Prevention of rat fissure caries by sodium fluoride varnish (Duraphat) with different fluoride concentrations

125 Osborne-Mendel rats were weaned at 22-23 days, inoculated with Streptococcus sobrinus and fed a cariogenic diet for 40 days. The control group received no treatment; the study groups received applications of Duraphat containing 2.3, 1.1, or 0.6% fluoride or a placebo varnish on days 21-23. The placebo varnish had no effect on caries. Fissure caries was significantly reduced by the 2.3 and 1.1% fluoride varnishes, whereas the caries reduction found after treatment with the 0.6% fluoride varnish was not statistically significant. These results suggest that reducing the fluoride content of Duraphat by half does not significantly reduce its caries-preventive effect, but the progress of caries seems to be somewhat slower with the 2.3% fluoride varnish.