Formation and resorption of bone induced by demineralized bone matrix implants in rats

Demineralized bone matrix was implanted in the abdominal wall of growing rats. 45Ca and 3H-proline were injected 21 days after implantation, and groups of animals were killed at 30 minutes to 16 days. Implants, tibial metaphyses and diaphyses, and incisor teeth were assayed for ash weights and isotope content. The net increase in mineral content was largest in the early phase of bone formation. Three weeks after implantation, the mineral accretion was approximately 10% of tibial metaphyses, or 0.06 mg ash per milligram implanted bone matrix. In both these tissues, the net increase in ash weight was only one-fourth of the accretion because of the high rate of resorption.