgical complications in 2009 (Table 6.2), while only a small percentage of oral

surgeons (6.5%) and periodontists (8.1%) did not experience any surgery-related complications.

The following complications were reported by the largest number of general dentists – lack of

primary implant stability (18.3%), need to abort a surgical site (12.9%), and lack of prosthetic

treatment plan (9.3%) (Table 6.2). The following complications were reported by the largest

number of oral surgeons – sinus membrane perforation (during a direct sinus lift procedure)

(80.6%), significant thread exposure (74.2%), and lack of primary implant stability (71.0%).

The following complications were reported by the largest number of periodontists – lack of

primary implant stability (70.3%), sinus membrane perforation (during a direct sinus lift

procedure) (62.2%), and poor surgical stent design (59.5%). The following complications were

reported by the largest number of prosthodontists – lack of primary implant stability (41.2%),

incision line opening (41.2%), and lack of prosthetic treatment plan (29.4%). There was a

statistically significant difference in the experience of all commonly mentioned complications

among the four professional groups.

A much more significant proportion of oral surgeons and periodontists experiences specific

surgical complications compared to general dentists and prosthodontists (Table 6.2). None of the

specific surgical complications were experienced by more than 18.3% of general dentists or by

more than 40.2% of prosthodontists, while four surgical complications (including lack of primary

implant stability, sinus membrane perforation, and poor surgical stent design) were experienced

by more than 50% of oral surgeons and periodontists.

58

6.B: Prosthodontic complications – results

Table 6.3: Prosthodontic complications reported by survey responders (N=435) in 2009

Prosthodontic complications n Percentage of cases (N=435)

(%)

healing abutment loosening 172 39.5

poor implant position 171 39.3

prosthesis loosening or dislodgement 161 37.0

limited interocclusal clearance for restoration 84 19.3

resin/acrylic/porcelain fracture 79 18.2

implant-supported overdenture clip loosening 65 14.9

cement extrusion 62 14.3

unable to fully seat impression coping or prosthesis

55 12.6

incorrect impression taken (or had to repeat impression)

54 12.4

prosthetic screw fracture 54 12.4

prosthesis failure 45 10.3

prosthetic or abutment screw head striping 27 6.2

implant is non-restorable 20 4.6

implant fracture during function 17 3.9

implant-supported overdenture clip fracture 13 3.0

no complications 96 22.1

other (specify) 26 6.0

Total* 1201 276.1

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Among the survey responders, 22.1% did not experience any prosthodontic complications in

2009 (Table 6.3). The following prosthodontic complications were reported by the largest

number of dentists (the number in brackets is the percentage of dentists who reported this

complication) – healing abutment loosening (39.5%), poor implant position (39.3%), and

prosthesis loosening or dislodgement (37.0%). The following prosthodontic complications were

reported by the smallest number of dentists – implant is non-restorable (4.6%), implant fracture

during function (3.9%), and implant-supported overdenture clip fracture (3.0%). Dentists who

experienced prosthodontic complications (435-96=339) checked off a total of 1105 responses

(1201-96=1105) to this multiple-response question. Hence, on average, dentists who actually

experienced prosthodontic complications experienced 3.2 different types of prosthodontic

complications in 2009.

59

Table 6.4: Prosthodontic complications reported by each professional group in 2009

Prosthodontic complications general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

healing abutment loosening n 133 14 15 10 172

0.127 % 37.3^ 56.0^ 42.9^ 55.6

poor implant position n 152 2 5 12 171

<0.001* % 42.6^ 8.0 14.3 66.7^

prosthesis loosening or dislodgement n 140 1 9 11 161

<0.001* % 39.2^ 4.0 25.7^ 61.1^

limited interocclusal clearance for

restoration

n 76 1 2 5 84 0.022*

% 21.3 4.0 5.7 27.8

resin/acrylic/porcelain fracture n 66 0 1 12 79

<0.001* % 18.5 0.0 2.9 66.7^

implant-supported overdenture clip

loosening

n 53 0 3 9 65 <0.001*

% 14.8 0.0 8.6 50.0

cement extrusion n 52 3 6 1 62

0.686 % 14.6 12.0^ 17.1^ 5.6

unable to fully seat impression coping

or prosthesis

n 50 0 1 4 55 0.033*

% 14.0 0.0 2.9 22.2

incorrect impression taken (or had to

repeat impression)

n 47 2 2 3 54 0.498

% 13.2 8.0 5.7 16.7

prosthetic screw fracture n 38 5 6 5 54

0.073 % 10.6 20.0^ 17.1^ 27.8

prosthesis failure n 37 2 3 3 45

0.791 % 10.4 8.0 8.6 16.7

prosthetic or abutment screw head

stripping

n 19 1 3 4 27 0.030*

% 5.3 4.0 8.6 22.2

implant is non-restorable n 15 1 0 4 20

0.002* % 4.2 4.0 0.0 22.2

implant fracture during function n 11 2 2 2 17

0.207 % 3.1 8.0 5.7 11.1

implant-supported overdenture clip

fracture

n 8 0 0 5 13 <0.001*

% 2.2 0.0 0.0 27.8

no complications n 70 10 15 1 96

0.001* % 19.6 40.0 42.9 5.6

other (specify) n 24 0 2 0 26

0.378 % 6.7 0.0 5.7 0.0

Total n 357 25 35 18 435

According to the survey, 42.9% of periodontists, 40.0% of oral surgeons, 19.6% of general

dentists, and only 5.6% of prosthodontists did not experience any prosthodontic complications in

2009 (Table 6.4). The following complications were reported by the largest number of general

dentists – poor implant positioning (42.6%), prosthesis loosening or dislodgement (39.2%), and

healing abutment loosening (37.3%). The following complication were reported by the largest

number of oral surgeons – healing abutment loosening (56.0%), prosthetic screw fracture

60

(20.0%), and cement extrusion (12.0%). The following complications were reported by the

largest number of periodontists – healing abutment loosening (42.9%), prosthesis loosening or

dislodgement (25.7%), prosthetic screw fracture (17.1%), and cement extrusion (17.1%). The

following complications were reported by the largest number of prosthodontists – poor implant

positioning (66.7%), resin/acrylic/porcelain fracture (66.7%), and prosthesis loosening or

dislodgement (61.1%).

Among the commonly mentioned prosthetic complications (Table 6.4), there were no statistically

significant differences in the experience of the following complications among the four

professional groups – healing abutment loosening (2 p-value=0.127), prosthetic screw fracture

(2 p-value=0.073), and cement extrusion (

2 p-value=0.686). However, among the commonly

mentioned prosthetic complications, there were statistically significant differences in the

experience of the following complications among the four professional groups – poor implant

position (2 p-value<0.001), resin/acrylic/porcelain fracture (

2 p-value<0.001), and prosthesis

loosening or dislodgment (2 p-value<0.001).

A more significant proportion of prosthodontists was exposed to prosthodontic complications

compared to other specialists and general dentists (Table 6.4). Five complications were reported

by 50% or more of prosthodontists, while only one complication was reported by more than 50%

of oral surgeons, and none were reported by more than 50% of general dentists and periodontists.

In fact, if the complication of “healing abutment loosening or dislodgement” were disregarded

from the analysis, then prosthodontic complications are revealed to be experienced by relatively

small percentages of surgical specialists. The second most commonly reported prosthodontic

complications (after “healing abutment loosening or dislodgement”) were prosthetic screw

fracture (reported by only 20.0% of oral surgeons) and prosthesis loosening and dislodgment

(reported by 25.7% of periodontists).

61

6.C: Biological complications – results

Table 6.5: Biological complications reported by survey responders (N=433) in 2009

Biological complications n Percentage of cases (N=433)

(%)

implant failure 167 38.6

gingival inflammation 124 28.6

healing abutment too short (leading to soft tissue overgrowth)

121 27.9

recession (implant collar or abutment visible) 109 25.2

no interproximal papilla (must be clinically significant)

100 23.1

severe continuous bone loss 96 22.2

multiple implant failures in the same patient 54 12.5

presence of a fistula 47 10.9

bisphosphonate-related osteonecrosis of the jaws

3 0.7

mandibular fracture 1 0.2

no complications 124 28.6

other (specify) 8 1.8

Total* 954 220.3

*Note: This is a multiple-response question. The total of all responses is more than 100%.

According to the survey, 28.6% of responders did not experience any biological complications in

2009 (Table 6.5). The following biological complications were reported by the largest number

of dentists (the number in brackets is the percentage of dentists who reported this complication)

– implant failure (38.6%), gingival inflammation (28.6%), and healing abutment being too short

(leading to soft tissue overgrowth) (27.9%). The following biological complications were

reported by the smallest number of dentists – presence of a fistula (10.9%), bisphosphonate-

related osteonecrosis of the jaw (0.7%), and mandibular fracture (0.7%). Dentists who

experienced biological complications (433-124=309) checked off a total of 830 responses (954-

124=830) to this multiple-response question. Hence, on average, dentists who actually

experienced biological complications experienced 2.6 different types of biological complications

in 2009.

62

Table 6.6: Biological complications experienced by each professional group in 2009

Biological complications general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

implant failure n 113 22 24 8 167

<0.001* % 32.2^ 73.3^ 68.6^ 47.1

gingival inflammation n 89 16 13 6 124

0.006* % 25.4^ 53.3 37.1 35.3

healing abutment too short (leading to

soft tissue overgrowth)

n 75 19 16 11 121 <0.001*

% 21.4 63.3^ 45.7^ 64.7^

recession (implant collar or abutment

visible)

n 76 12 13 8 109 0.005*

% 21.7^ 40.0 37.1 47.1

no interproximal papilla (must be

clinically significant)

n 65 14 10 11 100 <0.001*

% 18.5 46.7 28.6 64.7^

severe continuous bone loss n 50 19 18 9 96

<0.001* % 14.2 63.3^ 51.4^ 52.9^

multiple implant failures in the same

patient

n 30 11 9 4 54 <0.001*

% 8.5 36.7 25.7 23.5

presence of a fistula n 26 8 10 3 47

<0.001* % 7.4 26.7 28.6 17.6

bisphosphonate-related osteonecrosis

of the jaws

n 1 1 1 0 3 0.094

% 0.3 3.3 2.9 0.0

mandibular fracture n 0 0 0 1 1

<0.001* % 0.0 0.0 0.0 5.9

no complications n 119 1 2 2 124

<0.001* % 33.9 3.3 5.7 11.8

other (specify) n 7 0 1 0 8

0.772 % 2.0 0.0 2.9 0.0

Total n 351 30 35 17 433

Almost all specialists (oral surgeons, periodontists, and prosthodontists) experienced a biological

complication, while only 66.1% of general dentists experienced a biological complication in

2009 (Table 6.6). Among general dentists, the following biological complications were reported

most commonly – implant failure (32.2%), gingival inflammation (25.4%), and recession around

an implant (21.7%). Among oral surgeons, the following biological complications were reported

most commonly – implant failure (73.3%), healing abutment being too short (63.3%), and severe

continuous bone loss (63.3%). Among periodontists, the following biological complications

were reported most commonly – implant failure (68.6), severe continuous bone loss (51.4%), and

healing abutment being too short (45.7%). Among prosthodontists, the following biological

complications were reported most commonly – no interproximal papillae (64.7%), healing

abutment being too short (64.7%), and severe continuous bone loss (52.9%). There was a

63

statistically significant difference in the experience of all commonly reported biological

complications among the four professional groups (Table 6.6).

A much larger proportion of specialists reported biological complications compared to general

dentists (Table 6.6). None of the biological complications were reported by more than 50% of

general dentists (the most commonly reported biological complications was implant failure

reported by 32.2% of general dentists). By contrast, four biological complications were reported

by more than 50% of oral surgeons, two biological complications were reported by more than

50% of periodontists, and three biological complications were reported by more than 50% of

prosthodontists.

6.D: Patient-related complications – results

Table 6.7: Patient-related complications reported by survey responders (N=397) in 2009

Patient-related complications n Percentage of cases (N=397)

(%)

patient complaint of food impaction 120 30.2

slight patient dissatisfaction with aesthetics 96 24.2

ability to clean prosthesis impaired 56 14.1

patient cannot get used to prosthesis (poor

comfort) 24 6.0

speech impaired with prosthesis 21 5.3

significant patient dissatisfaction with aesthetics 16 4.0

aspiration or ingestion 6 1.5

no complications 190 47.9

other (specify) 16 4.0

Total* 545 137.3

*Note: This is a multiple-response question. The total of all responses is more than 100%.

According to the survey, 47.9% of responders did not experience a patient-related complication

in 2009 (Table 6.7). The following patient-related complications were reported by the largest

number of dentists (the number in brackets is the percentage of dentists who reported this

complication) – patient complaint of food impaction (30.2%), slight patient dissatisfaction with

aesthetics (24.2%), and impaired ability to clean prosthesis (14.1%). The following patient-

related complications were reported by the smallest number of dentists – speech impaired with

the final prosthesis (5.3%), significant patient dissatisfaction with aesthetics (4.0%), and

64

aspiration or ingestion (1.5%). Dentists who experienced patient-related complications (397-

190=207) checked off a total of 355 responses (545-190=355) to this multiple-response question.

Hence, on average, dentists who actually experienced patient-related complications experienced

1.7 different types of patient-related complications in 2009.

Table 6.8: Patient-related complications reported by each professional group in 2009

Patient-related complications general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

patient complaint of food impaction n 89 6 16 9 120

0.006* % 27.6^ 23.1^ 47.1^ 60.0^

slight patient dissatisfaction with

aesthetics

n 69 8 11 8 96 0.017*

% 21.4^ 30.8^ 32.4^ 53.3^

ability to clean prosthesis impaired n 39 4 7 6 56

0.014* % 12.1^ 15.4^ 20.6^ 40.0^

patient cannot get used to prosthesis

(poor comfort)

n 16 2 4 2 24 0.247

% 5.0 7.7 11.8 13.3

speech impaired with prosthesis n 12 1 3 5 21

<0.001* % 3.7 3.8 8.8 33.3

significant patient dissatisfaction with

aesthetics

n 7 2 3 4 16 <0.001*

% 2.2 7.7 8.8 26.7

aspiration or ingestion n 3 0 2 1 6

0.043* % 0.9 0.0 5.9 6.7

no complications n 165 13 9 3 190

0.006* % 51.2 50.0 26.5 20.0

other (specify) n 14 1 0 1 16

0.619 % 4.3 3.8 0.0 6.7

Total n 322 26 34 15 397

Among the survey responders, 51.2% of general dentists, 50.0% of oral surgeons, 26.5% of

periodontists and 20.0% of prosthodontists did not experience a patient-related complication in

2009 (Table 6.8). General dentists reported the following complications most commonly –

patient complaint of food impaction (27.6%), slight patient dissatisfaction with aesthetics

(21.4%), and impaired ability of clean prosthesis (12.1%). Oral surgeons reported the following

complications most commonly – slight patient dissatisfaction with aesthetics (30.8%), patient

complaint of food impaction (23.1%), and impaired ability to clean prosthesis (15.4%).

Periodontists reported the following complications most commonly – patient complaint of food

impaction (47.1%), slight patient dissatisfaction with aesthetics (32.4%), and impaired ability to

clean prosthesis (20.6%). Prosthodontists reported the following complications most commonly

65

– patient complaint of food impaction (60.0%), slight patient dissatisfaction with aesthetics

(53.3%), and impaired ability to clean prosthesis (40.0%). There was a statistically significant

difference in the experience of almost all patient-related complications among the four

professional groups. The complication of “patient cannot get used to the final prosthesis

(comfort impaired)” was the only exception (2 p-value=0.247).

66

6.E: Complications reported by each professional group – results

The same data on complications that has already been presented in Tables 6.1 through 6.8 with

the focus on each of the four types of complications can be reorganized to focus on each of the

four professional groups. Tables 6.9 through 6.13 will present the 20 most common

complications reported by each of the four professional groups.

Table 6.9: Top 20 complications reported by the largest percentage of general dentists in

2009

type of complication specific complication

percentage of

general

dentists (%)

prosthodontic poor implant position 42.6

prosthodontic prosthesis loosening 39.2

prosthodontic healing abutment loosening or dislodgement 37.3

biological implant failure 32.2

patient-related patient complaint of food impaction 27.6

biological gingival inflammation 25.4

biological recession around implant or abutment 21.7

biological healing abutment too short (leading to soft tissue overgrowth) 21.4

patient-related slight patient dissatisfaction with aesthetics 21.4

prosthodontic limited interocclusal space for restoration 21.3

biological no interproximal papilla (must be clinically significant) 18.5

prosthodontic resin/acrylic/porcelain fracture 18.5

surgical lack of primary implant stability 18.3

prosthodontic implant-supported overdenture clip loosening 14.8

prosthodontic cement extrusion 14.6

biological severe continuous bone loss 14.2

prosthodontic unable to fully seat restoration 14.0

prosthodontic incorrect impression taken 13.2

surgical aborted surgical site 12.9

patient-related ability to clean prosthesis impaired 12.1

Overall, the following complications were reported by the largest percentage of general dentists

in 2009 (the number in brackets is the percentage of general dentists who reported this

complication) – poor implant position (42.6%), prosthesis loosening or dislodgement (39.2%),

and healing abutment loosening (37.3%) (Table 6.9). None of the complications were reported

by more than 50% of general dentists. Only 2 of the top 20 complications reported by the largest

67

percentage of general dentists were surgical complications, and none of these were in the top 10.

In the top 20 complications reported by the largest percentage of general dentists, there were 9

prosthodontic, 6 biologic, 3 patient-related, and 2 surgical complications.

Table 6.10: Top 20 complications reported by the largest percentage of oral surgeons in

2009

type of complication specific complication

percentage of

oral surgeons

(%)

surgical sinus membrane perforation (during a direct sinus lift procedure) 80.6

surgical significant thread exposure 74.2

biological implant failure 73.3

surgical lack of primary implant stability 71.0

biological healing abutment too short 63.3

biological severe continuous bone loss 63.3

surgical surgical stent unusable 61.3

prosthodontic healing abutment loose 56.0

biological gingival inflammation 53.3

biological no interproximal papilla (must be clinically significant) 46.7

surgical temporary paraesthesia 45.2

surgical incision line opening 41.9

biological recession around implant or abutment 40.0

surgical cover screw of healing abutment not fully seated 38.7

biological multiple implant failure in the same patient 36.7

surgical limited patient opening 35.5

surgical aborted surgical site 32.3

patient-related slight patient dissatisfaction with aesthetics 30.8

biological fistula 26.7

patient-related patient complaint of food impaction 23.1

Overall, the following complications were experienced by the largest percentage of oral surgeons

in 2009 (the number in brackets is the percentage of oral surgeons who experienced this

complication) – sinus perforation (80.6%), significant thread exposure (74.2%), and implant

failure (73.3%) (Table 6.10). Nine complications were reported by more than 50% of oral

surgeons. Oral surgeons experienced mostly surgical and biological complications – there were

only 3 other complications in the top 20 complications reported by the largest number of oral

surgeons, and only 1 in the top 10. In the top 20 complications reported by the largest number of

68

oral surgeons, there were 9 surgical, 1 prosthodontic, 8 biologic, and 2 patient-related

complications.

