Effect of particulate porous hydroxyapatite on osteoinduction of demineralized bone autografts in experimental reconstruction of the rat mandible.

In an experimental model in the rat, a nonhealing bone defect was created in the left ascending mandibular ramus to test the effect of particulate porous hydroxyapatite (HA) on osteoinduction of demineralized bone autografts. The bone fragment removed was demineralized in HCl and used as an autograft for mandibular reconstruction. Granules of HA were added to the lingual and vestibular surfaces of the graft. The effect of this material was evaluated by determining the number of mesenchymal cells induced in the biomaterial and the central and peripheral zones of the bone graft, at 2-and 6-week intervals. The results show that the sites containing HA showed inhibition of osteoinduction by the bone matrix. In all groups, a proliferative gradient from the peripheral zone toward the center of the bone was observed. Similarly, the HA experienced a greater cellular increase in the regions in contact with the demineralized bone matrix.