It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF2) or titanium tetrafluoride (TiF4) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 x 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF2 pH 2.5; 0.15% TiF4 pH 2.1; 0.2% NaF pH 6.5, all 0.05 F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 M hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (+/- SD) for 16 teeth after 9 days was: SnF2 1.8 +/- 1.9 mu m, TiF4 3.1 +/- 4.8 mu m, NaF 26.3 +/- 4.7 mu m, control 32.3 +/- 4.4 mu m. Daily rinse with SnF2, TiF4 and NaF resulted in 94,90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising. Copyright (C) 2012 S. Karger AG, Basel