OUTCOME OF NON-SURGICAL ENDODONTIC TREATMENT

OUTCOME OF NON-SURGICAL ENDODONTIC TREATMENT

Sarah Abitbol

A thesis submitted in conformity with the requirements for the degree of Master of Science Graduate Department of Faculty of Dentistry University of Toronto

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Outcome of Non-surgical Endodontic Treatment Master of Science, 2001 Dr. Sarah Abitbol Graduate Department of Dentistry University of Toronto

ABSTRACT

This historical cohort study examined the outcome of non-surgical endodontic treatment and the influence of various factors on the outcome. Patients treated by Graduate Endodontics students were re-examined afier 4 to 6 years by an independent investigator. Outcome criteria

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were dichotomous the pdradicular tissues were classified as "healed" or "diseased". For Initial Treatment, 8 1% of the teeth wefe healed. The healing rate was 18% higher for teeth without pre-operative Apical Periodontitis than those with Apical Periodontitis @ < 0.01). For Retreatment, 7 1% of the teeth were healed. The healing rate for teeth with pre-operative perforation was 53% lower than for al1 othcr teeth (p 4 0.001). In conclusion, Apical Periodontitis was the major factor that influenced the outcome of Initial Treatment, while a pre-operative perforation was the major factor that influenced the outcome of Retreatment.

Acknowledgments

The completion of this thesis was made possible with the contribution of a nurnber of individuals. 1 would like to thank my supervisors, Dr. Shimon Friedman and Dr. Herenia P. Lawrence for their support and guidance during the elaboration of this project. 1 I especially indebted to Dr. S. Friedman; first, for giving me the opportunity to participate in this remarkable research and second, for the many hours spent reviewing this thesis. His vast knowledge in the field of endodontics and unreserved acadernic dedication makes him a great supervisor to work with. 1 express my appreciation to Dr.

H.P.Lawrence for her patience and good cheer in

continually impariing her knowledge with me, and for always being available and easily approachable. 1 would like to thank my cornmittee member Dr.Chris McCulloch for his positive insight

and comments throughout the research. 1 own a very special acknowledpent to two people who, although not directly involved

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in this thesis, volunteered to help me with it Dr. Calvin Tomeck, for reading and correcting it, and Dr. Thuan Dao, for her attention and suggestions.

I am especially gratefbl to Ms. Annemarie Polis for her technical support during the recording of the data and her exnotional support throughout this research project and the writing of the thesis. Last, but not least, I am etemally gratefûl to al1 the mernbers of my family who have supported me throughout the pursuit of my longtime dream

scientifically sound Endodontist.

iii

- to become a well-trained and

TABLE O F CONTENTS

Page

..

ABSTRACT .......................................................................................................................

11

Acknowledgments..............................................................................................................

111

...

Table of Contents ............................................................................................................... iv List of Tables ............................................................................................................... vil... List of Figures ................................................................................................................... x 1.

INTRODUCTION..................................................................................................

1

1.1

Historical Review ......................................................................................... 2

1.2

Appraisal of previous studies ....................................................................... 5 Early and unifom assembly of Patients......................................... I O Description of the Referral Pattern ................................................ I l Description of the Follow-up Recall rate ....................................... 12 Definition of Objective Outcome Criteria .....................................13 bb

.. Outcome assessment .........................................................17 Blind"

Adjustment for Extraneous Prognostic Factors .............................18 Appraisal Summary........................................................................20 1.3

Outcorne of treatment in teeth without Apical Periodontits ......................20 1.3.1

Initial Treatrnent............................................................................. 20

1.3.2

Retreatment ................................................................................... -22

1.4

Outcome of treatment in teeth with Apical Periodontitis ..........................22

..

1.4.1

initial Treatment............................................................................-22

1.4.2

Retreatment ...................................................................................-24

LI .

STATEMENT OF THE PROBLEM ................................................................ -26

m.

omc~nms OF THE STUDY ........................................................................27

IV.

EYPOTHESIS .....................................................................................................28

V.

MATERIALS AND METHODS ......................................................................-28

V.

V .1

Studied Population .........................................................................28

V.2

Recording of Data ......................................................................... -29

V.3

Patient Recall Strategies ...............................................................-30

V.4

Assessrnent Criteria .......................................................................30

V.5

Sample Size Estimation ................................................................3 1

V.6

StatisticalAnalysis......................................................................31

RESULTS .............................................................................................................33 .. ........................................................................................ 1

Initial Treatment.

33

V .1- 1 Total material .................................................................................34 V .1.2 Teeth without Apical Periodontitis ................................................36 V .1.3 Teeth with Apical Periodontitis .....................................................36 Retreatment ............................................................................................... -37 V.2.1 Total material ................................................................................. 38 V.2.2 Teeth without Apical Periodontitis ................................................ 39

V.2.3 Teeth with Apical Periodontitis ..................................................... 39

VI.

DISCUSSION ........................................................................................... 40

VII.

FUTURE RESEARCH ............................................................................ 50

REFERENCES.............................................................................................................77 APPENDICES

List of Tables

Pages

Table 1. Non-surgical endodontic treatrnent outcorne studies. ........................ ..52 Table 2.

Outcome of Initial Treatment with and without presperative Apical Periodontitis ....................................................3 3

Table 3.

Outcome of Retreatment with and without pre-operative Apical Periodontitis .......................................................54

Table 4.

Relation of studies to reporting guidelines by McMaster University .....................................................................S5

Table 5.

Univariate distribution of "the new population" subjected to initial Treatment (n = 277). ................................................................. 56

Table 6.

Univariate distribution of the analyzed population subjected to Initial Treatment (n = 120). ....................................................-........... -57

Table 7.

Response bias analysis to assess differences between the "new total population" and the responding population subjected to Initial Treatment. .......................................................... -3

Table 8.

Association between pre-operative factors and the outcome of endodontic Initial treatrnent (n = 120). .............................58

Table 9.

Association between intra-operative factors and the outcome of Initial treatment (n = 120). ...............................................59

Table 10. Association between post-operative factors and the outcome of initial treatment (n = 120). .............................................. ..S9 Table 1 1. Contingency table of pre-operative factor Pulp Vitality and Apical Periodontitis (n = 120). .........................................60 Table 12. Stepwise Logistic regression analysis for initial Treatment (n = 120)................................................................... 60

vii

Table 13. Association between pre-operative factors and the outcome of Initial Treatment in teeth without Apical Periodontitis (n = 48). .......................................................................... 60 Table 14. Association between intra-operative factors and the outcome of Initial treatment in teeth without Apical Periodontitis (n = 48). ................................................. 6 1 Table 15. Association between pst-operative factors and the outcome of initial treatment in teeth without Apical Periodontitis (n = 48). ................................................-61 Table 16. Association between pre-operative factors and the outcome of Initial Treatment in teeth with Apical Periodontitis (n = 72). ..........................................................................62 Table 17. Association between intra-operative factors and the outcome of Initial Treatment in teeth with Apical Periodontitis (n = 72). .......................................................................... 62 Table18. Association between pst-operative factors and the outcome of initial Treatment in teeth with Apical Periodontitis (n = 72). ........................................................................ ..63 Table 19. Stratified table of intra-operative factor Number of Roots and Treatment Sessions in teeth with Apical Periodontitis (n = 72) ...........................................................................63 Table 20. Univariate distribution of "the new population" subjected to Retreatrnent (n = 203). .........................................................................64 Table 2 1. Univariate distribution of the analyzed population subjected to Retreatment(n=56). .............................................................................-65 Table 22. Response bias analysis to assess differences between the "new total population" and the responding population subjected to Retreatment. ................................................................... ..66 Table 23. Association between pre-operattive factors and the outcome of Retreatment (n = 56). ........................................................66

Table 24. Association between intra-operative factors and the outcome of Retreatment (n = 56). ....................................................... -67 Table 25. Association between pst-operative factors and the outcome of Retreatment (n = 56).........................................................67 Table 26. Association between pre-operative factors and Retreatment in teeth without Apical Periodontitis (n = 26)................................................................................................. 68 Table 27. Association between intra-operative factors and Retreatment in teeth without Apical Periodontitis (n = 26)................................................................................................. 69 Table 28. Association between pst-operative factors and Retreatment in teeth without Apical Periodontitis (n = 26). ..............................................................................................

..69

Table 29. Association between pre-operative factors and Reîreatment in teeth with ApicaI Periodontitis (n = 30)................................................................................................. 70 Table 30. Association between intra-operative factors and Rdreatment in teeth with Apical Periodontitis (n = 30)................................................................................................. 7 1 Table 3 1. Association between pst-operative factors and Retreatment in teeth with Apical Periodontitis (n = 30). .....................7 1

List of Figures

Pages

Figure 1 . Radiographie evaluation of the assessrnent criteria.............................72 Figure 2 . Distribution of the study material for initial Treatment.......................73 Figure 3 . Recall rate for Initial Treatment...........................................................73 Figure 4

Exarnples of teeth classified as " healed"............................................74

Figure 5 . Examples of teeth classified as " diseased".........................................75 Figure 6. Distribution of the study material for Retreatment..............................76 Figure 7 . Recall rate for Retreatment.................................................................. 76

1.

INTRODUCTION

"It appears to me a most excellent thing for the physician to cultivate Prognosis; for by foreseeing and foretelling, in the presence of the sick, the present, the past and the b r e , he will be more readily believed to be acquainted with the circurnstances of the sick; so that

men will have confidence to intrust themselves to such a physician. And he will manage to cure best who has foreseen what is to happen fiom the present state of matters. ...It therefore becomes necessary to know the nature of such affections, how far they are above the powers of the constitution and, moreaver, if there be anything divine in the disemes, and to leam a

foreknowledge of this also. Thus a man will be the more esteaned to be a good physician, for he will be the better able to treat those aright who can be saved, having long anticipated everything ." Hyppocrates. The Book of Prognosis

Endodontic therapy is one of the basic procedures performed in dentistry, directed at prevention or elimination of Apical Periodontitis (Friedman 1998). Apical Periodontitis is a

disease of the tissues surrounding the mots of teeth, most ofien caused by extension of pulp disease and subsequent infection of the root canal systern (Nair et al. 1990). When Apical Periodontitis occurs in association with teeth that have had previous endodontic treatment, it can be due to persistence of the pnmary infection or the establishment of infection subsequent to treatment (Sundqvist et al. 1998, Nair et al. 1990).

Epidemiological stuàies have shown that in teeth that have not had endodontic treatment, the prevalence of Apical Periodontitis ranges fiom 0.6% (Eriksen 1991, 1998) to 8.4% (Imfeld 1991). In contrast, in root-filled teeth, the prevalence can reach as high as 6 1%

(Weiger et al. 1997). It appears, therefore, that dentists must deal with Apical Periodontitis on a daily basis and must be prepared to respond to patients' questions, such as: "1s my tooth worth treating?", " M a t are my chances of keeping the tooth after treatment?", "Will 1 sufier

an adverse outcome?", "Will healing be impaired?", "How long will my tooth last?". The answers to these questions relate to the practical presumption supporthg any treatment, that (a) benefits of the treatment will outweigh the risks, and (b) treatrnent is better than no

treatrnent. To presurne this assumption as correct, it is imperative to determine if the benefits of the particular treatrnent or the alternatives outweigh the negative consequences. This is the basis for appropnate care. Endodontic treatment currently benefits fkom innovations in treatrnent strategies and techniques, which are expected to irnprove the outcome of treatrnent relative to that achieved with older techniques. in order to detemine the impact of endodontic innovations on the appropriateness of care, and to provide an updated basis for treatment planning and communication with patients, cment treatment outcome studies guided by evidence-based principles are required.

1.1

Historical review Endodontics is the most recent branch of dentistry to be recognized as a specialty by

the American Dental Association (1963), but it has been practiced for centuries (Tagger

1967). Like medicine and the other branches of dentistry, endodontics began as an outgrowth of magic and superstition. As empincal treatment modalities developed over the years, the basis was formed for the scientific evolution of the specialty. From ancient Egypt and up to the 18th century, endodontic treatment had been perfomed to reduce tooth pain and drain alveolar abscesses (Curson 1965). Dunng the 19th century, three principal endodontic treatment techniques were developed

- pulp

capping, pulpotomy and root canal therapy.

However, until the beginning of the 20th century there was no development of an endodontic science. The lack of patented drugs and instruments, and critically, the lack of communication among professionals prevented the sprzad of empincal knowledge and experience fiom one dental center to another (Tagger 1967).

