Effect of soluble calcium on fluoride uptake by enamel from sodium monofluorophosphate.

The fluoride uptake by sound, acid-etched and artificial white spot lesions treated with sodium monofluorophosphate in dentifrice slurries, abrasive slurries, or calcium chloride solutions was determined. Fluoride uptake by sound enamel decreased in the presence of soluble calcium; however, uptake by etched and white spot enamel was greatly enhanced. The optimum Ca:MFP molar ratio was 0.5. Because fluorine-containing dentifrices probably inhibit dental caries by interaction with white spots or at the initial stage of acid-attack, the soluble calcium contained in saliva or a dentifrice might enhance the anti-caries effect of monofluorophosphate.