2020 Volume 63 Issue 5 Pages 461-466
Purpose: A C-shaped root canal has a complex configuration and sources of infection remaining in it make nonsurgical root canal treatment difficult. Here we report a case of endodontic retreatment with good prognosis by using cone-beam computed tomography (CBCT) and a dental operating microscope on a C-shaped mandibular second molar with chronic apical periodontitis.
Case: A 42-year-old male visited our hospital due to a dull and biting pain in his lower left posterior tooth for approximately one year. The metal inlay on the mandibular left second molar did not fit well and there were percussion pain and occlusal pain at the same tooth. Dental radiography and CBCT of the mandibular left second molar revealed a radiolucent area at the apex, poor root canal filling and separated file-like radiopacity in the root canal. Also, a C-shaped root canal was curved distobuccally at the apex area. Based on the diagnosis of chronic apical periodontitis, the mandibular left second molar was retreated. After removing the infected tissue and shaping the root canal along the C-shape under the microscope, the chief complaint was improved. Root canal obturation was performed and the final restoration with full cast crown was placed 9 months later. At one year after the root canal obturation, the radiolucent area had disappeared and there were no clinical symptoms.
Discussion and conclusion: It has been reported that the frequency of a C-shaped root canal in the mandibular second molar is higher in Asians than in Caucasians, and that the ratio in Japanese is about 30 to 60%. A C-shaped root canal rarely has the same shape from the orifice to the apex, and there are many branches and confluences, which often cause clinical difficulties. Moreover, compared to the coronal part of the root canal, an undercut exists in the middle and apical part, which often leads to residual infection. In this case, proper access cavity preparation, enlargement of the coronal part of the root canal, and preparation of the middle and apical part were performed under the microscope while referring to the preoperative CBCT images. This process enabled removal of the sources of infection, including residual necrotic pulp-like tissue, and led to good healing.
