Alveolar bone remodeling after tooth extraction in normal and osteopetrotic (ia) rats

One of the osteopetrotic mutations in the rat, incisors-absent (ia), exhibits generalized skeletal sclerosis and failure or delay of tooth eruption, characteristics of other osteopetrotic mutations. Osteopetrosis in ia rats is known to be due to a reduction in bone resorption, the result of the inability of ia osteoclasts to elaborate a ruffled border. During healing of extraction wounds, especially the initial period, osteoclastic resorption of alveolar bone is considered to be a significant feature, followed by new bone formation. We have studied extraction wound healing in osteopetrotic (ia) rats histologically in order to determine if their systemic reduction in bone resorption changes the sequence or rate of alveolar bone healing within and outside the socket after tooth extraction, In ia rats, the healing process was delayed in comparison to that of normal rats. Many osteoclasts were observed on the surface of alveolar bone, but there was little evidence of resorption. Bone formation in the socket following bone resorption was reduced and the newly formed trabeculae were irregular. In contrast, the quantity of resorption-independent (periosteal) new bone formation outside the socket was exaggerated compared to normal animals. These data indicate that the disturbance of new bone formation in the socket is probably related to the reduction in osteoclastic bone resorption.