Deposition of fluoride on tooth surfaces by a two-solution mouthrinse in vitro

A constant-composition fluoride (F) titration method was used to measure the amount of leachable F deposited on tooth surfaces in vitro by a 1-min rinse with a 228-ppm F solution (12 mmol/l sodium fluoride). The mean F uptake was 0.23 +/- (SE) 0.07 microgram/cm2, corresponding to less than 0.2% of the F contained in the rinse. The present study describes a new F rinse system that consisted of two solutions. Solution A contained a soluble calcium salt and a buffer. Solution B contained sodium fluorosilicate, a complex fluoride salt. When solutions A and B were combined, the free F ions produced by hydrolysis of fluorosilicate caused precipitation of calcium fluoride during the 1-min application time. The F uptake produced by the two-solution rinse was 4.36 +/- 0.16 micrograms/cm2, which was approximately 19 times greater than that produced by the sodium F rinse with the same F content. Since the cariostatic effects from F rinses are believed to derive from their ability to deposit labile F in the oral cavity, the two-solution rinse may be more efficacious than the rinses currently in use.