Dental Cone Beam CT is Effective in Identifying the Causative Tooth of Chronic Apical Periodontitis: A Case Report

Purpose: We report a case of chronic suppurative apical periodontitis accompanied by a sinus tract that appeared some distance from the causative tooth identified by using dental cone beam computed tomography (CBCT). Case: The patient was a 45-year-old man with a sinus tract in the gingiva at the apical region between the left maxillary lateral incisor and canine. An intraoral radiograph was taken to identify the cause of the sinus tract. A radiolucent area was observed around the left maxillary canine and was diagnosed as chronic suppurative apical periodontitis. As the first step of root canal treatment, access opening was initiated, but then suspended due to pain. The referring dentist suspected chronic suppurative apical periodontitis of the canine and the patient was referred to Tokyo Dental College, Suidobashi Hospital for further evaluation. A careful examination was carried out using CBCT, which presented a bone defect at the apical lesion of the left maxillary first premolar that passed through the palatal side of the left maxillary canine. The cortical bone between the canine and the lateral incisor was completely absorbed. The causative tooth was identified as the left maxillary first premolar, not the canine. Root canal treatment was performed on the infected root canal, including the application of calcium hydroxide, and the sinus tract disappeared. Result: In this case, it was difficult to identify the causative tooth only by the patient’s symptoms, visual examination, and intraoral radiography. However, the use of CBCT allowed a simple and accurate identification. We found CBCT to be effective in identifying the causative tooth during endodontic treatment.