69

Table 6.11: Top 20 complications reported by the largest percentage of periodontists in

2009

type of complication specific complication

percentage of

periodontists

(%)

surgical lack of primary implant stability 70.3

biological implant failure 68.6

surgical sinus membrane perforation (during a direct sinus lift procedure) 62.2

surgical surgical stent unusable 59.5

surgical aborted surgical site 56.8

biological severe continuous bone loss 51.4

patient-related patient complaint of food impaction 47.1

biological healing abutment too short 45.7

prosthodontic healing abutment loose 42.9

biological recession around implant or abutment 37.1

biological gingival inflammation 37.1

surgical significant thread exposure 35.1

surgical limited patient opening 35.1

patient-related slight patient dissatisfaction with aesthetics 32.4

surgical incision line opening 32.4

surgical temporary paraesthesia 32.4

biological no interproximal papilla 28.6

biological fistula 28.6

prosthodontic prosthesis loosening or dislodgement 25.7

biological multiple implant failure in the same patient 25.7

The following complications were experienced by the largest percentage of periodontists in 2009

(the number in brackets indicates the percentage of periodontists who experienced this

complication) – lack of primary implant stability (70.3%), implant failure (68.6%), and sinus

perforation (62.2%) (Table 6.11). Six complications were reported by more than 50% of

periodontists. In the top 20 complications reported by the largest number of periodontists, there

were 8 surgical, 2 prosthodontic, 8 biological, and 2 patient-related complications. Periodontists

experienced mostly surgical and biological complications (accounting for 16 out of the top 20

complications) – there were only 4 other complications in the top 20 complications reported by

the largest percentage of periodontists, and 2 in the top 10.

70

Table 6.12: Top 20 complications reported by the largest percentage of prosthodontists in

2009

type of complication specific complication

percentage of

prosthodontists

(%)

prosthodontic poor implant position 66.7

prosthodontic resin/acrylic/porcelain fracture 66.7

biological healing abutment too short 64.7

biological no interproximal papilla (must be clinically significant) 64.7

prosthodontic prosthesis loosening 61.1

patient-related patient complaint of food impaction 60.0

prosthodontic healing abutment loose 55.6

patient-related slight patient dissatisfaction with aesthetics 53.3

biological severe continuous bone loss 52.9

prosthodontic implant-supported overdenture clip loosening 50.0

biological implant failure 47.1

biological recession around implant or abutment 47.1

surgical lack of primary implant stability 41.2

surgical incision line opening 41.2

patient-related ability to clean prosthesis impaired 40.0

biological gingival inflammation 35.3

patient-related speech impaired with prosthesis 33.3

surgical treatment not prosthetically driven 29.4

prosthodontic prosthetic screw fracture 27.8

prosthodontic limited interocclusal space for restoration 27.8

The following complications were reported by the largest percentage of prosthodontists in 2009

(the number in brackets is the percentage of prosthodontists who experienced this complication)

– poor implant position (66.7%), veneering material fracture (66.7%), and healing abutment

being too short (64.7%) (Table 6.12). Ten complications were reported by 50% or more of

prosthodontists. Only 3 of the top 20 complications reported by the largest number of

prosthodontists were surgical complications, and none of these were in the top 10. In the top 20

complications reported by the largest number of prosthodontists, there were 3 surgical, 7

prosthodontic, 6 biological, and 4 patient-related complications.

71

6.F: Corrective actions taken in response to complications – results

Table 6.13: Corrective actions taken by survey responders (N=424) in 2009 in response to

complications

Corrective actions n Percent of cases (N=424)

(%)

communicated (consulted) with another

professional about an issue with the case 260 61.3

increased length of treatment 202 47.6

retook impression 124 29.2

remade prosthesis 112 26.4

performed additional surgical procedure(s) 107 25.2

dealt with patient's dissatisfaction 103 24.3

referred patient to a specialist 50 11.8

trephined (removed) the implant 40 9.4

submerged the implant (“put it to sleep”) 24 5.7

increased fee for treatment 20 4.7

contacted PLP (Professional Liability Program) 13 3.1

none 63 14.9

total* 1118 263.7

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Only 14.9% of survey responders indicated that they did not undertake any corrective actions in

response to a complication in 2009 (Table 6.13). The following corrective actions were reported

by the largest number of dentists (the number in brackets is the percentage of dentists who

reported taking this corrective action) – communicated with another professional about an issue

with the case (61.3%), increased treatment length (47.6%), and retook impression (29.2%). The

following corrective actions were reported by the smallest number of dentists – submerged the

implant (“put it to sleep”) (5.7%), increased fee (4.7%), and contacted PLP (3.1%).

72

Table 6.14: Corrective actions taken by each professional group in 2009

Corrective actions general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

communicated (consulted) with

another professional about an issue

with the case

n 223 8 17 12 260

<0.001* % 65.4^ 26.7 47.2^ 70.6^

retook impression n 113 0 2 9 124

<0.001* % 33.1 0.0 5.6 52.9^

remade prosthesis n 100 0 4 8 112

<0.001* % 29.3^ 0.0 11.1 47.1

trephined (removed) the implant n 16 13 9 2 40

<0.001* % 4.7 43.3^ 25.0 11.8

submerged the implant (“put it to

sleep”)

n 14 6 2 2 24 0.003*

% 4.1 20.0 5.6 11.8

performed additional surgical

procedure(s)

n 52 23 28 4 107 <0.001*

% 15.2 76.7^ 77.8^ 23.5

increased length of treatment n 141 20 27 14 202

<0.001* % 41.3^ 66.7^ 75.0^ 82.4^

increased fee for treatment n 9 2 2 7 20

<0.001* % 2.6 6.7 5.6 41.2

dealt with patient's dissatisfaction n 74 11 12 6 103

0.091 % 21.7 36.7 33.3 35.3

contacted PLP (Professional Liability

Program)

n 5 2 6 0 13 <0.001*

% 1.5 6.7 16.7 0.0

referred patient to a specialist n 48 0 0 2 50

0.015* % 14.1 0.0 0.0 11.8

none n 55 3 2 3 63

0.313 % 16.1 10.0 5.6 17.6

Total n 341 30 36 17 424

According to the survey, 16.1% of general dentists, 10.0% of oral surgeons, 5.6% of

periodontists, 17.6% of prosthodontists did not undertake any corrective actions in response to a

complication in 2009 (Table 6.14). Most general dentists reported taking the following

corrective actions – communicated with another professional about an issue with treatment

(65.4%), increased treatment length (41.3%), and remade prosthesis (29.3%). Most oral

surgeons reported taking the following corrective actions – performed additional surgery

(76.7%), increased treatment length (66.7%), and trephined (removed) an implant (43.3%). Most

periodontists reported taking the following corrective actions – performed additional surgery

(77.8%), increased treatment length (75.0%), and communicated with another professional about

an issue with treatment (47.2%). Most prosthodontists reported taking the following corrective

73

actions – increased treatment length (82.4%), communicated with another professional about an

issue with treatment (70.6%), and retook impression (52.9%).

There was a statistically significant difference in the utilization of almost all corrective actions

among the four professional groups (Table 6.14). The only exception related to “dealing with

patient’s dissatisfaction” (2 p-value=0.091), where a relatively similar percentage of all four

professional groups reported undertaking this corrective action in 2009.

74

6.G: Complications and corrective actions – discussion

6.G.I: Surgical complications – discussion

The lack of primary implant stability was the most widely reported surgical complication.

Primary stability is an important determinant of future implant success (38, 74) and is a key

determinant in advanced implant treatment approaches such as immediate placement and

immediate loading (130). Lack of primary stability makes the implant unsuitable for immediate

placement or immediate loading applications, and necessitates a submerged (two-stage) approach

to avoid micromotion trauma. In type IV bone (131) and with short implants, primary stability

can be especially hard to achieve, and high failure rates have been reported previously with

classic protocols in these scenarios (132). However, more contemporary approaches with

modified surgical protocols advocating under-preparing the osteotomy and involving the use of

osteotomes to compress the bone have been shown to yield comparable results even in type IV

bone (133). The same surgical principles have been utilized successfully to ensure primary

stability and successful integration of short implants (134, 135).

“Having to abort surgical site (after attempting unsuccessfully to place an implant)” was the

second most widely reported surgical complication. This complication can be related to the

inability to achieve primary stability (which was the most commonly mentioned surgical

complication, as discussed above), but can also be related to errors in osteotomy preparation,

significant loss of adjacent osseous plates, and bone of poor quality.

Miscommunication (or lack of communication between various treatment providers) has been

recognized as a significant component of some complications related to implant therapy (119).

The concept of “prosthetically-driven treatment” emphasizes that the purpose of osseointegrated

implants is to provide support or retention to the prostheses, and hence the implants’ position

must permit these functions to be carried out successfully. Problems can arise when implant

placement proceeds without prosthodontic reconstruction in mind, either because prosthodontic

input is not obtained (i.e., treatment is not prosthetically driven) or because prosthodontic input

75

is not communicated in a manner that is usable during the surgical phase (i.e., surgical stent is

unusable). The experiences relating to the miscommunication differed among the four

professional groups responding to this survey. A significant proportion of general dentists and

prosthodontists reported “treatment not being prosthetically driven” as a complication (the third

most common complication for both professional groups). By contrast, only a minority of

surgical specialists (oral surgeons and periodontists) reported this complication in the survey. At

the same time, “surgical stent is unusable” was reported by 60% of surgical specialists (who are

the end-users of the surgical guides), but by less than 10% of general dentists and prosthodontists

(who tend to fabricate the surgical guides). These observations may echo the occasional lack of

communication between those involved in the surgical and prosthodontic phases of therapy, as

well as the lack of understanding about the limitations and challenges of each of the treatment

phases (surgical and prosthodontic).

6.G.II: Prosthodontic complications – discussion

The top three prosthodontic complications reported by the largest number of dentists included

healing abutment loosening, poor implant position, and prosthesis loosening or dislodgement.

Dentists reported these three complications almost twice as often as they did any other

prosthodontic complication. Healing abutment loosening or dislodgement is a frequently

occurring complication that is usually easily remedied but may require a very minor surgical

intervention. The frequency of this complication has not been reported commonly in the

literature. Inadequate tightening of the healing abutment, incomplete seating of the healing

abutment (usually, due to hard or soft tissue interference or impingement), and interference from

a removable prosthesis or opposing teeth are the most likely factors to account for the loosening

of healing abutments.

Poor implant position is an umbrella term for departures from the ideal prosthetically-determined

implant position in the mesio-distal, bucco-lingual, or apico-coronal orientation. Severe cases of

implant malposition usually involve significant departures from the ideal position or departures

in more than one of the orientations noted above. The most difficult implant malpositions to

resolve successfully prosthetically are those with implants angled too buccally and positioned too

buccally and too shallowly simultaneously. In very severe situations, an implant might be

76

judged to be non-restorable and might have to be removed, repositioned surgically (136), or not

included in the final prosthesis. A much smaller percentage of dentists reported experiencing a

non-restorable implant (4.6%) compared to the percentage of dentists who reported experiencing

a poorly positioned implant (39.3%). This indicates that while poor implant position is a

significant issue, it can usually be resolved by virtue of prosthetic ingenuity and patient

adaptability.

Prosthesis loosening is a well-known complication and one whose management may range from

trivial to severe. Prosthesis loosening due to screw loosening is usually a function of excessive

forces on the prosthesis, improper use of torque driver for screw tightening, and poor joint and

screw function (72). Prosthesis loosening of cement-retained prostheses is usually due to

excessive forces on the prosthesis, poor abutment-prosthesis interface design, and use of

temporary cements. Estimates of the frequency of these occurrences vary, but prosthesis

loosening has consistently been reported as being one of the most frequent prosthodontic

complications of fixed prostheses (1-3, 57). A 2008 systematic review of single implant-

supported restorations concluded that screw loosening occurred with the cumulative incidence of

12.7% after 5 years, while loss of retention due to fracture of luting cement occurred with the

cumulative incidence of 5.5% after 5 years (2). A 2004 systematic review of fixed partial

dentures supported by implants concluded that screw loosening occurred with the cumulative

incidence of 5.8% after 5 years, while loss of retention due to fracture of luting cement occurred

with the cumulative incidence of 2.9% after 5 years (3). As suggested in Section 3.D, the

occurrence of this complication may be less frequent nowadays than in the past. The most recent

systematic review on this topic concluded that abutment screw loosening in single-implant

restoration is a rare event regardless of the geometry of the implant-abutment connection

(external or internal), provided that proper anti-rotational features and torque are employed (72).

6.G.III: Biological complications – discussion

Implant failure is one of the most consistently reported complications in the dental implant

literature (Tables 3.5 and 3.6 and Section 3.B.I) (2, 3). Implant failure along with prosthesis

failure are two of the basic benchmarks used in the vast majority of studies as primary outcome

variables. A large number of endogenous and exogenous factors have been identified as

77

causative or contributory factors to implant failure (20, 38, 74), and several theories have been

advanced to explain the mechanisms of implant failure (137, 138). Most theories focus on

infectious agents, healing deficits and loading factors to account for the clustering of implant

failures soon after implant placement (early failure) or within 1 year of loading (late failure).

Longitudinal studies have suggested repeatedly that the occurrence implant failure after two

years of placement occurs rarely (18, 20, 75). The literature seems to suggest that implant

success rates have improved in the last 30 years possibly owing to better understanding of the

biological and mechanical determinants of osseointegration as well as technological

improvements.

Implant failure is not synonymous with prosthesis failure. In this regard, large fixed

prosthodontic reconstructions are often over-engineered and allow for limited implant loss

without significant harm to the functionality of the actual reconstruction. Along these lines,

implant-supported overdentures may continue to function on a reduced number of implants. In

fact, recent research indicates that a smaller number of implants (compared to the number that is

commonly utilized) may be sufficient to support an overdenture in at least some applications

(139-141). Two other concepts related to implant treatment outcomes deserve to be mentioned –

success and survival. A successful implant (142) is one that conforms to a series of

predetermined parameters. A failed implant is one that is no longer osseointegrated and, hence,

is mobile and is unable to serve its primary functions of prosthesis support and retention. A

failed implant must be removed. A surviving implant is one that does not satisfy all of the

parameters of success (e.g., by experiencing significant bone loss), but is still present in the

mouth and is still performing its prosthesis-holding role. The designation of surviving implant

does not imply a diseased state or a higher risk of future failure. It simply reflects a departure

from the set of predetermined idealized parameters (142).

6.G.IV: Patient-related complications – discussion

Most problems grouped under the category of patient-related complications involve the interface

between the patient and the prosthesis fabricated for the patient. These complications may arise

due to errors in prosthesis fabrication or design, due to constraints on prosthesis design imposed

by local anatomic limitations (including malpositioned implants), or due to insufficient

78

adaptation by the patient (either due to insufficient time allotted for adaptation or due to a too-

drastic a change in the transition from a provisional to a final prosthesis). It is important to

recognize that the time-dependent process of patient adaptation to the prosthesis takes place with

the insertion of all dental prostheses, including implant-supported and -retained prostheses (34-

36). Hence, the contributions of unrealistic patient expectations, poor dentist consent and poor

communication between the patient and treating clinician(s) can also play a role, if this period of

adaptation or its extent is not anticipated by the patient.

The most commonly reported patient-related complication among the survey responders was the

patient complaint of food impaction. This issue has received only limited attention in the

literature, and its frequency of occurrence is uncertain. In addition to the several general factors

mentioned in the preceding paragraph that can lead to patient-related complications in general,

several other scenarios can lead specifically to the complication of food impaction, including the

frequent tilting of natural teeth next to edentulous spaces where implant-supported restorations

are subsequently placed, and the fact that implant diameter tends to be narrower than the

diameter of the teeth that they replace. Both of these scenarios lead to existence of spaces

between the restoration and the adjacent natural teeth (or other restorations) where food debris

can accumulate.

6.G.V: All complication types – overall discussion

Several observations suggest that while numerous complications are encountered in clinical

practice (as attested to by the results from this survey and data reported in several other studies

(1, 3, 4, 57)), severe complications are relatively rare (143). Most of the specific complications

reported in the survey by a large proportion of the survey respondents are relatively easily

managed and largely without permanent detrimental effects. On the other hand, a number of

surgical complications that are difficult to manage or are likely to result in significant patient

disability (such as severe post-operative infection, implant fracture during placement, damage to

adjacent tooth, permanent paraesthesia, and implant dislodgement into the sinus) were reported

by fewer than 3% of respondents. Similarly, among patient-related complications significant

patient dissatisfaction with aesthetics was one of the least commonly chosen complications

(4.0% of the dentists). Removal of the implant (i.e., trephining it out) and submerging of the

79

implant (i.e., “putting it to sleep”) were reported by a very small number of dentists, suggesting

that most implant issues are resolved in clinical practice without resorting to these “last resort”

measures. Similarly, PLP had been contacted by a very small percentage of dentists, suggesting

that severe complications are either encountered relatively infrequently or do not usually lead to

significant dissatisfaction by the patient.

The relative infrequency of severe complications reported in this thesis survey parallels

observations made by others (143). For example, a 7-year report on 353 patients treated at Mayo

Clinic with 1778 implants (143) revealed that although some sort of difficulty, challenge or

complication was encountered in the management of many patients, almost all were successfully

and conservatively managed. Implant-supported prosthesis use had to be permanently

discontinued in only 4 patients (who returned to the use of a conventional removable appliance).

Only a small percentage of dentists reported experiencing complications other than those listed

as options for each of the four complication categories. Only 11.0% of responders reporting

surgical complications, 6.0% of responders reporting prosthodontic complications, 1.8% of

responders reporting biologic complications, and 4.0% of responders reporting patient-related

complications selected “other” as an option. Furthermore, the overwhelming majority of “other”

responses were actually incorrect entries in the survey. Scrutiny of participants’ “other” entries

revealed that most “other” responses were already provided among the options but were missed

by the responders. The somewhat high 11.0% of “other” responses under the surgical

complications was due to dentists entering “implant failure”, which did not appear as an option

until the survey takers reached the question about biologic complications (four questions later).

