Evaluation of the endodontically-treated distolingual root of the mandibular first molar using cone-beam computed tomography

············································································································································································ This retrospective study evaluated the endodontic treatment of a separate distolingual (DL) root of the mandibular first molar, using conebeam computed tomography (CBCT) images. The study included CBCT images of patients at a Korean dental college hospital. All endodontically-treated mandibular first molars having a separate DL root, were investigated. The presence of periapical lesions in the distobuccal (DB) and DL root, as well as the presence and quality of canal filling, were assessed. The differences in the quality of the root canal filling between the DL root and the DB root were analyzed using a Fisher’s exact test. Multivariate logistic regression analysis separately identified the factors affecting untreated canal and adequately-filled canal of the DL root. A total of 215 mandibular first molars having a separate DL root, were found to be treated endodontically. The incidence of an untreated canal in the DL root was 28.8%, whereas only 39.5% of the DL canals had an adequate canal filling. The incidence of untreated canals was significantly higher in the DL root than in the DB root (p <0.001). The right side was significantly associated with the presence of untreated DL canal. Adequately-filled DL canal was also associated with tooth position, and was not associated with gender, age, or the presence of a periapical lesion. The canal of DL root of the mandibular first molar was more untreated and not adequately filled, as compared to the DB canal, especially in the right side tooth.