Fusion of permanent mandibular molars associated with periodontitis: a case report.

Dental twinning derives from abnormal events during the embryological development of tooth germs. The majority of fused teeth are found in the deciduous dentition, particularly in the anterior region of dental arches. Fusion of posterior teeth is considered a rare event. We report here a true case of posterior fusion between a second and third mandibular molar occurring in a black African woman. The morphology and the position of this abnormal tooth were responsible for a related periodontal problem.