COMPARATIVE STUDIES ON THE EFFECT OF DRUGS ON THE PATTERN OF CALCIFICATION OF INCISOR DENTIN OF RABBIT POST-PARTUM AND OF THE NEONATE.
I. Effect of calcium preparation
1973 Volume 23 Issue 3 Pages 211-222
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1973 Volume 23 Issue 3 Pages 211-222
Calcium requirement increases during pregnancy, leading to calcium deficiency and disturbance of calcification of dentin. Thus far, several calcium preparations have been administered to pregnant women and experimental animals in order to prevent calcium deficiency. However, method of administration has not been sufficientry. The present author has studied the changes in dentin calcification during pregnancy by means of vital staining with lead-EDTA in chronological sequence. Changes in the levels of serum calcium, inorganic phosphate, and alkaline phosphatase activity, all of which are intimately related to calcification, were also studied during pregnancy of the rabbit. The effect of the administration of calcium gluconate, calcium lactate, and calcium phosphate were compaired, by using, as indices, the state of the zone of hypocalcification of dentin of the pregnant rabbit in the last trimester, dentin of the newborn, and the blood components of both the parent and the newborn.
The results were as follows :
1. Calcification of dentin of the left mandibular incisor of pregnant rabbit was increasingly impaired during the last trimester of pregnancy. Three to five days befor delivery, a zone in dentin with a sign of marked hypocalcification was noted. Serum levels of calcium and inorganic phosphate were declined gradually as pregnancy progressed. After delivery, there were sudden increases in these parameters, and they returned to normal within a few days. Participation of parathyroid hormone and calcitonin was infered.
2. Administration of a small amount of lead-EDTA (30mg /kg body weight) during pregnancy produced a dark line of lead in the hard tissue of the parent and the fetus. This was used as the base line of the time. This method is more accurate and safer than the previous lead acetate method.
3. By using the pattern of hypocalcification of dentin formed in the later stage of pregnancy as an index, calcifying action of various calcium preparations were compared. The results indicated that calcification of both the parent and the fetus was most strongly accerelated by the administration of calcium gluconate, followed by calcium lactate and calcium phosphate. Little difference was found between the later two.
4. These calcium preparations did not influence the levels of serum calcium, inorganic phosphate, and the alkaline phosphatase activity as clearely as they did the pattern of calcification of dentin.
