BIOACTIVITY OF CAO.SIO2-BASED GLASSES - INVITRO EVALUATION

In order to fundamentally study compositional dependence of bioactivity of glasses, both the surface structural changes of P2O5-free CaO . SiO2 glass due to exposure to a simulated body fluid and the effects of adding a third component, such as Na2O, MgO, B2O3, Fe2O3, P2O5 and CaF2, were investigated. An acellular aqueous solution which had almost equal ion concentrations to those of the human blood plasma was used as the simulated body fluid. The surface structure changes were examined by electronprobe X-ray microanalysis, thin-film X-ray diffraction (XRD) and Fourier transform infrared (FTIR) reflection spectroscopy. It was found that even P2O5-free CaO . SiO2 glass forms an apatite layer on its surface in the simulated body fluid, and that the rate of formation of the surface apatite layer is increased with the addition of Na2O and P2O5 while it decreased with the addition of MgO, B2O3, CaF2 and Fe2O3. This indicates that even P2O5-free CaO . SiO2 glass can bond to living bone, forming the surface apatite layer in the body and that its bioactivity is increased with the addition of Na2O and P2O5 while it is decreased with MgO, B2O3, CaF2 and Fe2O3. It is speculated that a glass of the composition CaO . SiO2 100, Fe2O3 3 in weight ratio does not bond to living bone.