Abstract
Osteopetrosis is an inherited metabolic disease which produces an excessive accumulation of bone caused by deficiency of osteoclasts. It is characterized by systemic bone sclerosis, cranial deformation and failure of tooth eruption due to defective bone resorption. In this study, morphological change of the mandible was observed in growing Osteopetrotic (op/op) mutant mice. Deformation of the condylar process, non-ossification of the condyle head and underdevelopment of the lateral pterygoid muscle were observed in the mutant mice. Although these phenomena were brought about by failure of the bone remodeling, it was simultaneously suggested that the ossification of the condyle head concerned with the mastication.