Methods: Eighty bovine dentin samples (4 x 4 mm) were randomly divided into 8 groups, according to the following treatments: G1- untreated (control); G2- Acidic Phosphate Fluoride gel (APF-1.23%F) for 4 min; G3- fluoride varnish (NaF-2.26%F) for 6 h; G4- 0.5 W Nd:YAG laser (250 µm pulsewidth, 10 Hz, 35 J/cm2); G5- 0.75 W Nd:YAG laser (52.5 J/cm2); G6- 1.0 W Nd:YAG laser (70 J/cm2); G7- APF + 0.75 W Nd:YAG laser; G8- Varnish + 0.75 W Nd:YAG laser. After the treatments, half of each dentin surface was protected with nail varnish. The samples were stored in artificial saliva (30 mL/sample) for 24 h and submitted to 4 erosive cycles (Sprite light®, 30 mL/sample, 1 min). Between the erosive attacks, the blocks were maintained in artificial saliva for 59 min. The erosive wear was evaluated by profilometry.
Results: The mean wear (±SD, μm) was: G1-1.20±0.20A,E; G2-0.47±0.06B; G3-0.81±0.11C; G4-1.47±0.32A; G5-1.52±0.24D; G6-1.49±0.30A; G7-0.49±0.11B and G8-1.06±0.31C,E (ANOVA and Tukey's test, p<0.05).
Conclusions: The laser irradiation was not able to reduce dentin erosion. However, fluoride application was able to increase the dentin resistance to erosion, and APF showed better results when compared to F varnish.