Er,Cr:YSGG laser associated with acidulated phosphate fluoride gel (1.23% F) for prevention and control of dentin erosion progression

To evaluate the effect of Er,Cr:YSGG laser, associated with fluoride application, on the prevention/control of dentin erosion. Dentin slabs were embedded in acrylic resin, flattened, and polished. Half of the specimens were previously eroded (10min immersion in 1% citric acid solution) and half were kept sound. The specimens (n=10 each substrate) were randomly allocated into the experimental groups, according to the following treatments: control (no treatment); APF gel (1.23% F, 1min); Er,Cr:YSGG laser irradiation (P1: 0.25W, 20Hz, 2.8J/cm(2), tip S75, beam diameter of 750m, 1mm away from the surface); Er,Cr:YSGG laser irradiation (P2: 0.50W, 20Hz, 5.7J/cm(2), tip S75, beam diameter of 750m, 1mm away from the surface); APF gel+Er,Cr:YSGG laser P1 and; APF gel+Er,Cr:YSGG laser P2. Afterwards, the specimens underwent an erosion-remineralization cycling, consisting of a 5-min immersion into 0.3% citric acid, followed by 60-min exposure to artificial saliva. This procedure was repeated 4x/day, for 5days. Surface loss (SL, in m) was determined by optical profilometry. Specimens from each group were analyzed by environmental scanning electron microscopy (n=3). Data were statistically analyzed (=0.05). For the eroded specimens, APF gel presented the lowest SL, being different from the control. For the sound specimens, none of the groups differed from the control, except for Er,Cr:YSGGlaser P2, which presented the highest SL. When substrates were compared, only the eroded specimens of the control and APF + Er,Cr:YSGGlaser P1 Groups showed higher SL. Selective structure removal was observed for the laser-treated groups. None of the Er,Cr:YSGG laser parameters were effective in the prevention/control dentin erosion. Thelaser was also unable to enhance the protection of fluoride against dentin erosion.