Cemento-osseous dysplasia (COD) is a benign fibro-osseous lesion of bone characterized by the replacement of normal bone by fibrous tissue and subsequently followed by its calcification with osseous and cementum-like material. It arises from the fibroblasts of the periodontal ligaments.
|Orthopantamogram showing a well-defined radiopaque mass in the right mandible region extending from the distal root of 45 to the mesial root of 47 
As per WHO, there are three clinical presentation of cemento-osseous dysplasia.
Periapical cemento-osseous dysplasia
These occur in the anterior mandible and involve only a few adjacent teeth.
Focal cemento-osseous dysplasia.
involve few teeth in posterior mandible