成長期ラットの下顎骨の形態, 骨塩量および破砕強度に関する研究

Abstract

Importance of calcium intake in diet during the childhood from the infantile period through preschool age, school age, and puberty in the growth stage has been pointed out in recent years. Three-week-old male rats of Wistar strain were used and changes caused by supplying calcium in the debilitated mandible in the growth stage and also changes in the mandible given high calcium for an extended period were investigated morphologically, and for bone density and compressive strength. The results were as follows : 1. Morphological measurement 1) Coordinate analysis High calcium diet group and calcium-deficient diet + standard diet group, as compared with control group, both showed significant differences (p<0.05) in many measurement items. Decrease in the degree of growth in the mandibular morphology was observed. Calcium-deficient diet + standard diet group, as compared with high calcium diet group, showed further decrease in the degree of growth. 2) Actual length measurement A. Length measurement Control group showed high values followed by high calcium diet group and calcium-deficient diet + standard diet group. As compared with control group, high calcium diet group with a 5% significance level (excluding AI-Id') and calcium-deficient diet + standard diet group with a 1% significance level showed low values. As compared with high calcium diet group, calcium-deficient diet + standard diet group showed low values (excluding Id'-M3) with a 5% significance level. B. Height measurement Control group showed high values followed by high calcium diet group and calcium-deficient diet + standard diet group. As compared with control group, high calcium diet group and calcium-deficient diet + standard diet group with a significantly low values (p<0.01). As compared with high calcium diet group, calcium-deficient diet + standard diet group, Cd-Ag alone, showed significantly low values (p<0.05). 3) Angle measurement The measurement points of each group showed nearly same values. Only the coronoid process angle, control group showed significantly lower values with a 5% significance level as compared with high calcium diet group. 2. Bone density No significant differences were seen between control group and high calcium diet group. Calcium-deficient diet + standard diet group, as compared with control group and high calcium diet group, showed significantly low values (p<0.05). 3. Compressive strength Control group showed no significant differences as compared with high calcium diet group. Calcium-deficient diet + standard diet group showed significantly low values (p<0.05) as compared with control group and high calcium diet group. On the basis of the foregoing findings, for the mandible in the growth stage, administration of high calcium for an extended period does not necessarily result in favorable effect. Nor sufficient recovery can be expected for the debilitated mandible in low-age children even with administration of standard diet.