Onlay bone augmentation with an osteoinductive implant.

The repair of contour defects of craniofacial bone can be accomplished by several methods, including autogenous bone grafts, demineralized bone, and alloplastic materials. The objective of this study was to assess a biodegradable, xenogeneic, osteoinductive implant for craniofacial onlay bone augmentation. Twelve New Zealand White rabbits each had craniofacial onlays consisting of three experimental materials: 1) autograft; 2) allogeneic, demineralized block implant; and 3) partially purified osteoinductive protein (osteogenin) with allogeneic collagen and 50:50 poly (DL-lactide-co-glycolide). Implants with host bone were recovered after 20 weeks and assessed by histomorphometric methods. There was no evidence of adverse local reaction to the three treatments. No significant difference in bone replacement or bone density resulting from each of the implant types was demonstrated. In conclusion, the osteoinductive implants were well tolerated, and over the 20-week period they appeared to maintain their contour as onlays.