EFFECTS OF IONS DISSOLVED FROM BIOACTIVE GLASS-CERAMIC ON SURFACE APATITE FORMATION

Non-bioactive glass-ceramic A-W(Al) containing apatite and wollastonite in a MgO-CaO-SiO2-Al2O3 glassy matrix did not form an apatite layer on its surface in a simulated body fluid with ion concentrations nearly equal to those of human blood plasma and also in the fluids with small amounts of the calcium and silicate ions added individually, but formed the apatite layer in the fluid with the calcium and silicate ions added simultaneously. This indicates that the calcium and silicate ions dissolved from bioactive glass-ceramic A-W containing the apatite and wollastonite in a MgO-CaO-SiO2 glassy matrix play a cooperative and important role in forming an apatite layer on its surface in the body, to give the glass-ceramic bioactivity. The calcium ion might increase the degree of the supersaturation of the surrounding body fluid, and the silicate ion might provide favourable sites for nucleation of the apatite on the surfaces of glass-ceramic.