Anticaries Potential of Experimental SnF₂ Dentifrice Formulations

Objectives: Anticaries efficacy of stannous fluoride, although well established, is highly dependent upon its availability in a dentifrice. Formulations of SnF₂ were recently developed to evaluate the impact of polymeric excipients on anticaries efficacy in an artificial-mouth caries model. The aim of the study was to determine anticaries potential of two experimental SnF₂ dentifrice formulations (1100ppmF^-) with varying ratios of Sn to Polymer when compared to NaF-based over-the-counter (OTC-1100ppmF^-) and prescription level (Rx-5000ppmF^-) dentifrices.

Methods: Methods: Human enamel specimens were inoculated with Streptococcus mutans and exposed for seven days to circulating TrypticSoyBroth+5%sucrose for 30min, 3x/day, and to a mineral wash solution for the rest of the day. Developing biofilms were exposed (2x/day) to one of four dentifrice slurries: NaF-OTC, NaF-Rx, EXP1SnF₂, EXP2SnF₂. Final biofilm amount was estimated. Specimens were sectioned and caries lesions analyzed by cross-sectional-microhardness to determine %mineral loss and area under the curve (AUC). Specimens were stained to determine lesion depth using confocal microscopy.

Results: Results: Both experimental SnF₂ dentifrices reduced the number of biofilm bacteria more than 2-fold compared to the NaF products. Specimens treated with the experimental SnF₂ dentifrices developed significantly smaller lesions than those in the NaF groups (NaF-OTC=42.6±4.3µm, NaF-Rx=28.0±3.1µm, EXP1SnF₂=17.6±1.6µm, EXP2SnF₂=17.2±2.8µm). Enamel specimens treated with SnF₂ had significantly less mineral loss than those in the other groups (AUC for SnF₂ groups 7071 and 6803, respectively vs. 6397 for NaF-Rx and 6284 for NaF-OTC). In all statistical comparisons, the experimental SnF₂ formulations were not significantly different (p>0.05) from each other, but significantly more effective than NaF at either concentration (p<0.05). The high-concentration NaF was significantly better in limiting lesion depth than the over-the-counter NaF (p<0.05), showing a dose response.

Conclusions: Conclusions: The two experimental SnF₂ dentifrice formulations showed higher anticaries potential than commercially available NaF dentifrices at similar and higher F^- concentrations.