A histological comparison of the tissue interface of bioglass and silica glass

The objectives of the present article are to confirm the bone bonding phenomenon of Bioglass (BG) developed by Hench et al., and to observe the singularity of tissue reaction to it. BG and nonreactive silica glass (SG) were implanted in the femurs of rabbits and rats. Histological examination revealed that a relatively acellular zone with little inflammation was formed on BG surface at 1 day after implantation. Neither fibrous tissue nor a distinct boundary was observed between BG and bone after 7 days. On the contrary, a moderate postoperative inflammatory reaction was observed on SG at 1 day, and fibrous tissue was observed between SG and bone after 7 days. From these findings, it was confirmed that BG bonded directly with bone. As the relatively acellular zone observed on BG surface at 1 day was replaced by bone after 7 days, the formation of this zone might play an important role in bone-bonding process. Further research should be focused on the mechanism and biological meaning of bone bonding, for this phenomenon can not be explained by the conventional pathological theory of foreign body encapsulation.