Influence of Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin

This in vitro study evaluated the influence of the Er,Cr:YSGG laser, associated or not to desensitizing agents, in the prevention of acid erosion in bovine root dentin. Eighty dentin specimens were selected and divided into eight groups (n=10): G1: negative control; G2: positive control (5% fluoride varnish-FV); G3: Er,Cr:YSGG laser; G4: FV+laser; G5: 3% potassium oxalate; G6: 3% potassium oxalate+laser; G7: biphasic calcium silicate/phosphate gel (gel); G8: gel+laser. Laser parameters: 0.5 W, 6.25J/cm(2) at 1-mm distance. The erosive drink used was a cola soft-drink (pH=2.42 at 4 degrees C), lasting 5 min, twice a day, with 6-h intervals between the challenges, during 14 days. Kolmogorov-Smirnov and Levene's tests were satisfied. The surface roughness data were submitted to ANOVA and Tukey post hoc tests. For the wear profile, Kruskal-Wallis and Dunn post hoc tests were used. Afterwards, the Spearman correlation test was performed. All statistical tests assumed a significance level of 5% (alpha=0.05). G1 presented the highest surface roughness value after the erosive challenge (3.586 mu m(2)+/- 0.205 mu m(2)) and the G7 presented the lowest surface roughness value after the erosive challenge (1.071 mu m(2)+/- 0.180 mu m(2)). For the lost volume, G4 presented the lowest percentage (9.7%+/- 0.9%), while G1 had the highest percentage (41.8%+/- 2.5%), both with p<0.05. There was a weak correlation between the response variables (rho=0.33). All groups presented lower values of surface roughness and loss of volume when compared to the negative control group. For the surface roughness, the biphasic calcium silicate/phosphate gel presented the best result. For volume loss, the 5% fluoride varnish+Er,Cr:YSGG laser showed the best results compared to the other groups.