An X-ray diffraction and solubility study of equilibration of human enamel-powder suspensions in fluoride-containing buffer.
Various amounts of enamel-apatite powder were suspended in an acetate buffer (pH 4.5) containing sufficient fluoride to give molar ratios of fluoride/apatite from zero to unity. The suspensions were equilibrated at 20 degrees C for periods between 4h and 1 year, with continuous gentle stirring. Solubility studies showed dissolution of hydroxyapatite, formation and re-dissolution of calcium fluoride and formation of fluorapatite. The amount of mineral dissolved was low during the fluorapatite formation and increased by a factor of approx. 10 as equilibrium was approached. The fluoride content of the solid apatite, which ranged from 0.1 to 70 mol% fluorapatite, only influenced the solubility slightly, whereas the fluoride content of the bathing solution had a large effect. X-ray diffraction showed a linear correlation between the fluoride content and the a-axis of the apatite.
D001031:Apatites / Q000378:metabolism; D002124:Calcium Fluoride / Q000378:metabolism; D003743:Dental Enamel / Q000378:metabolism*; D003747:Dental Enamel Solubility; D005459:Fluorides / Q000378:metabolism*; D006801:Humans; D006882:Hydroxyapatites / Q000378:metabolism; D066298:In Vitro Techniques; D013997:Time Factors; D014961:X-Ray Diffraction
D001031:Apatites; D006882:Hydroxyapatites; C028869:fluor-hydroxylapatite; D002124:Calcium Fluoride; D005459:Fluorides