Bone regeneration under the influence of a bone morphogenetic protein (BMP) beta tricalcium phosphate (TCP) composite in skull trephine defects in dogs.

Beta tricalcium phosphate (TCP) was employed as a nonimmunogenic biodegradable delivery system for bovine bone morphogenetic protein (BMP). A BMP/TCP composite was implanted in adult dogs with skull trephine defects of a critical size of 1.4 cm that would otherwise remain unhealed in the lifetime of the individual. BMP/TCP implants induced 91%-100% incorporation by deposits of new bone. In comparison, control implants of TCP impregnated with bovine serum albumin (BSA/TCP) induced 0%-8% incorporation, or only marginal host bed reactive bone formation. The retention of unabsorbed TCP in the host bone four months after implantation suggests that further research should be encouraged to obtain a formulation of sintered calcium phosphate that could be resorbed more rapidly and in the process more completely replaced by bone.