Mechanisms of action of fluoridated acidic liquid dentifrices against dental caries

• Why this paper is important?
• Reduction of fluoride intake by children is important to minimize dental fluorosis.
• There is uncertainty about the effectiveness of low-F dentifrices to prevent caries.
• Additional insights are given into the mechanism of action of low-F/pH dentifrices, low-F acidic dentifrices may have a better cariostatic effect than the neutral ones.

ObjectiveThis study attempted to clarify the mechanisms of action of fluoridated acidic liquid dentifrices against dental caries.DesignIn the in vitro leg, enamel specimens were submitted to a pH-cycling model, treated with distinct dentifrices (0, 550 μgF/g pH 4.5 and pH 7.0, 1100 or 5000 μgF/g pH 7.0) and analyzed using hardness. Alkali-soluble fluoride (F) deposition was quantified on pre-demineralized specimens treated with the dentifrices. In the clinical leg, 2-to-4-year-old children who had been using liquid dentifrices for 6 months (550 μgF/g pH 4.5 or pH 7.0 or 1100 μgF/g pH 7.0) had their plaque samples collected 5 and 60 min after the last brushing. Fluoride uptake in whole plaque was evaluated.ResultsThe reduction of the pH had a partial preventive effect on subsurface hardness loss only. [F] had a significant influence on the deposition of fluoride, surface and subsurface hardness loss. In vivo, the reduction of the pH was able to significantly increase plaque F uptake, leading to similar levels as those found for the neutral dentifrice containing twice [F].ConclusionThe results obtained from in vitro studies whose design does not include the presence of dental plaque should be interpreted with caution.