The first endodontic treatment procedure to be assessed for its outcorne was pulp capping (Curson 1965). Thomas Rogers reported at a meeting of the Odontological Society of London in 1857, that of 220 teeth treated by pulp capping, 202 were considered to be bbsuccessfiil"- the patients reported no clinical signs and symptoms. In 1870, G.V. Black reviewed 42 pulp-capped teeth in patients under 20 years old, followed over 10 years. In 37 of these teeth symptoms occumed within 5 years. The turn of the 20& century brought about two developments that had a significant and lasting impact on endodontics. Miller (1 898) established the bacteriological basis of endodontic diseases by showing that the pulp cavities of teeth with necrotic pulps were infected, and by postulating îhat the formation of a dento-alveolar abscess reflected the spread of the infection fiom the pulp cavity toward the periapical tissues. Concurrent1y, Price (1 900) used the newly invented radiograph to demonstrate teeth with incomplete root canal

fillings and periapical radiolucencies, and advocated the use of radiography for the diagnosis of pulpless teeth (Tagger 1967). Coolidge (1927) was the first to report on the outcome of root canal therapy using radiographs. Of the 147 teeth treated with vital pulps, onJy 5 showed periapical radiolucency after 2 to 12 years. Of the 160 teeth that presented initially with periapical radiolucency, 59% healed cornpletely and 36% showed marked improvernent. In 1932, Appleton reported on the effect of bacteriological controls on the outcome of treatment in teeth with periapical infection, using radiographs for determination of treatment outcome. In 1936, Buchbinder used basic statistical methods to differentiate between "success" rates

obtained in teeth without (88%) and with (45%) periapical disease. Again, radiographic evaluation was used to establish the outcome of treatment, and the criterion used to define "success" was complete bone regeneration. The aforementioned eariy reports and others, culminated in Strindberg's (1956) landmark study, which established the standard for the assessment of endodontic treatment outcome. in this comprehensive retrospective study of 529 endodontically treated teeth, the outcome criteria were based on clinical and radiographic measures pertaining to the treated roots. Success was defined as "no clinical symptoms present, and the radiographic contours,

width and structure of the periodontal margin normal or widened mainly around the excess root canal filling material". Failure was defined as "the presence of any clinical symptoms,

and radiographic appearance where the lesion was decreased, unchanged or increased in size". Where no lesion was present pre-operatively, emergence of a new lesion indicated failure of treatment. Uncertain cases weie considered "those roots where the radiographic appearance was ambiguous or technically unsatisfactory, control radiographs could not be

repeated, or where a tooth was extracted pnor to 3 years follow-up due to unsuccessful treatment of anothw root of the tooth". Strindberg also studied the influence of certain factors on treatment outcome and concluded that a minimum period of 4 years was required to radiographically determine treament success. Strindberg's landmark report has been followed by many studies on the outcome of endodontic treatment, in which a variety of methods and evaluation criteria were used. Due to this diversity, the results of the studies Vary considerably. The reported outcornes of non-

surgical endodontic treatment are listed in Table 1.

1.2

Appraisal of Endodontic Treatment Outcorne Studies The diverse methodology and results of the many endodontic treatment outcome

studies render thern difficult and inappropnate to compare with each other. The major variability arnong these studies is related to some or al1 of the following (Friedman 1998):

Comwsition of the studv material (a) Toofh type. number of roots: Some studies included only anterior teeth (Adenubi & Rule

1976, Harty et al. 1970), or single-rooted teeth (Bystr6m et al. 1987, Sjogren et al. 1997, Sundqvist et al. 1998), whereas others pooled single- and multi-rooted teeth together. Treatment outcome can differ between single- and multi-rooted teeth (anterior and posterior, respectively), depending on the definition of the unit of evaluation (roots or teeth) and possibly, due to anatomic complexity or difficulty of access.

(b) SampIe size: Sample size is a critical factor determining the power of a clinical study, and

thus the ability to substantiate statistically significant differences among groups. The smaller the difference between compared outcomes, the larger is the sample or population required in each group to achieve sufficient power (Fletcher et al. 1996). For example, for a difference in healing rate of 5% to 10% between single- and two-session treatments, Trope et al. (1999) calculated that a population of over 450 subjects would be required. Many of the studies did not meet the required sample size (Table 1). Furthemore, the loss of cases to follow-up fiequently reduced the sample size even more. in those studies there could be no significant differences in outcome found for specific variables, whereas in studies of larga populations the same variables were found to significantly influence the outcome. (c) Proportion of teerh with and without Apical Penodontiris: Presence of Apical

Periodontitis at the outset of treaûnent has been shown to adversely influence the outcome of treatment (Tables 2 and 3). As the proportion of teeth with Apical Periodontitis in studies

varied fiom ni1 (Engstr6m & Lundberg 1965, Ashkenaz 1979) to 1 0 % (Bystrom et al. 1 987, Sjogren et al. 1997, Trope et al. 1999, Weiger et al. 20ûû), the reported outcomes varied accordingly (Table 1).

(4 Proportion of Initial Treatment and Retreament: Retreatment of teeth in which Apical Periodontitis persistai or emerged after previous treatment has been associated with a poorer outcome than that of Initial Treatrnent (Tables 2 and 3). As the proportion of teeth subjected to Retreatment in studies varied from ni1 (Sj6gren et al. 1997, Weiger et ai. 2000) to 100 % (Sundqvist et al. 1998, Bergenholtz et ai. 1979), the reported outcornes varieci accordingly (Table 1).

(e)

Case selection and inclusion/erclusion criteria: Case selection is the process of

discriminating cases according to their prognosis. In some studies attempts were made to exclude cases deemed to have an unfavorable prognosis (Harty et al. 1970), whereas occasionally, the study material consisted of only such cases (Akerblom & Hasselgren 1988). Also, teeth already comprornised by periodontal disease or procedural mors may have been included in specific studies (Friedman et al. 1995) and adversely influenceù the overall outcome. As case selection in studies varied nom none to strict, the reportai outcomes varied accordingly.

Intra-o~erativetreatment ~rocedures

(a) Providers of freotment: Experienced and skillfùl operators are less likely to compromise the outcome of treatment by perfoming procedural mors (ingle et al. 1994). Study results may Vary, therefore, depending on the providers of treatment and their expertise. As providers of treatment varied from undergraduate students to specialists (Table 4), the

reported treatment outcomes varied accordingly. (b) Treatment procedures: New er endodontic treatrnent techniques and materials are

expected to facilitate treatment and improve treatment outcome. As treatment procedures varieù fiom reportedly ineffective ones, such as Kloroperka N - 0 (Eriksen et al. 1987, Kerekes & Tronstad 1979, Halse & Molven 1987) to allegedly most effective ones, such as the "Schilder technique" (Pekruhn L986), the reported outcomes may have varieci accordingly. In this context, of particultir interest are studies in which a negative bacterial culture was a prerequisite for root filling (Engstrh & Lundberg 1965, Seltzer et al. 1 963,

Bender & Seltzer 1964), and studies in which teeth with Apical Periodontitis were treated in one session (Sjogren et al. 1997, Peknihn 1986), as opposed to the more wmmon multisession treatment. (c) Post-operative restomtion: The influence of the definitive restoration (type and placement

time interval) on the outcome of endodontic treatment is, at best, vague. One study (Heling & Shapira 1978) reported a better outcome when definitive restoration was placed immediately

afier treatment than when the restoration was delayed. Nevertheless, as restorations at the foIlow-up examinations varied fiom temporary to definitive (Safavi et a/.1987), the reported treatment outcomes varied accordingly.

Methodolow of study (a) Shuty design: Retrospective studies differ in many respects nom prospective studies, and

the reported outcomes may differ accordingly (Table 1). Furthemore, several studies were designed to answer one specific research question (Zeldow & Ingle 1963, Sj6gren et al. 1997, Sundqvist et al. 1998, Weiger et al. 2 0 0 , Trope et al. 1999); they may not qualify for cornparisons with other studies in regards to g e n d results. (8) Interpretation of radiographs: Radiographs are used as the principal measure for

assessing the treatment outcome, yet their interpretation varies considerably (Goldman et al. 1972, 1974). Blinded examiners, standardized in interpretation of radiographs are an essential component of the evaluative process. As this requirement was met in just a few of the studies,

the reported outcomes in the other studies may have been skewed.

(c) Observation period: Emerging or healing of Apical Periodontitis are dynamic processes,

thetefore, sufficient time is required to properly evaluate these events. 0rstavik (1996) established that the peak of healing and emerging Apical Periodontitis after endodontic treatment occurted within the first year, yet completion of healing occasionaily required 4

years. Of the cases that healed by 4 years, only 5 1% appeared mmpletely healed at one year. Similarly, of the cases where Apical Periodontitis ernerged within 4 years after treatment, only 76% demonstrated Apical Periodontitis at one year. As observation periods in studies varied fkom 6 months (Seltzer et al. 1963) to 17 years (Halse & Molven 1987), the reported

treatment outcornes varied accordingly (Table 1). Furthemore, as the observation period lengthens, chances of coronal and periodontai deterioration increase, potentially exerting adverse influence on the outcorne of endodontic treatment. (d) Criteriafor a)aiuation: Lack of standardized criteria is one of the main difficulties when

analyzing the outcorne of endodontic treatment. When only radiographic criteria are employed (Storms 1963, Seitzer et al. 1963, Bender & Seltzer 1964, Morse et al. 1983, Halse & Molven 1987, Swartz et al. 1983) "failures" due to clinical presentation are not taken into

account. #en

a decreased radiolucency is considered a "success" (Harty et al. 1970, Shah

1988), the outcome is considerably better than when stringent clinical and radiographic criteria are employed.

The aforernentioned variability among the previous studies suggests that they differ considerably in the quality of evidence they pmvide regarding the outcome of endodontic treatment. Thetefore, results of those studies have to be interpreted with discretion. With the exponential growth of the published literature, there is an increased nsk that studies of lesser

quality of evidence will outnumber and outweigh those of better quality. Hence the use of an efficient strategy for appraisal of studies is irnperative. This appraisal differentiates properly designeci studies fiom others, according to established criteria that will permit the selection of stronger evidence and exclusion of weaker evidence.

The seiection criteria are based upon guidelines recommended by the Department of Clinical Epiderniology and Biostatisitics at McMaster University Health Sciences Centre ( 198 1). These guidelines were original1y established to judge the strengtb of published

articles related to the clinical course and prognosis of disease. These guidelines state the following requirements: (1) patients in the study must be assembled at an early and uniforni point in the course of their disease (eg., when they received therapy), (2) the referral pattern for patient inclusion must be descxibed, (3) the follow-up recall rate must be described, (4) objective outcome criteria must be defined, (5) outcome must be assesseci blindly, and ( 6 ) influence of extraneous prognostic factors must be taken into account. The following section appraises the endodontic treatment outcome studies according to the criteria highlighted above (Table 4).

1.2.1

Earl~ and Unifonn Assemblv of Patients

For a prognostic study, the strongest evidence is derïved from a prospective design with patients assembled before the srudy is initiated and then observed over time. The

retrospective outcome studia (Table 1) were prone to recall bias and lacked a strict protocol in the methodology employed to record the data. These studies, therefore, are excluded from discussion in this thesis.

Studies in which patients are selected at an early and unifom point in the course of the disease or treatment are called "inception whort studies". h the majority of prospective endodontic outcome studies (Table 1) the selected population has been clearly described. In two prospective studies, however, the "inception cohort" was not described (Bender & Seltza 1964, Grossman et al. 1964). Because the results of these studies are subject to interpretation, they are excluded from discussion in this thesis.

In several studies cxclusive controlled populations were selected, such as teeth presenting with Apical Periodontitis (Sj6gren et al. 1997, Trope et al. 1999, Weiger et al. 2000), teeth with calcified root canals (Akerblom & Hasselgren 1988), teeth with persistent Apical Periodontitis after previous treatment (Sundqvist et al. 1998), or patients who did not take antibiotics prior to treatment (Zeldow & Ingle 1963, Matsumoto et al. 1987, Weiger et

al. 2000). In the majority of studies, however, the selected population included d l patients presenting for treatment (Friedman et al. 1995, Sjogren et al. 1990, Pekrhun 1 986). Most fiequently the bbinceptioncohort" was defined according to inclusion~exclusion criteria related to the tooth condition, while only a few studies considered health as an

inclusion/exclusion criterion (Trope et al. 1999, Weiger et al. 2000, Shah 1988). Therefore, for the purpose of discussion in this thesis, the "inception cohort" relates to tooth condition.

1.2.2

Description of Referral Pattern

The referraal pattern of the patient population participating in the smdy can influence the siuày resuits because of variation in: (1) Wpe of patients being treated, (2) providers of treatment, and (3) case selection criteria. Studies perfiormed in university clinics (Table 4)

may have interna1 validity, but they cannot be generalized to represent the population at large. The general population is better represented by patients treated in pnvate clinics, which are usually treated or referred by genera1 practitioners fiom the community. In such studies (Table 4), treatment is frequently perfomied by endodontists who have greater expertise than the students who wmrnonly provide treatment in university-based studies. The pattern of referral can also introduce bias, since the average case treated by undergraduate students is generally less complicated than cases treated by graduate students or specialists.

