Providing Titanium with Bioactivity by the Use of Low-melting Glass

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Titanium is only biocompatible and has no ability to bond to bone though it is widely used in clinical field as one of the important bone-implant. It is thus needed to provide it with bioactivity. In the present project enameling bioactive glass has been successfully attempted.1. Exploiting bioactive glasses(1) CaO-B_2O_3-SiO_2Apatite formation on the glasses in this system were examined by soaking them in a simulated body fluid (SBF), known as Kokubo solution. Almost all the glasses exhibited bioactivity or deposited apatite though too much content of boron oxide depressed the bioactivity.(2) Na_2O-B_2O_3-SiO_2Bioactivity was also examined for the sodium borosilicate glasses and was correlated to the local environment of Si. ^<29>Si MAS NMR spectra showed that the glasses around a composition 30Na_2O・20B_2O_3・50SiO_2 was very bioactive because about 80% Si atoms had two bridging oxygen atoms.2. Bioactivity of glass-coated Ti(1) CaO-B_2O_3-SiO_2A glass of composition 45CaO・30SiO_2・25B_2O_3 was selected for enameling Ti since it was one of the most bioactive glasses and had a thermal expansion coefficient most similar to that of Ti. The glass-coated Ti deposited apative within about 12 hours when soaked in SBF.(2) Na_2O-B_2O_3-SiO_2Ti specimen coated with a sodium borosilicate glass of composition 35.9SiO_2・21.1Na_2O・38B_2O_3・5CaO exhibited bioactivity in 7 days.