Morphological studies on the healing process of tooth extraction wounds in whole body irradiated rats

The present studies were performed to investigate the healing process of the tooth extraction wound in whole body irradiated rats and to clarify the effect of irradiation on bone metabolism. One hundred and seven Wistar rats of about 100 g body weight were used and divided into 3 groups. Whole body irradiated rats were given single exposure with a dose of 8 Gy. The region of the left upper molars of local irradiated rats as controls, was exposed to 8 Gy. On the 7th day after irradiation, the left upper first molar of each rat was extracted. The rats were sacrificed at intervals of 1 to 14 days after extraction. Non-irradiated rats were sacrificed at the same intervals after extraction. The maxillary bone including the extraction wound was evaluated, histologically, histometrically and ultrastructurally. From the histological and histometrical findings, the difference of the healing process between non-irradiated rats and locally irradiated rats is not significant. In whole body irradiated rats, the healing process especially in the socket was disturbed. The osteoblastic new bone formation following production of granulation tissue was interfered with. Ultrastructurally, the cytoplasmic organellae were poorly developed in the osteoblast and osteoid formation was reduced in the socket. But periosteal new bone formation was the same as that of the locally irradiated rats. In whole body irradiated rats, the osteoclasts in the interradicular alveolar bone were decreased and have smaller nuclei, compared with non-irradiated and locally irradiated rats. Histometrically, the amount of bone loss was decreased in whole body irradiated rats. Ultrastructurally, the cyoplasmic organellae and ruffled border were poorly developed in the osteoclasts of whole body irradiated rats. The findings suggested that irradiation induced cytological changes not only in osteoblasts but in osteoclasts and these changes resulted in the delayed healing of extraction wound. (author) 106 refs