To repair bony defects with tansplanted bone in the body, fresh autogenous bone is undoubtly, the most effective bone graft for clinical applications. But the demineralized bone has the matrix-induced bone formation which was suggested by Urist
in
1965.
many authors assiasted that demineralized bone powder induces phenotypic conversion of mesenchymal cells into osteoblasts, with high-density bone formation. The process of inducing differentiated cell s becomes osteogenic properties.
The purpose of this study was to evaluate the osteoinductive capacity of allogenic freeze-dried demineralized bone block (FDD, 7×7mm) and to compare FDD with the same size of deep-frozen allogenic bone (DF), fresh autogenous bone (A) after
implantation.
The histological and ultrastructural features of tissue responses were examined after 1, 2, 4, 6, 8 weeks implantation of each experimental groups in the operative site of the New Zealand white rabbits.
@ES The results wee as follows:
@EN 1. Inflammatory cell infiltration generally has appeared at 1 week, but reduced at 4 weeks in each group, but most severe in DF group.
2. Osteoblastic activity has increased for 4 weeks, but decreased at O weeks in each group and there was no significant difference among experimental groups.
3. New bone formation ahs begun at 1 week, least activations in A groups, and showed the revesal line of bone formation among each group at 6 to 8 weeks.
4. Bone resorption has appeared at 1 week, but disappeured at 4 weeks in both A and DF groupos, but more severe in DF than A gorups.
5. In ultrastructural changs, the DF group have showed the most remarkable osteoclastic activities among experimental groups.
6. Osteoid or tangled collagen fibrils near the implanted sites were replaced by more mature, lamellated bomy trabeculae during bone remodeling. There was little difference among each experiemntal groups.
7. During the convertion osteoblasts to osteocytes which embedded within the bone matrix, there was organless-poor cytoplasm, increased nuclear chromatin, abundant rough endothelial reticulum (RER) in each groups.
From the above the findings, the DF group showed more bone resorption and foreign body reaction than FDD and A groups, and FDD group showed more new bone formation or osteoblastic activity than DF and A groups in early stage. There was no
significant
difference of cellular activities among the FDD, DF, and A groups according to the time.
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