Endodontic therapy in a 3-rooted mandibular first molar: importance of a thorough radiographic examination.

This case report describes endodontic therapy on a mandibular first molar with unusual root morphology. In the initial treatment the working length had been determined with only an apex locator; no periapical radiographs had been obtained because the patient was pregnant. The root canal into an additional distolingual root had not been found and was therefore left untreated, which led to treatment failure after 11 months. The radiographic examination performed in a subsequent endodontic treatment allowed detection of the anomalous root and completion of the root canal treatment. The distolingual root canal would have been identified during the initial endodontic therapy if a thorough radiographic examination had been carried out. This report highlights the importance of radiographic examination and points out the need to look for additional canals and unusual canal morphology associated with a mandibular first molar. Radiographic examination during pregnancy is also discussed.