Radiographic And SEM Evaluation Of Demineralized Freeze-dried Bone Allograft For Bone Regeneration In The Bone Defect Around Implant

Objective To compare the effection on the bone regeneration of demineralized freeze-dried bone(DFDBA), DFDBA and recombinant human bone morphogentic protein-2(rhBMP-2), DFDBA and titanium membrane. Methods CDIC implants were put in the thighs, then 4mm 3 mm 3 mm bone defects were made around implants. In order to repair the bone defects, DFDBA,DFDBA +rhBMP2, DFDBA+ titanium membrane were used. At 4, 8, 12 weeks of postoperation, the specimens were assessed by computer- assisted densitometric image analysis. The bone regeneration and density were analysed for osseointegration; and the specimens were assessed by SEM,The gap between new bone and implant was recorded, in order to analysed the primary stability of implant and osseointegration. Results The image analysis indicates: In DFDBA group, bone defects were occupied by new bone slowly. At 12 weeks postoperatively, new bone was connected with host bone, basically. But there are definitely difference between new bone and host bone density (P<0.01). It indicated that DFDBA could be applied for repair of peri-implan bone defect, but its bone regenerative process was long; In DFDBA+ rhBMP-2 group, new bone was fromed earlier than that of DFDBA group. At 12 weeks postoperatively, there were no difference between new bone and native bone, in term of bone density(P<0.05). This demonstrated that rhBMP-2 could increase osteoinduction of DFDBA; In DFDBA+ titanium membrance group, the bone formative process was similar to that of DFDFB+ rhBMP-2. But at 8 weeks postoperatively, the amount of new bone and bone density were increased greatly. It indicates that titanium membrane has the capacity of guided bone regeneration. It can also keep fibrous tissue from new bone.The SEM indicates: In DFDBA group,fibrous tissue and calcium materials were found in the gap between host bone and implant at 4 weeks postoperatively. In DFDBA+ rhBMP group, new bone was found in the region of bone graft, and some of new bone were near the implant surface. In DFDBA+titanium membrane group, new bone grew along implant, but the gap was definitely clear. In DFDBA group: the amounts of new bone and calcium crystals were increased at 8 weeks postoperatively, but the gap is still clear. In DFDBA+rhBMP-2 group: woven new bone formed along implant, the gap was shortened. In DFDBA+ titanium membrane group, fibrous-like new bone and calcium deposit were increased, the gap became small. At 12 weeks postoperatively, DFDBA group, new bone near to implant surface. The gap unclear. In DFDBA+rhBMP-2 group: new bone covered the gap and connected with host bone tightly. In DFDFA + titanium membrane group calcium deposit increased and a large amount of new bone covered the gap. In three different groups, the gaps were reduced with experimental periods (p<0.05). Conclusion DFDBA has good bone forming capacity, and is helpful to good primary stability of implant. RhBMP-2 and titanium membrane could promote bone forming process for DFDBA.