Interactions between bone and hydroxyapatite filled 4 META/MMA-TBB adhesive cement in vitro and in physiological environment

These studies examined the effects of hydroxyapatite (HA) filled PMMA-4 META cement in bone. The cement's liquid portion was of 4-methacryloyloxyethyl trimellitate anhydride (4-META), methyl methacrylate (MMA) monomer, and initiator tri-n-butyl borane (TBB). Powder was of 50 wt.% polymethyl methacrylate (PMMA) and 50 wt.% porous HA particles. In vitro study showed the tensile bond strength was reversibly proportional to HA filler content and size. All specimens were evaluated using light microscopy and scanning electron microscopy (SEM). In vivo study of 4 dogs for 4 and 12 weeks showed HA filled PMMA-4 META cement stabilizes the cement-bone interface. All microscopic examinations showed not only exposed HA particles at the surface of the apatite filled resin cement but demonstrated areas of direct bone apposition with no fibrous tissue, also in the resin portion. This reinforces the importance in inducing bone apposition and thus contributing to the overall implant-cement stability.