1.2.3

Description of Follow-Ur, R e d Rate

The entire "inception cohort " in a prospective

shrdy

should be accounted for at the

end of the follow-up penod. und the clinical status of the treated cases known. Interpretation of the study results depends to some degree on how the characteristics of the patients who actually completed the study compare with the characteristic of those who did not. Also, it is

important to know how the actual results obtained may have differed if al1 the treated subjects remained in the study (Spilker 1991). Patients may not retum for recall examination for different reasons, including (Spilker 1991): (1) loss of interest, (2) too long follow-up pexiod, (3) relocation to another area, (4)

anergence of intercurrent illness, (5) treatment failure, (6) relief of syrnptoms. A study must, therefore, distinguish patient "dropouts" (they do not rehirn for recall examination at their own volition) nom bbdiscontinuers"(they are excluded fiom the study by the investigator, for specific and accountable reasons, eg. death or relocation to another area). The above

distinction is important if an accurate recall rate is to be established. Discontinuas are excluded from the study population, whereas dropouts are not - they may represent a missing population. For example, in the 1990 study by Sjogren et al., where only 356 of 770 patients were re-examineci, the recall rate appears to be 46%. If the discontinuers are excluded, however, the recall rate inmeases to 82%, which is far more acceptable. Only few prospective endodontic outcome studies diligently described the reasons for recall default (Engstriim & Lundberg 1965, Sjogren et al. 1990, Sjogren et al. 1997, Friedman et al. 1995). Other studies did not conform with the aforernentioned criteria (Seltzer et al. 1963, Bender & Seltzer 1964, Zeldow & ingle 1963, Grossman et al. 1964, Kerekes & Tronstad 1979, Barbakow et al, 1980, 1981, Pekruhn 1986, Matsumoto et al. 1987, Shah 1988, Akerblom & Hasselgren 1988, Chugal et al. 200 1). Because the results in those studies may be considerably skewed, they are excluded fkom discussion in this thesis. The unit of evaluation used to calculate the recall rate should be consistent with that

used to calculate the results. In some studies the recall rate was calculated as a percentage of presenting patients, whereas the outcornes were calculated on the basis of treated roots (0rstavik 1996, Sjogren et al. 1990). This confusion c m be avoided by employing only one tooth per patient, thereby equating the patient recall rate to the overall outcome rate (Weiger et al. 2 0 ) .

1.2.4

Definition of Obiective Outcome Criteria

(a) The outcome of the treatment should be established in terms of "dimensions"and "measures" (Bader & Shugars 1995). The Institute of Medicine cornmittee has listed seven

dimensions that can be assigned for health studies (Bader & Shugars 1995): (1) survival and life expectancy, (2) symptoms states, (3) physiologic states, (4) physical functions states, (5) ernotional and cognitive states, (6) perception about present and future heaith, and (7) satisfaction with health care. Within each dimension, several outcorne measures can be used. Frequently, different 4'outcomes" cm be determineci for every treatment pdormed, each of which may be considered from different perspectives, in accordance with how the information is to be used (Bader & Shugars 1995). Bader & Shugars (1995) classified dental outcornes within a set of four dimensions: (1) physical~hysiologicaldimension - presence of pathosis, pain and assessrnent of function,

(2) psychological dimension - perceived aesthetics, level of oral health, satisfaction with oral health status, self-concept and inter-personal relations, (3) economic dimension

- including

direct and indirect cost, and (4) longevity/mrvival dimension - pulp death, tooth loss, time until repeat treatment for sarne condition or new condition.

In the literature concerned with endodontic treatment outcome, mainly the dimension of the physiologic states has been considered, namely the presence or absence of disease. The outcome measures for Apical Periodontitis are usually clinical and radiographic, yet several studies used only radiographs to measure the outcorne (Table 4). However, variation exists not only in outcome measures, but also in the actual criteria used. In some studies, "success"

was strictly defined as absence of both clinical signs and symptoms and radiographic evidence of disease (Akerblom & Hasselgren 1987, BystrOm el al. 1987, Friedman et al. 1995, Kerekes & Tronstad 1979, Klevant et al. 1983, SjOgren et al. 1990, 1997, Sundqvist et

al. 1998, Chugal et al. 2001). in other studies, "success" was defined as absence of clinical

signs and syrnptoms, while radiographically, disease was either absent, reduced in extent or unchanged (Seltzer et al. 1963, Bender & Seltzer 1964, Matsumoto et al. 1987, Shah 1988).

(b) To facilitate reproducibility of research, the outcome should be measured as objective& as possible. Many studies presented vague and subjective outcome measures, such

as the patient or tooth being "uncornfortable" (Shah 1988, Grossman et ai. 1964). Another fiequent1y used subjective measure was the radiographic category of "uncertain", "questionable" or "doubtfùl" (Engstrorn et al. 1964, Engstriim & Lundberg 1965, Kerekes & Tronstad. 1979, Klevant & Eggink 1983, Akerblom & Hasselgren 1988). Likewise, "Incomplete healing" (Weiger et al. 2000) leaves some doubt as to the actual treatment outcome, when the follow-up period is long enough for the outcome to be conclusive. Furthemore, differences in outcome measures exist even within the definition of clinical signs and symptoms. For example, tenderness to percussion alone may be considered

as evidence of endodontic treatment failure (Grossman et al. 1964). However, tenderness to percussion is not an exclusive syrnptom of endodontic disease, and it can reflect oral conditions such as periodontal disease, traumatic occlusion or food impaction (Friedman et

al. 1995). Therefore, tenderness to percussion may be ignored, as long as there are no other radiographic and clinical signs and symptoms present (Friedman et al. 1995).

in an attempt to address the limitations of subjective radiographic criteria in the evaluation of treatment outcome, the Periapical Index (PAI) was introduced by 0rstavik et al. in 1986. The PA1 is based upon the cornparison of the assessecl radiograph with a set of five radiographic images, representing heaithy and diseased priapical tissues. Images representing healthy periapical tissues are assigned a score of I and 2, and images

representing Apical Periodontitis are assigned a score fiom 3 to 5, according to increasing extent and severity. The scoring system is based on Brynolfs (1967) histologie and radiographie investigation of periapical tissues of teeth in cadavers. Calibration of the

observers is a requirement when reliable scores are desired, particularly when multiple observers are employed.

(c) While it is important to define outcome criteria as objectively as possible, if is equally important to apply them consistent& throughout the study. Goldman et al. (1972), assessed the agreement among 6 examiners who were assigned to read radiographs of 253 teeth. They found the inter-examiner agreement was only 47%, and five examiners out of six agreed 67% of the time. Intra-examiner agreement ranged nom 73% to 80% (Goldman et al. 1974). Zakariasen et al. (1 984) found that the inter- and intra-examiner reliability depended more on the examiner per se than on the technical quality of the radiographs. Because intraand inter-examiner differences can be a confounding factor that influences the results of the study, examiners must be properly caiibrated and the level of reliability established, in order to consistently apply the defined aiteria. In many studies the examiners were not properly calibrated (Strindberg 1956, Seltzer et al. 1963, Zeldow & hgle 1963, Bender & Seltzer 1964, Engstfim et al. 1964, Engstr6m & Lundberg 1965, Grossman et al. L 964, Kerekes & Tronstad 1979, Barbakow et al. 1980, 1981, Klevant & Eggink 1983, Peknihn 1986, Safavi et al. 1987, Bystfim et al. 1987, Matsumoto et al. 1987, Shah 1988, Akerblom & Hasselgren

1988, Friedman et al. 1995, Caliskan & Sen 1996, Weiger et al. 2000, Chugal et al. 200 1 ) . In a few, however, the inter- and intra-examiner reliability were calibrated and evaluated (Sundqvist et al. 1998), and a significant level of agreement was reported using Cohen's

Kappa test (Sjôgren et al. 1990, Sjogren et al. 1997). Bergenholtz et al. (1979) calibrated the examiners but did not specifi the test used. Where the PA1 was used for evaluation, calibration of the observers was a prerequisite (Trope et ai. 1999, 0rstavik 1996, Eriksen et al. 1987).

1.2.5

"Blind" Outcome Assessrnent Investigators rnemring the outcorne should be drfferent fiorn those who provide

treatment. This is essential if two sources of bias are to be avoided: (1) expectation bias, that

occurs when examiners evaluate their own treatment; this often skews the results toward success, and (2) diagnostic suspicion bias, that occurs when examiners consider specific prognostic factors more relevant than others.

in many of the endodontic treatment outcome studies blinded examiners who were not involved in the treatment phase were employed (Table 4). in contrast, in several studies evaluations had been carried out by the providers of treatment (Strindberg, 1956, Seltzer et al. 1963, Bender & Seltzer 1964, Pekruhn 1986, Caliskan & Sen 1996, Shah 1988),

introducing bias to the assessment. In a few studies the examiners were not even specified (Grossman et al. 1964, Klevant & Eggink 1988, Matsumoto et al. 1987, Akerblom & Haselgren 1988). Only those studies where examination was definiteiy blinded are discussed

in this thesis.

1.2.6

Adiustment for Extraneous Promiostic Factors Extmneous Prognostic Factors are those characteristics that may predict the course

of the disease and thus the treatment outcorne; their influence must be taken inro account.

There are many factors that may influence the outcome of endodontic treatment, and they can be divided into the following categories: (1) Pre-operative factors

-

age, gender, tooth

location, clinical signs and symptoms, responses to pulp testing, Apical Periodontitis and its extent, and periodontal defects; there are additional factors specific to retreatment - density, length and material of the existing root filling, previous perforation, and time elapsed since initiai Treatrnent. (2) Intra-operative factors - nurnber of treatment sessions, use and type of intracanal medicaments, sealer used, root filling technique, length and voids, sealer extrusion, complications, temporary seal, inter-appointment emergency, and antibiotics. (3) Postoperative factors - intraradicular p s t , and coronal restoration. Traditionally, the "gold standard" for evaluating treatrnent outcornes has been the Randomized Controlled Trial. In a randomized controlled trial the specific prognostic factor that is under study is isolated by controlling al1 other prognostic factors. in this manner, the efficacy, or maximum effect of the treatment can be detmined. However, randomized controlled trials are limited by the fact that the treatment outcome is measured under "ideal" conditions, which may not reflect the reality of health care, when different variables coinfluence the treatment outcome. Observational studies can be applied to assess the effectiveness of treatment; however in such studies the prognostic factors cannot be controlled by the investigator; only be observed and recordecl to facilitate analysis of the data.

Different endodontic treatment outcome studies have highlighted various factors as being prognostic, but the tme impact of some of these factors on the outcome should be interpreted with discretion. Several studies were indeed randomized controlled trials by design (Engstrom et al. 1964, Engsh6m & Lundberg 1965, Zeldow & Ingle 1963, Klevant &

Eggink 1983, Eriksen et al. 1987, Caiiskan & Sen 1996, Bystrom et al. 1987, Trope et al. 1999, Weiger et al. 2000,) - in these studies the most important pre-operative prognostic factor, presence of Apical Periodontitis, as well as al1 the intra-operative factors were controlled. Several other studies were descriptive by design and assessed the outcume of treatment Wormed in a clinical or university setting; the extraneous prognostic factors were less rigorously controlled in these studies (Barbakow et al. 1980, 1981,Grossrniin et al. 1964, Kerekes & Tronstad 1979, Pekruhn 1986). in a few studies the pre-operative presence of Apical Periodontitis was isolated only for statistical analysis (Seltzer et al. 1963, Shah 1988, Barbakow et al. 1981 , Sjogren et al. 1990).

In a few studies, systemic pre-operative factors were assessed, such as intake of systemic antibiotics (Zeldow & Ingie 1963, Matsumoto et al. 1987, Weiger et al. 2000). However, the influence of antibiotics on the prognosis of non-surgical endodontic treatment

has never been established. The general systemic condition of the patient was controlled only in two studies (Strindberg 1956, Storms 1963). This factor is difficult to assess, because a patients' health status may change over the period of observation, particularly in long-tenn studies.

In observationai descriptive studies, the extraneous prognostic factors were mainly identified by recording the data before, dunng and after treatment, so as to enable a more

accurate analysis of the results (Engstriim et al. 1964, Engstrom & Lundberg 1965, Seltzer et al. 1963, Bender & Seltzer 1964, SjOgren et al. 1990, Sundqvist et al. 1998, Chugal et al. 200 1). In two studies ( H a . et al. 1970, Smith et al. 1993) the intra-operative procedures and

associated factors were modified during the course of the study. Because the results in these studies may be considerably skewed, they are excluded from discussion in this thesis.

1.2.7

&maisal Sumrnarv Appraisal of the outcome studies according the guidelines established by McMaster

University, highlighted seven articles that meet the criteria (Table 4). The seven selected articles f o m the basis for reference in the next section, regarding the outcome of initial Treatment and Retreatment. In al1 seven studies, the assessrnent criteria used were those established by Strindberg (1956); however, the category b'uncertain" was excluded because its use in these studies did not clearly follow Srindberg's definition. In the following section the outcome "complete healing" is used in lieu of "success" ofien used in the quoted studies.

