F-19 AND P-31 NMR-SPECTROSCOPY OF CALCIUM APATITES

Glass ceramics that include apatite crystals are used as implant materials. Because most of these glass ceramics are comprised of fluoride-containing glass compositions, the included apatites could be hydroxyapatite, fluorapatite or fluoride-substituted hydroxyapatite. However, these apatites differ in regard to their solubility and thermal stability. The purpose of the current study was to determine the possibilities of distinguishing between these apatities. High resolution solid-state F-19 and P-31 magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of two fluorapatites, a hydroxyapatite and a fluoridated hydroxyapatite have been obtained. Using P-31 NMR investigations it is possible to distinguish between calcium apatites and other calcium phosphates, but the distinction between fluoride-containing apatite and hydroxyapatite is not possible. However, F-19 high-resolution solid-state NMR investigations permit the distinction between these various apatites. The results of the NMR investigations could be used for the characterization of glass ceramics. The application of those results was demonstrated using a newly developed apatite-containing glass ceramic.