Outcome of Endodontic Micro-resurgery: A Retrospective Study Based on Propensity Score-matched Survival Analysis

The purpose of this retrospective study was to evaluate and compare the outcome of endodontic micro-resurgery with that of primary endodontic microsurgery and determine prognostic factors affecting the outcome of micro-resurgery.

A clinical database was searched for endodontic microsurgery cases between 2001 and 2016. Nearest neighbor 2:1 propensity score matching for the following 5 variables was performed for cases of primary microsurgery and those of micro-resurgery: age, sex, tooth type, lesion type, and postoperative restoration. For the matched cases, the outcome was categorized as success or failure according to clinical and radiographic evaluations performed at least 1 year after surgery. Kaplan-Meier survival analysis and log-rank tests were performed to compare the outcome of primary microsurgery with that of micro-resurgery over time. For the micro-resurgery group, multivariate Cox proportional hazard regression analysis was performed to identify prognostic factors and estimate their effects.

In total, 571 cases of endodontic microsurgery (498 primary microsurgery and 73 micro-resurgery cases) were identified, and 146 cases of primary microsurgery were matched to 73 cases of micro-resurgery through 2:1 propensity score matching. After matching, all covariates demonstrated an absolute standardized difference of <0.1. The estimated 5-year success rates were 91.6% and 87.6% for primary microsurgery and micro-resurgery, respectively (P = .594). The tooth type was found to be the only contributing factor for the outcome of micro-resurgery, with molars showing a higher probability of failure than anterior teeth (hazard ratio, 8.53; P = .002).

Within the limitations, the findings of this study suggest that the outcome of endodontic micro-resurgery is comparable with that of primary endodontic microsurgery.