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Three groups of bioactive composite (designated AWC, HAC and TCPC) each consisting of bisphenol-α-glycidyl methacrylate (Bis-GMA)-based monomers and a bioactive filler of either AW glass-ceramic (AW-GC), hydroxyapatite (HA) or β -tricalcium phosphate (β -TCP) powder were made in order to evaluate the influence of a kind of bioactive filler and its content on mechanical properties and osteoconductivity of the composite. The proportion of each filler added to the composite was 50, 70, and 80% (w/w). Nine types of sample were subjected to the mechanical testing. The compressive and bending strengths of AWC were higher than HAC and TCPC in each filler content. The composites were evaluated in vivo by packing them into the intramedullary canals of rat tibiae. To compare osteoconductivity of the composites, an affinity index was calculated. AWC showed higher affinity index than HAC and TCPC in each filler content. Results suggest that that higher osteoconductivity of AWC were due to higher reactivity of AW-GC powder on the composite surface. AWC shows promise as a basis for developing highly bioactive and mechanically strong composite materials.

We evaluated bone-bonding strength of bioactive bone cements (AWC and HAC). AWC consisted of AW-GC powder and bisphenol-α-glycidyl metacrylate (Bis-GMA)-based resin and HAC consisted of hyodroxYapatite powder and the same resin of AWC. The proportion of powder added to each cement was 70% w/w. In order to compare the failure load, cement plates which had an uncured surface on one side and a cured surface on the other were made. HAC plates were also made in the same way as AWC plates. One of the plates was soon implanted into the proximal metaphysis of the tibiae of a male Japanese white rabbit so as not to damage the surface properties, and the load was measured by a detaching test 8 weeks after implantation. The failure load for AWC on its uncured surface (2.05 ± 1.11 kgf, n=8) was significantly (p<0.0001) higher than that for AWC on its cured surface (0.28 ± 0.64 kgf, n=8). The load for HAC on its uncured surface (1.40 ± 0.68 kgf, n=8) was significantly (p<0.0006) higher than that on its cured surface (0.00 ± 0.00 kgf, n=8). There was no significant difference between the load for AWC and that for HAC on their uncured surfaces (p=0.086) and on their cured surfaces (p=0.45) although the value for AWC was higher than that for HAC. The reason is that surface roughness for HAC is larger than that for AWC. Therefore, mechanical interlocking may be more effective for HAC compared with AWC. Histologically direct bone formation was observed both AWC and HAC on their uncured surfaces and Ca-P-rich layer was observed only on the uncured surface of AWC. We concluded that the uncured surface was useful for exposing bioactive powder on the surface of the cement and effective for inducing bone-bonding.

We reported previously that a bioactive PMMA-based cement was obtained by using a dry method of silanation of AW-GC particles, and using high molecular weight PMMA beads. In this report, commercial PMMA bone cements (CMW1, Surgical Simplex) containing AW-GC filler in the ratio of 70wt% were investigated (abbreviated as B-CMW1 and B-Surg Simp). Their handling properties were similar to the commercial CMW1 cement that does not contain bioactrve powder (C-CMW1) as dough and setting times were 3 and 8 minutes respectively for both types of bioactive cements compared to 2 and 6 minutes respectively for C-CMW1. Bending strength of plates made from both bioactive cements and C-CMW1 cement was 90 ± 7 MPa for B-CMW1 and 98 ± 7 MPa for B-Surg Simp compared to 92±6 MPa for C-CMW1 after one day of immersion in simulated body fluid (SBF). These cements were also implanted in the medullary canals of rat tibiae. After 4 and 8 weeks of implantation, the bone-cement interface was examined using scanning electron microscope and Giemsa surface staining and the affinity index was calculated. After 8 weeks it was 55.5±10.8 for B-CMW1 and 49.4 ± 4.6 for B-Surg Simp compared to 2.0±1.4 for C-CMW1 indicating higher bioacivity than that previously reported.