Transformation of calcium fluoride for caries prevention.

Oral application of fluoride for caries prevention may tend to form calcium fluoride (CaF 2) instead of the desired fluorapatite. In view of this, the transformability of CaF2 to fluorapatite has been studied. This investigation shows that CaF2 can be converted to fluorapatite in phosphate solutions ar various temperatures ranging between 25 and 75 degrees C in the pH range of 6.5 to 8.5. In the initial stage, phosphate ions, believed to be HPO4= adsorb on the particle surface. A dissolution/precipitation mechanism is proposed for the growth of fluorapatite.