Solubility behaviour of synthetic hydroxyapatites in aqueous solution: influence of amorphous constituents on pH value.

Some hydroxyapatites show a considerable increase of pH in aqueous solution. Rinsing experiments were performed on two commercial samples, and the pH value was plotted as a function of time. The plots lead to the conclusion that a soluble amorphous phase is responsible for the increase in pH. This investigation was supported by X-ray diffraction, microscopy and chemical analyses.