This study concerned the bone mineral content during the healing process of the bone defect in the premolar mandibular region. The materials which were obtained from the excised mandibles were measured respectively with ¹²⁵I-photon absorptiometry in the 1st, 2nd, 3rd, 4th, 8th, 12th, 16th and the 24th week after the operation. The bone mineral content was then compared with the results obtained by photodensitometry, three-dimensional plots of digital displays and histological findings.

The bone mineral content obtained by ¹²⁵I-photon absorptiometry varied within a range of 0.058 to 0.197g/cm² over a period of 24weeks. The bone mineral content decreased during the 1st and 2nd week after surgery, and then increased from the 3rd to 8th week. Though the changes in bone mineral content fluctuated slightly after the 8th week, the highest mineral content was obtained during the 16th week. Bone mineral content decreased by osteoporotic changes during the 24th week after the operation. The changes in values obtained by ¹²⁵I-photon absorptiometry coincided with the histological fndings, threedimensional plots of the digital displays, and values obtained by photodensitometry.