The very small percentage of dentists selecting “other” signifies that most key complications

were accounted for in the survey.

As alluded to above, the proportion of dentists reporting specific complications must be viewed

in light of several factors. First, the proportion of dentists performing particular procedures

would likely have an impact on the frequency of complications’ reporting. For example, sinus

membrane perforation as a clinically important complication would only occur to those who

perform direct sinus lift procedures. Similarly, the large number of dentists who did not report a

surgical complication in 2009 must be considered in the context of a limited number of dentists

80

involved in the surgical phase of implant treatment (Table 5.3). Second, it must also be viewed

in light of referral patterns and the likelihood of the patient reporting a specific type of concern

to a specific professional. For example, the patient would likely bring implant-supported

overdenture looseness due to clip fracture to the attention of a general dentist or a prosthodontist

rather than to the attention of an oral surgeon or a periodontist.

There was a significant difference between the four professional groups with respect to

experience of complications. First, the four professional groups reported a different mix of

complications. General dentists and prosthodontists experienced a wide array of complications

as evidenced by a fairly even mix among the four complication categories present in the top 20

complications reported by the largest percentage of general dentists and prosthodontists. By

contrast, oral surgeons and periodontists experienced principally surgical and biological

complication categories in the top 20 complications reported by the largest percentage of oral

surgeons and periodontists. The number of biologic complications experienced was relatively

constant among the four professional groups. The more narrow range of complications

experienced by surgical specialists is possibly related to their more restrictive scope of practice.

This survey revealed that only a minority of surgical specialists were involved in the

prosthodontic phase of therapy (Table 5.3).

Second, complications were reported by different percentages of the four professional groups.

None of the specific complications were reported by more than 50% of the general dentists. The

most commonly reported complication – poor implant position – was reported by 42.6% of

general dentists. By contrast, 9 complications were reported by more than 50% of the oral

surgeons, 6 complications were reported by more than 50% of periodontists, and 10

complications were reported by more than 50% of prosthodontists. This difference could

indicate that specialists are exposed to and manage a wider mix of complications compared to

general dentists. This is likely due to the greater number of patients seen for implant therapy by

the individual specialists than general dentists (Table 5.4), due to the referral patterns of patients

with complications to specialists, and due to the specialists’ longer duration of involvement in

implant dentistry (Table 5.4) (and, hence, greater length of follow-up for treated patients). It is

also likely that patients presenting to specialists for implant treatment might have treatment

needs and problems that are more complex than those seen in patients who are selected for

81

treatment by general dentists. Readers are specifically cautioned against misinterpreting the

data as if implying that certain groups experience complications more frequently than

others. The data presented in this thesis does not allow any statements to be made with

respect to the frequency of occurrence of events.

6.G.VI: Corrective actions – discussion

Corrective actions were investigated in this survey as an entity that is distinct from complications

themselves. It was thought to be important to differentiate the issues that may give rise to

corrective actions from the corrective actions themselves. Some items among the corrective

actions – such as removing an implant or “putting an implant to sleep” – were likely to be

undertaken only in response to a complication. Others – such as discussing the treatment with

another clinician or referring a patient to a specialist – may have been undertaken for a variety of

reasons. This potential uncertainty in interpretation was obviated by specifying within the

survey that the question on corrective actions referred specifically to actions taken in response to

a complication.

Very few dentists chose to increase fees in response to a complication in 2009. This is an

interesting finding in light of the fact that many corrective actions – such as remaking the

prosthesis or conducting an additional surgical procedure – are likely to require additional time

and financial commitments by the dentists. Maintaining the fees at the original pre-complication

level is possibly a deliberate strategy by the dentists to diffuse a tense situation and to keep the

patient’s trust and confidence. In fact, reduction or waiving of fees as a goodwill gesture is one

of the simple strategies that may help prevent or minimize patient dissatisfaction and risk of a

complaint or a lawsuit (144). By contrast, raising fees or attempting to enforce fees collection in

the context of a complication or a patient’s dissatisfaction with treatment are some of the reasons

suspected to contribute to the patient’s decision to file a lawsuit or a complaint to a regulatory

body (145-147). A review of legal cases in Israel (5) revealed that patients paying their own bills

without third-party involvement filed all the legal claims, suggesting that finances may play an

important role in the patients’ attitudes towards complications.

82

Chapter 7

Opinions on Complications

7.A: Causes of complications – results

Table 7.1: Causes of complications chosen by survey responders (N=397)

Causes of complications n

Percent of cases

(N=397)

(%)

poor treatment planning 286 72.0

unrealistic patient expectations 226 56.9

lack of experience 191 48.1

poor patient compliance 182 45.8

poor inter-professional communication 167 42.1

compromised medical status 160 40.3

poor knowledge of complications 150 37.8

failure to refer to a professional with greater experience (not referring to a specialist)

149 37.5

poor knowledge of implant concepts 148 37.3

poor clinical skills 139 35.0

treatment not prosthetically driven 137 34.5

company advertising portraying implant treatment as very simple and risk-free

112 28.2

poor exam 96 24.2

ignoring dental disease elsewhere in the mouth 86 21.7

lack of follow up 78 19.6

conducting surgical procedure in an infected site 73 18.4

excessive implant system complexity 65 16.4

poor consent 52 13.1

failure to follow manufacturer's recommendations 45 11.3 Total* 2542 640.3

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Survey responders stated that the following were the most important underlying causes of

complications (the number in brackets is the percentage of dentists who selected the option) –

poor planning (72.0%), unrealistic patient expectations (56.9%), and clinician’s lack of

experience (48.1%) (Table 7.1). The following underlying causes of complications were judged

to be least important – excessive complexity of the implant system (16.4%), poor consent

(13.1%), and failure to follow manufacturer’s recommendations (11.3%).

83

Table 7.2: Causes of complications chosen by each professional group

causes of complications general

dentist

oral

surgeon perio prostho total

2 P-

Value

poor treatment planning n 225 27 20 14 286

0.003* % 70.8^ 93.1^ 57.1^ 93.3^

unrealistic patient expectations n 170 21 26 9 226

0.033* % 53.5^ 72.4^ 74.3^ 60.0

lack of experience n 142 21 17 11 191

0.007* % 44.7 72.4^ 48.6 73.3^

poor patient compliance n 144 18 16 4 182

0.149 % 45.3^ 62.1 45.7 26.7

poor inter-professional communication n 132 15 9 11 167

0.012* % 41.5 51.7 25.7 73.3^

compromised medical status n 121 14 21 4 160

0.041* % 38.1 48.3 60.0^ 26.7

poor knowledge of complications n 105 19 16 10 150

<0.001* % 33.0 65.5 45.7 66.7

failure to refer to a professional with

greater experience (not referring to a

specialist)

n 108 16 16 9 149

0.020* % 34.0 55.2 45.7 60.0

poor knowledge of implant concepts n 102 18 17 11 148

<0.001* % 32.1 62.1 48.6 73.3^

poor clinical skills n 97 20 13 9 139

<0.001* % 30.5 69.0 37.1 60.0

treatment not prosthetically driven n 108 12 6 11 137

0.002* % 34.0 41.4 17.1 73.3^

company advertising portraying

implant treatment as very simple and

risk-free

n 89 7 14 2 112

0.232 % 28.0 24.1” 40.0 13.3”

poor exam n 66 13 8 9 96

<0.001 % 20.8 44.8 22.9 60.0

ignoring dental disease elsewhere in

the mouth

n 56 13 11 6 86 0.001

% 17.6 44.8 31.4 40.0

lack of follow up n 58 9 3 8 78

0.001 % 18.2 31.0 8.6” 53.3

conducting surgical procedure in an

infected site

n 53 10 6 4 73 0.096

% 16.7” 34.5 17.1 26.7

excessive implant system complexity n 56 8 1 0 65

0.014 % 17.6 27.6” 2.9” 0.0”

poor consent n 35 8 6 3 52

0.053 % 11.0” 27.6” 17.1 20.0”

failure to follow manufacturer's

recommendations

n 32 4 4 5 45 0.048

% 10.1” 13.8” 11.4” 33.3

Total n 318 29 35 15 397

%

Note: 1) * indicates statistical significance among the four professional groups for a specific option.

2) ^ indicates the top three reported complications within each professional group.

3) ” indicates the bottom three options for each professional group.

84

General dentists (Table 7.2) stated that the most important causes of complications were poor

planning (70.8%), unrealistic patient expectations (53.5%), and poor patient compliance (45.3%).

Oral surgeons stated that the most important causes of complications were poor planning

(93.1%), clinician’s lack of experience (72.4%), and unrealistic patient expectations (72.4%).

Periodontists stated that the most important causes of complications were unrealistic patient

expectations (72.4%), compromised medical status (60.0%), and poor planning (57.1%).

Prosthodontists stated that the most important causes of complications were poor planning

(93.3%), poor inter-professional communication (73.3%), poor knowledge of implant-related

concepts (73.3%), clinician’s lack of experience (73.3%), and treatment not being prosthetically

driven (73.3%).

Although there was some agreement with respect to the causative importance of some options

(such as poor planning and unrealistic patient expectations – both of which featured prominently

as the most important causes for the survey responders as a whole and for the individual

professional groups), there was significant disagreement among the professional groups with

respect to the causes of complications in terms of absolute percentages and the relative

importance of specific causes (Table 7.2). The differences of opinion among the four

professional groups were statistically significant (2 p-value<0.05) for 15 out of 19 potential

causes of complications. Only the following four potential causes of complications

demonstrated agreement among the four professional groups with respect to the frequency with

which they were selected – conducting surgical procedure in an infected site (2 p-value=0.096),

poor consent (2 p-value=0.053), poor patient compliance (

2 p-value=0.149), and company

advertising portraying implant treatment as very simple (2 p-value=0.232).

7.B: Causes of complications – discussion

Very little is known about the broad underlying causes of complications related to the use of

osseointegrated implants. Although each specific complication type may have its own unique set

of causative factors, the rationale for this question was to gain an understanding of the broad

85

issues that dentists thought were important as (direct or indirect) causative or contributing agents

to the occurrence of complications, in general. In particular, it was important to include

educational, organizational, and design factors that can lead to complications rather than focus

exclusively on individual practitioner’s clinical judgement or manual proficiency (7). Future

investigations could build on the main themes identified in this survey and tailor them to the

particular needs of more specific research questions. However, it was essential to begin with

more general issues so that the overarching problems could be identified.

Some agreement in the relative importance of the causes of complications was observed among

the four professional groups. For example, two causes (poor planning and unrealistic patient

expectations) were observed to be consistently among the most important causes of

complications, while three causes (poor consent, failure to follow manufacturer’s

recommendations and excessive implant system complexity) were consistently observed to be

among the least important causes of complications. However, significant differences of opinion

(2 p-value<0.05) were observed among the four professional groups with respect to the majority

of causes of complications. This is likely due to the differences in the scope of practice related

to implant therapy (Tables 5.3 and 5.4) and the resultant differences in the types and frequency

of complications and potential causes of complications seen by the different professional groups.

Poor planning was selected as the most important cause of implant complications (Table 7.1).

This reflects the concept that poor decisions made at the planning stage can have a significant

and far-reaching negative impact at multiple stages of implant treatment and follow up. This

notion that poor planning plays a pivotal role in the occurrence of complications is supported by

the studies examining malpractice cases in Germany (114) and Israel (5).

“Unrealistic patient expectations” was selected as the second most important cause of

complications (Table 7.1). The prominent role of unrealistic patient expectations among the

causes of complications was somewhat unexpected, since only a fraction of complication types

involve direct patient perceptions and evaluations. However, many complications ultimately

have an impact on patient-relevant outcomes such as therapeutic experience (length of treatment,

cost, number and invasiveness of interventions etc.) and aesthetic and functional outcomes. The

elective nature of dental implant treatment, the patient’s frequent lack of awareness of the

86

challenges of their care, the dentists’ frequent difficulty in visualizing the prosthodontic end-

result, and the difficulties in restoring the hard and soft tissues lost subsequent to natural tooth

loss can make it a challenge to meet patient’s expectations. Patients present to dentists with

anatomic realities and limitations as well as a set of expectations (148, 149). The ability to meet

patients’ expectations is one of the dominant determinants of patients’ satisfaction with

treatment, and presence of unmet expectations can lead to decreased satisfaction with treatment

(150-153). Although the patient’s anatomic realities and limitations may be ascertained readily

during pre-operative or intra-operative assessment, patient expectations with respect to treatment

experience and outcome of care are far more difficult to judge accurately pre-operatively and to

modify.

As dental implants have moved from being a novel therapeutic saviour used to address the

debilitating consequences of edentulism to a readily available consumer commodity advertised

as a seamless cure for all things dental, patients’ exposure to and awareness of dental implants

have increased significantly (154, 155) and have resulted in patients having high expectations of

implant treatment (148, 156). In particular, while the first patients seeking treatment with

osseointegrated implants focused on improvements in function (19, 157), patients in the

contemporary society increasingly seek aesthetic as well as functional improvements (158). All

interventions involve the time-dependent elements of healing and adaptability (34-36), neither of

which is completely under the dentists’ control. All artificial devices depart somewhat from the

biological structures they aim to replace and emulate. This departure from “ideal” may provide

the focus point for disagreement between providers and consumers of care. Despite the

shortcomings of all artificial devices, studies have repeatedly and convincingly demonstrated

high levels of patient satisfaction with implant prostheses (159, 160). Although managing

patient expectations is never easy, the data in this thesis suggest that meeting the patients’

expectations may be especially difficult due to constraints that can be imposed by complications.

The data from this thesis that place “unrealistic patient expectations” so prominently as a

possible causative factor of complications associated with dental implants corroborate

observations from the medical field (50, 161). The suggestion that patients themselves

(including their conduct, communication skills, and expectations) may play a role in causing or

contributing to the occurrence of some complications is an intriguing possibility that is being

87

increasingly explored in the medical field (50). As shown in a survey of physicians conducted in

2002 (161), 58% of respondents thought that patients were “often” or “somewhat often” at least

partially responsible for errors made in their own care.

Clinician’s lack of experience was selected as the thirds most important cause of complications

(Table 7.1). This assertion finds some support in the clinical dental literature. For example,

some studies have reported implant failure to be greater among novice surgeons (162). In

particular, one research group (70) observed that inexperienced surgeons (defined as those who

placed fewer than 50 implants) had an implant failure rate that was twice that of more

experienced colleagues, and the highest failure rate was observed for the first nine cases. At the

same time, other studies have suggested that level of training does not impact on the success rate

for dental implant treatment (163). In this regard, an investigation of implant failure rates as a

function of oral surgery resident level of training concluded that these two variables were

independent of each other (163). However, this finding must be interpreted with caution. A high

level of supervision is likely present in a surgical residency program and this would be expected

to mitigate against errors, complications, and failures that might otherwise occur. By contrast,

practitioners in private practice, who may have limited knowledge and experience, do not have

the “luxury” of continual expert advice and oversight and inadvertently may make erroneous

judgments that clinicians with greater experience would not be expected to make.

Based on the foregoing, it would seem that clinicians with limited prior implant treatment

experience should expect a learning curve (70) and should choose treatment cases accordingly

(131, 164, 165). Indirect support for the concept that learning and experience have an impact on

treatment outcome is found in the literature documenting the early experiences and experiments

with osseointegrated implants carried out by the Branemark group (19, 166, 167). This group

identified four chronological phases based on the gradual changes and improvements in

treatment protocols – developmental phase (the earliest) and three routine phases 1, 2, and 3

(with the 3rd

phase being the most recent) (167). During the developmental phase, treatment was

developed by trial and error based on fundamental surgical and prosthodontic principles.

Moving from developmental phase to routine phases 1 through 3, the treatment techniques,

materials and approaches continued to be modified, refined, and perfected based on prior

experience during the preceding phases and creating, in the end, a standard treatment

88

methodology. Comparisons of outcome data among these four phases clearly show that the

earliest developmental groups had the highest failure rates, while the lowest failure rates were

seen in the latter groups (especially, routine groups 2 and 3) (167).

In the medical literature, clinician’s lack of experience has also been cited as an important

causative factor in complications. Several studies (67, 68) correlated the level of residency

training with the number or severity of errors. For example, in separate investigations it was

found that prescription errors were more common among first year residents than among other

clinicians (67), and that mistakes were more common with inexperienced clinicians, or when

new techniques were introduced (69). Physicians are known to acknowledge the role that

experience plays in achieving successful treatment outcomes. A 2002 survey of physicians (161)

demonstrated that respondents thought that a preventable error is more likely to occur at a low-

volume hospital (as opposed to a high-volume hospital), and, similarly, “limiting high-risk

procedures to those who perform many of these procedures” was one of the most effective

possible solutions to the problem of medical errors.

Although, the putative causative factors that were investigated in this question on the causes of

complications may seem intuitive, only a minority of them have been rigorously investigated.

Concerns have been raised about drawing quick conclusions between the hypothesized causative

processes and the adverse outcomes (complications) they are eventually presumed to cause (22).

The objective of this thesis was to ascertain dentists’ opinions regarding the causes of

complications. Until strong clinical research is able to support the importance of these factors,

caution is advised in interpretation of the dentists’ opinions on the causative factors leading to

complications.

89

7.C: Preventive strategies to decrease occurrence of complications –

results

Table 7.3: Strategies to prevent occurrence of complications chosen by survey responders

(N=405)

Preventive strategies n

Percent of cases

(N=405)

(%)

better treatment planning 275 67.9

be self-critical and learn from complications 230 56.8

treatment to be prosthetically driven 229 56.5

refer difficult cases to a specialist 218 53.8

better dentist education 209 51.6

better inter-professional communication 195 48.1

better patient education 172 42.5

implant companies to publish more information about complications

149 36.8

better dissemination of research about complications 148 36.5

greater research into complications 140 34.6

greater pre-testing of technologies before introduction to the market

92 22.7

follow manufacturer recommendations 84 20.7

establish mandatory implant complication reporting system 46 11.4

greater professional body role 43 10.6

establish a specialty of implantology 25 6.2 Total* 2255 556.8

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Most survey responders (Table 7.3) stated that the following actions should be undertaken to

decrease the occurrence of complications (the number in brackets represents the percentage of

dentists who selected the option) – better treatment planning (67.9%), being self-critical and

learn from complications (56.8%), and treatment to be prosthetically driven (56.5%). The

following options were selected least often when answering what should be done to decrease the

occurrence of complications – mandatory implant complication reporting (11.4%), greater

professional body role (10.6%), and establishment of the specialty of implantology (6.2%).

