Pre and intraoperative factors impact on periapical healing of endodontically treated molars: a multicentric observational study.

INTRODUCTION: Pre and intraoperative clinical variables of endodontic procedures are diverse among operators and schools, which may adopt different guidelines. Thus, it is challenging to establish comparisons regarding differences which can potentially influence the desired periapical healing. Thus, this study aimed to evaluate the influence of operative factors on the clinical and radiographic success of root canal treatment between two postgraduation centers. METHODS: The treatment outcome of 134 molars was assessed. Besides preoperative data, variations between treatment protocols were also collected. The root canal treatment was classified as 'success' or 'failure' according to the Periapical Index score. Participants were followed-up for up to 48 months. Bi and multivariate models, using Poisson regression with robust variance, were used. RESULTS: The overall success rate of the root canal treatment was 79.9 %. Preoperative apical periodontitis was significantly associated with a poorer success rate (P = 0.007) of 71.6 % whereas when apical periodontitis was absent, the success rate raised to 90 %. The strength of this association was held even when the model is adjusted for age, sex, treatment protocol, tooth location, obturation level, and recall period. Hydraulic vertical condensation filling technique was associated with a 4-fold rate of overextension (P < 0.001). None of the other technical variables affected the outcome of endodontic treatment. CONCLUSION: The presence of apical periodontitis is highly associated with worse endodontic prognostic, despite the guideline adopted by the postgraduation center. CLINICAL RELEVANCE: Meaningful further development and research must provide innovative tools and techniques for endodontists, focusing mainly on anatomical complexity challenges. In this sense, a substantial increase in endodontic success rates in high complexity teeth treatment, such as molars, could be expected.