Clinical diagnosis of internal resorption: an exception to the rule.

This paper describes a case in which the radiographic appearance of a resorptive lesion in a mandibular incisor tooth posed difficulty in the diagnosis of its origin. The lesion did not conform to the normally accepted criteria for diagnosis of internal resorption. Clinical examination did not support the diagnosis of external cervical resorption. Serial histological section of the extracted tooth subsequently confirmed the diagnosis of internal resorption. The criteria for differential diagnosis of resorptive lesions with smooth outlines in the cervical regions of teeth are discussed together with the rationale for their management.