BIOACTIVE BONE-CEMENT - COMPARISON OF APATITE AND WOLLASTONITE CONTAINING GLASS-CERAMIC, HYDROXYAPATITE, AND BETA-TRICALCIUM PHOSPHATE FILLERS ON BONE-BONDING STRENGTH

A study was conducted to compare the bone-bonding strengths of three t ypes of bioactive bone cement, consisting of either apatite- and wolla stonite-containing glass-ceramic (AW-GC) powder, hydroxyapatite (HA) p owder, or p-tricalcium phosphate (P-TCP) powder as an inorganic filler and bisphenol-a-glycidyl methacrylate (Bis-GMA) based resin as an org anic matrix. Seventy percent (w/w) filler was added to the cement. Rec tangular plates (10 x 15 x 2 mm) of each cement were made and abraded with #2000 alumina powder. After soaking in simulated body fluid for 2 days, the AW cement (AWC) and IIA cement (HAC) formed bonelike apatit e over their entire surfaces, but the TCP cement (TCPC) did not. Plate s of each type of cement were implanted into the tibial metaphyses of male Japanese white rabbits, and the failure loads were measured by a detaching test at 10 and 25 weeks after implantation. The failure load s of AWC, HAC, and TCPC were 3.95, 2.04, and 2.03 kgf at 10 weeks and 4.36, 3.45, and 3.10 kgf at 25 weeks, respectively. The failure loads of the AWC were significantly higher than those of the HAC and TCPC at 10 and 25 weeks. Histological examination by contact microradiogram a nd Giemsa surface staining of the bone-cement interface revealed that all the bioactive bone cements were in direct contact with bone. Howev er, scanning electron microscopy and energy-dispersive X-ray microanal ysis showed that only AWC had contacted to the bone via a Ca-P rich la yer formed at the interface between the AW-GC powder and the bone, whi ch might explain its high bone-bonding strength. Neither the HAC nor t he TCPC contacted the bone through such a layer between each powder an d the bone, although the HAC and TCPC directly contacted with bone. Ou r results indicate that all three types of abraded and prefabricated c ement have bonding strength to bone, but AWC has superior bone-bonding strength compared to HAC and TCPC. (C) 1998 John Wiley & Sons, Inc.