90

Table 7.4: Strategies to prevent occurrence of complications chosen by each professional

group

Preventive strategies general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

better treatment planning n 217 23 23 12 275

0.623 % 66.8^ 74.2^ 67.6^ 80.0^

be self-critical and learn from

complications

n 175 26 21 8 230 0.013*

% 53.8^ 83.9^ 61.8^ 53.3

refer difficult cases to a specialist n 157 23 27 11 218

<0.001* % 48.3 74.2^ 79.4^ 73.3^

treatment to be prosthetically driven n 179 22 15 13 229

0.014* % 55.1^ 71.0 44.1 86.7^

better dentist education n 162 17 20 10 209

0.457 % 49.8 54.8 58.8 66.7

better inter-professional

communication

n 153 15 17 10 195 0.521

% 47.1 48.4 50.0 66.7

better patient education n 136 10 17 9 172

0.256 % 41.8 32.3 50.0 60.0

implant companies to publish more

information about complications

n 119 13 11 6 149 0.870

% 36.6 41.9 32.4 40.0

better dissemination of research about

complications

n 114 13 13 8 148 0.465

% 35.1 41.9 38.2 53.3

greater research into complications n 111 12 10 7 140

0.653 % 34.2 38.7 29.4 46.7

greater pre-testing of technologies

before their introduction to the market

n 72 5 10 5 92 0.448

% 22.2 16.1” 29.4 33.3

follow manufacturer recommendations n 65 10 5 4 84

0.298 % 20.0 32.3 14.7” 26.7”

establish mandatory implant

complication reporting system

n 28 6 8 4 46 0.005*

% 8.6” 19.4” 23.5” 26.7”

greater professional body role n 20 8 8 7 43

<0.001* % 6.2” 25.8 23.5” 46.7

establish a specialty of implantology n 19 0 5 1 25

0.095 % 5.8” 0.0” 14.7” 6.7”

Total n 325 31 34 15 405

%

Most general dentists (Table 7.4) stated that the following actions should be undertaken to

decrease the occurrence of complications – better treatment planning (66.8%), treatment to be

prosthetically driven (55.1%), and dentists to be self-critical and learn from complications

(53.8%). Most oral surgeons stated that that the following should be done to decrease the

occurrence of complications – be self-critical and learn from complications (83.9%), better

treatment planning (74.2%), and refer difficult cases to specialists (74.2%). Most periodontists

stated that the following should be done to decrease the occurrence of complications – refer

91

difficult cases to specialists (79.4%), better treatment planning (67.6%), and be self-critical and

learn from complications (61.8%). Most prosthodontists stated that the following should be done

to decrease the occurrence of complications – treatment to be prosthetically driven (86.7%),

better treatment planning (80.0%), and refer difficult cases to specialists (73.3%).

There was significant agreement with respect to the possible preventive strategies to decrease the

occurrence of complications. The differences of opinion among the four professional groups

were not statistically significant for 10 out of the 15 potential preventive strategies (Table 7.4).

Only the following 5 potential preventive strategies registered a statistically significant

difference in the opinions among the four professional groups – treatment to be prosthetically

driven (2 p-value=0.014), greater professional body responsibility (

2 p-value<0.001), be self-

critical and learn from complications (2 p-value=0.013), refer difficult cases to specialists (

2 p-

value<0.001), and mandatory implant complication reporting (2 p-value=0.005).

7.D: Preventive strategies to decrease occurrence of complications –

discussion

The objective of the question on preventive strategies was to elucidate what broad strategies

could be undertaken to prevent occurrence of complications. Ultimately, preventive strategies

are meant to address the causes of complications. In this regard, each complication and each

cause of complications may have its own extensive list of potential preventive strategies.

However, it was not intention of this investigation to produce an exhaustive list of overly

specific strategies but, instead, to investigate a limited set of preventive strategies that might

cover the broadest possible range while focusing on the most pertinent and widely applicable

educational, organizational, and other approaches to prevention of complications (7).

Some broad agreement on what should be done to prevent complications was observed among

the four professional groups. Three potential preventive strategies – “better treatment planning,”

“being self-critical and learning from complications,” and “referring difficult cases to specialists”

– were recommended most frequently as preventive strategies, while two other preventive

strategies – “establishing a specialty of implantology” and “establishing a mandatory implant

92

complication system” – were least frequently recommended. There was significant agreement

among the four professional groups with respect to most possible preventive strategies to

decrease the occurrence of complications.

“Better treatment planning” and “treatment to be prosthetically driven” were the most frequently

selected strategies for prevention of complications arising during or subsequent to treatment with

osseointegrated implants. The importance given to prosthetic treatment planning prior to

surgical intervention as a preventive strategy is an indication of a well-acknowledged

communication issue in implant dentistry (168). Surgical and anatomic restrictions may lead to

implant placement in a position that is obtrusive to an optimal restorative outcome (119). Since

surgical implant placement and restorative implant treatment are often done by two different

clinicians, the actions of one clinician can have a direct negative effect on the ability of the other

clinician to provide a satisfactory treatment outcome for the patient. The need for implant

treatment to be prosthetically driven means that optimal implant position should be dictated

largely by restorative, rather than exclusively surgical, considerations (168).

Interestingly, specialists were significantly more likely than general dentists to regard “referral of

difficult cases to a specialist” as a significant strategy for preventing complications. Only half of

the general dentists (48.3%) (the fifth most important prevention strategy) but 70-80% of

specialists (consistently in the top three of the most important prevention strategies) selected

“referral of difficult cases to a specialist” as a significant strategy for preventing complications.

This finding was echoed in the question about the underlying causes of complications. There,

“failure to refer to a specialist” was regarded as one of the most important causative factors by

34.0% of general dentists and by 45.7% to 60.0% of specialists. Specialists, by virtue of their

advanced education and experience (126-128, 169), are not only better able to prevent

complications but also to manage them. The contrast between the views of general dentists and

specialists may also be accounted for by their differences in the number and the difficulty of

implant patients treated by each group (Table 5.4).

The fact that the following three options – mandatory implant complication system (11.4%),

greater professional body role (10.6%), and establishment of the specialty of implantology

(6.2%) – were selected least often when answering what should be done to decrease the

93

occurrence of complications may suggest that dentists do not desire greater regulatory oversight

or involvement in this field. The support for a new specialty of implantology appears to be

particularly low. Regulatory statutes on the status of implantology as a dental specialty vary

widely around the world as do dentists’ opinions on this matter (96). Dentists in some

geographic regions support the existence or emergence of the specialty of implantology or the

necessity of additional advertisable qualifications before a practitioner is permitted to engage in

the practice of implant dentistry. For example, in a 2004 survey of a convenience sample of 104

general dental practitioners in the U.K. (among whom only 2.8% had dental implant experience)

(96), 68.9% thought that a dentist should have an implantology qualification before being able to

advertise provision of dental implant services to the public. Roughly the same percentage

(69.8%) felt that there should be a specialty of implantology. Although the specialty of

implantology exists in a number of jurisdictions (e.g., Columbia (170)), this is not so in North

America (171) or in most member states of the European Union (172). In North America, the

field of implantology is recognized to be an integral part of general dentistry and of a number of

dental specialties including oral surgery, periodontics, and prosthodontics (173). However,

informal proposals for granting specialty status to implantology have been advanced and debated

in North America (174, 175).

The development of a system that requires mandatory reporting of complications is an integral

part of a number of initiatives aimed at identification of global trends in medical adverse events.

Establishing error reporting systems (both mandatory and voluntary) has been a consistent

recommendation of a large number of organizations focusing on reduction of medical errors (e.g.

Institute of Medicine [IOM] and Quality Interagency Coordination Task Force [QuIC] (8)).

Such systems are able to identify potential problems before they could become noted by the

individual medical professionals. Only one country – Finland (81) – is known to keep a record

of all implanted devices (including osseointegrated dental implants) and to make this information

available publicly.

Very little is known about public’s perception of what should be done to prevent medical errors.

In a 1997 telephone survey of US adults (32) the most effective strategies for prevention of

medical errors were felt to be (percentage in brackets indicates the percentage of responders who

chose that option) “preventing doctors with bad track record from providing care” (75%), “better

94

training of doctors” (69%), “careful selection of doctors by patients” (61%), “better patient

information” (54%), and “formation of an independent organization to investigate causes of

medical mistakes” (52%). At the same time, “lawsuits against those who make medical

mistakes” (29%) and “stricter government regulation of health care system” (27%) were felt to

be less effective in preventing complications or errors.

95

7.E: Severity of complications – results

Table 7.5: Most severe complications chosen by survey responders (N=403)

Complications n

Percent of cases

(N=403)

(%)

permanent paraesthesia 259 64.3

increased number of surgical procedures 203 50.4

poor appearance of the final prosthesis 199 49.4

unable to achieve satisfactory outcome as it was originally envisioned

181 44.9

damage to adjacent tooth 178 44.2

increased possibility of treatment failure 178 44.2

frequent breakage of the final prosthesis 176 43.7

poor comfort of the final prosthesis 165 40.9

increased cost of treatment 149 37.0

increased complexity of treatment 136 33.7

interference with proper speech with the final prosthesis 125 31.0

increased length of treatment 117 29.0

increased length of recovery from surgery 112 27.8

increased number of non-surgical procedures 106 26.3

temporary paraesthesia 99 24.6

cleaning difficulty of the final prosthesis 87 21.6

increased effort on the part of the dentist 61 15.1

increased number of radiographs 29 7.2 Total* 2560 635.2 *Note: This is a multiple-response question. The total of all responses is more than 100%.

Most survey responders (Table 7.5) reported that the following were the most severe

complications (the number in the brackets indicates percentage of dentists who selected this

option) – permanent paraesthesia (64.3%), increased number of surgical procedures (50.4%), and

poor appearance of the final restoration (49.4%).

96

Table 7.6: Most severe complications chosen by each professional group

Complications general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

permanent paraesthesia n 204 25 23 7 259

0.122 % 63.4^ 80.6^ 65.7^ 46.7^

increased number of surgical

procedures

n 154 23 19 7 203 0.043*

% 47.8^ 74.2^ 54.3^ 46.7^

poor appearance of the final prosthesis n 155 17 19 8 199

0.801 % 48.1^ 54.8 54.3^ 53.3^

unable to achieve satisfactory outcome

as it was originally envisioned

n 137 20 17 7 181 0.124

% 42.5 64.5^ 48.6 46.7^

damage to adjacent tooth n 138 19 15 6 178

0.257 % 42.9 61.3 42.9 40.0

increased possibility of treatment

failure

n 138 16 18 6 178 0.620

% 42.9 51.6 51.4 40.0

frequent breakage of the final

prosthesis

n 143 11 14 8 176 0.642

% 44.4 35.5 40.0 53.3^

poor comfort of the final prosthesis n 132 14 16 3 165

0.351 % 41.0 45.2 45.7 20.0”

increased cost of treatment n 124 9 9 7 149

0.299 % 38.5 29.0 25.7 46.7

increased complexity of treatment n 101 15 14 6 136

0.198 % 31.4 48.4 40.0 40.0

interference with proper speech with

the final prosthesis

n 104 10 8 3 125 0.530

% 32.3 32.3 22.9 20.0

increased length of treatment n 87 11 13 6 117

0.354 % 27.0 35.5 37.1 40.0

increased length of recovery from

surgery

n 91 12 6 3 112 0.230

% 28.3 38.7 17.1” 20.0”

increased number of non-surgical

procedures

n 81 8 11 6 106 0.542

% 25.2 25.8 31.4 40.0

temporary paraesthesia n 79 7 9 4 99

0.988 % 24.5 22.6 25.7 26.7

cleaning difficulty of the final

prosthesis

n 73 4 9 1 87 0.269

% 22.7” 12.9” 25.7 6.7”

increased effort on the part of the

dentist

n 48 5 5 3 61 0.954

% 14.9” 16.1” 14.3” 20.0”

increased number of radiographs n 26 2 1 0 29

0.467 % 8.1” 6.5” 2.9” 0.0”

Total n 322 31 35 15 403

%

Most general dentists (Table 7.6) stated that the following complications were most severe –

permanent paraesthesia (63.4%), poor appearance of the final restoration (48.1%), and increased

number of surgical procedures (47.8%). Most oral surgeons stated that the following

complications were most severe – permanent paraesthesia (80.6%), increased number of surgical

97

procedures (74.2%), and unable to achieve satisfactory outcome as it was originally envisioned

(64.5%). Most periodontists stated that the following complications were most severe –

permanent paraesthesia (65.7%), increased number of surgical procedures (54.3%), and poor

appearance of the final restoration (54.3%). Most prosthodontists stated that the following

complications were most severe – poor appearance of the final restoration (53.3%), frequent

breakage of the final restoration (53.3%), increased number of surgical procedures (46.7%),

permanent paraesthesia (46.7%), and unable to achieve satisfactory outcome as it was originally

envisioned (46.7%).

Substantial agreement emerged in the opinions of dentists regarding the severity of

complications (Table 7.6). Almost all severity options demonstrated no statistically significant

difference in the opinions on severity among the four professional groups. Three complications

(increased number of surgical procedures, permanent paraesthesia, and poor appearance of the

final restoration) were consistently selected by the four professional groups as being most severe,

and three complications (increased number of radiographs, increased effort on the part of the

dentist, and cleaning difficulty of the final restoration) were consistently selected as being least

severe.

7.F: Severity of complications – discussion

Dentists were asked to select the most severe complication(s) from a list of mostly patient-

focused negative outcomes. We used “patient-friendly” terminology avoiding complex dental

terms where possible. Complications ranged from those affecting the process of care (e.g.,

duration of treatment, cost, recovery from surgery, number of procedures or appointments) to

those affecting the outcome of care (e.g., perception of prosthesis appearance, speech, comfort,

cleaning, and breakage). In future investigations, the opinions held by members of the public on

implant-related complications will be examined. In particular, it would be interesting to examine

if the opinions on severity of complication differ between dentists and the general public. No

such information is available in the dental implant literature, and inconsistent results have been

reported comparing opinions of medical professionals to those of patients or members of the

98

public when considering complications (56). Divergence of opinions may occur because patients

may not be aware of the importance of a symptom that they perceive as minor, while the health

care professionals may not regard an issue as a complication, if they perceive it to be a part of a

normal post-operative course (176). Whereas the patient is the only one who can give a full

account of the post-operative course, the treating clinician has a better knowledge of what to

expect and what to characterize as a deviation from normality (177). The views of both parties

may need to be taken into account to gain a better overall view.

Several severity grading scales for complications have been proposed in the medical literature

(46, 47, 52). However, the majority of studies in the medical field do not use grading scales in

reporting complications, and those studies that do use grading scales simply tend to group them

under the subjective and ill-defined categories of “minor complications” and “major

complications” (56). Although the terms “major” and “minor” are used commonly in the

medical literature, they have been applied inconsistently among authors, treatment centers, and

over time periods, and many authors have argued against their continued use (56). Along these

lines, the terms “major” and “minor” were not used in this thesis, and, instead, the respondents to

the survey were asked to select the complications or outcomes of complications that they felt

were most severe in their impact on the dentist, the patient, or both.

The survey responders selected permanent paraesthesia as the most severe complication (Table

7.5). Permanent paraesthesia (usually described as loss of sensation that persists longer than 6-

12 months after injury) is an irreversible outcome of nerve damage. It may interfere with social

functioning and is known to be a major factor leading to litigation (both in implant dentistry

(116) and in other surgical procedures, such as surgical removal of mandibular third molars

(178)). Several studies (179, 180) have investigated alteration in inferior alveolar nerve

sensation subsequent to the surgical placement of implants in the mandible. Bartling et al. (105)

found that none of the patients in their study who had implants placed in the mandible (with the

use of computer tomography imaging when necessary) had permanent altered sensation by 6

months. In contrast, Van Steenberghe et al. (181) reported that 6.5% of patients had altered

sensation at 1 year after implant placement in the mandible. Higher rates of temporary and

permanent paraesthesia have also been reported (182) possibly owing to different study

methodologies, variations in surgical technique, or availability of advanced imaging techniques

99

(such as computer tomography and cone-beam computer tomography). Cases of permanent

paraesthesia that led to legal action have been associated with the use of unnecessarily long

implants, inadequate imaging (i.e., the use of a single rather than multiple imaging modalities),

and violation of mandibular canal during instrumentation (rather than being the result of

mucoperiosteal flap elevation) (116). Liability was acknowledged in all cases of permanent

paraesthesia (5, 116), but only in 67% of legal cases involving dental implants in general (5),

highlighting the significant role that prevention could play in combating the occurrence of this

complication.

Several items in the survey used here allow for the differentiation in the perception of severity of

various complications in the minds of the respondents. While permanent paraesthesia was

considered to be the most severe complication, temporary paraesthesia scored close to bottom of

the list (Table 7.5). This may be a reflection of the fact that a complication with temporary

effects is far more likely to be accepted by the patient than one which is permanent or long-

lasting. Thus, a review of legal cases in Israel involving inferior alveolar nerve paraesthesia

following implant surgery concluded that only cases of permanent paraesthesia resulted in legal

action (116). The increase in the number of surgical procedures was the second most severe

complication. It scored higher in severity compared to other items describing process of care

such as increased number of non-surgical procedures, increased length of treatment, and

increased complexity of treatment. This suggests that dentists consider surgical intervention to

be a more significant step compared to non-surgical dental interventions. In the medical

literature, re-operation is also considered a significant adverse event (25) and is one of several

parameters tracked by quality assurance programs (8).

Poor appearance (49.4%) was the third most chosen complication in severity. In the minds of the

responders, it proved to be more severe than other items that refer to the patient’s perception of

the restoration such as cleaning difficulty (21.6%), interference with proper speech (31.0%), and

poor comfort (40.9%). This may be a reflection of the role that aesthetics plays in our society or

of the value that patients place on appearance as either an outcome measure or as the reason for

therapy (149). Although osseointegrated implants were applied at first with the primary goal of

improving patients’ oral function (19, 157), more recent research initiatives as well as

improvements in technology and techniques sought to optimize aesthetic outcomes and to be

100

able to deliver optimum aesthetic as well as functional results (183-185). Numerous studies

evaluating determinants of successful outcome of prosthodontic interventions suggested that

satisfaction with aesthetics is the dominant predictor of patient satisfaction (186-188).

