Reasons For Failure of Endodontically Treated Teeth: A Cross-Sectional Study

Background: Post-treatment disease after non-surgical root canal treatment remains clinically consequential, and reported reasons for failure of endodontically treated teeth vary across studies due to differing endpoints and categorization schemes. Objective: To identify the reasons for failure of endodontically treated teeth presenting with post-treatment disease and to evaluate associations with patient- and tooth-related factors. Methods: A cross-sectional study conducted from April 2019 To December 2022, assessed endodontically treated teeth with periapical radiolucency and/or symptoms in the outpatient departments of two teaching hospitals in Islamabad. Two calibrated operators performed standardized clinical and periapical radiographic evaluations and assigned a single primary failure reason using a predefined categorization framework (8). Frequencies and percentages were calculated, and associations between failure categories and age group and gender were evaluated using chi-square testing. Results: In the analytical dataset (n=374), endodontic reasons were most frequent (58.6%, n=219), followed by combined endodontic and restorative reasons (24.3%, n=91). Restorative reasons (5.6%), vertical root fracture (5.1%), endodontic failure despite apparently adequate treatment (3.7%), and non-restorable caries/cuspal fracture (2.7%) were less common, while periodontal, prosthetic, and orthodontic reasons were not observed. Failure was more frequently represented in mandibular teeth (64.7%) than maxillary teeth (35.3%), with mandibular molars most commonly affected (53.2%). Conclusion: Endodontic technical reasons predominated among failing endodontically treated teeth in this OPD-based cohort, and mandibular molars were most frequently represented, supporting the importance of technical endodontic quality and definitive coronal sailing.