The influence of varnish and high fluoride on erosion and abrasion in a laboratory investigation

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- 45200 ppmF), Duraphat® (NaF 22600 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