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 crea ted in the left ascending mandibular ramus to test the effect of parti culate porous hydroxyapatite (HA) on osteoinduction of demineralized b one autografts. The bone fragment removed was demineralized in HCl and used as an autograft for mandibular reconstruction. Granules of HA we re added to the lingual and vestibular surfaces of the graft. The effe ct of this material was evaluated by determining the number of mesench ymal cells induced in the biomaterial and the central and peripheral z ones of the bone graft, at 2- and 6-week intervals. The results show t hat the sites containing HA showed inhibition of osteoinduction by the bone matrix. In all groups, a proliferative gradient from the periphe ral zone toward the center of the bone was observed. Similarly, the HA experienced a greater cellular increase in the regions in contact wit h the demineralized bone matrix.