The functional equivalence of demineralized bone and tooth matrices in ectopic bone induction

The objective of this study was to determine whether demineralized rat incisor matrices were a more potent inducer of ectopic endochondral bone formation than demineralized diaphyseal bone matrices derived from the same donors. Twenty-five-milligram disks of demineralized bone or tooth matrix obtained from adolescent Long-Evans rats were implanted in a standardized ectopic site. Biochemical and histometric measurements of bone formation revealed that the two matrices were functionally equivalent inducers of endochondral bone formation. The induced pellicle of bone reached a maturation point 18 days after implantation. Dentin matrix implants generated a significantly greater amount of mineralized tissue than did bone matrix implants. This difference could be explained on the basis of remineralization of the dentin particles to a greater degree than the bone matrix particles. Initial observations suggesting a more robust osteoinductive activity in demineralized incisor matrix can be attributed to the decreasing activity of bone matrix from older donors when compared to younger donors. The extent of osteoinduction by the two substrata was equivalent when the matrices were matched for age.