A study was carried out by dual energy X-ray absorptiometry in the bone defects of sixteen beagles to determine the bone mineral content (BMC) and density (BMD) of the mandibular premolar region. Both shallow and deep defect groups which were obtained from the excised mandibles were measured on the onset as well as the 4th, 8th, and the 24th weeks after the operation. These were then compared with the values obtained by the intact opposite side to confirm the bone recovery rate.
In the shallow bone defect group, the ratio of BMC to control decreased gradually from 95.1% to 82.4% over a period of 24 weeks, then the BMD ratio showed almost equal quantities of the control at all times. In the deep bone defect group, the BMC ratio increased from 52.4% to 89.8% in the first 4-week interval, followed by a decreasing change that resulted in 82.7% at the 24 weeks. The BMD ratio of the deep defects increased from 82.5% to 97.6% in the first 4 weeks, and thereafter that showed the same level as the control side.
The bone mineral change was influenced by the depth of bone defects. BMC was a sensitive parameter to the regeneration of the bone defects, however, BMD was affected by only the deep defects. At the end of the observation period, BMC of both shallow and deep defects showed a regular level in contrast to the control side.