Protein adsorption to hydroxyapatite and to calcium fluoride in vitro and amino acid analyses of pellicle formed on normal enamel and on calcium-fluoride-covered enamel in vivo

Abstract

Fluoride treatment of enamel has been reported to result in the formation of a layer of a CaF₂-like material on the enamel surface. Protein adsorption to enamel is a specific process dependent on the nature of the surface, and little is known about protein adsorption to CaF₂. Albumin and lysozyme were adsorbed to hydroxyapatite (HA) and CaF₂ powder in vitro, and protein adsorption patterns constructed. In vivo pellicle was collected from three volunteers from fluoride-treated enamel and from normal enamel, and the amino acid compositions analyzed separately. The results showed that CaF₂ took up small amounts of proteins as compared with HA. When the CaF₂ was pretreated with a phosphate buffer, pH 6.8, the protein adsorption increased markedly. The amino acid analyses showed no major differences in the amino acid compositions between pellicle collected from CaF₂-covered enamel and pellicle collected from normal enamel. This lack of difference is presumably due to the adsorption of phosphate ions to the CaF₂ crystals and hence changed surface properties.

Key Words:

• Electron spectroscopy (XPS analysis)
• in vitro and in vivo adsorption
• protein analysis