It would appear that there is only one other study that investigated the ranking of the severity of

complications with respect to implant dentistry (6). In the investigation by Van Waas et al. (6), a

small group of specialists ranked complications with implant-supported overdentures (Table 2.7)

using a 5-point ordinal scale – “the clinical performance scale for implants” (Table 2.6). As

discussed earlier (Section 3.F), the “clinical performance scale” used by Van Waas et al. (6)

intrinsically regards implant failure as the most severe complication and judges other

complications by the likelihood with which they may lead to implant failure. Hence, it is not

surprising that implant failure and implant fracture were judged to be the most severe

complications (score of 4 out of 4), while permanent paraesthesia (referred to in this study (6)

study as “severe disturbance of the mental nerve”) had a score of 2 out of 4. The drawbacks of

this study (6) were discussed earlier (Section 3.F). This thesis differed in a number of significant

aspects from Van Waas et al. study (6), and this might account for the differences in results.

Van Waas et al. (6) examined complications as they would be perceived by the dentists without

regard for the subsequent steps that might be needed to remedy or treat the complication in

question. Their ranking was achieved using a consensus building method using a small number

of specialists. By contrast, this survey instrument in this thesis focused mostly on patient-

relevant outcomes. The dentists in this survey were asked to choose the most severe

complications from a limited list of 18 items, and the severity ranking was inferred from the

relative frequency with which each of the complications was chosen. Implant failure and

implant fracture were not on this list, and neither were most of the other 49 specific

complications that made up the specific complications of the four questions on surgical,

prosthodontic, biologic, and patient-related complications. Notably, each complication might

create a range of difficulties ranging in severity from trivial to very severe; hence, attempting to

rank complications without the knowledge of the ultimate impact on the patient or the dentist is

of limited value (64). For example, a failed implant under a full-arch screw-retained prosthesis

can be retrieved easily (frequently without local anesthesia) and might require no additional

treatment. By contrast, an implant that has failed under a full-arch cemented prosthesis could

present an entirely different problem and one that is much more difficult to solve. An implant

101

that fails prior to prosthesis fabrication is an unfortunate event. But it has much less of an impact

than an implant that fails after it was already restored with a single crown. Lastly, for most

patients, implant failure represents just the beginning of efforts to ameliorate the effects of the

failure. It can lead to additional steps such as additional surgical procedures, increased length of

treatment, or increased fees, and it is the relative severity of these steps or outcomes that was

examined in the survey instrument used in this thesis.

Overall, there appears to be little agreement among the four professional groups as to the causes

of complications (Table 7.2), some agreement on what should be done to decrease occurrence of

complications (Table 7.3), and a great deal of agreement on the severity of complications (Table

7.6) as well as the preventability of complications (Table 8.1). This suggests that beliefs

regarding the causes of complications are specialty- or educational background-specific, and, as

such, they may be influenced by the types of procedures performed or by the types of

complications encountered in clinical practice. However, beliefs regarding the severity of

complications and their preventability appear to be independent of specialty affiliation or

educational background as evidenced by the similar choices being made by members of all four

professional groups in this survey. Perception of severity of any particular complication may

depend of such attributes as reversibility, impact on patient functioning, impact on the treatment

outcome, and even likelihood of legal or professional liability arising as a result of the

complication. Ultimately, however, the factors that govern formation of these beliefs are

unknown.

102

7.G: Source of knowledge about complications – results

Table 7.7: Sources of knowledge about complications identified by survey responders

(N=418)

Sources of knowledge about implant complications n

Percent of cases

(N=418)

(%)

continuing education courses 346 82.8

my own experience 287 68.7

speaking with colleagues 227 54.3

conferences 175 41.9

dental implant journals 164 39.2

implant company representatives 100 23.9

textbooks 94 22.5

specialty program 61 14.6

dental school curriculum 25 6.0 Total* 1479 353.8

*Note: This is a multiple-response question. The total of all responses is more than 100%.

Table 7.7b: Sources of knowledge about complications identified by survey responders who

graduated in the last 10 years (N=50)

Sources of knowledge about implant complications n

Percent of cases

(N=50)

(%)

continuing education courses 39 78.0

speaking with colleagues 32 64.0

my own experience 27 54.0

dental implant journals 17 34.0

textbooks 14 28.0

specialty program 12 24.0

conferences 11 22.0

dental school curriculum 9 18.0

implant company representatives 4 8.0 Total* 165 330.0*

Note: This is a multiple-response question. The total of all responses is more than 100%.

Survey responders (Table 7.7) obtained the most information on implant complications from the

following sources – continuing education courses (82.8%), dentist’s own experience (68.7%),

and speaking with colleagues (54.3%). Interestingly, the dental school curriculum (6.0%) was

103

the least important source of information regarding implant complications. The minimal

importance of dental school curriculum as a source of information regarding implant

complications was found even among those who graduated from dental school within the last 10

years (i.e., among those who likely had significant exposure to dental implant therapy as part of

their undergraduate curriculum (189, 190)) (Table 7.7b).

Table 7.8: Sources of knowledge about complications identified by each professional group

Sources of knowledge about implant

complications

general

dentist

oral

surgeon

period

ontists

prostho

dontists total

2 P-

Value

continuing education courses n 292 23 25 6 346

<0.001* % 86.6^ 76.7^ 69.4^ 40.0

my own experience n 227 25 24 11 287

0.323 % 67.4^ 83.3^ 66.7^ 73.3^

speaking with colleagues n 183 16 19 9 227

0.971 % 54.3^ 53.3 52.8 60.0^

conferences n 126 22 20 7 175

<0.001* % 37.4 73.3^ 55.6 46.7

dental implant journals n 122 13 21 8 164

0.041* % 36.2 43.3 58.3 53.3

implant company representatives n 91 1 5 3 100

0.012* % 27.0 3.3 13.9 20.0

textbooks n 71 11 7 5 94

0.168 % 21.1 36.7 19.4 33.3

specialty program n 18 9 22 12 61

<0.001* % 5.3 30.0 61.1^ 80.0^

dental school curriculum n 19 2 3 1 25

0.927 % 5.6 6.7 8.3 6.7

Total n 337 30 36 15 418

%

General dentists (Table 7.8) obtained most of their information concerning complications with

implant treatment from continuing education courses (86.6%), their own experience (67.4%),

and by speaking with colleagues (54.3%). Oral surgeons obtained most of their information on

implant complications from their own experience (83.3%), continuing education courses

(76.7%), and conferences (73.3%). Periodontists obtained most of their information on implant

complications from continuing education courses (69.7%), their own experience (66.7%), and

their specialty program training (61.1%). Prosthodontists obtained most of their information on

implant complications from specialty program (80.0%), their own experience (73.3%), and by

speaking with colleagues (60.0%). For each of the four professional groups, dental school

104

curriculum was one of the least likely sources of information about implant complications (range

from 5.6% to 8.3%)

7.H: Source of knowledge about complications – discussion

The survey responders indicated that the most common source of information about implant

complications was continuing education courses. The importance of continuing education

courses in implant education observed in this survey parallels the observations made in several

national surveys (90, 91). For instance, almost all dentists involved in the provision of implant

care in Switzerland in 2006 undertook further training in implantology (91), and 65.8% of all

New Zealand dentists attended at least one continuing education implant course (90).

Personal experience appears to play a significant role in providing dentists with knowledge and

information about complications arising from therapy with osseointegrated implants. This

observation is encouraging because it suggests that dentists are able to learn from the

complication that they had observed or experienced. This observation of the importance of

personal experience is substantiated by the findings obtained from the answers to the question in

the thesis survey relating to what should be done to prevent complications. There, “being self-

critical and learning from complications” was the second most commonly chosen option (second

only to “better treatment planning”) as a key to what should be done to decrease occurrence of

complications (Table 7.3).

Dental school curriculum was ranked consistently as one of the least important sources of

information regarding the management and aetiology of complications. However, this must be

viewed in the context of the relatively recent widespread introduction of implant dentistry into

the undergraduate curriculum (189, 190). Nonetheless, even among recent graduates (Table

7.7b) dental school was still ranked as one of the least important sources of information. This

may reflect an actual void in the undergraduate implant curriculum or a poor recall of learned

information. Although education in implant dentistry is now a consistent part of virtually all

105

dental school curricula (189, 190), the topic of complications is perhaps being inadequately

addressed.

In relation to the foregoing, osseointegrated dental implants have been successfully utilized in

academic centers since the late 1960’s (19). However, dental implants were introduced to the

undergraduate curriculum only relatively recently. Two 2002 surveys of dental schools in

Europe (189) and the United States (190) demonstrated that prior to 1990 only a small

percentage of schools offered undergraduate implant courses. The percentage of schools

teaching undergraduate implant courses rose rapidly during the 1990s, and by 2000 the vast

majority of schools offered these courses. Surveys of dentists in the U.K. (96) and New Zealand

(90) corroborated these findings. Only 24.5% of responders to a 2004 survey of general dental

practitioners in the U.K. stated that they were taught implant dentistry at an undergraduate level

(96). A 2004 survey of New Zealand dentists (90) showed that only 20.5% had implant

curriculum in their primary degree program. This percentage corresponded roughly to the 20.5%

of the New Zealand dentists who graduated within the last 10 years.

106

7.I: Responsibility to keep dentists informed about potential implant

complications – results

Table 7.9: Responsibility for informing dentists about potential implant complications as

chosen by all responders (n=418)

Responsibility for informing dentists about potential

implant complications Frequency

Percent

(%)

my own – it is my responsibility to educate myself 325 77.8

implant company 35 8.4

regulatory body 31 7.4

dental school 27 6.5

Total 418 100.0

Table 7.10: Responsibility for informing dentists about potential implant complications as

chosen by each professional group

Responsibility for informing

dentists about potential implant

complications

general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

my own – it is my responsibility

to educate myself

n 271 25 20 9 325

0.012*

% 80.4^ 80.6^ 57.1^ 60.0^ 77.8

implant company n 28 2 4 1 35

% 8.3 6.5 11.4 6.7 8.4

regulatory body n 20 2 5 4 31

% 5.9 6.5 14.3 26.7 7.4

dental school n 18 2 6 1 27

% 5.3 6.5 17.1 6.7 6.5

Total n 337 31 35 15 418

% 100.0 100.0 100.0 100.0 100.0

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)

general

dentists

oral

surgeons

period

ontists

prostho

dontists

general dentists

0.978 0.005* 0.019

oral surgeons

0.233 0.290

periodontists

0.579

prosthodontists

107

Among survey responders (Tables 7.9 and 7.10), the majority of dentist (77.8%) and the majority

of each of the four professional groups stated that it was the dentists’ own responsibility to

educate themselves on the subject of implant complications. However, a notable percentage of

periodontists and prosthodontists (approximately 40%) felt that the responsibility for educating

dentists about complications resided elsewhere – with an implant company, a dental school, or a

regulatory body. In particular, 26.7% of prosthodontists (vs. 7.4% for the overall sample of

dentists) felt that regulatory bodies (e.g., American Dental Association [ADA], Canadian dental

association [CDA], Royal College of Dental Surgeons of Ontario [RCDSO]) have a

responsibility to educate dentists about implant complications. However, only the difference of

opinion between general dentists and periodontists (2 p-value=0.005) was statistically

significant (p-value<0.008) once the Bonferroni correction for multiple comparisons was done

(0.05/6=0.008) (Table 7.11).

7.J: Responsibility to keep dentists informed about potential implant

complications – discussion

Most dentists felt that it was their own responsibility to educate themselves about implant

complications. The high value the dentists place on keeping themselves informed confirmed the

answers given to previous questions in this survey regarding the sources of information about

implant complications and regarding prevention of implant complications. The responders to

this survey had already indicated earlier (Table 7.7) that they received most of their information

on implant complications from continuing education courses, personal experience, and

consultation with colleagues.

108

7.K: Percentage of patients experiencing complications – results

Table 7.12: Percentage of patients experiencing complications reported by each

professional group and by all survey responders (n=428)

Percentage of patients experiencing

complications (%)

general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

0-5 n 272 23 23 9 327

0.039* % 78.6 76.7 65.7 52.9 76.4

>5 n 74 7 12 8 101

% 21.4 23.3 34.3 47.1 23.6

n 346 30 35 17 428

% 100.0 100.0 100.0 100.0 100.0

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)

general

dentists

oral

surgeons

period

ontists

prostho

dontists

general dentists

0.804 0.082 0.013

oral surgeons

0.333 0.094

periodontists

0.374

prosthodontists

Overall, most survey responders (76.4%) stated that only 0-5% of their patients experienced a

complication in 2009, while 23.6% of dentists stated that more than 5% of their patients

experienced a complication (Table 7.12). However, while just over 20% of general dentists

stated that more than 5% of their patients experienced complications in 2009, a larger percentage

of specialists stated that more than 5% of their patients experienced complications. Almost half

of prosthodontists (47.2%) stated that more than 5% of their patients experienced complications.

However, the difference in opinion between general dentists and prosthodontists (2 p-

value=0.013) was no longer statistically significant (p-value<0.008) following the Bonferroni

correction for multiple comparisons (0.05/6=0.008) (Table 7.13).

109

7.L: Percentage of patients experiencing complications – discussion

A relatively low percentage of patients was reported by their dentists to have experienced a

complication with dental implant treatment in 2009. The less than 5% complication rate may

seem low compared to the frequency of occurrence of the numerous specific complications as

reported in several narrative and systematic reviews (1-4, 20, 57) (Chapter 3). For example,

implant failure rate alone has been repeatedly reported to be around 5% (20, 21, 181). The cause

for this slightly lower than expected rate of complications is uncertain, but may be accounted for

by several factors. First, as alluded to earlier (Section 3.D), the time delay in publication of

research on complications may mean that contemporary experience of complications is, in fact,

less frequent than the research published previously on the basis of the historical data suggests.

Second, the clinical situations treated in private practices may be of lesser complexity than those

treated in academic centers (where most of the research on implant complications is published)

and, hence, clinical cases treated in contemporary private practices may be less likely to

experience complications.

A trend was observed for the specialists to report that a greater percentage of their patients

experienced a complication with respect to implant therapy as compared to the general dentists.

This was particularly pronounced in the case of prosthodontists. However, none of these trends

were statistically significant, possibly due to the limited number of prosthodontists who

completed the survey and the resultant lack of power to detect a difference.

110

Chapter 8

Preventability of Complications

8.A: Results

Table 8.1: Preventability of complications

type of

complication

is it

preventable?

general

dentists

oral

surgeons

period

ontists

prostho

dontists total

2 P-

Value

surgical yes

n 268 26 30 15 339 0.336

% 89.9 83.9 85.7 100.0 89.4

total n 298 31 35 15 379

prosthodontic yes

n 296 20 29 13 358 0.342

% 87.3 95.2 90.6 76.5 87.5

total n 339 21 32 17 409

biological yes

n 219 16 20 9 264 0.523

% 67.8 55.2 64.5 60.0 66.3

total n 323 29 31 15 398

patient-related yes

n 269 24 25 13 331 0.713

% 82.5 88.9 78.1 86.7 82.8

total n 326 27 32 15 400

new

complication in

2009

yes n 53 3 4 3 63

0.501 % 63.1 100.0 50.0 60.0 63.0

total n 84 3 8 5 100

Overall, the survey responders stated that the majority of complications of all four categories

(surgical, prosthodontic, biological, and patient-related) were preventable (Table 8.1). This was

particularly so with respect to surgical, prosthodontic, and patient-related complications (where

89.4%, 87.5%, and 82.8% of the dentists respectively stated that they were preventable).

Biological complications were felt to be less preventable than the other three complication

categories, with only 66.3% of the dentists stating that biological complications were

preventable. There was no statistically significant difference among the four professional groups

with respect to opinions on preventability of any category of complications.

111

Similar information was obtained when dentists were asked about their experience with new

complications in 2009. A quarter of the dentists (24.7%) stated that they experienced a new

complication in 2009 (i.e., a complication that they were not aware of until one of their patients

experienced it). Among these dentists, 63.0% indicated that this new complication could have

been prevented had they had prior educational information about this particular complication.

8.B: Discussion

Issues of preventability were ascertained on two separate occasions. First, respondents were

asked about preventability of each of the four categories of complications. Second, the dentists

were asked whether they had experienced a new complication in 2009 that they were not aware

of until one of their patients experienced it for the first time. Those who answered “yes” were

asked if they thought this complication could have been prevented had they had prior

information about this specific complication.

Survey responders as a whole and all four professional groups stated that complications were

largely preventable. This was particularly apparent with respect to the surgical, prosthodontic,

and patient-related complication categories (where 80-90% of dentists stated that they were

preventable). Biological complications were also preventable but this opinion was held by a

lower percentage of dentists (66.3%). The fact that biological complications were less

preventable than the other categories may be explained by the presence of complications within

this category that are dependent on patient’s biological response and patient’s intrinsic factors

that are imperfectly understood and not necessarily under the dentist’s control. Under these

circumstances, the ability to precisely predict outcome of treatment (including the possibility of

negative outcome or failure) may be hampered. Three biological complications in particular –

absence of interproximal papilla (191, 192), implant failure, and recession – can be difficult to

predict, to treat, or both. For example, a substantial amount of literature on implant failure (20,

38, 74) has been published and a number of risk factors (74) have been identified (see Section

3A). However, the retrospective determination of the cause of implant failure in any given

112

situation is very difficult and uncertain, and the cause is often attributed to vague parameters

such as “poor surgical technique” or “clinician’s inexperience”.

The issue of preventability of complications (15) has only rarely been examined in the medical

literature and even then largely indirectly. In particular, preventability has been evaluating by

estimating the proportion of adverse outcomes that are due to error or negligence (15). For

example, a severe allergic reaction that resulted from a patient receiving a medication to which

the patient was known to be allergic would be considered a preventable complication. By

contrast, preventability of complications has not been examined or defined in the dental implant

literature. In this survey, preventability was defined broadly as follows: “preventability” means

that with additional effort or attention the complication could have been avoided or its negative

consequences significantly diminished. To avoid the uncertainty in the definition or the

differences in interpretation of the term “preventability” from influencing the results, this term

was defined explicitly within the survey.

An interesting trend, that was not statistically significant, was observed between prosthodontists

and surgical specialists with respect to preventability of surgical and prosthodontic

complications. With respect to surgical complications, prosthodontists were more likely than

surgical specialists (100.0% vs. 84.8%) to think that they were preventable. With respect to

prosthodontic complications, prosthodontists were less likely than surgical specialists (76.5% vs.

92.5%) to think that they were preventable. No such trend was observed in examining biological

and patient-related complications. Each of these professional groups (prosthodontists and oral

surgeons) is challenged with treating and resolving the most difficult and tasking situations

within their respective scopes of practice. The study results might suggest that each group of

specialists may have an acute appreciation of the limitations in preventability of complications

within its own scope of practice while at the same time holding a more optimistic view of the

ability of the other specialty group to prevent complications within its scope of practice.

