Effect of stannous and fluoride concentration in a mouth rinse on erosive tissue loss in enamel in vitro.

The aim of this in vitro study was to investigate the influence of stannous and fluoride ion concentrations in various experimental solutions on erosion progression in enamel. Human enamel specimens were subjected to a cyclic de- and remineralisation procedure for 10 days, with six demineralisation periods per day, of 5 min each. Erosive demineralisation was performed with 0.05 M citric acid (pH 2.3). Except in the control group, specimens were treated for 2 min with test solutions after the first and the sixth demineralisation. Test solutions were: 1500 mg/L F(-) groups: group 1: 2800 mg/L Sn(2+); group 2: 2100 mg/L Sn(2+); group 3: 1400 mg/L Sn(2+); group 4: 700 mg/L Sn(2+); 1000 mg/L F(-) groups: group 5: 2100 mg/L Sn(2+); group 6: 1400 mg/L Sn(2+). All preparations were adjusted to pH 4.5. Tissue loss was determined profilometrically after the last experimental day. As expected, the greatest tissue loss (microm, mean+/-S.D.) was found in the control group (72.6+/-11.5). All test solutions were able to reduce tissue loss significantly (p <or= 0.001). The reduction of tissue loss by test solutions depended on the ratio of the tin concentration to the fluoride concentration. Lowest values were obtained by the application of the solutions of group 1 (7.8+/-2.5) and group 5 (7.6+/-5.2). Solutions with high concentrations of tin and fluoride are very effective in reducing erosive tissue loss, and their efficacy increased with increasing ratios of tin to fluoride concentrations.