幼若期口腔組織の放射線障害に関する実験的研究

Abstract

For the purpose of studying radiation injury on mandibles at growth stage, the mandibles of young adult dogs were irradiated with X-ray of 200 kVp, and the irradiated intraoral tissues such as gingival membrane, teeth and mandibles were investigated macroscopically and the teeth and mandibles radiologically. The result were as follows : 1. As the injury on irradiated skin, partial epilation began two days after irradiation and ulceration (4 out of 16 cases) formed at 79 days and worsened further, and necrosis was seen in all subjects at 195 days. From one to three weeks was the acute phase when partial epilation, wet erosion, swelling, total epilation, pseudomembraneous formation were seen. After two months was the critical phase when ulceration and necrosis were observed. Between these two phases, a recovery phase with crust formation and desquamation was observed. 2. As the injury on the intraoral tissue, pigment loss in the gingival membrane began four days after irradiation. Ulceration of gingiva (2 out of 16) formed at 30 days and worsened, and exposure of the alveolar bone was observed at 208 days. At 220 days, bone fracture (6 out of 16) was observed. From one to three weeks after irradiation was the acute phase when pigment loss in the gingival membrane, reddening of the gingiva, and easy bleeding were observed. The third months was the critical phase when ulcerated gingiva, necrosis, exposure of the alveolar bone, and loose teeth were observed. The eighth months was the terminal phase when loose teeth, bone exposure, and gingival necrosis besides bone fracture were observed in all subjects. 3. Formation of necrosis in the gingiva leading to necrosis of the skin corresponding to the third premolar was found in four cases. Formation of necrosis in the skin corresponding to the third premolar leading to necrosis of the gingival membrane was found in 12 cases. 4. In radiological findings, enlargement of periodontal membrane space, disappearance of lamina dura (6 out of 16), and resorption of the alveolar crest (6 out of 16) began in the subjects at 1 month. Worsening began with bone destruction (10 out of 16), bone destruction accompanied by osteosclerosis, and erosion of inferior border of the cortical bone (8 out of 16) in the subjects at 3 months. Formation of sequestrum (4 out of 16) at 6 months and bone fracture (6 out of 16) at 8 months were observed. From one to four months was the critical phase when enlargement of periodontal membrane space, disappearance of lamina dura and of periodontal membrane space, bone destruction, and erosion of the cortical bone were observed. Thereafter, formation of sequestrum and bone fracture were seen. 5. In radiological findings for the subjects with formation of ulceration, enlargement of periodontal membrane space, and resorption of the alveolar crest were the early findings and lamina dura image around the bone destruction image followed. In radiographic findings for the subjects with formation of ulceration of the skin corresponding to the third premolar, the early findings were resorption of the alveolar crest, lamina dura, disappearance of periodontal membrane space, and disorder in trabeculae. Bone destruction image accompanied by osteosclerosis was observed thereafter.