RESUMEN
BACKGROUND: The aim of this study was to investigate the potential of concentrated fluoride varnishes to reduce enamel loss from repeated cycles of citric acid erosion and toothbrush abrasion in vitro. METHODS: Polished human enamel samples were exposed to fluoride varnishes: Bifluorid10® (NaF&CaF2- 45,200 ppmF), Duraphat® (NaF 22,600 ppmF), Fluor-Protector® (difluorsilane 1000 ppmF) and a control coating of copal ether varnish (0 ppmF) group and a deionized water group. For each group of 16 samples, nine cycles of erosion and nine cycles of erosion-abrasion [1 cycle=erosion (0.3% citric acid, pH 3.2, 5 min)+artificial saliva (1 h, pH 7.0)+abrasion (120 linear strokes in artificial saliva from Oral B medium soft brushes 300 g loading]. The change in the enamel surface was evaluated using optical profilometry. RESULTS: Duraphat® and Bifluorid10® applications had a median (IQR) step height of 4.21 um (1.59) and 5.01 um (1.02). This was statistically significantly less than Fluor-Protector® 6.83 um (1.25), copal ether 7.22 um (1.97) and water 7.39 um (1.96) (p<0.001). For erosion-abrasion, both Duraphat® and Bifluorid® had statistically lower step heights than the other products (p<0.01). CONCLUSIONS: The action of fluoride in a range of single-application topical varnishes was effective in reducing enamel wear from erosion and erosion-abrasion in this laboratory study.