Factors affecting outcome of non-surgical root canal treatment

336 Pages·2008·6.56 MB·English

Factors affecting outcome of
non-surgical root canal treatment

A thesis submitted by
Yuan Ling Ng BDS (HK), MSc (Lond), MRD RCS (Lond)
for the degree of
DOCTOR OF PHILOSOPHY
University College London
University of London

Unit of Endodontology
Division of Restorative Dental Sciences,
UCL Eastman Dental Institute
University College London
2008
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Abstract
Aims
To investigate the probability of success and influencing factors for primary and
secondary root-canal-treatments using two outcomes (absence of apical periodontitis [AbAP]
and tooth survival [TS]).
Methodology
Part 1 involved meta-analyses of previous outcome data selected, extracted and agreed
by three reviewers. Statistical heterogeneities and their sources were investigated using meta-
regression.
Part 2 involved prospective follow-up of upto four years of root-canal-treatments in an
Eastman cohort. AbAP by root was estimated and the associated prognostic factors were
investigated using logistic regression. TS was estimated and prognostic factors investigated
using Cox regression. Potential interactions between factors and primary/secondary root-canal-
treatment were explored. Clustering effects within patients were adjusted in all models using
robust standard error.
Results
Meta-analyses revealed the pooled AbAP associated with primary and secondary root-
canal-treatments were 75%(70%–80%) and 77%(61%–88%), respectively. Three (periapical
lesion, root filling extent, quality of restoration) of the four prognostic factors identified for
primary root-canal-treatment also had significant influence on secondary root-canal-treatment.
Prospective data revealed insignificant difference in AbAP between primary (83%[81%–
85%]) and secondary (80%[78%–82%]) treatment. The influence of 11 prognostic factors
(including 3 from meta-analyses) was the same for both treatments except, “EDTA-as-an-
additional-irrigant”; it had no effect on primary treatment but significantly increased success of
secondary treatment (OR=2.3[1.4–3.8]).
Meta-analysis revealed the pooled TS probabilities (2–10 year) ranged from 72–86%;
with 4 prognostic factors (Tooth type & function, restoration, proximal contacts).
Prospective data found that 4-year TS after primary treatment (95.4%[94%–97%]) or
secondary treatment (95.3%[94%–97%]) were similar; with fourteen prognostic factors including
2 from the meta-analysis.
Conclusions
Meta-analyses and prospective data were in concordance. Success based on AbAP or
tooth-survival, and the prognostic factors for primary and secondary root-canal-treatment were
similar. Only “EDTA-as-an-additional-irrigant” had different effects on the two treatments. This
study revealed some new prognostic factors.
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DECLARATION
I hereby certify that the work embodied in this thesis is entirely the result of my own
investigations. This research project has not been submitted either in part or in full for a
degree or diploma to this or any other University or examination board elsewhere.

––––––––––––––––––––––––––––––
Yuan Ling Ng

August 2008

The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published
without the prior written consent of the author.
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ACKNOWLEDGMENTS

I gratefully acknowledge the contribution of the following colleagues for their
moral support and for the help that was instrumental bringing this thesis to
fruition;

Professor Kishor Gulabivala for his supervision, mentorship, inspirations, and
sharing his great mind with me.

Dr Vera Mann for her supervision, helpful and practical advice on statistical
analyses and presentation of this thesis.

All postgraduate students and staff in the Unit of Endodontology for completing
the data collection forms meticulously.

Shahrzad Rahbaran for being a reviewer for the systematic reviews/meta-
analyses.

Jose Figueiredo, Shishir Singh, Wendy Taylor, Murray Saunders, Glynis Evans,
Rahul Gloria, Barbara Swistak, Giampiero Rossi-Fedele, Sanjay Ardeshna for
providing me with clinical, academic and administrative cover in my part-time
absence.

Nicole Gray, Raquel Lopez, Rebecca Jury, Tauhida Begum, Caroline Balay for
providing clinical assistance for the review clinics.

Shelaine Carney, Edhererovieno Abugo, Alex Bruinsma for providing reception
support for the review clinics.

Dr. David Moles, Dr. James Lewsey, Professor Mark Gilthorpe, Dr. Chris Frost
for their teaching and advice on statistics.

My parents, brothers and sister-in-laws for their unfailing support.

