The Buffalo study: outcome and associated predictors in endodontic microsurgery: a cohort study.

AIM To 1) evaluate and compare the success rate of endodontic microsurgery (EMS) using periapical radiographs (PAs) and cone-beam computed tomography (CBCT) scans; 2) identify prognostic factors affecting the outcome; and 3) correlate the effect of guided tissue regeneration (GTR) on the pattern of apical bone remodeling. METHODOLOGY Eighty-two patients (101 teeth) who received EMS were included and followed-up using clinical and radiographic examination (PAs and CBCT scans). Two calibrated endodontists evaluated the radiographic healing (favorable or unfavorable) by assessing PAs and CBCT. The success (favorable radiographic outcome with no clinical symptoms) and survival rates (tooth retention without clinical symptoms) were calculated, and the cause of failure (diseased or fractured) was identified. Pretreatment (Age, sex, tooth type, position, sequence of treatment, quality of root canal before surgery, presence/absence of through-and-through lesion, presence/absence apico-marginal defect) and treatment (presence/absence of errors during surgery, type of error (major or minor), retro-preparation depth, presence/absence of an isthmus, retro-filling material used, presence/absence bone graft material and/or resorbable membrane) factors were recorded. Data were statistically analyzed to determine the inter-observer, intra-observer, and inter-radiographic agreements. Univariate, bivariate, and logistic regression analysis were used to determine prognostic factors affecting the outcome, and the effect of GTR on the pattern of apical bone remodeling. The significance level was set at 5%. RESULTS Sixty-eight patients (83 teeth) presented for outcome evaluation (Recall rate: 84%). The survival rate was 93%. The success rate was 88% using PA and 86% using CBCT when vertical root fracture (VRF) cases were included. 94% using PAs, and 91% using CBCT when VRF cases were excluded. The intra- and inter-observer agreements were substantial using CBCT, slight to a fair agreement using PA (P < 0.001), and slight to moderate for inter-radiographic agreement. The presence of a major procedural error during the surgery was the only negative predictor for the outcome of EMS (P = 0.013). GTR did not affect the success rate or the type of healing using PA but affected the type of healing on CBCT (complete vs incomplete healing) and the pattern of cortical plate remodeling (P < 0.001) CONCLUSION: The success and survival rate of endodontic microsurgery was very high, and the occurrence of a major procedural error during surgery was the only factor affecting the outcome. GTR did not improve the outcome but it affected the quality of apical bone remodeling following EMS.