Solubility and crystallinity in relation to fluoride content of fluoridated hydroxyapatites

Fluoridated hydroxyapatites were synthesized at 80 degrees C (pH 7.4) to study their crystallinity and solubility in relation to fluoride content. The crystallinity of fluoridated hydroxyapatities increased initially, then decreased, and finally increased again with the degree of fluoridation, whereas the decrease in relative solubility of fluoridated hydroxyapatites at 25 degrees C (pH 4.0) was proportional to the logarithm of the fluoride content.