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Contents

Index Content Pages
Title 1
Abstract 2
Declaration 3
Acknowledgements 4
Contents 5–14

Chapter 1 – Introduction 15–
79

1.0 Justification for the study 15
1.1 Definition of root canal treatment 17
1.2 Biological distinctness of disease entities requiring root canal 18
treatment
1.3 Historical perspective on concepts underpinning root canal treatment 19
1.3.1 Concepts of bacterial infection, pulp diagnosis and pulp therapy 20
1.3.2 The origin of root canal treatment 21
1.3.3 The focal infection era 23
1.3.4 The basis for modern endodontics 25
1.4 Radiographic methods for assessment of periradicular diseases 25
1.4.1 Correlation between histological and radiographic findings 25
1.4.2 Alternative imaging of periapical tissue 26
1.4.3 Interpretation of radiographic images 27
1.5 Biological rationale of root canal treatment 29
1.5.1 Microbiology of untreated teeth with apical periodontitis 29
1.5.2 Effect of root canal treatment procedures on bacterial flora 32
1.5.3 Microbiology of root treated teeth with persistent apical periodontitis 34
1.6 Guidelines and standards for root canal treatment 36
1.7 Variation in teaching and practice of root canal treatment 36
1.8 Prevalence of periradicular disease, root canal treatment and its quality 38
1.9 Outcome of root canal treatment 40
1.9.1 Overview of methodological characteristics of previous studies 40
1.9.2 Overview of prognostic factors for resolution of periapical disease by 51
root canal treatment
1.9.3 Overview of prognostic factors for survival of teeth after primary or 71
secondary root canal treatment
1.10 Conclusions of the literature reviewed 78
1.11 Aims and objectives of the present study 79

Chapter 2 – Materials and methods 80–
100

2.0 Time-line for PhD programme 81
2.1 Meta-analysis of data from previous clinical studies on success of 82
primary and secondary treatment using absence of apical periodontitis
as an outcome measure
2.1.1 Literature search 82
2.1.2 Study selection, quality assessment and data extraction 82
5
2.1.3 Estimation of pooled success rates 83
2.1.4 Estimation of effect of each clinical factors on success rate 83
2.1.5 Assessment of statistical heterogeneity and its source 83
2.2 Meta-analysis of data from previous data on primary and secondary 84
root canal treatment using tooth survival as an outcome measure
2.2.1 Literature search 84
2.2.2 Study selection, quality assessment and data extraction 84
2.2.3 Estimation of pooled survival rates 85
2.2.4 Estimation of effect of each clinical factor on survival rate 85
2.2.5 Assessment of statistical heterogeneity and its source 85
2.3 Prospective clinical study to investigate the effect of various clinical 85
factors on the outcome of primary and secondary root canal treatment
2.3.1 Ethical approval 85
2.3.2 Inclusion criteria 85
2.3.3 Exclusion criteria 85
2.3.4 Primary and secondary root canal treatment in the unit of 86
Endodontology
2.3.5 Follow-up appointments 87
2.3.6 Follow-up clinical examination data 87
2.3.7 Radiographic assessment of outcome 88
2.3.8 Determination of outcome 89
2.3.9 Data management 90
2.3.10 Statistical analysis 97

Chapter 3 – Results 101–
127

3.1 Meta-analysis of previous data on success rates of primary root canal 101
treatment based on absence of apical periodontitis as the outcome
measure
3.1.1 Search results, study selection and data extraction 101
3.1.2 Methodological characteristics of selected studies 101
3.1.3 Success rates by study characteristics 102
3.1.4 Success rates by clinical factors 109
3.1.5 Summary of results 127
3.2 Meta-analysis of previous data on success rates of secondary root 128
canal treatment based on absence of apical periodontitis as the
outcome measure
3.2.1 Search results, study selection and data extraction 128
3.2.2 Methodological characteristics of selected studies 129
3.2.3 Success rates by study characteristics 131
3.2.4 Success rates by clinical factors 134
3.2.5 Summary of results 146
3.3 Meta-analysis of the previous data on the survival of teeth after primary 147
or secondary root canal treatment
3.3.1 Search results, study selection and data extraction 147
3.3.2 Characteristics of selected studies 147
3.3.3 Survival rates 149
3.3.4 Prognostic factors for tooth survival 150
3.3.5 Summary of results 156
3.4 General results of prospective clinical study 157
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3.4.1 Inclusion and exclusion of teeth following primary or secondary root 157
canal treatment
3.4.2 Radiographic observer agreement 160
3.5 Results of investigation of primary or secondary root canal treatment 161
outcome using absence of clinical and radiographic measures of apical
periodontitis
3.5.1 Proportion of success by examination methods 161
3.5.2 Identification of prognostic factors predicting success rate using 162
logistic regression
3.5.3 Final multivariable logistic regression model building using the 182
combined dataset
3.5.4 Summary of results 187
3.6 Results of investigation of tooth survival after primary or secondary 188
root canal treatment
3.6.1 Probabilities of tooth survival 188
3.6.2 Identification of prognostic factors predicting tooth survival using 189
survival regression analyses
3.6.3 Final multivariable Cox regression model building 200
3.6.4 Summary of results 206

