The Effect Of Simvastatin-Bio-Oss Mixture On Bone Defect Healing Around Implants

Background;Implantations bone grafting is the main method of curing bone shortage around the implant and how to improve osteoinductiveness in bone implant comes to the research focus on bone implant material. The article is going to focus on the effect of simvastatin of osteoinductiveness on bone defect healing around implants.Objective:Compare the reparation effect of bone defect around the implants as well as bone incremental change of the mixture graft with simvastatin-Bio-Oss, testing the ability to promote osteogenesis, to provide experimental evidence and theory basis to further experiment and clinical selection of bone graft materials.Methods:24healthy Japan white big-ear rabbits were selected. The animals were randomly divided into A, B, C and D groups, with6in each. Defects and holes were made on the bilateral tibia in the1/3of each side to make the matching planting socket with the implant. Implantations were embedded in holes, formed a3×3mm bone defect area on the implant side, with appropriate depth of exposing the implant. The mixture graft with simvastatin-Bio-Oss in the bilateral tibia was implanted in experimental group (A, B groups) by0,5mg and1.0mg respectively. Bio-Oss was simply implanted in the control group (C group). Nothing was implanted in D group. The bone mineral density was then observed and analyzed at4and8weeks postoperative.4% of paraformaldehyde was used for systemic perfusion fixation at all experimental animals. Then intercept the tibia specimens containing implants for general observation, histomorphology and immunohistochemical detection, observing and calculating both bone morphology and histological changes on bone defect area around implants. The experiment data was analyzed statistically by One-way ANOVA and SNK test with SPSS13.0statistics software, with inter-group comparison t tested with two independent samples.Results:Overall observation:4and8weeks after operation, repair of bone defect performed better in group A and B than in C and D; group C outdid group D and there’s no obvious difference between group A and B.Bone mineral density test:Comparing with4weeks after operation, bone mineral density was superior in group A, B, C and D when they were at8weeks after operation, with significant statistics difference(P<0.01).4weeks after operation, bone mineral density was higher in group A、B and C than in group D (P<0.05)and no obvious difference between group A、B and C (P>0.05).8weeks after operation, bone mineral density was higher in group A and B than in group C and D (P<0.05), with group C higher than group D (P<0.05)and no obvious difference between group A and group B (P>0.05).Histomorphology observation:Comparing with4weeks after operation, quantity of new bone matrix were more in group A, B, C and D when they were at8weeks after operation, with significant statistics difference(P<0.01).4weeks after operation, quantity of new bone matrix were more in group A, B than in group C and D (P<0.05),with group C superior to group D (P<0.05) and no obvious difference between group A and B (P>0.05).8weeks after operation, quantity of new bone matrix were more in group A, B than in group C and D (P<0.05), with group C outdid group D (P<0.05) and no obvious difference between group A and B(P>0.05).At eighth week, the mature lamellar bone tissue has formed in both group A and B; a small amount of Bio-Oss were observed among mesh weaving bone in group C; group D was with thick trabecular bone woven into the mesh.Immunohistochemical staining:4weeks after operation, the expression of bone defect BMP-2in group A and B widely appears in immature bone cells, osteoblasts and bone matrix, strongly positive. Positive staining in bone defect area in both group C and D is slightly lighter than in group A and B, with group D being the lightest one.8weeks after operation, bone plate matrix staining faded obviously in group B, with positive cells lessening and staining lightering, appearing in a small amount of residual immature bone cells and osteoblasts. There’s no obvious difference between group A and group B in positive staining area.Group C and D were with more positive cells than group A and B, mainly expressed in terms of osteoblasts. Group D was with relatively deeper bone plate matrix staining. The positive staining areas of4groups were totally lighter than they were at the4weeks after operation.Conclusion;1. Topical application of Simvastatin-Bio-Oss mixture can obviously promote the bone defect healing around implants.2. Simvastatin’s promotion effect toward bone tissue in defect area is actualized by expression increase of BMP-2.3. Simvastatin of0.5mg and1.0mg selected in the experiment is without obvious difference in promoting new bone growth.