Objectives: The aim of this in vitro study was to investigate the efficacy of various experimental tin- and fluoride-containing mouth rinses with stepwise reduced concentrations of the active agents on erosion progression in enamel.
Methods: Human enamel specimens were subjected to a cyclic demineralisation and remineralisation procedure for 10 days with 6 demineralisation periods per day, 5 min each. Erosive demineralisation was performed with 0.05 M citric acid (pH 2.3). Except in the control groups, the specimens were treated for 2 min with experimental mouth rinses after the first and sixth demineralisations. The tin concentrations ranged between 800 and 2800 ppm, and fluoride concentrations of 500 and 250 ppm were used. All preparations were adjusted to pH 4.5. As positive control, a commercially available, tin-containing mouth rinse was used (pH 4.2, 409 ppm Sn(2+), 250 ppm F(-)). Tissue loss was determined profilometrically.
Results and conclusion: As expected, the highest tissue loss was found in the negative control group. All experimental mouth rinses were able to reduce tissue loss significantly (p< or =0.001). The best reduction was achieved by the 2800 ppm Sn(2+), 500 ppm F(-) solution (80%). The lowest reduction was achieved by the 800 ppm Sn(2+), 250 ppm F(-) solution (54%). Amongst the 500 ppm F(-) solutions, in the Sn(2+) concentration range of 2800-800 ppm, only small differences in efficacy were observed, meaning that the tin concentration can probably be reduced without losing efficacy. This factor is particularly important if one regards the possible clinical applicability of such mouth rinses.