Preventability of complications has not been directly addressed in the dental implant literature.

However, opinions have been expressed that complications are largely avoidable given the

iatrogenic nature of many complications (5, 117). The results of three malpractice studies in

Germany and Israel (5, 114) support the contention that dental implant complications (especially,

113

severe complication) are preventable (62, 117). Reviews of these legal cases identified errors

and deficiencies in diagnosis and planning in the overwhelming majority of malpractice cases

(5). Consequently, liability was acknowledged in the majority of cases (5) and in all cases of

permanent altered sensation (5, 116). All studies highlighted the deficiencies in preoperative

assessment, diagnosis and planning as causative agents in complications. Since preoperative

assessment, diagnosis and planning occur prior to the inception of the actual treatment,

correction of errors at these stages would have far reaching positive consequences in prevention

of negative treatment occurrences and unsatisfactory outcomes.

The dentists’ belief in a high degree of preventability of complications is encouraging, since it

suggests that the frequency or severity of complications may be decreased. The belief in

preventability of treatment complications expressed by the respondents in this research is in an

agreement with research findings from the medical hospital management field (16, 17),

government policies (8), the views of the public (32), and the experience in reducing

complications in several inherently risky activities (such as aviation (193) and medical

anaesthesia (194)). In the Harvard Medical Malpractice study (15) errors in management were

identified in 58% of adverse events. Leape et al. (15) concluded that although prevention of

many adverse events is hampered by limitations in current medical knowledge, the high

proportion that is due to management errors suggests that many others are potentially

preventable. Several inherently risky human activities (e.g., aviation (193)) and medical

endeavours (e.g., anaesthesia (194)) have been able to decrease substantially the occurrence of

accidents or complications by rigorously seeking out and eliminating sources of errors (195).

While limitations in current knowledge preclude us from eliminating negative occurrences in

health care entirely, the successes in aviation (193) and anesthesia (194) clearly demonstrate the

potential degree to which errors, accidents, and complications can be prevented.

114

Chapter 9

Overall Discussion and Conclusions

9.A: Study limitations

The observations and conclusions reported in this thesis must be interpreted within the

limitations of the study design. In this regard, several features of the survey could have biased

the results. One problem faced by this investigation was a low response rate that probably

limited analysis of some subgroups due to low numbers (i.e. the problem of inadequate power

could have prevented some of the findings from reaching statistical significance). The survey

was relatively long and many questions had a large number of options – this can lead to fatigue

on the part of the respondents and may account for lower response rates to some questions

towards the end of the survey. Due to these limitations, the outcomes of this investigation may

be regarded as preliminary. In spite of these limitations, evidence from medical and dental

literature corroborated many of the observations and conclusions, thereby enhancing the notion

that the themes explored in this survey accurately reflect the clinical experiences and opinions of

the dental professionals.

The study relied entirely on self-reporting, thereby putting faith in the dentists’ ability and

willingness to recall information accurately. The degree to which professionals self-report

adverse events is unknown and is understandably hard to investigate. Self-reporting of events is

a function of event recall and willingness to report it. It is hypothesized that event types that

occurred more frequently or that created a strong emotional imprint on the dentist (due to their

severity or patient impact, for example) would be more likely to be recalled and registered as a

survey response. The discrepancy between the occurrence of adverse events and their voluntary

reporting (28) as well as the discrepancy between patient-perceived occurrence of post-operative

complications and surgeon-perceived occurrence of complications (176, 177) has been reported

in several studies in the medical literature dealing with hospitalized patients. To address the

possible hesitancy of some potential survey participants in revealing information about

complications and adverse events that they experienced, the web-based survey was deliberately

conducted anonymously.

115

The response rate was 23%, which might be considered to be relatively low. However, this is

compatible with the response rates reported in a number of other recent surveys of Ontario

dentists (e.g. a 17.3% response rate in a mailing survey of Ontario dentists’ local anesthetic use

(196) and a 15% response rate to a web-based survey examining opinions on endodontic

treatment (Dr. Amir Azarpazhooh, Personal Communication)). Nonetheless, the desired sample

size for general dentists was actually exceeded. High response rates were achieved from the

specialists (e.g. 45.1% response rate for periodontists and 40.0% response rate for

prosthodontists), but the ability to reach the desired sample size for specialists was significantly

hampered by the limited number of valid e-mail addresses available.

E-mail addresses were available for only a non-random subset of dentists in Ontario. (This issue

was already discussed in Section 5.B.) Hence, caution should be exercised in extrapolating data

from this survey sample to the entire dentist population of Ontario.

9.B: Study strengths

The major strength of this study was the ability to investigate the experience of complications

and opinions on a range of issues related to implant complications on the same geographically

defined population of dentists. This study was one of the first of its kind to investigate the

opinions of dentists regarding complications in implant dentistry. This study was also one of the

first to evaluate a large range of complications on a large single population, and was one of the

first to report on dentists’ experience with a number of specific complications. Such

complications included lack of primary implant stability, having to abort a surgical site, use of a

wrong implant brand (i.e., other than what was requested by the referring dentist), surgical stent

unusable (or not made how the dentists wanted it made), and food impaction.

This study was the first to look into the distribution of specific complications reported by a

population of dentists (rather than investigating the frequency of occurrence among dentists).

The following example makes the distinction clear. If 50 occurrences of a specific complication

occurred among 50 dentists, the frequency of occurrence would be one complication per dentist.

However, it is possible that all 50 occurrences were related to one single dentist, while the other

116

49 dentists had never encountered this complication. The distribution of the specific

complication in a dentist population would have taken that into account. Because only 1 dentist

out of 50 experienced the complication, only 2% (1 in 50) would have reported this complication

in this survey. Therefore, this approach allows for the determination of how widely an issue is

encountered among dentists, rather than determining how frequently it is encountered. An issue

that is reported by a small number of dentists may still be very important by virtue of its severity

or the frequency with which it occurs among those dentists. However, the educational and

preventive approaches that might be pursued would vary significantly depending on the

proportion of dentists affected by the problem.

It is important to point out that a web-based survey rather than a traditional mail-out survey was

used in this study. Web-based surveys provide a number of significant benefits over traditional

mail-based surveys, and in recent years these benefits have been increasingly acknowledged and

utilized. Web-based surveys have been demonstrated to be valid alternatives to traditional mail-

and telephone-based surveys (197) while potentially enhancing survey completion rates (198)

and significantly reducing turnaround time and administration costs. These advantages have led

researchers to increasingly rely on web-based surveys in preference to the traditional mail-out

surveys. The accessibility of the target population to the internet remains the most important

issue with web-based surveys (197). However, this concern was considered to be minimal for

our study due to the above average usage of the internet among Canadian dentists (199).

The medical field contains a very broad literature base on complications, but there is a dearth of

such literature in the sphere of dental implant treatment. In the course of this thesis, concepts

and examples drawn from the medical literature were frequently used. Yet, significant

differences exist in the provision and consumption of health care between the in-patient medical

setting and the out-patient dental setting. These differences must be carefully considered when

interpreting medical literature and attempting to view it with a dental setting in mind. In

particular, most patients receiving dental implants do so for elective reasons seeking

improvements in the quality of life. Therefore, dental implant treatment is almost always an

elective treatment, and the assessment of risks and benefits must be viewed in this light.

117

9.C: Implications and conclusions

The goal of dental implant treatment is to address patient-centered concerns in a cost-effective

and minimally intrusive manner that provides the patient with the greatest therapeutic benefit and

exposes the patient to the least risk. Since no intervention is entirely risk-free, the range of

possible complications must always be considered. This cross-sectional survey was a

preliminary attempt to clarify the relative experience of dentists with specific dental implant

complications in contemporary private practices and to determine dentists’ opinions regarding

those complications. A large number of complications and corrective actions were characterized

and reported in a single dentist population serving a large and diverse community of several

million people in Ontario, Canada. The knowledge of how complications are distributed among

different professional groups of general dentists and specialists may allow future intervention

strategies to be implemented targeting these specific groups, ultimately enhancing the quality of

implant treatment delivery.

This survey is one of the first to investigate dentists’ opinions on complications in a systematic

manner. Overall, there was little agreement among the four professional groups regarding the

causes of complications, some agreement regarding what should be done to decrease occurrence

of complications, and a great deal of agreement regarding the severity of complications and their

preventability. This suggests that beliefs regarding the causes of complications are specialty- or

educational background-specific. Thus, they may be influenced by the types of procedures

performed or by the types of complications encountered in clinical practice. However, beliefs

regarding the severity of complications and their preventability appear to be independent of

specialty affiliation or educational background.

The majority of dentists felt that complications were preventable. This observation reinforces

research results from other healthcare settings (15-17). Preventability of complications

highlights the need to focus on improvements in operator education, skill, and judgment as well

as improvements in technology that facilitate acquisition of operator knowledge and skill or

improve operator judgment. The focus on these human elements is likely to lead to further

reductions in complications associated with implant treatment. Nonetheless, many procedures

118

carry risks that are understood incompletely and cannot be prevented entirely given the current

state of knowledge. A two-pronged approach dealing with the occurrence of both preventable

and currently non-preventable complications may be actively pursued to minimize the burden of

complications. Preventable complications may be addressed through educational channels and

through improvements in inter-professional and provider-patient communication. Currently non-

preventable complications may be addressed through research into their causative elements,

through preferential selection of procedures with a favourable complication profile, and through

careful patient selection that takes into account the gravity of the underlying condition and the

probability of successful treatment outcome. The dental workplace may be designed to permit

surveillance of adverse outcomes and to permit implementation of strategies to prevent their

occurrence and recurrence. Ideally, dentists would be able to address problems in their practices

preventively before the problems actually occur. Future research efforts should investigate the

impact of various intervention strategies aimed at prevention of dental implant complications.

119

Bibliography

(1) Goodacre CJ, Bernal G, Rungcharassaeng K, Kan JYK. Clinical complications with implants

and implant prostheses. J Prosthet Dent 2003;90(2):121-132.

(2) Jung RE, Pjetursson BE, Glauser R, Zembic A, Zwahlen M, Lang NP. A systematic review

of the 5-year survival and complication rates of implant-supported single crowns. Clin Oral

Implants Res 2008;19(2):119-130.

(3) Pjetursson BE, Tan K, Lang NP, Bragger U, Egger M, Zwahlen M. A systematic review of

the survival and complication rates of fixed partial dentures (FPDs) after an observation period

of at least 5 years. Clin Oral Implants Res 2004;15(6):667-676.

(4) Berglundh T, Persson L, Klinge B. A systematic review of the incidence of biological and

technical complications in implant dentistry reported in prospective longitudinal studies of at

least 5 years. J Clin Periodontol 2002;29 Suppl 3:197-212.

(5) Givol N, Taicher S, Halamish-Shani T, Chaushu G. Risk management aspects of implant

dentistry. Int J Oral Maxillofac Implants 2002;17:258-262.

(6) Van Waas MA, Geertman ME, Spanjaards SG, Boerrigter EM. Construction of a clinical

implant performance scale for implant systems with overdentures with the Delphi method. J

Prosthet Dent 1997;77(5):503-509.

(7) Kohn LT, Corrigan JM, Donaldson MS editors. To err is human: building a safer health

system. Washington, D.C.: National Academy Press; 1999.

(8) Quality Interagency Coordination Task Force. Doing what counts for patient safety: Federal

actions to reduce medical errors and their impact. Washington: QuIC Task Force; 2000.

(9) The Joint Commission. About the Joint Commission. Available at:

http://www.jointcommission.org/AboutUs/. Accessed 8/1, 2010.

(10) Banja J. Medical errors and medical narcissism. Boston: Jones and Barlett; 2005.

120

(11) Gawande A. Complications: a surgeon’s notes on an imperfect science. New York:

Metropolitan Books; 2002.

(12) Gawande A. The learning curve. The New Yorker 2002 Jan 28, 2002.

(13) Wachter R, Shojania K. Internal bleeding: the truth behind America’s terrifying epidemic of

medical mistakes. New York: Rugged Land; 2004.

(14) Gawande AA, Thomas EJ, Zinner MJ, Brennan TA. The incidence and nature of surgical

adverse events in Colorado and Utah in 1992. Surgery 1999;126(1):66-75.

(15) Leape LL, Brennan TA, Laird N, Lawthers AG, Localio AR, Barnes BA, et al. The nature

of adverse events in hospitalized patients. Results of the Harvard Medical Practice Study II. N

Engl J Med 1991;324(6):377-384.

(16) Bhasale AL, Miller GC, Reid SE, Britt HC. Analyzing potential harm in Australian general

practice: an incident-monitoring study. Med J Aust 1998;169(2):73-76.

(17) Fischer G, Fetters MD, Munro AP, Goldman EB. Adverse events in primary care identified

from a risk-management database. J Fam Pract 1997;45(1):40-46.

(18) Albrektsson T, Dahl E, Enbom L, Engevall S, Engquist B, Eriksson AR, et al.

Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted

Nobelpharma implants. J Periodontol 1988;59(5):287-296.

(19) Branemark PI, Hansson BO, Adell R, Breine U, Lindstrom J, Hallen O, et al.

Osseointegrated implants in the treatment of the edentulous jaw: experience from 10-year period.

Stockholm: Almqvist & Wiksell; 1977.

(20) Esposito M, Hirsch JM, Lekholm U, Thomsen P. Biological factors contributing to failures

of osseointegrated oral implants. (I) Success criteria and epidemiology. Eur J Oral Sci

1998;106:527-551.

(21) Creugers NH, Kreulen CM, Snoek PA, de Kanter RJ. A systematic review of single-tooth

restorations supported by implants. J Dent 2000;28(4):209-217.

121

(22) Hofer TP, Kerr EA, Hayward RA. What is an error? Eff Clin Pract 2000;3(6):261-269.

(23) Martin RCG, Brennan MF, Jaques DP. Quality of complication reporting in the surgical

literature. Ann Surg 2002;235(6):803-813.

(24) Morris JA, Carrillo Y, Jenkins JM, Smith PW, Bledsoe S, Pichert J, et al. Surgical adverse

events, risk management, and malpractice outcome: morbidity and mortality review is not

enough. Ann Surg 2003;237(6):844-851.

(25) Dekutoski MB, Norvell DC, Dettori JR, Fehlings MG, Chapman JR. Surgeon perceptions

and reported complications in spine surgery. Spine 2010;35(9):9-9.

(26) Brennan TA, Leape LL, Laird NM, Hebert L, Localio AR, Lawthers AG, et al. Incidence of

adverse events and negligence in hospitalized patients. Results of the Harvard Medical Practice

Study I. N Engl J Med 1991;324(6):370-376.

(27) Rampersaud YR, Moro ERP, Neary MA, White K, Lewis SJ, Massicotte EM, et al.

Intraoperative adverse events and related postoperative complications in spine surgery:

implications for enhancing patient safety founded on evidence-based protocols. Spine

2006;31(13):1503-1510.

(28) Mirza SK, Deyo RA, Heagerty PJ, Turner JA, Lee LA, Goodkin R. Towards standardized

measurement of adverse events in spine surgery: conceptual model and pilot evaluation. BMC

Musculoskelet Disord 2006;7:53-53.

(29) Homsted L. Institute of Medicine report: to err is human: building a safer health care

system. Fla Nurse 2000;48(1):6-6.

(30) Jacobs S, O'Beirne M, Derfiingher LP, Vlach L, Rosser W, Drummond N. Errors and

adverse events in family medicine: developing and validating a Canadian taxonomy of errors.

Can Fam Physician 2007;53(2):271-276.

(31) National Coordinating Council for Medication Error Reporting and Prevention. NCC MERP

Index for Categorizing Medication Errors. 2001; Available at:

http://www.nccmerp.org/pdf/indexColor2001-06-12. Accessed 8/1, 2010.

122

(32) National patient safety foundation at AMA. Public opinion of patient safety issues: research

findings. 1997; .

(33) The Joint Commission. Definition of sentinel event. Available at:

http://www.jointcommission.org/SentinelEvents/. Accessed 8/1, 2010.

(34) Haraldson T, Carlsson GE. Bite force and oral function in patients with osseointegrated oral

implants. Scand J Dent Res 1977;85(3):200-208.

(35) Jemt T. Failures and complications in 391consequitively inserted fixed prostheses supported

by Branemark implants in edentulous jaws: a study of treatment from time of prosthesis

placement to the first annual checkup. Int J Oral Maxillofac Implants 1991;6:270-276.

(36) Lundqvist S, Haraldson T, Lindblad P. Speech in connection with maxillary fixed

prostheses on osseointegrated implants: a three-year follow-up study. Clin Oral Impl Res

1992;3(4):176-180.

(37) Laney WR editor. Glossary of oral and maxillofacial implants. Berlin: Quintessence

Publishing Co, Ltd; 2007.

(38) Duyck J, Naert I. Failure of oral implants: aetiology, symptoms and influencing factors. Clin

Oral Investig 1998;2(3):102-114.

(39) Lang NP, Berglundh T, Heitz-Mayfield LJ, Pjetursson BE, Salvi GE, Sanz M. Consensus

statements and recommended clinical procedures regarding implant survival and complications.

Int J Oral Maxillofac Implants 2004;19 Suppl:150-154.

(40) Garg AK. Implant dentistry: a practical approach. 2nd ed. China: Mosby Elsevier; 2010.

(41) Taylor TD. Prosthodontic problems and limitations associated with osseointegration. J

Prosthet Dent 1998;79(1):74-78.

(42) Chee W, Jivraj S. Failures in implant dentistry. Br Dent J 2007;202(3):123-129.

123

(43) Cehrell MC, Karasoy D, Kokat AM, Akca K, Eckert SE. Systematic review of prosthetic

maintenance requirements for implant-supported overdentures. Int J Oral Maxillofac Implants

2010;25:163-180.

(44) Johansson G, Palmqvist S. Complications, supplementary treatment, and maintenance in

edentulous arches with implant-supported fixed prostheses. Int J Prosthodont 1990;3(1):89-92.

(45) Payne AGT, Solomons YF. The prosthodontic maintenance requirements of mandibular

mucosa- and implant-supported overdentures: a review of the literature. Int J Prosthodont

2000;13:238-245.

(46) Clavien PA, Sanabria JR, Strasberg SM. Proposed classification of complications of surgery

with examples of utility in cholecystectomy. Surgery 1992;111(5):518-526.

