A bioactive bio-enamel was prepared by coating two different glasses on a titanium metal in sequence, the first coat was for better bonding between a bio-enamel and the titanium and the second coat for promoting its bioactivity, which means hydroxyapatite formation. The ground glass coat and bioactive glass coat were fired at 900 degrees C for 5minutes and 850 degrees C for 30 seconds in an Ar atmosphere, respectively. The hydroxyapatite forming behavior on the bio-enamet was compared with that on the bulk bioactive glass with the same composition of the bio-enamel. The rate of hydroxyapatite formation on the bio-enamel was much faster than that on the corresponding bulk bioactive glass. The behavior of hydroxyapatite formation also improved when the bulk bioactive glass was heat-treated at 850 degrees C for 20 seconds. It is believed that the heat-treatment of the glasses makes the leaching of cations from the glass surface easier and enhances the rate of the hydroxyapatite formation.

Keywords: bioactive glass, titanium, bio-enamel. hydroxyapatite, silica-rich layer