Is the Erosion-Protective Effect Still Maintained when Tin Concentrations Are Reduced in Mouth Rinse Solutions?

OBJECTIVE: As a preventive measure, tin (Sn2+)-containing products have a great potential to prevent enamel surface loss during erosive challenges, but adverse effects of high Sn2+ concentrations, such as astringent feeling of the teeth, are reported. Therefore, the main aim of this in vitro study was to develop a solution with lower Sn2+ concentrations that can still prevent dental erosion. METHODS: A total of 162 enamel specimens were prepared from human premolars, which were selected from a pool of extracted teeth. The specimens were randomly distributed to 9 groups (each group n = 18 enamel specimens) according to the different test treatments: a humid chamber (no treatment) as the negative control, the commercial Elmex(R) Erosion Protection mouth rinse as the positive control, and 7 solutions either with lower Sn2+ concentrations and/or containing flavoring. The experiment included 4 cycles, consisting of pellicle formation by incubating the specimens with 200 muL of human saliva at 37 degrees C for 1 h, then placing the specimens in the treatment for 2 min (60 mL, 30 degrees C, shaking at 70 rpm), and later submitting them to an erosive challenge for 1 min in citric acid (60 mL 1%, pH 3.6, 30 degrees C). Surface hardness was measured with a Vickers diamond and surface reflection intensity was measured with a reflectometer. RESULTS: The control group performed significantly worse than all other solutions containing Sn2+. In general, there were no significant differences among the Sn2+-containing groups, and they presented similar protective effects on the enamel even when Sn2+ concentrations were reduced and flavorings were added. CONCLUSION: Sn2+ concentrations in mouth rinses may be lowered to 200 ppm without compromising the anti-erosive properties of the solution.