Impact of the quality of coronal restoration versus the quality of root canal fillings on success of root canal treatment: a systematic review and meta-analysis

Abstract

Introduction: Thorough cleaning and shaping of root canals are essential for periapical healing. Restoration of endodontically treated teeth is also required for them to function and prevent coronal leakage. This study compared the impact of the quality of root canal treatment versus the quality of coronal restoration in treatment outcomes.

Methods: Literature search was conducted using the search terms "coronal restoration," "root canal," "periapical status," and "quality." Articles that evaluated the effect of the quality of root filling and coronal restoration or both on the success of root canal treatment were selected. Nine articles were identified and were reviewed by 3 investigators. Data were collected based on predetermined criteria. Percentages of teeth without apical periodontitis were recorded for each category: adequate root canal treatment (AE), inadequate root canal treatment (IE), adequate restoration (AR), and inadequate restoration (IR). Data were analyzed using meta-analysis for odds ratios (ORs).

Results: After adjusting for significant covariates to reduce heterogeneity, the results were combined to obtain pooled estimates of the common OR for the comparison of AR/AE versus AR/IE (OR = 2.734; 95% confidence interval [CI], 2.61-2.88; P < .001) and AR/AE versus IR/AE (OR = 2.808; 95% CI, 2.64-2.97; P < .001).

Conclusions: On the basis of the current best available evidence, the odds for healing of apical periodontitis increase with both adequate root canal treatment and adequate restorative treatment. Although poorer clinical outcomes may be expected with adequate root filling-inadequate coronal restoration and inadequate root filling-adequate coronal restoration, there is no significant difference in the odds of healing between these 2 combinations.

Fig. 1

A schematic of the comparisons made in the meta-analysis. AR: adequate restoration; AE: adequate root canal treatment; IR: inadequate restoration; IE: inadequate root canal treatment; Solid connection line: comparison performed; Dotted line: comparison not performed due to expected results.

Fig. 2

Forest plot of odds ratios and 95% confidence limits (CL) based on data from 9 studies for the comparison of AR/AE vs AR/IE with regard to absence of apical periodontitis (AR: Adequate restoration; AE: Adequate root canal treatment; IE: Inadequate root canal treatment). Overall estimate is based on combined data from the 9 studies. The size of each rectangle is proportional to the total sample size for the AR/AE vs. AR/IE comparison in that study. The size of the diamond is proportional to the combined sample size for the 9 AR/AE vs. AR/IE comparisons. The solid line indicates an odds ratio of 1.0 and the dashed lines indicate odds ratios of 0.5, 10.0, and 30.0, respectively. OR: odds ratio; LCL: lower confidence level; UCL: upper confidence level.

Fig. 3

Forest plot of odds ratios and 95% confidence limits (CL) based on data from 9 studies for the comparison of AR/AE vs IR/AE with regard to absence of apical periodontitis (AR: Adequate restoration; AE: Adequate root canal treatment; IR: Inadequate restoration). Overall estimate based on combined data from the 9 studies. The size of each rectangle is proportional to the total sample size for the AR/AE vs. IR/AE comparison in that study. The size of the diamond is proportional to the combined sample size for the 9 AR/AE vs IR/AE comparisons. The solid line indicates an odds ratio of 1.0 and the dashed lines indicate odds ratios of 0.5, 10.0, and 30.0, respectively. OR: odds ratio; LCL: lower confidence level; UCL: upper confidence level.

Fig. 4

Forest plot of odds ratios and 95% confidence limits (CL) based on data from 9 studies for the comparison of IR/AE vs AR/IE with regard to absence of apical periodontitis (AR: Adequate restoration; IE: Inadequate root canal treatment; IR: Inadequate restoration; AE: Adequate root canal treatment). Overall estimate based on combined data from the 9 studies. Size of each rectangle is proportional to the total sample size for the IR/AE vs AR/IE comparison in that study. Size of the diamond is proportional to the combined sample size for the 9 IR/AE vs AR/IE comparisons. The solid line indicates an odds ratio of 1.0 and the dashed lines indicate odds ratios of 0.2 and 10.0, respectively. OR: odds ratio; LCL: lower confidence level; UCL: upper confidence level.