Risk analysis of failure of root canal treatment for teeth with inaccessible apical constriction

Summary Objective The risk of failure of root canal therapy was assessed in teeth with inaccessible apical constriction and factors influencing treatment outcome in these teeth were analyzed. Methods From the same 57 patients, one tooth with inaccessible apical constriction ( n =57) and one tooth with adequate accessibility ( n =57) were included in this retrospective investigation. Cox regression analysis was used to analyze factors that may have influenced the outcome one or more years after obturation. These factors included inaccessibility, systemic disease, canal curvature, preoperative periradicular lesion, widening of periodontal ligament space, patient gender and age, size of master apical file, preoperative pulp vitality, years of operator experience and obturation length. Results Inaccessible apical constriction was a significant factor related to outcome (odds ratio, 5.301). Preoperative presence of periradicular lesion significantly influenced the outcome in cases with inaccessibility (odds ratio, 4.448). Conclusion Inaccessibility increases the risk of root canal therapy failure particularly in teeth with preoperative periradicular lesion.