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

Background: Bone morphogenetic proteins (BMPs) have shown considerable prom ise as a therapeutic: agent to enhance periodontal regeneration although th e 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 degradin g gelatin carriers on BMP-2-induced periodontal healing. Method: Recombinant human bone morphogenetic protein-7 (rhBMP-2) was incorp orated 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 pl ugs. Effects of BMP were evaluated in surgically created rat periodontal fe nestration defects which were processed for histology 10 days post-operativ ely. The rats were divided into 4 groups and the control defects were treat ed 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 d egrading gelatin (BMPs or BMPf respectively). Results: BMPf greatly increased bone formation compared with the control (C ONf) (1.67 +/-0.65 versus 0.34 +/-0.11x10(-4) m(2)), but no significant dif ferences were observed with BMPs and CONs. In contrast, new cementum format ion was significantly greater in the BMPs group compared with all other gro ups (p<0.05). Conclusion: Release kinetics of BMP may have important effects on the outco me of BMP-induced periodontal regeneration. New bone formation may be affec ted by rapid-release kinetics although further investigation is necessary t o confirm tl;is. In contrast. new cementum formation is promoted by slow re lease of BMP.