13

Treatment Outcome in Teeth without Apical Periodontitis

1.3.1

Initial Treatment

Teeth without Apical Periodontitis are endodontically treated for a variety of indications, diffenng with regards to the condition of the pulp, as follows: (1) healthy pulp, in

teeth that will undergo extensive restoration requiring a post retention, and (2) irreversibly inflamed or necrotic pulp.

The randomizecî controllad trial by Engstem's et al. (1 964)assessed the influence of root canal infection, dernonstrated by bacterial culture, on the outcome of root canal treatment. The "inception cohort" were patients treated at the Royal School of Dentistry in Stockholm, selected according to the results of the culture test. The experimental group consisted of teeth that had positive culture at the time of root filling, and the control were teeth that had negative culture. Al1 teeth were treated by students and followed up for 4 to 5 years. The recall rate was 72%. Of teeth that presented without Apical Periodontitis, 89% remained completely healed. The outcome in teeth that had a positive cul-

at the time of

root filling was significantly poorer than in teeth that had a negative culture, with healing rates of 81% and 9S%, respectively. Persisting root canal infection (positive culture) was the main factor that affected the outcome of treatment. Other factors that adversely influenced the outcome were, root canal preparation to the apex compared with short of the apex, and extrusion of root filling material. In a subsequent study (Engstrh & Lundberg 1965) 89% of roots that had a negative culture healed, compared with 73% of roots that were similarly treated but had a positive culture. Sjogren et al. (IWO), examined 849 roots treated by undergraduate students and followed up for 8 to 10 years. The recall rate was 82% (patients). The teeth were treated acconiing to a strict protocol and were bacteriologically sarnpled before root filling. The healing rate for non-infected mots was 96%, regardless of the pulp being vital or necrotic. None of the potential prognostic factors examined, including age, gendei, perïodontal defect, and post restoration, were found to significantly influence the outcome of treatment.

in surnrnary, the healing rate for Initial Treatment in teeth without Apical Periodontitis ranges fiom 89 % (Engstrim et al. 1964) to 96% (Sjogren et al. 1990).

1.3.2

Retreatment Root filled teeth without Apical Periodontitis are retreated when it is assumed that the

root canal system harbors bacteria, which can propagate a k the root canal environment is altered. Filled m a l s may harbor bacteria when: (1) the root filling is deficient (Molander et of. 1998), and (2) it becomes exposed to the oral cavity (Friedman et al. 1997). Placement of

a new restoration in such teeth can lead to ernergence of Apical Periodontitis. Retreatment of non-infected teeth has a high healing rate, in the range fiom 92% (Engstrtim et al. 1964) to 98% (Sjogren et al. 1990), which appears to be unaffected by any of the pre- or intra-operative factors. Neither one of the two studies assessed the influence of pst-operative factors.

1.4

1.4.1

Treatment Outcome in Teeth with Apical Periodontitis

InitialTreatrnent Teeth with Apical Periodontitis are endodontically treated with the goal of eliminating

root canal infection and the associated disease. Treating teeth with Apical Periodontitis, Engstrom et of. (1964) observed 76% wmplete healing. The outcome in teeth that had a positive culture at the tirne of root filling was significantly poorer than in teeth that had a negative cultxe, with a healing rate of 59%

and 83%, respectively. Persistent root canal infection (positive culture) was the main factor that influenced the outcome of treatrnent. Other factors that appeared to adversely influence the outcome, without statistical significance, however, were lesion size greater than 5 mm, overinstnimentation and extrusion of the root filling beyond the root end. Sjôgren et al. (1 997) confinned these results by studying 55 single-rooted teeth with

Apical Periodontitis. Teeth were followed for up to 5 years, and the recall rate was 96%. Al1 teeth were treated in a single session while advanced bacteriological techniques were used to record the culture status of the canal irnrnediately pnor to filling. Arnong the teeth with a negative culture, 94% healed completely. In contrast, among teeth with a positive culture the healing rate was only 68%. Of the prognostic factors examined, neither the periapical lesion size nor the level of instrumentation affecteci the outwrne.

Bystr6m et al. (1987), examined 79 single-rooted teeth with Apical Periodontitis treated by undergraduate students and followed up for 5 years. The recall rate was 56%. The teeth were treated in two or more sessions, and root-filled only after a negative culture was obtained. Overall, 85% of the teeth healed completely. Teeth that failed to heal were infected with A. israelii and A. propionica. There was a significant correlation between the size of the

periapical lesion and the nurnbers of bacteria cultured fiom the canal. The apical level of the root filiing did not significantly affect the outcome. Treating teeth with Apicd Periodontitis, Sj6gren et al. (1990) observed a complete healing rate of 86%. The level of mot canal instrumentation influenced the outcome - the outcome in teeth insûumented to the "apical constriction" was significantly better than in teeth that oould not be instrumented to that level, with a healing rate of 90% and 69%,

respectively. The apical level of the root filling also influenced the outcome - in roots where the filling reached within 2 mm of the apex the outcome was significantly better than in roots

that were filled short or beyond the apex, with a healing rate of 94%, 68% and 76%, respective1y. Weiger et al. (20ûû), in a randomized controlled trial examined 73 teeth with Apical Periodontitis treated in one or two sessions and followed fiom 6 months up to 5 years. The r d 1 rate was 92%. The overall complete healing rate was 78%, and it increased over time to exceed 90%. The outcome in teeth treated in one and two sessions (with calcium hydroxide dressing) did not differ significantly. The size of the periapical lesion exerted a significant influence on the outcome - there was almost 3 times higher nsk of failure to heal in teeth with periapical lesions greater than 5 mm compared with lesions smaller than 2 mm.

In swnmary, the healing rate for Initiai Treatment in teeth with pre-operative Apical Periodontitis ranges from 76% (Engstrom et al. 1964) to 86% (Sjogren et al. 1990).

1.4.2 Retreatment

Retreatment in teeth presenting with persistent Apical Periodontitis is one of the most challenging tasks in endodontic therapy, because of the technical difficulty associated with perfoming the procedure, but also because the main goal of therapy, eradication of the infection, is difficult to attain (Molander et al. 1998). The efficiency of retreatment may be compromised by the difficulty to eliminate al1 the previous filling material (Wilcox et al. 1987), by bacterial invasion of the dentinal tubules (Ando & Hoshino 1990) or the

periradicular tissues (Nair et al. 1990), and by the microbial flora being resistant to the

conventionai endodontic procedures (Sundqvist et al. 1998; Molander et al. 1998). Consequently, retreatment in teeth with Apical Periodontitis offers the lowest complete healing rate in non-surgical endodontics. Retreating teeth with Apical Periodontitis, Engstrom et al. (1964) observed a complete healing rate of 74%. The outcome in teeth with pre-operative laions smaller than 5

mm was better than in teeth with large;. lesions, with a healing rate of 76% and 67%, respective1y. Sjogren et al. (1990) obsewed complete healing in 62% of retreated teeth, and

corroboratecl the prognostic significance of the lesion size, with a healing rate of 68% and 38% for small and large lesions, respectively. in addition, the outcome was significantly better in teeth with dense root fillings that in teeth with inadequate seal, with a healing rate of

67% and 31%, respectively. ûther factors, such as root filling length and level of instrumentation, did not appear to influence the outcome. In contrast to teeth receiving Initial Treatrnent (see above p.24), discrepancy may possibly be explained by the considerably smaller sarnple size for Retreatment (n= 94) than for Initial Treatment (n= 204), and by the fact that overall, the healing rates for Retreatrnent were lower than those for initial Treatment. Sundqvist et al. (1998) studied 54 root-filled teeth with persistent Apical Periodontitis retreated by endodontists and followed up for 5 years. The recall rate was 93%. The teeth were retreated according to a strict protocol, using advanced bacteriological techniques. The overall complete healing rate was 74%. The microbial flora found in the retreated teeth was diffaent fiom that of untreated infected canals, with monoinfection by E. faecalis being a common finding. In the teeth infected with E. faecalis, the healing rate was only 66%.

Corroborating the earlier results of Ensgtrom et al. (1964), teeth where bacteria were still present at the time of root filiing had a significantly poorer outcome than teeth where cultures before root filling were negative, with a healing rate of 33% and 8096, respectively.

In summary, the healing rate for retreatrnent with previous Apical Periodontitis ranges fiom 62% (Sjogren et al. 1990) to 74% (Sundqvist et al., 1998)

II.

STATEMENT OF THE PROBLEM

Dentists, patients, and policy makers today are looking more than ever before for evidence base to support decisions regarding treatment, including endodontic treatment. Although the endodontic literature is replete with studies on the outcome of treatment, most studies do not confonn to the rigorous scientific methodologid criteria cmently accepted for outwme studies. Of the seven studies in the literature that follow scientifically acceptable criteria, only one descriptive longitudinal study (Sjogren et al. 1990) had a large sample size, consisting of al1 tooth types in teeth with and without Apical Periodontitis. In that study, roots rather than teeth were used as the unit of evaluation, potentially resulting in an elevated

success rate. Because the treatment technique in that study included components not widely applied today, such as mot filling with Kloropercha and bacteriological culture as a prerequisite for root fillhg, M e r observational studies are requireù to broaden the evidence base regarding the outcome of endadontic treatment and potential influencing factors. The Arnerican Association of Endodontists has recently highlighted the need for M e r outcome studies as a priority for research.

II. f

Long-term Aims

Conducting a large scale observational study on the oütcome of endodontic treatment is the first long-tm aim of the Toronto Study project. In 1993, the Faculty of Dentistry, University of Toronto established the first and, to date, the only Graduate Endodontics Program in Canada. Data pertaining to the endodontic treatment has been wllected and entered in a specific database since the outset of the program. The treated population has beem divided into 2-yea. phases, with Phase 1 covering the period f?om September 1993 and September 1995, Phase II, the period nom October 1995 to September 1997, and so on. n i e compiled database can serve as a suitable basis for a large scale, long-terni prospective study on the outcome of endodontic treatment. Furthexmore, several years into the Graduate Endodontics Program, a study is warranteci that will provide viable information regarding the outoome of treatment performed in the Graduate Endodontics Clinic. Generating such feedback is the second long-terni aim of the Toronto Study project.

III.

OBJECTIVES OF THE STUDY

This study was cmied out with the following objectives: 1) To assess the 4 to 6 year outcome of endodontic initial Treatment and Retreatment, performed at the Graduate Endodontics Clinic, Faculty of Dentistry, University of Toronto, fiom September 1993 to September 1995.

2) To assess the influence of the different pre-, intra- and pst-operative factors on the outcome of treatrnent.

IV.

HYPOTHESIS

The incidence of healing observed in this study would be comparable with that reported in those studies that confom to the guidelines proposed by the McMaster University

V.

MATERIAL A N D METHODS

Al1 treatment procedures were performed at the Graduate Endodontics C h i c , Faculty of Dentistry, University of Toronto. h f o m e d consent was obtained fiom al1 patients enrolled in the study at the beginning of treatment, including consent for participation in research and in the follow-up examination (Appendix 1).

V. 1

Studied Population The "inception cohort" consisted of 600 patients and 67 1 teeth. Of these, 405 teeth in

350 patients underwent Initial Treatment, and 266 teeth in 250 patients underwent

Reîreatment. Al1 treatments were perfonned by graduate students under supervision of qualified Endodontists.

V.2

Recording of Data Al1 the pre- and intra-operative information pertaining to each treated tooth, including

clinical and radiographic documentation, was recorded in a separate fonn (Appendix 2) by the treating graduate student imrnediately afier completion of treatment. The information

entered in these forms was wded, to allow direct transfer to the Microsoft Excel database program (Appendix 3). A full set of duplicate radiographs was attached to the form. Al1 radiogmphs were taken with the XCP itim film holder with a constant exposure, developed in an automatic developing device (DENT-X,Elmsford, N.Y., USA), and observed under standard conditions using a viewbox and magnification. The size of any periradicular radiolucency was measured across its widest diarneter by the provider of treatment, and recorded in millimeters. At the completion of treatment, patients were advised of the importance of the longt e m follow-up examinations to assess the outcome. Upon re-examination, the clinical and

radiographic findings were recorded by the principal investigator in a separate form for each tooth (Appendix 4), and then entered into the database. Again, the size of any periradicular radiolucency was measured across its widest diameter and recorded in millimeters. Prior to the radiographic evaluation, the pnncipal investigator was calibrated with a set of 100 periapical radiographs randomly selected fiom the Feriapical index calibration set

(0rstavik 1986), with modification of the measured outcome to include only two categories absence (O) or presence (1) of Apical Periodontitis. For multirooted teeth, if one root was assigned the score 1, the sarne score was assigned to the tooth as a whole. h parallel to the principal investigator, ail 100 teeth were viewed by the CO-principalinvestigator, who is more

experienced in conducting research in this area of study. Intra- and inter-examiner reliability

was then assessed using Cohen's Kappa statistic.

