Interplay Between Minerals in Bottled Water and Fluoride Toothpaste and Caries Lesion Remineralization

he aim of this in vitro study was to evaluate the effects of some bottled waters on fluoride toothpaste efficacy in enhancing caries lesion remineralization.

Early caries lesions were created in bovine enamel specimens and stratified into treatment groups based on Vickers surface microhardness (VHN). The present study followed a two (fluoride and fluoride-free toothpaste) by five (four bottled waters and tap water) factorial design. The treatment groups were bottled water with the following attributes: (a) 309.9 ppm Ca/1.20 ppm F; (b) 118.4 ppm Ca/0.16 ppm F; (c) 1.00 ppm Ca/1.01 ppm F; and (d) 0.1 ppm Ca/0.04 ppm F and tap water (48.7 ppm Ca/0.7 ppm F). The five water groups were paired either with 1100 ppm fluoride or fluoride-free toothpaste, yielding 10 groups. Specimens were pH-cycled for 10 days with the daily regimen comprised of twice daily toothpaste slurry, with four exposures to water in between. VHN was measured again and the difference was calculated (ΔVHN). Data were analyzed using two-way ANOVA at a 5% significance level.

The two-way interaction between water and toothpaste was significant (p<0.001). All groups except fluoride-free toothpaste/bottled water with 0.1 ppm Ca/0.04 ppm F (p=0.411) had significant increases in VHN after pH cycling (p≤0.023). Fluoridated toothpaste resulted in a higher rate of remineralization compared to fluoride-free toothpaste (all p<0.001). Bottled water with 1.20 ppm F/309.9 ppm Ca exhibited the greatest extent of remineralization within fluoride toothpaste groups (p<0.001) and higher remineralization than lower fluoride water in fluoride-free toothpaste groups (p≤0.006). Within the fluoridated toothpaste group, tap water exhibited significantly less remineralization than all bottled waters (all p<0.001).

Within the limitation of this study, bottled water with higher fluoride and calcium concentrations might improve fluoridated toothpaste efficacy by enhancing remineralization of early enamel caries-like lesions.