Nd:YAG laser irradiation associated with fluoridated gels containing photo absorbers in the prevention of enamel erosion.

Abstract

This study evaluated the combined effect of Nd:YAG laser irradiation and fluoridated gels containing photo absorbers against enamel erosion. Enamel specimens from bovine teeth were polished, eroded (10min, with 1% citric acid, pH=2.6), and randomly allocated into the experimental groups (n=8), according to the different surface treatments: fluoridated gels (F: 9047ppm F and F+Sn: 9047ppm F and 3000ppm Sn), with or without photo absorbers (E: erythrosine and MB: methylene blue), and associated or not with Nd:YAG laser irradiation (in contact; 0.5W; 50mJ; ~41.66J/cm2; 10Hz; 40s; pulse duration of 120μs). A placebo gel (PLA) associated or not with laser was used as control. All gels had pH=4.5 and were applied for 2min. Laser irradiation was performed during gel application. The specimens were then submitted to a 5-day erosion-remineralization cycling model using 0.3% citric acid (pH=2.6), 4×/day. Enamel surface loss (SL) was analyzed by optical profilometry in the end of the cycling (in μm). Data were analyzed by ANOVA and Tukey tests (α=0.05). Means (SD) of SL for the groups were the following (different superscript letters imply significant difference among groups): PLA (21.02±1.28)a, PLA+laser (19.20±0.96)ab, laser (17.47±1.50)b, F+Sn+E+laser (13.69±0.62)c, F+E+laser (13.52±1.16)c, F (13.10±1.08)c, F+laser (11.94±1.44)cd, F+Sn+MB+laser (11.90±4.02)cd, F+MB+laser (11.42±1.42)cd, F+Sn (11.12±1.20)cd, and F+Sn+laser (10.35±0.89)d. In conclusion, all fluoridated gels and the Nd:YAG laser irradiation reduced erosion development, but the combination of treatments did not promote further protection. The addition of photo absorbers to the fluoridated gels did not influence the anti-erosive effect of the combination of laser plus fluoridated gels.