Effects of different rhBMP-2 release profiles in defect areas around dental implants on bone regeneration

This study was undertaken to evaluate the effects of different rhBMP-2 release profiles in defect areas around dental implants on osseointegration and bone regeneration. Four beagle dogs (13-15 kg) were used. The defect was 3 mm deep and there was a 1 mm gap around the implant. Each of the four implants was installed on the right and left mandibular alveolar ridges. After the implants were placed, experimental groups were applied to the surrounding defect area (n = 8 in each group, the control group was not treated). The inject group was injected with rhBMP-2 solution directly. In the gel group, rhBMP-2 mixed with a hydrogel matrix was applied. In the particle-gel group, rhBMP-2-embedded poly(lactic-co-glycolic acid)(PLGA) microparticles mixed with hydrogel matrix were applied to maintain consistent release. Sequential fluorescent labeling and histological analysis were performed to evaluate the new bone formation and osseointegration in the defect area. In the control group, larger marginal bone loss was detected as compared with the other groups (P  <  0.05). The gel group showed significantly higher levels of BIC in the buccal and lingual defect areas compared with the other groups (P  <  0.05). New-bone percentages in the inject and gel groups formed more new bone than in the particle-gel and control groups (P  <  0.05). Despite the limitations of this study, the use of only hydrogel, which allows early release of rhBMP-2 followed by consistent extended release, showed better bone formation and osseointegration than simple injection or PLGA microparticles with hydrogel matrix.