Radiolucent lesion identified in unerupted mandibular left first permanent molar

Intracoronal resorption in an unerupted developing tooth is rare and most lesions of this type are incidentally found in radiographs taken for other purposes. A 5Y10M-old girl was referred to our clinic by a general practitioner for detailed examination of radiolucency identified in the unerupted mandibular left first permanent molar. Intraoral examination revealed that the affected tooth was unerupted, while the radiographic findings demonstrated a wide radiolucent area in the coronal part of the affected molar, which extended close to the pulp. There were no signs or symptoms associated with the tooth at the first examination. At 6Y4M of age, the affected tooth had emerged into the oral cavity, though the patient reported no symptoms. We performed surgical removal of the gingival tissue corresponding to the occlusal surface of the tooth under infiltration anesthesia and macroscopic appearance showed the affected tooth to be intact. However, when the enamel of the affected tooth was removed, a hollow portion approximately 2 mm into the tooth with no pulp exposure was revealed. Calcium hydroxide was applied to the bottom of the cavity and restoration with cement was performed. Three months after treatment, the patient had no abnormal signs or symptoms. A literature search found 15 similar cases, in which mandibular dentition was more frequently affected than maxillary dentition. As for treatment modalities in those cases, conservative restoration was preferably selected, though extraction was inevitable in approximately half.