In vivo comparison of synthetic osseous graft materials - A preliminary study

The purpose of this study was to compare the in vivo osseous healing respon se of 4 commercially-available synthetic bone grafting materials;hydroxylap atite (HA), calcium sulfate (CaSO4) plus autogenous bone, or a bioactive gl ass ceramic: with particle size of 300-360 mu m (BG1) or 90 to 710 mu m (BG 2). 4 osteotomy sites were prepared in each tibia of 10 adult male rabbits. One unfilled osteotomy site served as negative control (NC) and another si te filled with autogenous bone was the positive control (PC). All animals r eceived BG1 in 2 sites and BG2 in 2 sites. 5 animals received HA and five C aSO4 plus autogenous bone in the remaining 2 sites. Animals were sacrificed at 28 days post-surgery, histologic sections obtained and the % surface ar ea of new bone formation for each material was determined by computerized i mage analysis. All graft sites showed evidence of bone formation, i.e., (NC ) 41.95%; (PC) 50.41%; (BG1) 41.82%; (BG2) 40.36%; (HA) 41.83% and (CaSO4) 58.83%. Statistical analysis using an ANOVA with repeated measures on the m aterials common to all animals (excluding HA and CaSO4 groups) showed signi ficant differences between materials in surface area of bone, with positive controls better than negative controls, and BG1 and BG2 not significantly different from the negative control. These results indicate that synthetic graft materials can support new bone formation in surgically prepared defec ts. The utility of a rabbit model for studying physiologic osseous turnover and healing is questioned for studies of slowly resorbing synthetic graft materials.