Osteogenic efficiency of demineralized and lyophylized xenogeneic bone and syngeneic dentine implants in mice

Intramuscular implantation of demineralized and lyophilized rat bone matrix and murine lower incisors into thigh muscles of BALB/c mice results in deposits of bone adjacent to the implants, a phenomenon termed as ectopic osteogenesis. The yield of induced bone does not critically depend on the mass of implanted matrices, and thus on the quantity of bone morphogenetic proteins (BMPs) present in the implants. A positive correlation between bone matrix implant weight and the yield of induced bone was observed only 28 days post grafting, i.e. when endochondreal osteogenesis is completed and bone resorption has not advanced. A more consistent yield of bone induction wasobserved in the case of demineralized tooth implants. It is postulated that chondro/osteoinduction by demineralized, lyophilized matrix implants is not determined by the range of BMPs presumably released in proportion to implant size, but is rather limited by the population of responsive host mesenchymal cells.