The study on the bone mineral determination in the healing process of bone defects by ¹²⁵I-photon absorptiometry in dogs.

-Effect of feeding low calcium diets-

Abstract

The effects of Ca deficiency in bone repair of dogs were evaluated by ¹²⁵I-photon absorptiometry (¹²⁵I-PA) and the histological findings (H-E stain, contact microradiogram, labeling method). A bone defect at the experimental site was produced in the mandibular premolar region of dogs. The dogs were then divided into the normal diets group (ND group) and low Ca diets group (LCD group) after operation. The control site with a bone defect was equal to the experimental site on the contralateral region before sacrificing on the 1st, 2nd, 4th, 8th,16th and 24th week. Bone mineral content (BMC) of excised mandibles and the radius were measured using ¹²⁵I-PA. BMC in the control site slightly decreased from the 4th week, and then showed an obvious decrease from the 16th to 24th week in the LCD group. BMC in the experimental site decreased from the 16th to 24th week in the LCD group. During the 1st week after surgery, the BMC tended to decrease in the experimental site but then increased from the 2nd to 24th week in the LCD group. However, the amount of BMC between the experiment and control sites was different in the LCD group, because the amount was higher than the ND group during the 16th to 24th week. This observation indicated bone formation of bone repair continued in the LCD group from the 16th to 24th week, although BMC of bone defect at the experimental site decreased equally throughout the other bones.