Remineralization effects of a two-solution fluoride mouthrinse: An in situstudy

Results from previous studies show that a two-solution fluoride (F) rinse i s significantly more effective than a NaF rinse of the same F content of 25 0 mu g/g (ppm) in remineralizing enamel and root lesions in an in vitro cyc lic 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 evalu ated in an intra-oral remineralization model. Caries-like lesions were form ed in the enamel of extracted human molars with the use of a pH 4 demineral izing solution. Thin sections of the enamel (approximate to 120 mu m) conta ining lesions were prepared, and the mineral contents of the lesions were a ssessed by quantitative microradiography. With the cut surfaces protected b y nail varnish, 3 enamel specimens were mounted with wax in the lingual are as of a removable mandibular appliance. The study used a randomized, crosso ver design with seven subjects. In each of the 3 legs of the study, subject s wore the appliances continuously except when eating, drinking, and brushi ng their teeth. Twice daily (after breakfast and before bedtime), the subje cts 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 minera l contents of the lesions were again assessed quantitatively. The results s how 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. Th e 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 con tent (1000 ppm F).