V.3

Patient Recall Strategis Initially, letters were mailed to encourage patients to attend recall examinations

(Appendix 5). Non-responding patients were then called by telephone. This initial mailing resulted in a recall rate of 20%. To improve the recall rate, attempts to reach the non-responding patients were repeated by sending two additional recall letters. When letters returned undelivered, the hternet Bell Directory was used to search for the new addresses of the patients. A third recall letter was then mailed to the relocated patients, and again to those who not responded to earlier recall. This time, to encourage patients to respond, a "participation reward" of $50 was offered by letter (Appendix 6) and concurrently by telephone. Teeth that were extracted, deceased patients and those who could not be reached, were recorded in the database with the respective explanation.

V.4

Assessrnent Criteria Strict clinical and radiographie criteria were used according to Strindberg (1956),

with the exclusion of the 'bcertain" category. The tooth as a whole was considered the unit

-

of evaluation. Periapical tissues were classified as follows (Figure 1): ( 1) HEALED if there was (i) absence of periradicular radiolucency, beyond thickening of the periodontal ligament

space to double the nomal width, and (ii) absence of clinical signs and symptoms, 0 t h than

tendemess to percussion, or (2) DISEASED

-

if there was (i) emerged or residual

periradicular radiolucency (regardless of its size), or (ii) presence of signs and syrnptoms other than tendemess to percussion. Measurernents of the size of periapical radiolucencies before treatment and at recall examination were compared for descriptive purposes only; they were not used for outcome assessment.

V.5

Sam~leSize Estimation Sample size estimation for Initial Treatrnent and Retreatment was performed with the

cornputer software Epi-Info, using the Test of Proportion of healing based fkom previous studies. For Initial Treatrnent, with a power of 82%, 5% significance for a two-tailed test and

a proportion of healing of 80% (Sjogren et al. 1997), the required sample size was 170 teeth. Adjusting for a ciropout rate of 30%, the required sarnple size was 22 1 teeth. For Retreatment, with a power of 80%, 55% significance level for a two-tailed test and estimating a proportion of healing of 74% (Sundqvist et al. 1998), the estimated sample size was 74 teeth. Adjusting for a dropout rate of 30%, the required sample size was 96 teeth.

V.6

Statistical Anal-ysis Statistical analysis was perfonned in three parts, as follows:

(1) Univariate description of the data using percent frequencies.

(2) Bivariate associations between the pre-, intra- and pst-operative factors and the treatment outcome, using contingency tables and the Chi-square Test of Proportions or the

Fisher's Exact Test. The independent variables (prognostic factors) studied were the following:

fi) Pre-operative factors: gender, age (up to 45 years or older), tooth location (maxilla or mandible), number of roots (one or more), clinical signs and symptoms (present or absent), presence of Apical Periodontitis (present or absent), priodontal defect (present or absent). (i. 1) For Initial Treahnent on&, pulp vitality (vital or necrotic).

0.2) For Retreatntent on&, previous perforation (present or absent), time elapsed since previous treatment (up to 1 year or longer), previous root filling length (adequate or inadquate), previous root filling density (good or poor), previous root filling material (gutta-percha or other). (ii) Intra-operative factors: number of treatment sessions (one or more), intracanal

medication with calcium hydroxide (applied or not), root filling condensation (lateral, vertical or other), voids in root canal filling (present or absent), sealer extrusion (present or absent), complications (present or absent), and temporary seal used (Cavit,

IRM or Glass ionomer cernent). (iii) Post-operative factors:

type of restoration (ternporary or definitive), and

intracanal p s t (present or absent).

(3) Multivariate analysis was performed using Logistic Regession models to evaluate the joint associations arnong various factors.

Ail statistical tests were perfonned as two-tailed, and interpreted at the 5% significance level. Analyses were carried out separately for Initial Treatment and Retreatment. For either procedure the entire material was analyzed first, then a stratified (teeth without and with Apical Periodontitis) analysis was pexformed.

VI.

RESULTS

The Kappa score for inter-examiner agreement after the first session was k = 0.8, and after the second session perfonned one week apart, the Kappa score for intra-examiner agreement was k = 0.9. According to Landis and Koch (1 977), Kappa scores greater than 0.8 indicate "good agreement".

VI.1

initial Treatment Of 350 patients and 405 teeth treated, the "discontinuers" consisted of 9 deceased

patients (10 teeth) and 1 0 0 patients (1 18 teeth) who could not be reached. Thus 3 1% of the

teeth were excluded fiom the study, leaving a total of 277 teeth as the "new total population"-

(Figure 2). The distribution of these teeth according to pre- and intra-operative variables is presented in Table 5. The majority of the teeth were located in the maxillae (55%), and were multi-rooted (66%). Apical Periodontitis was f o n d in 57% of the teeth, and 55% of the teeth presented without any pre-operative clinical signs or symptoms. In 65% of the teeth the pulp was diagnosed as necrotic.

Of the "new total population" of 277 teeth, 136 teeth could not be re-examinai either because patients declined the recall (17 teeth) or did not respond (1 19 teeth). Thus, 49% of the teeth were fiom the 44dr~pout" patients, leaving 141 teeth (5 1%) of the 'hew total population" that were accounted for (Figure 3). From this remaining population, 2 1 teeth had

been extracted

- I 1 teeth due to periodontal disease, 5 teeth for restorative considerations,

and 4 teeth for unknown reasons. The 21 extracted teeth were excluded fiom statistical analysis, leaving 120 teeth that were analyzed. Univariate description of the analyzed teeth is presented in Table 6. To assas if the characteristics of the responding and the "new total" populations varied, a response bias analysis was perfomed using Chi-square at the 5% significance level. Two prognostic factors were used for this analysis (Table 7). There was no statistically significant diffaence between both populations. In the 141 teeth of the responding population, 57% presented with pre-operative Apical Periodontitis, compared with 56% in the 136 "dropout" teeth. For the pre-operative variable pulp vitality, the responding population included 68% of the teeth with necrotic pulp compared witb 60% in the "dropout" population.

VI. 1.1 Total material

Ninety seven teeth (8 1%) were classified as healed, and the remaining 23 teeth (19%) as having Apical Periodontitis (Fig. 4, A-D, Fig. 5

, C-D).Associations between the pre-,

intra- and pst-operative factors and the outanne of treatment are shown in Tables 8, 9 and 10, respectively. Of al1 the factors analyzed, only the differences related to pre-operative

Apical Periodontitis and Pulp Vitality were found to be statistically significant (Table 8). The healing rate for teeth without and those with Apical Periodontitis was 92% and 74%, respectively (p < 0.02). The healing rate for teeth with vital and those with necrotic pulps was 95% and 75%, respectively (p < 0.02). To assess whether pulp vitality and Apical

Periodontitis were associated variables, a Chi-square contigency table was calculated (Table 11). The association between pulp necrosis and Apical Periodontitis was highly siNficant, confirming the mutual relationship between these two variables @ c 0.00 1). Radiographic analysis of the 23 "diseased" teeth revealed that the size of the Apical Periodontitis lesion decreased in 13 teeth (57%), remaineci unchangeci in 4 teeth (17%), and increased in 6 teeth (26%) (data not shown). Clinically, only 4 of the 23 teeth (17%) presented signs or symptoms at the recall examination. Differences in healing rate greater than 10% were observed in relation with two additional factors

- nurnber

of roots and temporary seal (Tables 8 and 9, respectively).

However, these differences were not statistically significant, and neither were the smaller differences related to al1 other exarnined factors (Tables 8,9, 10).

Stepwise Logistic Regression analysis was used to assess the simultaneous effects of the prognostic factors adjusting for important effect modifiers, such as ternporary seal and treatment sessions (Table 12). Again, Apical Penodontitis was found to be the only statistically significant factor with the Odds Ratio of 3.7 1 (95% C.I. = 1.14 to 12.0) - there was dmost 4 times increased likelihood of the teeth not to heal if Apical Periodontitis was

present before initiating endodontic treatment than whem Apical Periodontitis was not present.

VI.1 -2 Teeth without h i c a i Periodontitis Of the 48 teeth that presented without Apical Periodontitis, 44 teeth (92%) rernained

healed. Associations between the pre-, intra- and pst-operative factors and the outcome of treatrnent are presented in Tables 13, 14 and 15, respectively. Differences related to al1 of the pre-, intra- and postsperative factors were found not to be statistically significant.

VI.I .3 Teeth with A ~ i c a Periodontitis l -

Of the 72 teeth that presented with Apical Periodontitis, 53 teeth (74%) healed. Associations between pre-, intra- and pst-operative factors and the outcome of treatrnent are presented in Tables 16, 17 and 18, respectively. Only differences related to the Number of Roots were statistically significant (Table 16). The healing rate for single-rooted and multirooted teeth was 87% and 63%, respectively @ < 0.03). Radiographic analysis of the 19 "diseased" teeth revealed that the size of the Apical Periodontitis lesion decreased in 13 teeth (68%), rernained unchanged in 4 teeth (2 1%), and

increased in 2 teeth (1 1%) (data not shown). Differences in healing rate greater than 10% were observed in relation with several factors

-

age, pulp vitality, number of treatment sessions, root filling technique, sealer

extrusion, temporary seal and definitive restoration (Table 16, 17 and 18). However, these diffaences, as the smaller ones related to al1 other examined factors, were not statistically significant.

To fùrther investigate the 18% difference in healing rate observed in relation to the number of treatrnent sessions, a stratified analysis was carried out to examine this factor separately for single- and multi-rooted teeth (Table 19). The healing rate for single-rooted teeth treated in two or more sessions and those treated in a single session was 96% and 6396, respectively (p < 0.05). For multi-rooted teeth, the difference in healing rate was not statistically signifiant.

VI.2 Retreatment

Of 250 patients and 266 teeth treated, the "discontinuers" consisted of 1 deceased patient (1 tooth) and 57 patients (62 teeth) who could not be reached. Thus 24% of the teeth were excluded from the study, leaving a total of 203 teeth as the "new total population" (Figure 6). The distribution of these teeth according to pre- and intra-operative variables is presented in Table 20. The majority of teeth were located in the maxillae (68%) and were single-rooted (5 1%). Apical Periodontitis was found in 57% of the teeth. Of the 'hew total population" of 203 teeth, 136 teeth could not be re-examined, because patients declined the recall (10 teeth) or did not respond (126 teeth). Thus, 67% of the teeth were from the "dropout" patients, leaving 67 teeth of the "new total population"

(33%) that were accounted for (Figure 7). From this remaining population, 11 teeth had been extracted - 2 teeth due to periodontal disease, 3 teeth for restorative reasons and 6 teeth for unknown reasons. The 1 1 extracted teeth were excluded fiom statistical analysis, leaving 56 teeth that were analyzed. Univariate description of the analyzed teeth is presented in Table

2 1.

To assess if the characteristics of the responding and the "new total" populations varied, a response bias analysis was pdormed using Chi-square at the 5% significance Ievel. One prognostic factor was used for this analysis (Table 22). There was a statistically significant difference (p < 0.03) between both populations. In the 67 teeth of the responding population, 58% presented with pre-operative Apical Periodontitis, cornpared with 7 1% in the 136 "dropout" teeth.

VI.2.1 Total material Forty-one teeth (7 1%) were classified as healed, and the remaining 15 (29%) as having Apical Periodontitis (Fig. 4, E-F, Fig. 5, A-B). Associations between the pre-, intra-

and pst-operative factors and the outcome of treatment are shown in Tables 23, 24 and 25, respectively. Of al1 the factors analyzed, oniy the differences related to the pre-operative presence of a perforation and the time elapsed fiom Initial Treatment to Retreatment were found to be statistically significant (Table 23). The healing rate for teeth without and those with a pre-operative perforation was 78% and 25%, respectively (p < 0.007). The healing rate for teeth that were initially treated within one year and those treated over one year before retreatment were 43% and 80%, respectively (p < 0.02). Radiographie analysis of the 15 "diseased" teeth revealed that the size of the Apical

Periodontitis lesion decreased in 7 teeth (47%), remained unchanged in 2 teeth (13%) and increascd in 6 teeth (40%) (data not shown). Clinically, 5 of the 15 teeth (33%) presented with signs or symptoms at the recall examination.

A diffaence in healing rate of 18% was observed in relation with the pre-operative

factor Apical Periodontitis. However, this difference was not statistically significant, and neither were the smaller differences related to al1 other exarnined factors.

VI.2.2 Teeth without Apical Periodontitis Of the 26 teeth that presented for Retreatment without Apical Periodontitis, 21 teeth (81 %) remained healed. Associations between the pre-, intra- and post-operative factors and the outcome of treatment are presented in Tables 26, 27 and 28, respectively. Only the

difference related to the time elapsed since previous treatment was f o n d to be statistically significant (Table 26). The healing rate for teeth that were initially treated within one year and those treated over one year before retreatrnent was 33% and 94%, respectively @ < 0.007).