(47) Strasberg SM, Linehan DC, Hawkins WG. The accordion severity grading system of

surgical complications. Ann Surg 2009;250(2):177-186.

(48) Camire E, Moyen E, Stelfox HT. Medication errors in critical care: risk factors, prevention

and disclosure. CMAJ 2009;180(9):936-943.

(49) Agency for Healthcare Research and Quality (AHRQ), Department of Health and Human

Services USA. Quality indicators. Available at:

http://www.qualityindicators.ahrq.gov/index.htm. Accessed 8/1, 2010.

(50) Buetow S, Kiata L, Liew T, Kenealy T, Dovey S, Elwyn G. Patient error: a preliminary

taxonomy. Ann Fam Med 2009;7(3):223-231.

(51) National Cancer Institute. Common Terminology Criteria for Adverse Events. Available at:

http://ctep.cancer.gov/protocolDevelopment/electronic_applications/ctc.htm. Accessed 8/1,

2010.

(52) Dindo D, Demartines N, Clavien P. Classification of surgical complications: a new proposal

with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004;240(2):205-

213.

124

(53) Pomposelli JJ, Gupta SK, Zacharoulis DC, Landa R, Miller A, Nanda R. Surgical

complication outcome (SCOUT) score: a new method to evaluate quality of care in vascular

surgery. J Vasc Surg 1997;25(6):1007-1014.

(54) Veen MR, Lardenoye JW, Kastelein GW, Breslau PJ. Recording and classification of

complications in a surgical practice. Eur J Surg 1999;165(5):421-424.

(55) Bruce J, Russell EM, Mollison J, Krukowski ZH. The measurement and monitoring of

surgical adverse events. Health Technol Assess 2001;5(22):1-194.

(56) Clavien PA, Barkun J, de Oliveira ML, Vauthey JN, Dindo D, Schulick RD, et al. The

Clavien-Dindo classification of surgical complications: five-year experience. Ann Surg

2009;250(2):187-196.

(57) Goodacre CJ, Kan JY, Rungcharassaeng K. Clinical complications of osseointegrated

implants. J Prosthet Dent 1999;81(5):537-552.

(58) Greenstein G, Cavallaro J, Romanos G, Tarnow D. Clinical recommendations for avoiding

and managing surgical complications associated with implant dentistry: a review. J Periodontol

2008;79(8):1317-1329.

(59) Misch K, Wang H. Implant surgery complications: etiology and treatment. Implant Dent

2008;17(2):159-168.

(60) Park SH, Wang HL. Implant reversible complications: classification and treatment. Impl

Dent 2005;14:211-220.

(61) Bashutski JD, Wang H. Common implant esthetic complications. Implant Dent

2007;16(4):340-348.

(62) Zarb GA, Schmitt A. The longitudinal clinical effectiveness of osseointegrated dental

implants: the Toronto study. Part III: problems and complications encountered. J Prosthet Dent

1990;64:185-194.

(63) Aglietta M, Siciliano VI, Zwahlen M, Bragger U, Pjetursson BE, Lang NP, et al. A

systematic review of the survival and complication rates of implant supported fixed dental

125

prostheses with cantilever extensions after an observation period of at least 5 years. Clin Oral

Implants Res 2009;20(5):441-451.

(64) Eckert SE. The greatest complication of them all. Int J Oral Maxillofac Implants

2010;25(1):17.

(65) Vlassis JM, Fugazzotto PA. A classification system for sinus membrane perforations during

augmentation procedures with options for repair. J Periodontol 1999;70(6):692-699.

(66) Palmqvist S, Sondell K, Swartz B. Implant-supported maxillary overdentures: outcome in

planned and emergency cases. Int J Oral Maxillofac Implants 1994;9(2):184-190.

(67) Lesar TS, Briceland LL, Delcoure K, Parmalee JC, Masta-Gornic V, Pohl H. Medication

prescribing errors in a teaching hospital. JAMA 1990;263(17):2329-2334.

(68) Wilson DG, McArtney RG, Newcombe RG, McArtney RJ, Gracie J, Kirk CR, et al.

Medication errors in paediatric practice: insights from a continuous quality improvement

approach. Eur J Pediatr 1998;157(9):769-774.

(69) Windsor JA, Pong J. Laporoscopoic biliary injury: more than a learning curve. Aust N Z J

Surg 1998;68:186-189.

(70) Lambert PM, Morris HF, Ochi S. Positive effect of surgical experience with implants on

second-stage implant survival. J Oral Maxillofac Surg 1997;55(suppl 5):12-18.

(71) Andreiotelli M, Att W, Strub J. Prosthodontic complications with implant overdentures: a

systematic literature review. Int J Prosthodont 2010;23(3):195-203.

(72) Theoharidou A, Petridis HP, Tzannas K, Garefis P. Abutment screw loosening in single-

implant restorations: a systematic review. Int J Oral Maxillofac Implants 2008;23(4):681-690.

(73) Kalpidis CD, Setayesh RM. Hemorrhaging associated with endosseous implant placement

in the anterior mandible: a review of the literature. J Periodontol 2004;75(5):631-645.

(74) Esposito M, Hirsch JM, Lekholm U, Thomsen P. Biological factors contributing to failures

of osseointegrated oral implants. (II) Etiopathogenesis. Eur J Oral Sci 1998;106(3):721-764.

126

(75) Buser D, Mericske-Stern R, Bernard JP, Behneke A, Behneke N, Hirt HP, et al. Long-term

evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective

multi-center study with 2359 implants. Clin Oral Implants Res 1997;8(3):161-172.

(76) Chan MFWY, Narhi TO, de Baat C, Kalk W. Treatment of the atrophic edentulous maxilla

with implant-supported overdentures: a review of the literature. Int J Prosthodont 1998;11(1):7-

14.

(77) Jokstad A, Braegger U, Brunski JB, Carr AB, Naert I, Wennerberg A. Quality of dental

implants. Int Dent J 2003;53(6):409-443.

(78) Lundqvist S, Lohmander-Agerskov A, Haraldson T. Speech before and after treatment with

bridges on osseointegrated implants in the edentulous upper jaw. Clin Oral Impl Res 1992;2:57-

62.

(79) Heydecke G, McFarland DH, Feine JS, Lund JP. Speech with maxillary implant prostheses:

ratings of articulation. J Dent Res 2004;83(3):236-240.

(80) Nedir R, Bischof M, Szmukler-Moncler S, Belser UC, Samson J. Prosthetic complications

with dental implants: from an up-to-8-year experience in private practice. Int J Oral Maxillofac

Implants 2006;21(6):919-928.

(81) The 2006 dental implant yearbook: the Finish dental implant register. 2006; Available at:

http://www.laakelaitos.fi/publikationer/medicintekniska.html. Accessed 1/1, 2010.

(82) Zurdo J, Romao C, Wennstrom JL. Survival and complication rates of implant-supported

fixed partial dentures with cantilevers: a systematic review. Clin Oral Implants Res 2009;20

Suppl 4:59-66.

(83) Eckert SE, Parein A, Myshin HL, Padilla JL. Validation of dental implant systems through a

review of literature supplied by system manufacturers. J Prosthet Dent 1997;77(3):271-279.

(84) Bragger U. Technical failures and complications related to prosthetic components of

implant systems and different types of suprastructures. In: Lang NP, Karring T, Lindhe J, editors.

Proceedings of the 3rd European workshop on Periodontology Berlin: Quintessence; 1999. p.

304-332.

127

(85) Carlsson GE, Kronstrom M, de Baat C, Cune M, Davis D, Garefis P, et al. A survey of the

use of mandibular implant overdentures in 10 countries. Int J Prosthodont 2004;17(2):211-217.

(86) Butterworth CJ, Baxter AM, Shaw MJ, Bradnock G. The provision of dental implants in the

National Health Service Hospital dental services--a national questionnaire. Br Dent J

2001;190(2):93-96.

(87) Japanese markets for dental implants. Impl Dent 2004;13(3):272-274.

(88) US markets for dental implants: executive summary. Impl Dent 2003;12(3):108-111.

(89) European markets for dental implants and final abutments 2004. Impl Dent 2004;13(3):193-

196.

(90) Reid D, Leichter JW, Thomson WM. Dental implant use in New Zealand in 2004. N Z Dent

J 2005;101(1):12-16.

(91) Lambrecht JT, Cardone E, Kuhl S. Status report on dental implantology in Switzerland in

2006. A cross-sectional survey. Eur J Oral Implantol 2010;3(1):71-74.

(92) Klugman R, Sgan-Cohen H, Stern N. A survey of dentists practicing implant dentistry in

Israel. J Prosthet Dent 1990;64(4):473-478.

(93) American Dental Association. 2007 Survey of current issues in dentistry: surgical dental

implants, amalgam restoration, and sedation. 2008; Available at: http://www.ada.org/1618.aspx.

Accessed 08/01, 2010.

(94) Huasong L, Yang H, de Groot K. A survey on dental care and oral implantology in Beijing,

China. Clin Oral Implants Res 1997;8(3):155-160.

(95) Akeredolu PA, Adeyemo WL, Gbotolorun OM, James O, Olorunfemi BO, Arotiba GT.

Knowledge, attitude, and practice of dental implantology in Nigeria. Implant Dent

2007;16(1):110-118.

(96) Gibson RL, Barclay CW. Dental implantology education: a survey of opinion and

experience of 106 general dental practitioners. Br Dent J 2006;201(6):367-370.

128

(97) Eckert SE, Koka S, Wolfinger G, Choi Y. Survey of implant experience by prosthodontists

in the United States. J Prosthodont 2002;11(3):194-201.

(98) Young MPJ, Carter DH, Sloan P, Quayle AA. Survey of clinical members of the association

of dental implantology in the United Kingdom: Part 1. Levels of activity and experience in oral

implantology. Implant Dent 2001;10:68-74.

(99) Lang NP, Wilson TG, Corbet EF. Biological complications with dental implants: their

prevention, diagnosis and treatment. Clin Oral Impl Res 2000;11 (Suppl 1):146-155.

(100) Zinner ID, Burke TM, Jansen CE, Neurohr FG, Small SA. Recognition of and solutions to

complications in implant prosthodontics. QDT 1998:170-182.

(101) Scacchi M, Merz BR, Schar AR. The development of the ITI dental implant system. Part 2:

1998-2000. Clin Oral Implants Res 2000;11 Suppl 1:22-32.

(102) Schwarz MS. Mechanical complications of dental implants. Clin Oral Impl Res

2000;11(suppl.):156-158.

(103) Gervais MJ, Wilson PR. A rationale for retrievability of fixed, implant-supported

prostheses: a complication-based analysis. Int J Prosthodont 2007;20(1):13-24.

(104) Salvi GE, Bragger U. Mechanical and technical risks in implant therapy. Int J Oral

Maxillofac Implants 2009;24(suppl):69-85.

(105) Bartling R, Freeman K, Kraut RA. The incidence of altered sensation of the mental nerve

after mandibular implant placement. J Oral Maxillofac Surg 1999;57(12):1408-1412.

(106) Binon PP. Implants and components: entering the new millennium. Int J Oral Maxillofac

Implants 2000;15(1):76-94.

(107) Taylor TD, Agar JR. Twenty years of progress in implant prosthodontics. J Prosthet Dent

2002;88(1):89-95.

(108) Esposito M, Hirsch JM, Lekholm U, Thomsen P. Failure patterns of four osseointegrated

oral implant systems. J Mater Sci Mater Med 1997;8(12):843-847.

129

(109) Balshi TJ. An analysis and management of fractured implants: a clinical report. Int J Oral

Maxillofac Implants 1996;11(5):660-666.

(110) Eckert SE, Meraw SJ, Cal E, Ow RK. Analysis of incidence and associated factors with

fractured implants: a retrospective study. Int J Oral Maxillofac Implants 2000;15(5):662-667.

(111) Rangert B, Krogh PH, Langer B, Van Roekel N. Bending overload and implant fracture: a

retrospective clinical analysis. Int J Oral Maxillofac Implants 1995;10(3):326-334.

(112) Shackleton JL, Carr L, Slabbert JC, Becker PJ. Survival of fixed implant-supported

prostheses related to cantilever lengths. J Prosthet Dent 1994;71(1):23-26.

(113) Carlson B, Carlsson GE. Prosthodontic complications in osseointegrated dental implant

treatment. Int J Oral Maxillofac Implants 1994;9(1):90-94.

(114) Figgener L, Kleinheinz J. Implant dentistry at the focus of liability lawsuits. Int J Oral

Maxillofac Implants 2004;19(3):382-386.

(115) Reason J. Human error: models and management. BMJ 2000;320:484-488.

(116) Chaushu G, Taicher S, Halamish-Shani T, Givol N. Medicolegal aspects of altered

sensation following implant placement in the mandible. Int J Oral Maxillofac Implants

2002;17(3):413-415.

(117) Worthington P, Bolender CL, Taylor TD. The Swedish system of osseointegrated

implants: problems and complications encountered during a 4-year trial period. Int J Oral

Maxillofac Implants 1987;2(2):77-84.

(118) Tinsley D, Watson CJ, Ogden AR. A survey of U.K. centres on implant failures. J Oral

Rehabil 1999;26(1):14-18.

(119) Binon PP. Treatment planning complications and surgical miscues. J Oral Maxillofac Surg

2007;65(7):73-92.

(120) Dillman DA. Mail and internet surveys: the tailored design method. 2nd ed. New York:

John Wiley & Sons, Inc; 2000.

130

(121) Dillman DA, Smyth JD. Design effects in the transition to web-based surveys. Am J Prev

Med 2007;32(5):90-96.

(122) Fleming CM, Bowden M. Web-based surveys as an alternative to traditional mail methods.

J Environ Manage 2009;90(1):284-292.

(123) Raosoft Inc. Sample size calculator. Available at: http://www.raosoft.com/samplesize.html.

Accessed 8/1, 2010.

(124) De Bruyn H, Koole S, Mattheos N, Lang NP. A survey on undergraduate implant dentistry

education in Europe. Eur J Dent Educ 2009;13 Suppl 1:3-9.

(125) Petropoulos VC, Arbree NS, Tarnow D, Rethman M, Malmquist J, Valachovic R, et al.

Teaching implant dentistry in the predoctoral curriculum: a report from the ADEA Implant

Workshop's survey of deans. J Dent Educ 2006;70(5):580-588.

(126) Commission on Dental Accreditation, American Dental Association. Accreditation

Standards for Advanced Specialty Education Programs in Periodontics. 2008; Available at:

http://www.ada.org/sections/educationAndCareers/pdfs/perio.pdf. Accessed 08/01, 2010.

(127) Commission on Dental Accreditation, American Dental Association. Accreditation

Standards for Advanced Specialty Education Programs in Prosthodontics. 2008; Available at:

http://www.ada.org/sections/educationAndCareers/pdfs/prostho.pdf. Accessed 08/01, 2010.

(128) Commission on Dental Accreditation, American Dental Association. Accreditation

Standards for Advanced Specialty Education Programs in Oral and Maxillofacial Surgery. 2008;

Available at: http://www.ada.org/sections/educationAndCareers/pdfs/oms.pdf. Accessed 08/01,

2010.

(129) Henry P. Educational perspectives and responsibilities. In: Albrektsson T, Zarb G, editors.

The Branemark osseointegrated implant Chicago: Quintessence; 1989. p. 81-89.

(130) Attard NJ, Zarb GA. Immediate and early implant loading protocols: a literature review of

clinical studies. J Prosthet Dent 2005;94(3):242-258.

131

(131) Lekholm U, Zarb GA. Patient selection and preparation. In: Branemark PI, Albrektsson T,

Zarb GA, editors. Tissue integrated prostheses: osseointegration in clinical dentistry Chicago:

Quintessence; 1985. p. 199-209.

(132) Jaffin RA, Bergman CL. The excessive loss of Branemark fixtures in type 4 bone: a 5-year

analysis. J Periodontol 1991;62:2-4.

(133) Martinez H, Davarpanah M, Missika P, Celletti R, Lazzara R. Optimal implant

stabilization in low density bone: a review. Clin Oral Implants Res 2001;12(5):423-432.

(134) Hagi D, Deporter DA, Pilliar RM, Arenovich T. A targeted review of study outcomes with

short (< or = 7 mm) endosseous dental implants placed in partially edentulous patients. J

Periodontol 2004;75(6):798-804.

(135) Renouard F, Nisand D. Impact of implant length and diameter on survival rates. Clin Oral

Implants Res 2006;17 Suppl 2:35-51.

(136) Hallman M, Carlsson B. Surgical correction of malpositioned implants: a case report. Clin

Oral Implants Res 1996;7:316-319.

(137) Chvartszaid D, Koka S, Zarb GA. Osseointegration failure. In: Zarb GA, Albrektsson T,

Baker G, Eckert SE, Stanford C, Tarnow D, et al, editors. Osseointegration: on continuing

synergies in surgery, prosthodontics, and biomaterials Chicago: Quintessence; 2008.

(138) Quirynen M, De Soete M, van Steenberghe D. Infectious risks for oral implants: a review

of the literature. Clin Oral Impl Res 2002;13:1-19.

(139) Cordioli G, Majzoub Z, Castagna S. Mandibular overdentures anchored to single implants:

a five-year prospective study. J Prosthet Dent 1997;78(2):159-165.

(140) Klemetti E. Is there a certain number of implants needed to retain an overdenture? J Oral

Rehabil 2008;35(suppl 1):80-84.

(141) Krennmair G, Ulm C. The symphyseal single-tooth implant for anchorage of a mandibular

complete denture in geriatric patients: a clinical report. Int J Oral Maxillofac Implants

2001;16(1):98-104.

132

(142) Smith DE, Zarb GA. Criteria for success of osseointegrated endosseous implants. J

Prosthet Dent 1989;62(5):567-572.

(143) Tolman DE, Laney WR. Tissue-integrated prosthesis complications. Int J Oral Maxillofac

Implants 1992;7:477-484.

(144) RCDSO. Waiving fees: a viable preventive strategy worth considering. Dispatch

2004;18(4):32-32.

(145) RCDSO. What to consider before using a collection agency. Dispatch 2009;23(2):24-25.

(146) RCDSO. Collection of delinquent accounts. Dispatch 2009;23(1):30-31.

(147) RCDSO. Counterclaims -- don't invite them. Dispatch 2002;16(2):32.

(148) Allen PF, McMillan AS, Walshaw D. Patient expectations of oral implant-retained

prostheses in a UK dental hospital. Br Dent J 1999;186(2):80-84.

(149) Rustemeyer J, Bremerich A. Patients' knowledge and expectations regarding dental

implants: assessment by questionnaire. Int J Oral Maxillofac Surg 2007;36(9):814-817.

