Autologous cortical bone block for repair of implant-site jaw bone defects / 中国组织工程研究

ABSTRACT

BACKGROUND: Autologous bone with good biocompatibility possesses the characteristics of bone conduction, osteoinduction and osteogenesis. However, the healing process after autologous bone grafting is still controversial. The focus of controversy is whether the bone graft is completely absorbed and replaced or whether it can retain cell viability for a long time. OBJECTIVE: To observe the histological changes in bone remodeling and regeneration after cortical bone grafting. METHODS: Six healthy beagle dogs were selected as the research animals. The maxillary premolars of experimental dogs were extracted and the bone plates with width of 10 mm, length of 15 mm and thickness of 2 mm were removed from the buccal side. A bone defect model was established. The corresponding size of cortical bone block was cut on the buccal side of the bilateral mandibular body. Cortical bone grafts were fixed in the maxillary defect area. On one side pure cortical bone block was used as grafting material; on the other side the implant was placed simultaneously with the bone graft. Samples were harvested at 3 and 6 months after bone grafting. The cell survival and bone graft resorption of autologous cortical bone graft were analyzed by gross observation and histological observation. The study protocol was approved by the Animal Ethics Committee of Dalian Medical University, China. RESULTS AND CONCLUSION: The size of the grafted bone was gradually reduced, and the margin was blunt and firmly bonded to the base bone. All implants lost after 6 months. A newly formed connection between the graft and the base bone was shown by hard tissue ground sections. The porosity of bone lacuna in the grafted bone block at 6 months was significantly lower than that at 3 months (P < 0.05). The grafted bone resorption rate at 6 months was significantly higher than that at 3 months (P < 0.05). These findings indicate that osseointegration exists between grafted cortical bone block and the base bone of the recipient area. Osteocytes in the graft bone partially remain alive. With the prolongation of healing period, the proportion of new bone cells increases, and the volume of the grafted bone gradually decreases. Osseointegration of the concurrent implant is disturbed due to the absorption of cortical bone graft.