Incidence of missed middle mesial canal in endodontically treated mandibular molar teeth: A cone-beam computed tomography study

Background: In endodontic treatment, the aim is to completely determine, shape, and fill all root canals in a three‑dimensional way. Missed canals lead to treatment failure. In mandibular molars, there may be an extra canal called the middle mesial canal between the mesiobuccal and mesiolingual canals. Aim: The aim of this study was to evaluate the prevalence of missed middle mesial canals in root canal-treated mandibular molar teeth. Materials and Methods: In this study, cone‑beam computed tomography (CBCT) images of 1054 patients were analyzed. We identified 121 endodontically treated mandibular molars and evaluated the prevalence of missed canals. Results: Although 33.05% of the root canal-treated teeth did not have a middle mesial canal, this canal was detected in the other 66.94%; 97.53% of teeth with a middle mesial canal could not be detected by clinicians. Conclusion: Clinicians performing endodontic treatment of mandibular molar teeth should not ignore the presence of the middle mesial canal. Thus, it is very important for clinicians to have sufficient information about the localization, morphology, and variations of the middle mesial canal.