COMPARATIVE STUDIES ON EFFECTS OF DRUGS ON CALCIFICATION FIGURE OF INCISOR DENTINE OF PREGNANT AND NEONATAL RABBITS

Abstract

In the calcification figure of the rabbit's incisor dentine, hematoxylin unstained hypocalcification layer was formed in the third trimester of pregnancy. Using this hypocalcification layer and the newborn in the fetal age as indicators, Miyahara reported in the 2nd report of a series of studies, the effects of calcium preparations and vitamin D have intimate relation with calcification of bone and tooth. In the present work, author used estradiol, estriol and progesterone, which are most deeply connected with pregnancy, and investigation was performed on their effects on the dentine calcification figure of mother rabbits and newborns in the fetal age, and on quantitative change in serum calcium and inorganic phosphate, which are closely related with calcification. The results were as follows : 1) Normal female rabbits were intramuscularly injected with 3mg/kg of estradiol, 1 mg/kg of estriol, and 5mg/kg of progesterone, and little effect was confirmed on the striped calcification figure or growth rate of dentine and quantitative changes in serum calcium and inorganic phosphate.2) In the dentine calcification figure of mother rabbits, the hematoxylin unstained layer, formed in the third trimester of pregnancy was replaced by hematoxylin blue or deep blue stained layer after the administration of 0.001 mg/kg of estradiol, or 0.001 mg/kg of estriol, or 5 mg/kg of progesterone.This action was exerted most strongly by estradiol and weakly by estriol and progesterone. The growth rate of dentine, which tended to decrease in the third trimeter of pregnancy, was restored by the administration of estradiol and progesterone, but hardly in any degree by estriol. Calcification in the fetal age was sometimes inhibited by any of these hormones, but most strongly by estradiol also in this case.3) The tendency of decrease in serum calcium level in pregnancy could be inhibited by the administration of estradiol, but neither by estriol nor by progesterone. However, the tendency of inorganic phosphate to decrease was arrested by any of them, though with difference in degree.