人顎骨におよぼす放射線の影響に関する組織学的研究

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Radiation therapy is an effective method of treatment, which has shown competence in the treatment of malignant tumors of the oral region. On the other hand, there have been many reports stating radiation therapy have caused injury to various tissues of jaw bones. Many of the studies concerning radiation injury so far has been carried out either employing clinical observation or experimental observation using animals which predisposition of species differs from that of human being. Also there has been a few reports on changes of human jaw bone tissues. However, all of them were surgical cases, and they did not take account of predisposition of age and the effect caused by local lesion. It is well known that decalcifying method is not appropriate for cytological observation, because leaving no exception, decalcification gives severe damage on tissue. In this study the author observes the changes in jaw bones caused by radiation therapy for malignant tumors of the oral region. Thirty-nine bones of autopsy cases which were obtained from the Department of Pathology, Kyushu Dental College, were examined roentgenologically and pathohistologically, using undecalcified specimens which are suitable for cytological observation. The results obtained were as follows : 1. Initial changes of osteoradionecrosis could not be found on roentgenograms. 2. Morphological changes of osteocytes caused by irradiation could be observed as atrophy, swelling, clearing, necrosis, destruction and empty lacuna. Those findings were clearly recognized when radiation dose was more than 1200 R. 3. Changes in osteocytic process (decreasing, disappearance) and the appearance of spherical corpuscles around the osteocyte were characteristic, especially the jaw bone was irradiated more than 1200 R. A deep-stained area around lacuna was observed distinctly in all of the radiated group, except the case of 900 R. These histologic changes were confirmed by using microradiogram as in the state of low calcification. 4. Bizarre resorption is considered to be produced by fusion of enlarged lacuna centering around the Haversian canal. And this is not a characteristic change in radiation injury, but irradiation accelerates the resorption. 5. In lamella, deep-stained part and vague-stained part were observed in all cases. 6. Deep-stained layers were evident in the alveolar bone, the apex of residual ridge, the thickened part of endosteum in substantia spongiosa, and the area adjacent to the periosteum at the bottom of the jaw bone. 7. Osteoblasts and fibroblasts in the periosteum were decreased in number and the periosteum was thickened with hyalinization. 8. Necrosis of osteocyte occured even in 1200 R and osteoradionecrosis is considered to be aseptic necrosis. 9. Slight fibrosis of bone marrow was found in all of the cases. However, this may have other causes besides radiation. 10. Osteomyelitis occurs due to the secondary infection and is not due to the direct effect by radiation. 11. Osteosclerosis was not found. Radiation injury of bones is considered to be mainly due to regressive tissue changes. 12. Characteristic changes of blood vessels by radiation was not found. 13. No remarkable relationship between the variation dose of radiation and tissue changes was recognized. However, frequency of bone injury tended to increase slightly with the increment of dose. 14. From the above findings, it may be suggested that the osteocyte has high radiosensitivity, and the fundamental tissue changes in radiation injury of bone is severe disturbances of metabolism of osteocyte which leads to halisteresis.
九州歯科学会の論文
1976-03-31

著者

徳富敏信
九州歯科大学歯科放射線学教室

人顎骨におよぼす放射線の影響に関する組織学的研究

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