An assessment of the osteoinductive potential of commercial demineralized freeze-dried bone in the murine thigh muscle implantation model

Early studies have demonstrated that implantation of laboratory preparation s of demineralized freeze dried bone (DFDB) into the thigh muscle of mice i nduces ectopic osteoinduction. However, with the development of commercial preparations of DFDB for clinical use, concerns have been raised as to the osteoinductive properties of such preparations. The aim of this study was t o investigate the osteoinductive potential of some commercial preparations of DFDB compared to a newly developed product which incorporates DFDB into a collagen sponge. Commercial preparations of DFDB or the DFDB/collagen spo nge were inserted into the thigh muscles of 60 adult Swiss CD-1 mice. At th e completion of each experimental period (7, 14, 30, 90 and 180 days), the animals were sacrificed, and the hindquarters of the mice were radiographed . The area where each graft had been placed was then excised, processed for light microscopy, and stained with hematoxylin and eosin or von Kossa's st ain. Histological analysis of the DFDB/collagen sponges demonstrated signif icant remineralization which increased with time. Remineralization of the D FDB/collagen sponges was verified by radiographs which showed a significant increase in radiopacity over time. There was no radiographic evidence of m ineralized tissue formation or remineralization in any of the commercial DF DB samples studied. At all time points studied, histological analyses faile d to show evidence of bone formation for any of the preparations. The resul ts suggest that commercially available DFDB is not osteoinductive in the mu rine model and question the use of such materials in clinical periodontics. The results found for the DFDB/collagen sponge indicate a, different mecha nism of activity from DFDB as evidenced by its rapid remineralization. The role this remineralization process has in osteoinduction is unknown and req uires further study.