Cemento-ossifying fibroma and benign cementoblastoma.

Cementum is a calcified dental tissue that covers the roots of teeth and is part of the periodontium. Its function is to help anchor the teeth in their sockets within the alveolar bone of the jaws. Two benign mesenchymal odontogenic tumors are uniquely distinguished by elaboration of cementum or cementum-like material: cemento-ossifying fibroma and benign cementoblastoma (true cementoma). Cemento-ossifying fibroma, which is also termed periodontoma, is characterized by production of cementum and bone in a fibrous stroma. It is a painless, slow-growing tumor usually detected in the third and fourth decade of life and is more common in women. The mandible is its site of predilection. Benign cementoblastoma is intimately associated with the roots of teeth, most commonly mandibular molars. It affects young patients, usually under the age of 20 years. Pain is a common symptom in addition to bone expansion. Benign cementoblastoma bears considerable histologic resemblance to osteoblastoma.