Remineralization effects of a two-solution fluoride mouthrinse: an in situ study

Results from previous studies show that a two-solution fluoride (F) rinse is significantly more effective than a NaF rinse of the same F content of 250 microg/g (ppm) in remineralizing enamel and root lesions in an in vitro cyclic de- and remineralization model. In the present study, the two-solution rinse and two NaF rinses with F contents of 250 ppm and 1000 ppm were evaluated in an intra-oral remineralization model. Caries-like lesions were formed in the enamel of extracted human molars with the use of a pH 4 demineralizing solution. Thin sections of the enamel (approximately 120 microm) containing lesions were prepared, and the mineral contents of the lesions were assessed by quantitative microradiography. With the cut surfaces protected by nail varnish, 3 enamel specimens were mounted with wax in the lingual areas of a removable mandibular appliance. The study used a randomized, crossover design with seven subjects. In each of the 3 legs of the study, subjects wore the appliances continuously except when eating, drinking, and brushing their teeth. Twice daily (after breakfast and before bedtime), the subjects received a one-minute rinse with 20 mL of (1) 250-ppm-F NaF rinse, (2) 1000-ppm-F NaF rinse, or (3) 228-ppm-F two-solution F rinse. At the end of the 14-day experimental period, the sections were retrieved, and the mineral contents of the lesions were again assessed quantitatively. The results show that both the 1000-ppm-F NaF and 228-ppm-F two-solution rinses produced a greater (p < 0.05) remineralization than did the 250-ppm-F NaF rinse. The remineralization produced by the two-solution rinse was not statistically different (p > 0.05) from that produced by the NaF rinse with 4x the F content (1000 ppm F).