顎骨の成長に関する実験的研究 : 食物の軟化による歯槽骨の変化

Abstract

Three-week-old male rats of Wistar strain were placed on formed diet, kneaded diet, and powdered diet. Effects of the diet on the alveolar bone and tibia in the growth stage were investigated radiologically, photographically, photo-densitometrically, histopathologically, and scanning electron microscopically. The changes in size and compressive strength of the bones were also examined. The results were as follows : 1. Radiologically, the alveolar bone in the kneaded diet and powdered diet groups decreased in thickness and trabeculae were fewer and arranged irregularly. In the tibia, no change was seen in the widths of interosseous cortex and medial cortex, but bone density was decreased slightly. 2. Photographically, the alveolar bone in the kneaded diet and powdered diet groups showed decrease in the whole densitometric curves and the arrangement pattern of trabeculae became flat. In the tibia, the densitometric curves of interosseous cortex and medial cortex in the kneaded diet group declined. 3. Photo-densitometrically, bone density of the alveolar bone in the kneaded diet and powdered diet groups decreased. Bone density of the tibia in the kneaded diet group showed no change but that in the powdered diet group decreased. 4. On the x-ray microanalyzer, the peak of Ca was higher than P in the alveolar bone in any diet groups. The quantitative analysis showed that the relative Ca ratio (Ca/[Ca]c) and P ratio (P/[P]c), as compared with controls, were higher in formed diet group than in kneaded diet group and powdered diet group. Similar results were also shown for the tibia. 5. The kneaded diet group showed decrease in the height of mandibular ramus. The powdered diet group showed decrease in both the mandibular length and the height of mandibular ramus. No changes in size were found in the tibia. 6. The compressive strengths of the alveolar bone and tibia decreased in the kneaded diet and the powdered diet groups. 7. Histopathologically, CMR findings of the alveolar bone in the kneaded diet and powdered diet groups showed decrease in the alveolar bone width, decrease in Haversian canals and bone cavities around Haversian canals, and increase in resorption cavities. General tissue findings of the alveolar bone showed increase in bone marrow and decrease in osseous layers, Haversian system, and bone lacunae. In the tibia, CMR findings and general tissue findings showed that decreases in Haversian canals and bone lacunae were light. Under the scanning electron microscope, osseous layers in the formed diet, kneaded diet, and powdered diet groups were formed wide on the whole. 8. On the basis of the foregoing findings, softened food was proved to affect the morphology of the jaw bones and the internal structures of the alveolar bone and tibia.