Fibrous dysplasia of bone and concomitant dysplastic changes in the dentin.

Fibrous dysplasia of bone and dentinal dysplasia have not been classified as related conditions. However, the present report describes a patient with both polyostotic fibrous dysplasia and dysplastic changes in the dentin. One bone lesion was first discovered on the right side of the mandible on a routine roentgenogram. There was an atypical radiolucency apical to a short-rooted molar with an obliterated pulp. Additional lesions were found on the left side of the mandible in the maxilla, in the frontal and occipital bones, in the ilium, in the proximal ulnae, and in the ribs. All lesions demonstrated an increased uptake of Tc99. A biopsy specimen of bone from the right side of the mandible showed small calcified islands in a cell-rich connective tissue. Microscopic analysis of the right first molar showed irregularly shaped dentin with the dentinal tubules arranged in a whorl-like fashion surrounding an almost completely obliterated pulp chamber and canal. Healing after tooth extraction and after the bone biopsy was unremarkable. After 6 months the alveolus was reorganized and the bone patterns appeared normal, although the radiolucent areas inferior to the teeth remained unchanged. The concomitant occurrence of dysplastic changes in bone and teeth may be a sign of a generalized defect in the mesenchymal hard-tissue-forming cells.