Recycled dentin root matrix for a carrier of recombinant human bone morphogenetic protein

Dysfunctional teeth, donated by community dental clinics, were recycled for research on bone morphogenetic protein (BMP) in health and disease. The crown remnants were trimmed away, and the roots were washed in 70% alcohol, demineralized, lyophilized, and prepared in one of two forms: (1) human partially demineralized root dentin matrix (PDM) or (2) autolysed, antigen-extracted root matrix (AAAD), including attached cementum. Composites of either PDM or antigen-extracted, autolysed, delipidized allogenic dentin matrix (AAAM) and recombinant human bone morphogenetic protein (rhBMP-2) were implanted in either normal or athymic mice. The percentage of muscle replaced by heterotopic bone was estimated by computer-assisted random point analysis. Implants of PDM and AAAD made from dysfunctional teeth exhibited little or no endogenous BMP activity and failed to induce new bone formation. Composites of 1 microgram of rhBMP-2 per 70 mg of PDM carrier induced 61% replacement of muscle by bone formation; 1 microgram of rhBMP-2 in 70 mg of AAAM matrix induced 78% replacement of muscle mass by bone; 2 or 5 micrograms of rhBMP-2 and 70 mg of AAAM carrier induced 100% replacement of thigh muscle mass by bone. In athymic mice, the areas of new bone were only slightly greater than those in normal mice. These observations suggest that root dentin prepared from extracted teeth may be recycled for use as a carrier of rhBMP-2 because it induces new bone formation in the periodontium.