A Series Of Experimental Studies Of Partially Demineralized Allogeneic Bone Grafts

There are highly significant correlations berween the biologic properties and the functions of bone grafting material. The mineral content of cortical bones from rat, mouse, dog,and humanity was determined at different time in demineralization. After that, the mechanical strength of cortical bones in different demineralization stages was determined in dog; The osteoinduction of allogeneic bone grafts in variant demineralization stages was examined by implanting them in muscle of rats; The antigenicity of allogeneic bone grafts in different mineral content was studied in mouse by periodically examining humoral immunologic reaction of host with antibody complement mediated cytotoxicity (ACMC) after transplantation. Finally, partially demineralized allogeneic bone (PDAB) was prepared according to the above results. A 3 cm long and full thickness continuous bone defect was created in the medial mandible of 18 adult dogs. The defects were filled with PDAB graft (n=12) or autogenous cortical bone (ACB) graft (n=6) . Repair of the grafts was periodically assessed by the examinations of radiograph, histology (light microscope and scanning electron microscope), ink injection inter-blood-vessel, and florescence of Tetracyline labelling up to six months postoperation. Bending strength of the grafted mandibulae was also tested at the fourth month and the sixth month postoperatively. We conclude that: 1) The preparation of PDAB has to be based on the rate of demineralization because of cortical bone from diferent species needs variant time to be demineralized to the same mineral content. 2) Over 60% of original mechanical strength can be obtained by PDAB when it's mineral content is biger then 23% in normal. 3) Allogeneic bone grafts have a same osteoinductive potential as their mineral content lower then 40%. 4) There is no difference in ACMC between PDAB grafts and isogeneic bone...