Fluor-hydroxyapatite solid solutions as alternative bioceramics

The various forms of apatite found in the human body include carbonated apatite, calcium deficient hydroxyapatite and fluorapatite. Fluorapatite is the most stable and is found in the enamel of teeth. The object of this work was to synthesize hydroxyapatite with various degrees of fluoride substitution and to assess the characteristics of the synthesized powder. Apatite was synthesized using a semi-bath method where ammonium phosphate was added dropwise into calcium nitrate adjusted to a pH of 9.2 and 25 degreesC. The solution was aged for one day, washed with distilled water and ethanol and dried. The precipitate exhibited blocky precipitate particles with a long axis dimension of 40-60 mum. The surface area of the dried precipitate was highest for the substituted apatites, decreasing to go m(2)/g for fluorapatite. The low density of the apatites was attributed to included ammonium and water. These additions also increased the solubility characteristics of the substituted apatites.