This review suggests that the use of fluoride supplements is associated with a reduction in caries increment when compared with no fluoride supplement in permanent teeth. The effect of fluoride supplements was unclear on deciduous teeth. When compared with the administration of topical fluorides, no differential effect was observed. We rated 10 trials as being at unclear risk of bias and one at high risk of bias, and therefore the trials provide weak evidence about the efficacy of fluoride supplements.
Effect of xylitol and xylitol-fluoride lozenges on approximal caries development in high-caries-risk children.
To evaluate the effect of xylitol- and xylitol/fluoride-containing lozenges on approximal caries development in young adolescents with high caries risk.
                A 2-year double-blind trial with two parallel arms and a nonrandomized reference group.
                One hundred and sixty healthy 10- to 12-year-old children with high caries risk were selected. After informed consent, they were randomly assigned into a xylitol and a xylitol/fluoride group. They were instructed to take two tablets three times a day (total xylitol and fluoride dose 2.5 g and 1.5 mg, respectively). The compliance was checked continuously and scored as good, fair, or poor. A reference no-tablet group was also selected (n = 70) for group comparison. The outcome measure was approximal caries incidence.
                The dropout rate was 28%, and 41% exhibited a good compliance with the study protocol. No statistically significant differences in caries incidence could be found between the study groups (P > 0.05). Among a subgroup of children who demonstrated good compliance, the mean DeltaDMFSa value was significantly lower in the xylitol/fluoride group compared to the xylitol group, 1.0 +/- 2.3 vs. 3.3 +/- 4.6 (P < 0.05), while no difference could be displayed between any of the study groups and the reference group (P > 0.05).
                The results from this 2-year trial did not support a self-administered regimen of xylitol- or xylitol/fluoride-containing lozenges for the prevention of approximal caries in young adolescents with high caries risk.