Effects of carrier release kinetics on bone morphogenetic protein-2-induced periodontal regeneration in vivo

Background: Bone morphogenetic proteins (BMPs) have shown considerable promise as a therapeutic: agent to enhance periodontal regeneration although the optimal characterisitics of a suitable release system are not known. Aim: The aim of this study was to compare the effects of slow and fast degrading gelatin carriers on BMP-2-induced periodontal healing. Method: Recombinant human bone morphogenetic protein-7 (rhBMP-2) was incorporated into gelatin and subsequently differentially cross-linked to produce slow and fast release carrier systems. Release kinetics were confirmed in vitro, by measuring release of I-125-growth hormone from similar gelatin plugs. Effects of BMP were evaluated in surgically created rat periodontal fenestration defects which were processed for histology 10 days post-operatively. The rats were divided into 4 groups and the control defects were treated with either slow or fast degrading gelatin (CONs or CONf respectively), whilst test groups were treated with 1.25 mug rhBMP-2 in the slow or fast degrading gelatin (BMPs or BMPf respectively). Results: BMPf greatly increased bone formation compared with the control (CONf) (1.67 +/-0.65 versus 0.34 +/-0.11x10(-4) m(2)), but no significant differences were observed with BMPs and CONs. In contrast, new cementum formation was significantly greater in the BMPs group compared with all other groups (p<0.05). Conclusion: Release kinetics of BMP may have important effects on the outcome of BMP-induced periodontal regeneration. New bone formation may be affected by rapid-release kinetics although further investigation is necessary to confirm tl;is. In contrast. new cementum formation is promoted by slow release of BMP.