Bone regeneration after topical BMP-2-gene delivery in circumferential peri-implant bone defects

Objectives: The aims of this study were to evaluate the rate of bone formation and osseointegration after topical gene delivery with a liposomal vector system carrying bone morphogenetic protein (BMP)-2 cDNA in combination with a collagen carrier and autologous bone as a carrier in freshly created peri-implant bone defects. Materials and methods: Eight domestic pigs received nine calvariae defects each (10 x 7 mm). A dental implant was inserted into the centre of each defect. In the test groups, the remaining space was filled with the liposomal vector/BMP-2 complex combined with a collagen carrier (n=18) or an autologous bone graft (n=18). Control groups were collagen only (n=18) and autologous bone graft only (n=18). Results: There was a significant difference in mineralisation rate in the BMP-2/bone graft (29.9% +/- 4.8 and 68.3% +/- 7.2) and bone graft only (22.6% +/- 2.6 and 49.4% +/- 13.9) groups after 7 and 28 days. Mineralisation values were also significantly higher in the BMP-2/collagen group (21.2% +/- 16.2 and 53.1% +/- 12.5) compared with the collagen-only group (8.2% +/- 7 and 41% +/- 8.1) in two different regions after 28 days. Also the bone-to-implant contact was significantly increased in the BMP-2/bone graft group after 28 days and in the BMP-2/collagen group after 7 and 28 days compared with their control groups. Conclusions: The results of this study show a significantly positive effect of liposomal vector/BMP-2 on bone regeneration and osseointegration in bony circumferential peri-implant defects.