VI.2.3 Teeth with h i c a i Periodontitis

Of the 30 teeth that presented for Retreatment with Apical Periodontitis, 19 teeth (63%) healed. Association between pre-, intra- and pst-operative factors and the outcome of treatment are presented in Tables 29,30 and 3 1, respectively. Differences related to al1 of the pre-, intra- and postsperative factors were found not to be statistically significant. Radiographie analysis of the 10 "diseased" teeth revealed that the size of the Apical

Periodontitis lesion decreased in 7 teeth (70%), remained unchangecl in 2 teeth (20%) and

increased in 1 tooth (10%) (data not show).

V.

DISCUSSION

This prospective historical d o r t study assessed the outcome of Initial Treatrnent and Retreatment perforrned at the Graduate Endodontic Clinic, Faculty of Dentistry, University of Toronto. The inception cohort was identified at the outset of the study and followed up to the present time. Al1 treatrnent procedures and the recording of the data followed a standardized protocol established prior to the initiation of the study. The referrd pattern in this study included al1 patients treated at the Graduate Endadontics Clinic fiom Septernber 1993 to September 1995, without pre-defined case selection criteria. A similar strategy was applied in the descriptive study by SjOgren et al. (1990). The majority of the patients were refmed fiom the Undergraduate Clinic, while many

were referred from the Emergency Clinic. The dental history of the latter fiequently revealed that they had not received regular dental a r e . Only few patients were referred fiom private practice; therefore, the cohort included in this study may not be representative of the general population. Furthemore, teeth treated in the Graduate Endodontics Clinic may have presented more complex conditions than those routinely treated by general practitioners, possibly introducing bias to the study material. The 4 to 6 year recall rate of 5 1% for Initial Treatment and 33% for Retreatment falls short of the guidelines suggested by McMaster University (198 1) for good quality evidence. Nevertheless, it is similar to the recall rate in several other prospective endodontic treatment outcome studies of comparable duration (Bystrom et al. 1987, Barbakow et al. 1980, Matsumoto et al. 1987). Those studies that achieved higher recall rates were mostly

randomized controlled h a i s in relatively srnall populations (Engstem et al. 1964, Engstrom & Lundberg 1965, Sjogren et al. 1997, Sundqvist et al. 1998, Weiger et al. 2000).

It appears that despite elaborate efforts to encourage as many patients as possible to attend the follow-up examination, including the offer of a monetary incentive ("participation reward"), the recall rate could not be improved. Possibly, this was because of the many patients referreù fkom the Emergency Clinic presented for endodontic treatrnent only, and did not receive further treatment at the Faculty of Dentistry. Other patients were not interested to r e m only for an endodontic follow-up examination. Uegardless of the cause, the rather low recall rate in the present study may reflet the reality of populations in large cities where a University clinic may attract mainly patients of low socio-economic background. Most studies in which hi& recall rates were achieved were pdormed in smaller communities than Toronto (Sjogren et al. 1990, 1997, Sundqvist et al. 1998, Weiger et al. 20001, where the University clinic may enjoy a different status, and attract a more balanceci population.

The response bias analysis performed using the extranenus prognostic factor, Apical Periodontitis, revealed that the examined and the dropout populations did not diffa significantly for Initial Treatment, but did differ significantly for Retreatment. In either case, the examined population may not tmly represent the entire population, because with as missing subjects as in this study there is the possibility their conditions varied considerably fiom those of the examined subjects. The outcome criteria used in this study were stringent. The "uncertain" category as defined by Strindberg (1956) was considered invalid for the purpose of this study and was eliminated for the following rasons: (1) inclusion of roots with ambiguous conditions would

introduce a subjective connotation to the assessment, (2) inclusion of teeth that were extracted within 3 years of treatment might skew the general results, because the reason for extraction could be endodontic failure, (3) four to six years after treatment the outcome was expected to be definitive (Strindberg 1956, Bystr6m et al. 1987, 0rstavik 1996) and dichotomous - completely healed or not, without an in between" category. "

TO be considered "healed", teeth had to demonstrate complete absence of periradicular radiolucency and clinical signs and symptoms other than tendemess to percussion, as suggested by Friedman et al. (1995).In the majority of the studies, tendemess to percussion was not specified; it could have been considered a sign of failure to heal. Percussion tendemess is not a pathognomonic sign of Apical Periodontitis, as it may be related to traumatic occlusion, food impaction or periodontal disease (Friedman et al. 1995); therefore, its undiscriminating inclusion with other signs and symptoms may have lowered the reported rate of complete healing in many studies. If the outcome criteria in this study were to exclude the clinical measures and relied exclusively on radiographic measures (Seltzer et al. 1963, Bender & Seltzer 1964, Kerekes & Tronstad 1979), even with the strict radiographic criteria the healing rate for Initial Treatment

and Retreatment would have b m 92% and 83%, respectively. If the radiographic criteria were extended to consider a reduced or unchanged lesion as b'healed" (Harty et al. 1970, Shah 1988), the healing rate for Initial Treatment and Retreatment would have been 95% and 90%, respectively. Clearly, exclusion of the clinical outcome measures skeius the results, because disease may become manifest clinically before there is radiographic evidence of Apical Periodontitis. It has been shown that 30% to 50% of the mineral content of bone must be lost

before bone loss can be observed radiographically (Bender 1982). Therefore, absence of periapical radiolucency does not rule out the presence of disease. One such example is the Acute Alveolar Abscess, where radiolucency is absent by definition.

If, in contrast, the outcome criteria excluded the radiographic measures and relied exclusively on clinical measures, the healing rate for Initial Treatment and Retreatrnent would have been 96% and 87%, respectively. Such criteria are consistent with the outcome dimension of " s u ~ v a l " , rather than "healing". The very high survival rates observed in this study for initial Treatment and Retreatment suggest that conservative endodontic treatment is definitively justified and should be attempted before tooth extraction and replacement is considered. To obtain consistency and reliability in the radiographic measurement of the outcome,

the examiner was calibrated, with "good agreement" (Landis & Koch 1977) achieved for inter- and intra-observer reliability. To fiirther minimize bias, the outcome was assessed "b1indly"- the examiner was different fiom the provider of treatment, and the final outcornes were generated by cornputer programmeci for the preset outcome criteria. in this mannei, the expectation bias and the diagnostic suspicion bias were controlled in compliance with the McMaster University (1981) guidelines, and in accordance with several previous studies (Weiger et al. 2000, Trope et al. 1999, Sundqvist et al. 1998, Sj6gren et al. 1997, 1990,

0rstavik 1996, Eriksen 1988, Bystr6m et al. 1987, Bergenholtz et al. 1979, Engstrim et al. 1964, Engstrom & Lundberg 1965).

Extraneous prognostic factors could not be controlled in this descriptive study; however, they were accounted for. Associations between the various factors and the outcome

were observed and analyzed, isolating specific prognostic factors when appropriate. Analysis of the results did not account for the number of treated teeth contributed by each patient. Originally, the database was set in a manner that precluded such accounting, and there was no policy in place to exclude any teeth beyond the first one treated in each patient. Nevertheless, tfiere is no good evidence to suggest that my particular systemic conditions do adversely influence the outcome of endodontic treatment (Murray & Saunders 2000). There is no evidence either to suggest that presence of a tooth or teeth with Apical Periodontitis does influence the outcome of treatment of other teeth in the sarne patient. Therefore, the inclusion in this study of several patients who had more than one tooth treated may not have had a significant impact on the study results. The 81% overall healing rate observed for Initial Treatment is consistent with the results reported by other researchers (Engstdm et al. 1964, Engstdm & Lundberg 1965, Sjogren et al. 1997). The specific healing rates of 92% and 74% for teeth without and those

with Apical Periodontitis, respectively, also agree with previous reports ((Engstrom et al. 1964, Engstrom & Lundberg 1965, Sj6gren et al. 1990, Sjogren et al. 1997). Thus, the prognostic factor that emerged as affecting the outcorne of treatment the most was the presence of Apical Periodontitis, comborating the results of the majority of studies on the outcome of endodontic treatrnent (Engstrom et al. 1964, Engstrom & Lundberg 1965, BystrOm et al. 1987, Sjogren et al. 1990).

Arnong teeth that initially presented with Apical Periodontitis the single-rooted teeth had a significantly higher healing rate than the multi-rooted ones, corroborating results previously reportecl by Friedman et al. (1 995). It is conceivable that the anatomy of the multirooted teeth presents a greater challenge for elimination of root canal infection. However, this finding may be directly related to the use of the tooth as the unit of evaluation, reflecting the double or triple probability of persistent disease in multi-rooted teeth, when they are assessed according to the worst ruot (Friedman 1998). When roots were used as the unit of evaluation in earlier studies (Strindberg 1956, Grahnen & Hansson 1964, the healing rate for single-

rooted teeth was considerably lower than for multi-rooted teeth. The dilemma regarding single-session treatrnent of teeth with Apical Periodontitis has been the focus of recent debate and at l e s t 3 clinical studies (Sjogren et al. 1997, Trope et al.

1999, Weiger et al. 2000). In the present study, a difference in healing rate of 18% was obsmed for teeth with Apical Periodontitis treated in one session ami those treated in two or more sessions. Further analysis of the data revealed that in single-rooted teeth with Apical Periodontitis the healing rate after treatment in two sessions was significantly higher than afier single session treaûnent. This appears to be the first time that single-session treatment of teeth with Apical Periodontitis was shown to adversely influence the outcorne. This finding suggests that medication of root cana1s between treatment sessions helps eliminate bacteria lefl afler the chernomechanical preparation of the root canal system (Sjogren et al. 1997, Bystrôm et al. 1983, 1981). For multi-rooted teeth, the difference in healing rate was not statistically significant; possibly, the very small number of multi-rooted teeth treated in one session precluded significance. A power analysis was perfomed to estimate sample size

required to detennine significance for the number of treatment sessions under the conditions of this study. With a power of 80% at a 5% significance level, expecting 18% difference in prevalence of disease for teeth treated in single or multiple sessions with a relative risk of almost 2, the study would require 110 teeth in each group.

The Odds Ratio for the intrasperative factor temporary seal was almost 2.14, indicating that the likelihood of a tooth not to heal was twofold if the temporary seal consisted of a t e m p o r q cernent such as iRM or Cavit, rather than a more permanent restorative material such as a glass ionomer cernent or composite resin. When a temporary cement is used the root canal system may become recontaminated, compromising the outcome of treatment (Saunders & Saunders 1994). Indeed, it has been shown that the outcome of root canal therapy may be influenced by the temporary or definitive nature of the restoration (Safavi et al. 1987). Nevertheless, because the difference in outcome related to the ternporary seal was not statistically significant, the aforementioned statements cannot be substantiated by the results of this study.

The 7 1% overall healing rate observed for Retreatment is approximately 10% lower than that previously reported by other researchers (Engstrom et al. 1964. Sjogren et al. 1990). The healing rate for teeth retreated with Apical Periodontitis is consistent with that reported by Sjogren et al. (1990), but 12% lower than that report4 in other shidies (Engstrim et al. 1964, Sundqvist et al. 1998). The healing rate of 8 1% for teeth without Apical Periodontitis is 12% to 17% lower than in the previous studies (Engstr6m et al. 1964, Sjogren et al. 1990).

This discrepancy may be attributed to the fact that in the previous studies a negative bacteriological culture was a prerequisite for root filling (Engstrom et al. 1964, Sj6gren et al.

1990), suggesting that in al1 the teeth the number of root canal bacteria was reduced below cultivable leveis. The same cannot be assumed with regards to the present study, where bacteriological controls were not perfomed. Moreover, of the 26 teeth retreated without Apical Periodontitis in this study, one tooth had a pre-operative perforation, 2 other teeth ed presented with signs and symptoms, and in 10 teeth a complication o c c ~ ~ ~during Retreatment. Clearly, therefore, this group is not representative of elective Retreatment for prevention of Apical Periodontitis, normally performed to improve the quality of the root filling in the absence of any evidence of disease. The non-typical nature of this group is reflective of the university clinic setting, where treatment of teeth may be attempted fint in the undergraduate clinic, and then refmed to the graduate clinic if complications arise. An interesting observation in the present study, not previously reported, was the 25%

incidence of intra-operative complications (perforation, untreated canal, crack, broken file or abernint anatomy) in Retreatment as compared to 10% in Initial Treatment. This diffeience may be attributed to the technical challenges presented by Retreatment, and the nsk associated with overcoming these challenges. Specifically, the 10 complications noted in the 26 teeth retreated without Apical Periodontitis highlighted the risk associated with elective

Retreatment to prevent disease where there is none. The 25% healing rate in teeth retreated with a perforation present was extremely low,

and significantly lower than in teeth that were retreated without a perforation. This aspect of Retreatment has not been previously elucidated in endodontic treatment outcome studies. However, there have been a few studies on the outcome of Initial Treatment after a perforation had occurred; the healing rate ranged fiom 54% (Benenati et al. 1986) to 89%

(Harris 1976). Perforation is a procedural accident that results in communication between the root canal systern and the periodontal ligament ( F u s & Trope 1996). According to ingle et

al. (1 994), perforation is the second most common cause for emerging/persisting disease after endodontic therapy. In general, the prognosis for root perforation in the apical and middle third is better than that of a perforation at the crestal bone level or at the floor of the pulp chamber (Stromberg et al. 1972, Fuss & Trope 1 996). The poor prognosis of a perforation close to the marginal periodonturn is probably due to the relatively short route to communication with the periodontal sulcus and oral cavity, that once established, complicates healing (Seltzer et al. 1970). In this study, the level of the perforation was not recorded, so it is impossible to assess the impact of the location of the perforation on the outcome of treamient. Of the eight teeth that presented with a perforation, seven had Apical Periodontitis, indicating that the perforation site was a h d y infected at the time of retreatment, and that the perforation was not effectively sealed. It must be ernphasized that recently perforation repair with mineral trioxide aggregate (MTA) has shown an excellent potential for improved results (Nakata et al. 1998). In the present study MTA was not used, because it was not yet çommercially available at the time. It is conceivable, therefore, that the extrernely poor outcome obsened in this study in teeth retreated with a perforation does not apply to teeth where perforations are adequately sealeù with MTA. The prognosis of the latter will becorne elucidated in future phases of the Toronto Study, because MTA started being used for perforation repair since 1998.

