Anatomic characteristics of the furcation and root surfaces of molar teeth and their significance in the clinical management of marginal periodontitis.

Treatment of periodontitis which involves the furcation area of molar teeth has always been a challenge. Sixty extracted human molar teeth were used for an anatomic study to clarify the possible morphologic factors which may affect the diagnosis, prognosis, and clinical management of periodontally involved teeth. Teeth were embedded in methylmethacrylate and cut in 70 microm cross sections from the cementoenamel junction to the apex. Cervical enamel projection, root and root trunk lengths, root proximities as well as depths of root concavities coronally, apically, and at the furcation roof were measured. Cervical enamel projections were observed in 30% of the teeth examined. The shortest root trunk was found at the buccal aspect of mandibular first molars, permitting furcation involvement at early stages of periodontal disease. The most apically located furcation was found at the distal site of maxillary first molars. Furcation roofs showed severe concavities and complex cementum morphology. Teeth exhibiting cervical enamel projection were found to have deeper root concavities compared to teeth without cervical enamel projection and mesial roots of mandibular molars possessed greater furcal concavities than distal roots. The presence of root concavities complicates the diagnosis of furcation involvement and restricts access of periodontal instruments, resulting in incomplete treatment. Furcation anatomy may also influence the long-term prognosis of the teeth by favoring the retention of bacterial deposits and making oral hygiene procedures almost impossible. The present study shows that knowledge of a tooth's unique anatomic characteristics is a prerequisite for effective periodontal therapy.