Chapter 4 – Discussion and conclusions 208–
253

4.1 Discussion of methodology 208
4.1.1 Systematic review and meta-analyses 208
4.1.2 Prospective study 211
4.2 Discussion of results 215
4.2.1 General results for meta-analyses 215
4.2.2 Success rates for primary and secondary root canal treatment based 216
on different outcome measures
4.2.3 Prognostic factors for success of treatment using absence of clinical 219
and radiographic signs of periapical disease as outcome measure
4.2.4 Prognostic factors for success of treatment using tooth survival as 238
outcome measure
4.3 Clinical implications of findings 242
4.3.1 Clinical implications based on prognostic factors identified for 242
absence of clinical and radiographic signs of periapical disease
4.3.2 Clinical implications based on prognostic factors identified for tooth 247
survival
4.4 Further studies 249
4.5 Conclusions 251

5 References 254–
286

6 Appendices 287–
336

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List of Tables

Table no. Table legend Pages
Chapter 1 – Introduction 15–
79
Subsection 1.4 – Radiographic methods for assessment of 25–
periradicular diseases 29
1.4.1 The probability index (PRI) (Reit & Gröndahl 1983) and periapical index 28
(PAI) (Ørstavik et al. 1986)
Subsection 1.9 – Outcome of root canal treatment 40–
78
1.9.1 Quality of previous randomized controlled trials on root canal treatment 42
procedures
1.9.2 CONSORT checklist items to include when reporting a randomized trial 43
1.9.3 Criteria for determination of periapical status 45
1.9.4 Examples of previous strategies for categorization of lesion size 54
Chapter 2 – Materials and methods 80–
100
Subsection 2.0 – Time-line for PhD programme 81
2.0 Time-line for PhD programme 81
Subsection 2.3 – Prospective clinical study on the outcome of 85–
primary and secondary root canal treatment 100
2.3.1 Demographic data, medical conditions and tooth / root type 90
2.3.2 Pre-operative data 91
2.3.3 Intra-operative data 93
2.3.4 Post-operative restorative data 95
2.3.5 Data collected at follow-up appointment 96
Chapter 3 – Results 101–
127
Subsection 3.1 – Meta-analysis of previous data on success rates 101–
based on absence of apical periodontitis after 127
primary root canal treatment
3.1.1 Reasons for exclusion of the 51 articles 103
3.1.2 Characteristics of studies selected 104
3.1.3 Clinical prognostic factors reported by studies 105
3.1.4 Estimated success rates by study characteristics 106
3.1.5 Results of meta-regression analysis to account for the source of 109
heterogeneity
3.1.6 Weighted pooled success rates (SR) by patient factors 110
3.1.7a&b Summary of meta-analyses for the effects of patients factors on success 111
rates of primary root canal treatment
3.1.8 Weighted pooled success rates (SR) by tooth type 111
3.1.9 Summary of meta-analyses for the effects of tooth type on success 112
rates of primary root canal treatment
3.1.10a&b Meta-regression analyses to account for heterogeneity in analysing the 112
effects to tooth type on the success rate of primary root canal treatment
3.1.11 Weighted pooled success rates (SR) by pre-operative pulpal and 113
periapical status
3.1.12 Summary of meta-analyses for the effects of pre-operative pulpal and 113
periapical status on success rates of primary root canal treatment
3.1.13a–e Meta-regression analyses to account for heterogeneity in analysing the 114
effects of pulpal and periapical status on the success rate of primary
root canal treatment
8
3.1.14 Weighted pooled success rates (SR) by use of rubber dam, apical size 116
and taper of canal preparation
3.1.15 Weighted pooled success rates (SR) by irrigant and medicament 117
3.1.16 Weighted pooled success rates (SR) by pre-obturation root canal 118
culture results
3.1.17a–c Summary of meta-analyses for the effects of pre-obturation culture test 119
results on success rates of primary root canal treatment
3.1.18 Weighted pooled success rates (SR) by root filling material and 120
technique
3.1.19a–c Weighted pooled success rates (SR) by apical extent of root filling 121
3.1.20a–c Summary of meta-analyses on the effects of apical extent of root filling 121
on success rates of primary root canal treatment
3.1.21 Meta-regression analyses to account for heterogeneity in analysing the 122
effects of apical extent of root filling on the success rate of primary root
canal treatment
3.1.22a&b Weighted pooled success rates (SR) by quality of root filling 123
3.1.23 Summary of meta-analyses for the effects of apical extent and quality of 124
root filling on success rates of primary root canal treatment
3.1.24 Meta-regression analyses to account for heterogeneity in analysing the 124
effects of quality of root filling on the success rate of primary root canal
treatment
3.1.25 Weighted pooled success rates (SR) by apical disturbance 124
3.1.26 Weighted pooled success rates (SR) by number of treatment visits 125