The time elapsed between Retreatment and previous Initial Treatment has never been reported as a prognostic factor. in this study, the healing rate for teeth retreated within one

year was 37% Iowa than for teeth retreated afier one year or longer. However, of the 14 teeth retreated within one year, 5 teeth presented with pre-operative perforations. This observation suggests that the results related to the influence of time elapsed between Initial Treatment and Retreatrnent were likely to be wnfounded by the predisposition of those teeth. As highlighted previously, the characteristic setting of the study in a university clinic might have resulted in a non-typical nature of the teeth subjected to Retreatment within a short time from completion of Initial Treatment. Pre-operative Apical Periodontitis was not f o n d to significantly influence the outcome of Retreatment, although there was a difierence in healing rate of 18% in favor of teeth without Apical Periodontitis. This finding is in conflict with the results of previous studies on Retreatment (Engstem et al. 1964, Sjogren et al. 1990), where the presence of Apical Periodontitis had a strong negative influence on the outcome. The lack of significance found in this study may be related to the lack of statisticai power for this prognostic factor. A p w e r analysis was perfonned to estimate the sample size required to determine significance for presence or absence of Apical Periodontitis in retreated teeth under the conditions of this study. With a power of 81% at the 5% significance level, expecting 18% difference in prevalence of disease for teeth retreated without or with Apical Periodontitis with a relative

risk of 1.9, the sîudy would require 100 teeth in each group. One of the main objectives of this study was to assess the outcome of treatment

Wormed in the Graduate Endodontic Clinic at the Faculty of Dentistry, University of Toronto. The treatment outcome achieved for Initial Treatment is consistent with that achieved by other operators in different settings, whereas for Retreatment, the outcome

appears to be poorer. These results are rather disappinting, because the current treatment strategies applied in this shidy have been comrnonly perceived to improve the outcome of treatment. The fact that state-of-the-art treatment did not improve the outcome reinforces the concept that Apical Periodontitis is a disease resulting fiom the interaction of multiple factors, including bacteria, the host immune system and the environment (Sundqvist 1992). Control of the disease depends on the capacity of the clinician to control at least the bacterial and environmental factors, so that the host immune system can overcome the infection and

enable healing. In conclusion, this study corroborated previous ones identi-g

Apical Periodontitis

as the main factor that affects the outcome of endodontic treatment. Nevertheless, other

factors such as the number of roots and presence of a perforation, also had a significant impact on the outcome of treatment.

1 .

FUTURE RESEARCH

This study was a descriptive observational study and the findings obtained may help to formulate new hypotheses for fuhue research. In this way, this study may help in the planning and design of new studies with higher hierarchy of evidence base, such as randomized controlled trials. In the present study several prognostic factors were associated with large differences in outcome, however, without statistical significance. This may be related to the lack of statistical power for some of these prognostic factors. The power analysis calculated on the basis of the present results, established the number of teeth

required in each group to assess the prognostic value of those factors. As the Toronto study continues, it is expected that pooling the present study population with that of füture phases will meet the required sample size. For the number of treatment sessions in teeth with Apical Periodontitis subjected to initial Treamient, the power analysis determined that at least 110 teeth per group would be required. Considering future recall rates to remain unchanged from the present one, this requirement may be fulfilled in 9 years, when 4 more two-year phases of the Toronto Study will be analyzed. For the role of Apical Periodontitis in Retreatment, the power analysis detemined that at least 100 teeth per group would be required. This

requirement may be fulfilled in 4 years, when 2 more phases of the Toronto Study will be analyzed. This study constituted the first phase of the Toronto Study. Presently, Phase II is being carried out.

Table 1 . Study

Non-surgicalendodontic treatment outcome studies. Design

FoUow-up (Yean)

N

Recall (96)

AP (%)

RTX Outcome (%) (9-6) Success Uncertain Failure

Strindberg ( 1956) Grahnen et al. (1 961) Seltzer et al. ( 1963) Zeldow et al. (1 963) Bender et al. ( 1964) Engstrtim et al. (1964) Grossman et al. ( 1964) Engstrom et al. (1 965) Storms ( 1963) Harty et al. ( 1970) Heling et al. (1970) Adenubi et al. (1976) Ashkenaz ( 1979) Bergenholtz et al. (1 979) Kerekes et al. ( 1979) Barbakow et al. ( 1980) Barbakow et al. ( 1 98 1 ) Morse et al.( 1983) Klevant et al. (1983) Swartz et al. (1983) P e k n h (1986) Bystriirn et al. (1987) Matsumoto et al. (1987) Halse et al. (1988) Shah (1 988) Akerblom et al. (1988) Enksen et al. (1 988) Augsburger ( 1990) Sjogren et al. ( 1990) Smith et al. ( 1993) Friedman et al. ( 1995) CaIiskan et al. (1996) 0rstavik ( 1 996) Sj6gren et al. (1997) Sundqvist et al. (1998) Trope et al. (1 999) Weiger et al. (2000) Ricucci et al. (2000) Chugal et al. (2001) AP = Apical Periodontits, RTX = Retrcatmenî, p = prospective, F retrospective,.

= mots (as

opposai to teeth)

Table 2.

Outcome of Initial Treatment, with and without pre-operative Apical Periodontitis. Treated without AP

Study Strindberg ( 1 956) Grahnen et al. (196 1 ) Seltzer et al. (1963) Bender et al. ( 1964) Engstr6rn et al. (1 964) Grossrnan et al. ( 1964) Engstr6m et al. ( 1965) Stonns (1963) Harty et al. ( 1970) Heling et al. ( 1 970) Adenubi et al. ( 1976) Ashkenaz ( 1979) Kerckes et al. (1 979) Barbakow et al. (1980) Morse et al. ( 1983) Peknihn ( 1986) Bystrtim et al.( 1987) Matsumoto et 01. ( 1987) Haise et al. ( 1 988) Akcrblom et al.(1988) Sjôgren et al. ( 1990) Smith et al. ( 1993) Friedman et al. ( 1995) Caiiskan et al. (1996) 0rstavik ( 1996) Sjogren et al. (1997) Trope et a.1 ( 1999) Weiger et al. (2000) Chugal et a.1 (2001 )

Success (%)

Treated with AP Success (%)

93 88 93 89 88 90 78

88 78 76 77 76 62

-

97

81

86

79

91 53

%

82

97

-

97

91

93 95

92 96

98

89

AP = A p i d Peridontitis, = roots, in bold = statistical significant differences

85 67 65

63 86 81 69

81 75 91 74 >90

63

Table 3.

Outcome of Retreatment, with and without pre-operative Apical Periodontitis. Retreated without AP

Retreated with AP

N

Success (94)

323* 68

95 94 93

123 118* 85

84 74 74

322*

94

173*

98

42

100

234* 94* 86 54

48 62 56 74

Study

N

Strindberg (1 956) Graben et al. (196 1) Engstr6m et al. (1 964) Bergenholtz et al. ( 1979) Sj6gm et al. (1990) Friedman et al. ( 1995) Sundqvist et al. (1 998) AP = Apicd Periodontitis,

64

Succtss (%)

-

= roots, in M d = statistical significant differcnces

Table 4.

Relation of studies to reporting guidelines suggested by McMaster University. Study

Type of referrd

Treatmcnt provider

Recaii (96)

Blind Critcria assessrnent

Strindberg ( 1956) Seltzer er al. ( 1963) Zeldow et al. (1963) Bender er al. ( 1964) Engstrôm et 4L (1964) Engstrôm et crl. (1965) Grossrnan er al. ( 1 964) Kerekes et al. ( 1979) Bcrgenholtz et al. (1979) Barbakow er al. ( 1980) Barbakow et al. (198 1) Klevant et al. (1983) Pcknihn (1986) Sdavi er al. (1987) Bystr6m a UL (1987) Matsumoto et al. (1987) Shah (1988) Akcrblom et al. (1988) Eriksen et al. (1988) Sj5gren et aL (1990) Friedman et al. (1995) C a l i s h et al. ( 1996) 0rstavik ( 1996) Sj-n et a 1 (1997) Sundqvist et al. (1998) Trope et al. ( 1999) Weiger et 4 (2000) Chugal - er al. (2001) p = privatt, u = university, e = endodontist, s = studcnts, d = dentist, c = clinical, r = radiographie, b =: bactaiological culturing applicd. In bold = studics best conforming with criteria of McMaster University.

Table 5.

Univariate distribution of the "new total population" siibjected to lnitial Treatment (n = 277). Prognostic factor

Frequency

Percent

Sex

Tooth location

55

maxilla mandible

151 126

46

Sign and symptoms

YeS no

124 153

45 55

Apical Periodontitis

present absent

158 119

43

necrotic vital

179 98

35

1 22

65 212

24

none YeS

74

27

203

73

lateral vertical other

148 118 11

43 4

YeS no

152 125

55 45

Yes no

23 23 1

12 83

temPorarY

81 195

29 70

Treatment sessions

Intracanal medication Filling technique

Sealer extrusion Complications

T e m p 0 seal ~

definitive

57

65

77

53

Table 6.

Univariate distribution of the analyzed population subjected to Initial Treatment (n =120). Prognostic factor

Frequency

145 > 46

Sex

d e female

Twth location

maxilla mandible 1 52

Signs and symptoms

no Yes

Apical Periodontitis

present absent

Pulp vitality

necrotic vital

Intra-operative Treatment sessions

1 12

intracanal medication

none

Y= Filling technique

laterai vertical other

Y= no Sealer extrusion

Y= no

Complications

Y= no

P o w definitive Post-omxative Restoration

permanent t-porasr

Post

Y= no

Percent

Table 7.

Response bias analysis to assess differences between the "new total population" and the responding population subjected to Initial Treatment. AP

Response

Total

Responded

Absent 60 (43%)

141 (1000/0)

Did not respond

76 (56%)

60 (44%)

136 (100%)

X2-

test df =1, p = 0.78, AP = Apical Periodontitis

Response

Table 8.

AP

Present 8 1 (57%)

Pulp vital

Pulp necrotic

Total

Responded

45 (32%)

96 (68%)

l4l(lûû%)

Did not respond

54 (40%)

82 (60%)

136 (100%)

Association between pre-operative factors and the outcome of Initial Treatment (n = 120) N

Heriled

P-value

39 81

77

0.450

> 46

83

Tooth location

rnaxilla rnandible

69 51

83 79

0.565

Number of mots

1 22

Signs and symptoms

no 0.014

Prognostic factor A S

5 45

Sex

Y= Apical Pendontitis

Pulp vitality

present absent necrotic vital

x2- test, df =1, a < 0.05

72

74

48

92

83 37

75 95

0.01 1

Table 9.

Association between intra-operative factors and the outcome of Initial Treatment (n= 1 20). Prognostic factor

N

('w

P-value

Treatrnent sessions

1 22

23 97

78 81

0.727

Intracanal medication

none CaOH

26

81 81

0.993

lateral vertical other

64 50 6

78

0.379*

Filling technique Voids Sealer extnision Complications

Tempomy seal n2-test,

94

YeS

22

no

98

YeS

62

no

58

YeS no tmPOW

definitive

Table 10.

Hesled

86 67 82 81

0.897

77 85

0.326

82 75

0.534

102 33 86

70 85

0.06 1

12

df = 1, except (df = 2), a < 0.05,

Association between pst-operative factors and the outcome of Initial Treatment (n= 120). Prognostic factor Restoration Post x2- test except

Permanent

111

temPorarY

9

Y=

63

no

45

= Fisher's

Exact test, df =1, a c 0.05

80 89

84 80

1 .OO* 0.57

Table 1 1.

