NaF rinse and dentifrice concentrations on enamel lesion demineralization

To compare the in vitro effectiveness of two mouthrinses containing different concentrations of NaF to reduce enamel lesion demineralization.

Nine extracted caries-free molars were selected and cleaned. The teeth were painted with acid resistant varnish, leaving a 1 mm × 4 mm window exposed. The teeth were cycled in a demineralizing solution at pH 4.5 for a total for 96 hours. The teeth were sectioned longitudinally through the unpainted window using a hard-tissue microtome, producing 96 sections. The sections were measured and photographed under polarized light microscopy using water and Thoulet's 1.47 as imbibing mediums. Six treatment groups were randomly created: (A) water control group, (B) 0.05% rinse group once a day (C) 0.02% rinse group twice a day, (D) 1,500 ppm paste group used twice a day, (E) combination group containing 0.05% rinse once a day, and 1,500 ppm paste twice a day, and (F) combination group containing 0.02% rinse and 1,500 ppm paste twice a day. A 10-day cycling protocol was carried out. All sections were then re-measured and re-photographed. A statistical analysis was performed to detect any differences between pre- and post-treatment groups.

There was a statistically significant difference in lesion depth between the water control group and the 1,500 ppm paste group as well as the 0.05% rinse in combination with 1,500 ppm paste group (P= 0.0184). No statistically significant differences were found between the control group and any other groups. A statistically significant difference was found in lesion area between the two rinse groups alone and the 1,500 ppm paste group, as well as the 0.05% rinse in combination with the 1,500 ppm paste group (P= 0.0002). An analysis of the results suggested that both rinse concentrations performed equally well in reducing lesion demineralization when used alone. However, only the 0.05% rinse used in combination with 1,500 ppm paste decreased lesion demineralization as compared to the water control group, and was equally as effective as the 1,500 ppm paste alone.

Within the limitations of this in vitro study, it was found that a fluoride containing dentifrice (1,500 ppm) and a combination of a fluoride containing dentifrice (1,500 ppm) and a 0.05% (210 ppm) fluoride rinse were more effective at reducing demineralization of enamel lesions than sodium fluoride rinses at concentrations of 0.02% and 0.05% alone or the combination of 0.02% NaF rinse with fluoride toothpaste.