Transmission electron microscopic study of interface between bioactive bone cement and bone: Comparison of apatite and wollastonite containing glass-ceramic filler with hydroxyapatite and beta-tricalcium phosphate fillers

We developed a bioactive bone cement that consists of apatite and wollaston ite containing glass-ceramic (AW-GC) powder and bisphenol-a-glycidyl methac rylate (Bis-GMA) based resin. In this study, we made three types of cement (designated AWC, HAC, and TCPC) consisting of either AW-GC, hydroxyapatite (HA), or beta-tricalcium phosphate (beta-TCP) powder as the inorganic fille r and Bis-GMA based resin as the organic matrix. These cements were implant ed into rat tibiae and cured in situ. Specimens were prepared 1, 2, 4, and 8 weeks after the operation and observed using transmission electron micros copy. Each of the bone cements was in direct contact with the bone. In AWC- implanted tibiae, the uncured surface layer of Bis-GMA based resin was comp letely filled with newly formed bone-like tissue 2 weeks after implantation . The AW-GC particles were surrounded by bone and were in contact with bone through an apatite layer. No intervening soft tissue was seen. In MAC-impl anted tibiae, it took 4 weeks for the uncured layer to completely fill with newly formed bonelike tissue. The HA particles were also in contact with b one through an apatite layer. In TCPC-implanted tibiae, it took 8 weeks for the uncured layer to fill with newly formed bonelike tissue. The new bone that formed on the TCPC was not as dense as that on the AWC or HAC, and an intervening apatite layer was not evident. Results indicated that AWC had h igher bioactivity than either MAC or TCPC. (C) 1999 John Wiley & Sons, Inc.