(150) Hsieh MO, Kagle JD. Understanding patient satisfaction and dissatisfaction with health

care. Health social work 1991;16(4):281-290.

(151) Jackson JL, Chamberlin J, Kroenke K. Predictors of patient satisfaction. Social science

medicine 2001;52(4):609-620.

(152) Jackson JL, Kroenke K. The effect of unmet expectations among adults presenting with

physical symptoms. Ann Intern Med 2001;134(9):889-897.

(153) Rao JK, Weinberger M, Kroenke K. Visit-specific expectations and patient-centered

outcomes: a literature review. Arch Fam Med 2000;9(10):1148-1155.

(154) Narby B, Kronstrm M, Sderfeldt B, Palmqvist S. Changes in attitudes toward desire for

implant treatment: a longitudinal study of a middle-aged and older Swedish population. Int J

Prosthodont 2008;21(6):481-485.

133

(155) Berge TI. Public awareness, information sources and evaluation of oral implant treatment

in Norway. Clin Oral Implants Res 2000;11(5):401-408.

(156) Heydecke G, Thomason JM, Awad M, Lund J, Feine J. Do mandibular implant

overdentures and conventional complete dentures meet the expectations of edentulous patients?

Quintessence Int 2008;39(10):803-809.

(157) Lundqvist S, Carlsson GE. Maxillary fixed prostheses on osseointegrated dental implants.

J Prosthet Dent 1983;50(2):262-262.

(158) Carlsson GE, Kayser A, Owall B. Current and future trends in prosthodontics. In: Owall B,

Kayser AE, Carlsson GE, editors. Prosthodontics: principles and management strategies London:

Mosby-Wolfe; 1996. p. 237-249.

(159) Al-Omiri M, Hantash RA, Al-Wahadni A. Satisfaction with dental implants: a literature

review. Implant Dent 2005;14(4):399-406.

(160) Locker D. Patient-based assessment of the outcomes of implant therapy: a review of the

literature. Int J Prosthodont 1998;11(5):453-461.

(161) Blendon RJ, DesRoches CM, Brodie M, Benson JM, Rosen AB, Schneider E, et al. Views

of practicing physicians and the public on medical errors. N Engl J Med 2002;347(24):1933-

1940.

(162) Morris HF, Manz MC, Tarolli JH. Success of multiple endosseous dental implant designs

to second-stage surgery across study sites. J Oral Maxillofac Surg 1997;55(12):76-82.

(163) Melo MD, Shafie H, Obeid G. Implant survival rates for oral and maxillofacial surgery

residents: a retrospective clinical review with analysis of resident level of training on implant

survival. J Oral Maxillofac Surg 2006;64(8):1185-1189.

(164) Dawson A, Chen S editors. The SAC classification in implant dentistry. Berlin:

Quintessence; 2009.

(165) Renouard F, Rangert B. Risk factors in implant dentistry. 2nd ed. Paris: Quintessence;

2008.

134

(166) Adell R, Lekholm U, Rockler B, Branemark PI. A 15-year study of osseointegrated

implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10(6):387-416.

(167) Adell R, Eriksson B, Lekholm U, Branemark PI, Jemt T. Long-term follow-up study of

osseointegrated implants in the treatment of totally edentulous jaws. Int J Oral Maxillofac

Implants 1990;5(4):347-359.

(168) Garber DA. The aesthetic dental implant: letting the restoration be the guide. J Am Dent

Assoc 1995;126:319-325.

(169) Commission on Dental Accreditation, American Dental Association. Accreditation

Standards for Dental Education Programs. 2010; Available at:

http://www.ada.org/sections/educationAndCareers/pdfs/predoc.pdf. Accessed 08/01, 2010.

(170) WHO Oral Health Country/Area Profile Program (CAPP). Columbia. Available at:

http://www.whocollab.od.mah.se/amro/colombia/data/colombiamanpow.html. Accessed 08/01,

2010.

(171) Schleyer T, Eaton KA, Mock D, Barac'h V. Comparison of dental licensure, specialization

and continuing education in five countries. Eur J Dent Educ 2002;6(4):153-161.

(172) Sanz M, Widstrom E, Eaton KA. Is there a need for a common framework of dental

specialties in Europe? Eur J Dent Educ 2008;12(3):138-143.

(173) A.D.A. Dentistry definitions. Available at: http://ada.org/495.aspx. Accessed 8/1, 2010.

(174) McCann D. Implantology. Does it merit specialty status? J Am Dent Assoc

1990;121(3):322-323.

(175) Schnitman PA. Implant dentistry. Will it be the ninth recognized specialty? N Y State Dent

J 1993;59(5):51-54.

(176) Franneby U, Gunnarsson U, Wollert S, Sandblom G. Discordance between the patient's

and surgeon's perception of complications following hernia surgery. Hernia 2005;9(2):145-149.

135

(177) Franneby U, Sandblom G, Nyren O, Nordin P, Gunnarsson U. Self-reported adverse events

after groin hernia repair, a study based on a national register. Value Health 2008;11(5):927-932.

(178) Venta I, Lindqvist C, Ylipaavalniemi P. Malpractice claims for permanent nerve injuries

related to third molar removals. Acta Odontol Scand 1998;56(4):193-196.

(179) Dao TT, Mellor A. Sensory disturbances associated with implant surgery. Int J Prosthodont

1998;11(5):462-469.

(180) Sensory Disturbances Following Implant Surgery: A Prospective Psychophysical Pilot

Study. IADR; 2004; ; 2004.

(181) van Steenberghe D, Lekholm U, Bolender C, Folmer T, Henry P, Herrmann I, et al.

Applicability of osseointegrated oral implants in the rehabilitation of partial edentulism: a

prospective multicenter study on 558 fixtures. Int J Oral Maxillofac Implants 1990;5(3):272-281.

(182) Ellies LG, Hawker PB. The prevalence of altered sensation associated with implant

surgery. Int J Oral Maxillofac Implants 1993;8(6):674-679.

(183) Buser D, Belser U, Wismeijer D editors. Implant therapy in the esthetic zone: single-tooth

replacement. Berlin: Quintessence; 2007.

(184) El-Askay AES. Reconstructive aesthetic implant surgery. Iowa: Blackwell Munksgaard;

2003.

(185) Palacci P editor. Esthetic implant dentistry: soft and hard tissue management. Chicago:

Quintessence; 2001.

(186) Brewer A. Selection of denture teeth for aesthetics and function. J Prosthet Dent

1970;23:368-373.

(187) Carlsson GE, Otterland A, Wennstrom A, Odont D. Patient factors in appreciation of

complete dentures. J Prosthet Dent 1967;17:322-328.

(188) Vallittu PK, Vallittu ASJ, Lassila VP. Dental aesthetics - a survey of attitudes in different

groups of patients. J Dent 1996;24:335-338.

136

(189) Afsharzand Z, Lim MVC, Rashedi B, Petropoulos VC. Predoctoral implant dentistry

curriculum survey: European dental schools. Eur J Dent Educ 2005;9(1):37-45.

(190) Lim MVC, Afsharzand Z, Rashedi B, Petropoulos VC. Predoctoral implant education in

U.S. dental schools. J Prosthodont 2005;14(1):46-56.

(191) Pradeep AR, Karthikeyan B. Peri-implant papilla reconstruction: realities and limitations. J

Periodontol 2006;77:534-544.

(192) Zetu L, Wang HL. Management of inter-dental/inter-implant papilla. J Clin Periodontol

2005;32:831-839.

(193) Helmreich RL. On error management: lessons from aviation. BMJ 2000;320:781-785.

(194) Gaba DM. Anaesthesiology as a model for patient safety in health care. BMJ

2000;320(7237):785-788.

(195) Perrow C. Normal accidents: living with high-risk technologies. New York: Basic Books;

1984.

(196) Gaffen AS, Haas DA. Survey of local anesthetic use by Ontario dentists. J Can Dent Assoc

2009;75(9):649-649.

(197) Braithwaite D, Emery J, De Lusignan S, Sutton S. Using the Internet to conduct surveys of

health professionals: a valid alternative? Fam Pract 2003;20(5):545-551.

(198) Cook C, Helath F, Russel T. A meta-analysis of response rates in Web or Internet-based

surveys. Educational and Psychological Measurement 2000;60:831-836.

(199) Flores-Mir C, Palmer NG, Northcott HC, Huston C, Major PW. Computer and Internet

usage by Canadian dentists. J Can Dent Assoc 2006;72(2):145-145.

137

Appendix 1: The Survey

Introductory page

Implant Complications Survey – Consent

Dear Colleague,

I am conducting a survey to determine the nature and types of dental implant complications that

occur in private dental practices. This survey is undertaken as part of my M.Sc. research.

Your opinions are important to help us understand the nature and the causes of complications

that are encountered during implant treatment. The information gained from this study will allow

educational initiatives to focus on implant complication prevention. The ultimate aim is to

minimize the frequency of implant complications in private practices. The survey consists of

multiple-choice questions, and its completion will take approximately 15 minutes.

Your completion of this survey is completely voluntary and all responses are anonymous and

completely confidential. All necessary measures to protect your privacy have been utilized in

accordance with the University of Toronto’s Ethics Committee. By completing this survey you

will provide the principal investigator with permission to use its contents for research and

educational purposed only. Regulatory bodies do not have access to the survey’s contents.

If you have any questions or if you experience any difficulties with the survey, you can contact

me at 647-669-3671 (david.chvartszaid@dentistry.utoronto.ca).

Your input is very important to me and to your colleagues. Thank you in advance for your

participation.

Sincerely,

David Chvartszaid, DDS, MSc

3rd year resident, Discipline of Periodontics, Faculty of Dentistry, University of Toronto

138

Implant treatment expertise questions

Q1. You are a(an)

general dentist

oral surgeon

periodontist

prosthodontist

Q2. What is your level of expertise in surgical implant treatment?

advanced

average

basic knowledge

none

Q3. What is your level of expertise in prosthodontic implant treatment?

advanced

average

basic knowledge

none

Q4. With respect to implant treatment, you provide:

exclusively prosthodontic implant treatment

primarily prosthodontic implant treatment and limited surgical implant treatment

both surgical and prosthodontic implant treatment

exclusively surgical implant treatment

primarily surgical implant treatment and limited prosthodontic implant treatment

I do not place or restore dental implants

139

Complication questions

Q5. Did you experience, manage or treat the following surgery-related implant

complications in 2009?

(Check all that apply.)

significant bleeding

sinus membrane perforation (during a direct sinus lift procedure)

lack of primary implant stability

had to abort a surgical site after attempting unsuccessfully to place an implant

limited patient opening or unable to fit instruments

surgical stent “unusable” (not made how you would have made it or does not fit)

surgical treatment not prosthetically driven (implant placed without restorative input)

implant brand used other than what was requested by the referring dentist

significant thread exposure

cover screw or healing abutment not fully seated

damage to adjacent tooth

implant fracture (during placement)

incision line opening

implant dislodged into the sinus

severe post-operative infection (e.g. osteomyelitis, sinusitis)

temporary paraesthesia (or altered sensation)

permanent paraesthesia (or altered sensation)

I did not experience and did not manage (or treat) any surgery-related implant

complications in 2009

other (briefly describe)

The question below will ask you if a particular type of complication is "preventable".

"Preventable" means that with careful attention during treatment planning, execution or

follow-up the occurrence of this complication (or complication type) could be significantly

reduced or eliminated.

Q6. In general, are surgery-related implant complications (listed above) preventable?

yes, they are usually preventable

no, they are usually not preventable

Q7. Did you experience, manage or treat prosthodontic implant complications in 2009?

(Check all that apply.)

healing abutment loosening or dislodging

poor implant position (depth/angulation/spacing)

limited interocclusal space (for prosthesis fabrication)

implant non-restorable

unable to fully seat implant component or final restoration

incorrect impression taken (e.g. wrong component used), had to repeat impression, or

unable to take impression

resin/acrylic/porcelain fracture

prosthesis loosening

140

prosthetic or abutment screw head stripping

prosthetic screw fracture

implant-supported overdenture clip (attachment) loosening

implant-supported overdenture clip (attachment) fracture

implant fracture (during function)

cement extrusion subgingivally/retained cement

prosthesis failure or need to remake prosthesis

I did not experience and did not manage (or treat) any prosthodontic implant

complications in 2009

other (briefly describe)

Q8. In general, are prosthodontic implant complications (listed above) preventable?

yes, they are usually preventable

no, they are usually not preventable

Q9. Did you experience, manage or treat biological implant complications in 2009?

(Check all that apply.)

no interproximal papilla or unable to close interproximal embrasure (must be

clinically significant)

healing abutment too short (leading to soft tissue overgrowth)

gingival inflammation (peri-implant mucositis)

fistula

recession – implant (or final abutment) is visible through the buccal gingiva

peri-implantitis (severe continuous bone loss)

implant failure

multiple implant failure within the same patient

mandibular fracture

bisphosphonate-related osteonecrosis of the jaw

I did not experience and did not manage (or treat) biological implant complications in

2009

other (briefly describe)

Q10. In general, are biological implant complications (listed above) preventable?

yes, they are usually preventable

no, they are usually not preventable

Q11. Did you experience, manage or treat patient-related implant complications in 2009?

(Check all that apply.)

aspiration or ingestion of implant/component/driver

speech impaired with final prosthesis

ability to clean final prosthesis impaired

patient cannot get used to final prosthesis (comfort impaired)

slight patient dissatisfaction with aesthetics

significant patient dissatisfaction with aesthetics

patient complaint of food impaction

I did not experience and did not manage (or treat) any patient-related implant

complications in 2009

141

other (briefly describe)

Q12. In general, are patient-related implant complications (listed above) preventable?

yes, they are usually preventable

no, they are usually not preventable

Q13. Taking all types of implant complications into account, what percentage of your

patients treated during 2009 experienced at least one implant complication?

0-5%

6-10%

11-15%

16-20%

21-25%

26-30%

>30%

Q14. Did you take the following corrective actions as a result of an implant treatment

complication in 2009?

(Check all that apply.)

communicated with lab/dentist/specialist about an issue with the case

retook impression

remade implant-supported prosthesis

trephined out (removed) an implant

buried an implant (“put implant to sleep”)

performed additional surgical procedures

increased length of treatment, number of procedures or office visits

increased professional fee or lab fee

had to deal with patient’s dissatisfaction

contacted PLP (Professional Liability Program)

referred patient to a specialist

no, I did not take any of the above corrective actions as a result of an implant

treatment complication in 2009

142

Opinions on complications

Q15. A cause of a complication is defined as an underlying issue or factor leading to a

complication.

Which of the following are the most important underlying causes of most complications?

(Check one or more.)

poor overall planning (including excessive treatment complexity or risk)

poor inter-professional communication

poor basic knowledge of implant-related concepts

poor technical/surgical skills in performing implant-related treatments

lack of knowledge on how to recognize, manage or treat complications

lack of experience

conducting surgical procedure in an infected or inflamed site

ignoring dental disease on adjacent teeth or elsewhere in the mouth

failure to follow manufacturer’s recommendations

poor clinical or radiographic exam

lack of follow-up

failure to refer to a professional with greater experience (poor case selection)

implant placement not prosthetically driven (e.g. not using a surgical guide)

poor consent

poor patient compliance (including very poor oral hygiene)

compromised patient’s medical status (including smoking)

unrealistic patient expectations (including patient demand for procedures of increased

difficulty or risk)

excessive implant system complexity

company advertising portraying implant treatment as very simple or risk-free

Q16. What do you feel should be done to decrease the frequency and severity of

complications in private practice? (Check one or more.)

follow manufacturer’s recommendations

greater pre-testing of technologies before their introduction to the market

better patient education and consent

better dentist education

implant placement to be prosthetically driven

better treatment planning

refer difficult cases to a specialist

greater professional body role (e.g., CDA, ODA, RCDSO) in setting and enforcing

standards

establish a specialty of Implantology

be self-critical and learn from the complications

better inter-professional (dentists, lab) communication

mandatory implant complication reporting system

implant companies to publish more information on implant complication

experience/prevention

greater research into the nature and types of implant complications

better dissemination of research information about implant complications

143

Q17. The following is a list of complications or steps that may be needed to resolve a

complication.

Ultimately, all of them cause a negative treatment outcome in terms of some parameter

(such as increased cost, time, morbidity, effort etc.).

Which of the following negative outcomes are most severe? (Check one or more.)

increased cost of treatment

increased duration of recovery from surgery (increased time off work)

increased number of radiographs taken (or need for additional imaging)

increased length of treatment

increased number of non-surgical procedures

increased number of surgical procedures

increased overall complexity of treatment

increased effort on the part of the dentist(s)

temporary paraesthesia (or altered sensation)

permanent paraesthesia (or altered sensation)

damage to adjacent tooth

cleaning difficulty of the final restoration (e.g. bridge)

interference with proper speech of the final restoration

poor appearance of the final restoration

poor comfort of the final restoration

frequent breakage (need for repair) of the final restoration

increased possibility of total treatment failure in the future

inability to achieve a satisfactory outcome as it was originally envisioned

Q18. Where does most of your knowledge related to implant complications come from?

(Check one or more.)

my own experience

speaking with colleagues

dental implant journals

continuing education courses

implant company/reps

textbooks

conferences

dental school curriculum

specialty program

Q19. Whose responsibility is it to make dentists aware of the potential complications with

dental implant treatment?

my own – it is my responsibility to educate myself

implant company

dental school

regulatory body

144

Demographic questions

Q20. What year did you graduate from the Dental School?

1950-1959

1960-1969

1970-1979

1980-1989

1990-1999

2000-2009

Q21. If you are a specialist, what year did you graduate from the specialty program?

1950-1959

1960-1969

1970-1979

1980-1989

1990-1999

2000-2009

I am not a specialist

Q22. How many years have you been involved in implant dentistry?

0-5

6-10

11-15

16-20

>20

Q23. How many patients did you finish treating with implants in a typical month of 2009?

0-5

6-10

11-15

16-20

21-25

>25

Q24. How many implants did you surgically place in a typical month of 2009?

0

1-10

11-20

21-30

31-40

41-50

51-60

61-70

71-80

>80

145

Q25. How many implants did you finish restoring in a typical month of 2009?

0

1-10

11-20

21-30

31-40

41-50

51-60

61-70

71-80

>80

Q26. Did you experience a complication in 2009 that you were not aware of until you

experienced it yourself?

yes

no

Q27. If yes, do you feel that having prior knowledge of this complication would have helped

you prevent it?

yes

no