[The cariostatic mechanisms of action of fluorides. A review]

In the past the inhibition of caries by fluorides was ascribed to the reduced solubility of enamel due to the incorporation of F- into the enamel mineral. During the last years the understanding of the cariostatic mechanism has changed fundamentally. Based on these new findings the loosely bound fluorides, which are present in the surroundings of the teeth after application of topicals, are regarded as decisive for the caries preventing effect by causing an inhibition of demineralization, enhancing the remineralization process and supporting the precipitation of CaF2. The formation of CaF2 is induced after application of topicals, and the material stays relatively stable in the mouth, due to adsorbed HPO4(2-) ions at the surface of CaF2. During the cariogenic challenge, CaF2 releases F- ions due to the reduced concentration of HPO4(2-) ions at acidic pH values. The CaF2 therefore functions as a pH-controlled F(-)-reservoir and is the most important supplier of free F- ions during the cariogenic challenge.