99mTc-MDP를 이용한 동종골 이식의 평가에 관한 실험적 연구

AN EXPERIMENTAL STUDY ON THE EVALUATION OF MANDIBULAR ALLOGENEIC BONE GRAFT WITH 99mTC-MDP BONE SCAN

Freeze-dried allogeneic bone graft has frequently used to restore the defects of maxillofacial bone caused by diseases and trauma recently. But an objective method for the early and exact evaluation of the bone graft healing remains to be developed. The purpose of this study was to evaluate the healing state of mandibular allogeneic bone graft in experimental animals using 99mTc-MDP bone scan. Thie study was designed to compare three diagnostic methods at 1, 2, 4, 6, 8 week intervals after allogeneic bone graft in dogs mandible: the conventional radiography, the histologic examination and the bone scan with 99mTc-MDP. The obtained results were as follows. 1. The static image and the tomography of the bone scan demonstrated greater radioactivity in the experimental grafts than in the control during the whole experimental period. And the analysis on the tomography was clearer and more accurate than on the static image because of avoidance of overlapping with other neighbouring anatomic structures. 2. The radioactivity ratios between the counts for pixel in the bone graft area and the counts for pixel in the control area showed increased figures at one week, decreased at two weeks, increased and reached peaks between 4 and 6 weeks. In experimental animal E the radioactivity ratio at 8 weeks was lower than at 6 weeks, but remained rather higher than in the control. 3. On the histologic findings, the recipient and the graft were united with fibrous connective tissue which indicated incomplete union even at 8 weeks. In the recipients, trabecular bone formation was predominant between 2 and 4 weeks. In the grafts, there was localized necrosis at the bone marrow and bone absorption by osteoclasts were observed through the whole experimental period. 4. The radioactivity ratios seemed to be correlating to the bone graft healing in the comparision of conventional radiography and histologic findings. When it was compared with conventional radiography and histologic findings, the radioactivity ratio was believed to be associated with blood flow, bone maturation, other various factors, and provided more objective results. Therefore the bone scan method was considered to be the most useful objective method for evaluating the bone graft healing.