EFFECT OF FLUORIDE NUCLEATION ON GLASS-CERAMIC FORMATION

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The Biocompatibility of Calcium Phosphate Ceramics, in various forms, have been well documented in the literature. Its hydroxyapatite-like composition makes it especially attractive as a potential bone and/or tooth replacement material. These ceramics, like all conventional ceramics, exhibit low tensile strength which limits their use. Glass-ceramic techniques have been used to produce fine grained calcium phosphate ceramics of high strength, a hardness value similar to enamel and better chemical resistance to citric acid than tooth enamel. The glass-ceramic process has special characteristics which allow new processes to be applied. Since the material originates as a glass, it has the potential to be cast and perhaps easily bonded to metal based on the fact that glass in its molten state will "wet" other materials. Calcium phosphate glasses containing small amounts of a third component can form a glass-ceramic. Alumina-oxide has been reported as a nucleating agent in the production of calcium phosphate glass-ceramics. Fluoride is a commonly used nucleating agent in many glass-ceramic systems. The proposed research project is designed to obtain specific thermal, chemical and mechanical property data on a compositional range of alumina-oxide and calcium fluoride nucleated calcium phosphate glass-ceramics. This proposal will attempt to address two central questions. First, does the use of fluoride as opposed to alumina-oxide nucleating agents improve or diminish certain physical, chemical and mechanical properties of the resulting glass-ceramic? Secondly, do the viscous and thermal expansion properties of an easily achievable glass-metal seal? The application of this technique to both implant and crown and bridge fabrication offers the potential to improve current technology in these areas.