顎骨の成長に関する X 線的, 光顕的ならびに走査電顕的研究 : 食物の硬軟による下顎頭の変化

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Effect of food hardness on the mandibular condyle at growth stage was investigated by administering food of various hardness and calcium content to three-week-old male rats of Wistar strain. The rats were divided into formed food group, kneaded standard food group, kneaded mixed food group, powdered standard food group, and powdered mixed food group. The results were as follows : 1. Radiological findings. In the kneaded standard food group as compared with the formed food group, dense osseous layers became sparse in the mandibular condyle, and trabeculae decreased in number and were runnung a little irregularly. Morphology of the mandibular condyles in the kneaded mixed food group was about the same as morphology of those in the formed food group, but osseous layers were sparse and irregular. In the powdered standard food group, the outer form was rather unclear, dense osseous layers were quite thin and irregular, and trabeculae considerably decreased in number. The powdered mixed food group showed an increasing tendency in the number of trabeculae, as compared with the powdered standard food group. 2. Analytical findings on the X-ray microanalyzer. In any group, the peak values of Ca were higher than those of P. The characteristic X-ray image also showed higher density Ca than P in any individual trabecula. Relative Ca ratios (Ca/[Ca]c) and relative P ratios (P/[P]c) were determind in comparison with the formed food group. In the other food groups as compared with the fomed food group, it turned out quantities of Ca and P were found decreased. Ca showed similar values in the kneaded standard food groups and the kneaded mixed food group. The values of the powdered mixed food group and powdered standard food group decreased. In P, the values of the kneaded standard food group, powdered mixed food group, and powdered standard food group were decreased in descending order. 3. Histopathological findings 1) Contact microradiogram findings Granular trabeculae of primary spongiosa and trabeculae of secondary spongiosa in the condyle had very little correlation with the amount, high or low, of calcium content in food and trabeculae decreased with decrease in hardness of food and the degree of calcification decreased. Trabeculae of secondary spongiosa in the groups given food with high calcium content showed accelerated calcification in comparison with that of the standard food group. 2) General tissue finindings In comparison with the formed standard food group, proliferative chondrocytes and hypertorphic chondrocytes increased with decrease in hardness of food. Calcified matrix surrounding hypertrophic chondrocytes and subchondrocyte bone formation decreased. In high calcium-content food group, increase in calcified matrix surrounding hypertrophic chondrocytes, findings of erosion of calcified matrix by chondroclasts, and trabeculae in the zone of subchondrocyte bone formation was seen. 4. Scanning electron microscopic findings In comparison with the formed food group, incomplete fusion of calcospherites and sparse collagen fibrils were seen around the walls of chondrocyte lacunae and uncalcified matrix were also seen with softening of food. The cartilaginous ossification were seen in the surface osseous parts at the lower erosion layers. The osseous layers in the zone of subchondrocyte bone formation generally showed bone construction surrounding bone lacunae, though different in degrees, and the opening of bone tubules were seen at the bottom of bone lacunae.
九州歯科学会の論文
1991-02-25

顎骨の成長に関する X 線的, 光顕的ならびに走査電顕的研究 : 食物の硬軟による下顎頭の変化

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