Effects of rhBMP-2 on Mandibular Distraction Osteogenesis and its OPG Expression in Rabbits

Objective:To investigate the effects of rhBMP-2 on mandibular distraction osteogenesis and the expression of OPG in the period of distraction osteogenesis.Methods:Unilateral mandibular osteotomies were performed in 48 mature rabbit.rhBMP-2 1.5mg with the collagen carrier was implanted in the osteotomy side of mandibles.Only collagen sponge was implanted in the control group.The mandibles of 48 rabbits were lengthened by 4mm using a distractor,The animals were killed on 1,3,7,14 days of consolidation period.The distracted calluses were harvested and processed for histological and immunohistochemistry study of OPG.Results:The regenerated bone was found in the distraction gap after mandibular lengthening.But the rhBMP-2 was better.Staining for OPG was localized in osteoblasts of the periosteal region after completion of distraction.The mandibular side treated with rhBMP-2 had greater amount of new bone formation than that treated with collagen sponge.OPG was found in the cytoplasm of osteoblasts and stained brown or dark brown by immunohistochemistry.At the same time,OPG expression indicated that there was siganificant difference between rhBMP-2 group and control group(P0.05).Conclusion:rhBMP-2 could accelerate bone formation of mandibular distraction osteogenesis in rabbit.rhBMP-2 could increase the expression of OPG.