3.1.27a–c Summary of meta-analyses for the effects of treatment visits on success 125
rates of primary root canal treatment
3.1.28ab Weighted pooled success rates (SR) by post-operative restorative 126
status of the tooth
3.1.29 Summary of meta-analyses for the effects of quality coronal restoration 126
on success rates of primary root canal treatment
3.1.30 Meta-regression analyses to account for heterogeneity in analysing the 127
effects of coronal restoration on the success rate of root canal treatment
Subsection 3.2 – Meta-analysis of previous data on success rates 128–
of secondary root canal treatment based on 146
absence of apical periodontitis as the outcome
measure
3.2.1 Reasons for exclusion of the 21 articles 128
3.2.2 Characteristics of selected studies 130
3.2.3 Estimated success rates by study characteristics 133
3.2.4 Clinical prognostic factors reported by selected studies 136
3.2.5a–k Pooled weighted success rates by pre-operative clinical factors based 137
on strict criteria
3.2.6 Summary of meta-analyses for the effects of pre-operative periapical 138
status on success rates of secondary root canal treatment
3.2.7 Pooled weighted success rates by use of rubber dam and apical extent 140
& size of canal preparation based on strict criteria
3.2.8 Pooled weighted success rates by type of irrigant and medicament 141
based on strict criteria
3.2.9 Pooled weighted success rates by pre-obturation root canal culture 142
results based on strict criteria
3.2.10 Summary of meta-analyses for the effects of pre-obturation root canal 142
culture results on success rates of secondary root canal treatment
3.2.11a–d Pooled weighted success rates by factors related to root filling based on 143
strict criteria
3.2.12a&b Summary of meta-analyses for the effects of apical extent of root filling 144
on success rates of secondary root canal treatment
9
3.2.13 Pooled weighted success rates by factors related to number of 145
treatment visits based on strict criteria
3.2.14 Pooled weighted success rates by quality of post-operative restoration 145
based on strict criteria
3.2.15 Summary of meta-analyses for the effects of quality of post-operative 146
restoration on success rates of secondary root canal treatment
Subsection 3.3 – Meta-analysis of previous data on the survival of 147–
teeth after primary or secondary root canal 156
treatment
3.3.1 Reasons for exclusion of the 17 articles 147
3.3.2 Characteristics of and survival rate reported by the selected studies (n= 148
14)
3.3.3 Prognostic factors investigated in selected studies 150
3.3.4 Summary of meta-analyses for the effects of tooth type on survival 153
probability of teeth after root canal treatment
3.3.5 Results of analyses by Tan et al. (2006) 154
3.3.6 Pooled estimated survival probabilities by apical extent of root fillings 155
3.3.7 Summary of meta-analyses for the effects of type of restorative status of 155
teeth after treatment
Subsection 3.4 – General results of prospective clinical study 157–
160
3.4.1 Reasons for patients’ non-attendance at recall and for exclusion of teeth 159
with at least 2 year follow-up
3.4.2 Number of cases included for the prospective analyses 159
3.4.3 Characteristics of patients and teeth that were excluded from or 160
included in the analyses of absence of clinical and radiographic signs of
apical periodontitis after treatment
Subsection 3.5 – Results of investigation of primary or secondary 161–
root canal treatment outcome using absence of 187
clinical and radiographic measures of apical
periodontitis
3.5.1a–c Clinical signs & symptoms and radiographic outcome after root canal 161
treatment
3.5.2 Number of years for complete resolution of periapical lesion 162
3.5.3 Unadjusted effects of patient characteristics using logistic regression 163
analysis
3.5.4 Unadjusted effects of tooth & root type and developmental anomaly 164
using logistic regression analysis
3.5.5 Effects of tooth & root types adjusted for pre-operative periapical status 164
using logistic regression analysis
3.5.6 Unadjusted effects of pre-operative tooth factors (common to both 166
primary and secondary root canal treatment) using logistic regression
analysis
3.5.7 Effects of potential common significant pre-operative tooth factors 167
adjusted for pre-operative periapical status using logistic regression
analysis
3.5.8 Unadjusted and adjusted effects of pre-operative tooth factors, unique 168
to secondary root canal treatment, using logistic regression analysis
3.5.9 Fate of fractured instruments by type of instrument 168
3.5.10 Unadjusted effects of operator’s qualification & prediction of prognosis 169
and treatment visits using logistic regression analysis
3.5.11 Unadjusted and adjusted effects of protection of teeth with metal band 170
using logistic regression analysis
3.5.12 Unadjusted effects of intra-operative factors (location of canals) using 171
logistic regression analysis
10