SURFACE-CHEMISTRY OF BIOACTIVE GLASS-CERAMICS

General principles governing the bioactivity of glass-ceramics are discussed on the basis of surface chemical studies of glass-ceramic A-W containing crystalline apatite and wollastonite, and related materials. The apatite phase in the glass-ceramics did not play an important role in forming chemical bond of the glass-ceramic to the bone. An apatite layer formed on the surface of the glass-ceramic in vivo was responsible for the bonding of the glass-ceramic to the bone. It was shown that a chemical bond between apatite crystals in the body environment can give a fairly strong bond. The surface apatite layer was shown to be formed by a chemical reaction of calcium and silicate ions dissolved from the glass-ceramic with the surrounding body fluid. A P2O5-free CaO·SiO2 glass also formed the surface apatite and bonded to the bone. The same type of apatite layer as the surface apatite was formed even on the surfaces of various kinds of ceramics, metals and polymers, when they were placed near a glass dissolving the calcium and silicate ions in a simulated body fluid. These results show that bioactive materials having various functions can be obtained using glasses and glass-ceramics based on the simple components of CaO and SiO2. © 1990.