Contingency table of pre-operative factors Pulp Vitality and Apical Periodontitis (n = 120). AP

Pulp Vitality

Necrotic

X2-

Table 1 2.

Total

No AP

64 (77%)

19 (23%)

83 (100%)

test,d F 1,p c 0.0001, AP = Apical Periodontitis

Stepwise Logistic regression analysis for Initial Treatment (n= 1 20). Odds Ratio

95% C.I.

P-vdue

Temporary seal def =O /remp=l

2.14

0.81 - 5.71

0.06 1

Treatment sessions

1.21

0.37 4.01

-

0.741

3.7 1

1.14 - 12.0

0.029

~rognosticfactor

multi=O /single= 1

Apical Periodontitis no =O /yes = I

Table 1 3.

Association between pre-operative factors and the outcome of Initial Treatment in teeth without Apical Periodontitis (n = 48). Prognostic factor

N

Herled

P-value

./. Age

Sex

Tooth location

Signs and symptoms

hilp vitaiity

5 45 > 46 d e fernale maxilla maadible no

13 35 19 29 27 21 28

100

0.562

89 95

1.O03

Y=+

20

100

necrotic

19 29

84 97

vital Fisher's exact test, df =l,a < 0.05

90

93 91 86

1 .O01 0.130

0.280

Table 14.

Association between intra-operative factors and the outcome of initial Treamient in teeth without Apical Periodontitis (n = 48). N

Prognostic factor

Htded

('m

P-value

Treatment sessions

1 22

1i 37

100 89

0.56

Iniracanal medication

none CaOH

11

100

0.56

37

89

28 18 2

93 89 100 100 91

Filling technique Voids Sealer extrusion

Complications

laterai vertical other Y= no

6 42

0.8 1 1-00

Y s no YeS

no

Fisher's exact est, df = 1, cxcept (df = 2), a < 0.05,

Table 15.

Association between pst-operative factors and the outcome of Initial Treatment in teeth without Apical Periodontitis (n = 48). Prognostic factor Restoration

fost

permanent temporary

44 4

Y=

31 14

no

Fisher's exact test, df =1, a < 0.05,

91 1 O0 90 93

1.O0

1 .O0

Table 16.

Association between pre-operative factors and the outcome of Initial Treatment in teeth with Apical Periodontitis (n = 72). Prognostic factor

N

Herled

P-value

26 46

65 78

0.232

> 46 Sex

male female

40 32

73 75

0.8 1 1

Tooth location

maxilla mandible

42

76 70

0.55 1

30

64 8

72 88

0.67 1

Age

Signs and symptoms

5 45

('w

no

Y=

Pulp vitality

necrotic vital

XZ- test except *= Fisher's Exact test, df = 1, a c 0.05

Table 17.

Association between intra-operative factors and the outcome of Initial Treatment in teeth with Apical Periodontitis (n = 72). Prognostic factor Treatment sessions

1 52

Intracanal medication

noue CaOH

Filling technique

lateral vertical

other Voids

Yno

Sealer extnision

Y=

no Complications

Yes no

Temporary seal

rnPoraSr

definitive X2-

test except ** = Fisher's exact test, df = l except (df = 2)' a < 0.05

Table 18.

Association between pst-operative factors and the outcome of Initial Treatment in teeth with Apical Periodontitis (n = 72). Prognostic factor

Heded

N

-

P-value

(W Restoration

permanent temP0rarY

73 80

67 5

1 .OOO*

Post X2-

Table 19.

test except * = Fisher's Exact test, df = 1, a < 0.05

Stratified table of intmoperative factor Number of Roots and Treatment Sessions in teeth with Apical Periodontitis (n=72). Number of Roots Trertment !Sessions Single-rooted 1 52

Fisher's Exact test, df = 1, a < 0.05,

N

Healed

P-value

(y4 8 23

63 96

0.043

Table 20.

Univariate distribution of the "new total population" subjected to Retreatment (n = 203). Prognostic factor

Frequency

5 45 > 46 Sex

male fernale

Tooth tocation

maxilla mandible

Signs and symptoms

no

Y= 1 22

Apical Periodontitis

present absent

Inîra-omtive Treatment sessions

1

12 Intracanal medication

none Y-

Filling technique

lateral vertical other

Y=+ no

Sealer extrusion

Y= no

Complications

Y= no temporary definitive

Percent

Table 2 1.

Univariate distribution of the analyzed population subjected to Retreatment (n = 56). --

Prognostic factor

-- -

-- -

-

Frequency

Percent

15 41 23 33 40 16 47 9 27 29 51 4 8 46 14 39 21 31 8 45 41

27 73 41 59 71 29 84 16 48 52 91 9 15 85 26 74 40 60 15 85 79 21 54 46

Pre-ouerative Age

145 > 46

Sex

Tooth location

Signs and symptoms

male fernale maxilla mandible no Y-

Number of roots Periodontal defect

1 32 no

Perforation

Y=

Time previous Tx Filling length

Y=

no 5 1 year lyear adequate inadequate

'

Filling density

dood l'"or

Core material

gutta-percha others present absent

Apical Periodontitis

II 30 26

Intra-operat ive

Treatment sessions Intracanal medication

1 12 none

YFilling technique

laterai vertical ohr

Voids

Y=

no Sealer extrusion

F no

Complications

Y=

Tcmporary s d

no WPOW definitive

12 44 13 43 27 26 3 14 42 32 24 14 42 19 26

21 79 23 77 48 46

44 5

90 1O 67 33

6

25 75 57 43 25 75 34 64

Post-omtive Restoration

permanent

Post

YeS

tcmporary

no

37 18

Table 22.

Response bias analysis to assess diffaences between the "new total population" and the responding population subjected to Retreatment. Response

AP

AP Absent

Responded

Present 38 (58%)

29 (43%)

67 (1000/0)

Did not respond

96 (71%)

40 (29%)

136 (1000/0)

XZ- test, df = l ,

Table 23.

Total

= 0.021

Association between pre-operative factors and the outcorne of Retreatment (n = 56). Prognostic factor

N

Bealed

5 45

Age

> 46 Sex

male femaie

Tooih location

maxilla mandible

Signs and symptoms

no

Y= Number of mots Apical Pefiodontitis

1

>2 YS no

Periodontal defects

no Yes

Perforation

Y=s

no Time previous Tx

I 1 year ' l m

Filling length

adquate i.Mdquate

Core matetial

8utta-percha others

Filling density ..

good poor --

- - -

Fisher's exact test cxcept

= x2- test, df = 1, a < 0.05

P-vaiue

Table 24.

Association between intra-operative factors and the outcome of Retreatment (n = 56). N

Prognostic factor

Healcd

P-vaiue

(W Treatment sessions

12 44

75 71

1.O0

22

inaacanal medication

none CaOH

13 43

77 70

0.73

Filiing technique

lateral vertical other

27 26 3

70 69 100

0.52**

Sealer extrusion

Yes no

32 24

71 72

0.93*

Complications

Yes no

14 42

86 67

0.30

Temporary seal

temPOrarY definitive

19 36

68 72

0.76

1

Voids

Fisher's exact test except = X2- test, df =1 except ** (df = 2), a < 0.05

Table 25.

Association between postsperative factor and the outcome of Retreatment (n = 56). N

Prognostic factor

Herld

P-vdue

(W Restoration

permanent

tcmpOrarY Post

Y= no

Fisher's Exact test, df = 1, a < 0.05

44 5

77 40

O. 10

37 18

73 72

1.O0

Table 26.

Association between pre-operative factors and Retreatment in teeth without Apical Periodontitis (n = 26). N

Prognostic factor

Healed

(W Age

5 45 > 46

Sex

male female

Tooth location

maxilla mandible

Signs and symptoms

no yes

Number of roots

1 2 2

Time previous Tx

51 year > 1 year

Corn materiai

gutta-percha others

Filling length

adquate Sequate

Filling density

good Poor

Fisher's Exact test, df = 1, a < 0.05

P-value

Table 27.

Association between intrasperative factors and Retreatxnent in teeth without Apical Periodontitis (n = 26). Prognostic factor

N

Healcd

P-value

('w

Treatrnent sessions

1 52

6 20

100 75

0.29

Intracanal medication

none CaOH

6 20

100 75

0.29

Filling technique

laterd vertical other YeS no

15

0.49.

2

73 89 100

Y=

10 16

90 75

0.61

8 17

63 88

0.28

Sealer extrusion Complications

no Temporary seal

temPorarY

definitive

9

Fisher's Exact test, df = l except l(df = 2), a < 0.05

Table 28.

Association between pst-operative factors and the outcome of Retreatment in teeth without Apical Periodontitis (n = 26). N

Prognostic factor

Heaieâ

P-vaiue

(Va)

Restoration

permanent te~porary

Post

F S

no Fisher's Exact test, df = 1, a < 0.05

22 1 17 8

82 100 77 100

1 .O0

0.26

Table 29.

Association between pre-operative factors and Retreatment in teeth with Apical Periodontitis (n = 30). Prognostic factor

Sex

Tooth location

Signs and symptoms

N

male

Healed (W

P-value

14 16

57 69

0.5 1

femde milla mandible

19

53

O. 14

II

82

no

YS Periodontal defect

no

Perforation

Y= Y= no

Time previous tx Filling length

l year

8

50

> 1 year

21

67

adequate

14 15

73

_
2 mm) 2. Adequate (0-2 mm) 4. Long present=1)

Filling voids (worst mot) (absen-; Sealer extrusion (absen-; prestat= 1) Complications

O. Noue 1. Perforation 2- Untreated canal 4. Crack observcd 8. Broken file 20. Aberrant anatomy

Temporary seal (add, if also crown)

1. Cavit 2. W Z O E 3. Term 4. GYCWAM

10. Crown Inter-appoint ment emergcncy (absmM; premit= 1) Antibiotics (nad; yes= 1 ) . W. Post-operative interview Eotered by: 3 1. Pain, according to scaie of 1-1 0 32. Swelling (absen-, prescnt=l) 33. Analgesic required (no*; yes= 1) V, Final observation Entered by: 34. Observation period (years) 3. 1.5 4.2 5.3 6.4 35.

36. 37. 38. 39.

Clinicai s i p s & symptoms (absenmi present=l) Sponrancous pain Swclling Sinus tract Percussion sensitive Radiolucency s k (worst root) O. None 1. 10 mm

40.

Restoration (add relevant numbcrs)

41.

Root fiacture (abstnW; prescrits 1)

1. Temporary filling 2. Definitive filling 3. Post 6. Crown

APPENDIX 4

Recalis TOOTH #

Code Number Surname, name Address

-

Telephone

Observation period (years)

-

Clinical signs and symptoms (absent O, present = 1) spontareous pain Swelling Pefcussion sensitive Sinus Tract Radiolucency Size (worst root)

1.

.

2 3. 4.

10mm

Restoration (add relevant numbers) 1 Temporary filling 2 Definitive fiiling 3 . Post 6. Crown

. .

Root Fracture (absent = 0, present = 1)

Comments

-

-

APPENDIX 5

UNIVERSITY OF TORONTO FACULTY OF DENTISTRY ENDODONTIC POSTGRADUATE CLINIC

Date: Re: FoaOw-up Exizrninatwn

Dear

In the past you had endodontic (root-canal) treatment performed in our WC.It is now time to re-examine the treated tooth/teeth. It û emphasized that follow-up examinations of treatid teeth are very important, so to detect as early as possible any condition which may lead to symptoms and complications.

Kindly contact Our dinic at (416) 979-4900, extension 4547, to schedule a follow-up appointment tirne. This service is an essential part of the treatment provided, and there is no additional fee required. Respectfully,

UNIVERSITY OF TORONTO FACULTY OF DENTISTRY GRADUATE ENDODONTICS CLMIC

$50 Guaranteed if you corne to the

DATE: 16 November, 2000

Graduate Endodontics Clinic for mfoiiow-up exrrniaation

In the past year, we attempted to invite you for a follow-up examination of the ROOT clinic. Because we strongly believe this followup examination is beneficial to yoy we are offaing you a ONE-nm~ REWARD OF SSO* to be received upon cornpletion of the follow-up examination. During your appointment, your tooth will be examiad clinicelly, and a x-ray will be taken to determine its condition. You will then be explained the results of the examination. To daim this reward* do the following: 1. Phone Ms. Heather Hyslop at (416) 979-4900 est: 4547 to schedule a RECALL CANAL TREATMENT~Sperformed in our

APPOmNT;

2. Show up in the Graduate Endodontics Clinic at the scheduled time.

Dr. Sarah Abitbol

*

Poyarenr WUk in b c form of o ckcque md&d tu you d h i n 30 doys o/er examindon; or if vou arefer you niül recek $JO ma towrds your next treatment at the Facu& of Den*, Ui&ersi@ of Toronta

-

-