Effect of Er,Cr:YSGG laser associated with fluoride on the control of enamel erosion progression.

OBJECTIVE: To evaluate the effect of Er,Cr:YSGG laser associated or not with acidulated phosphate fluoride (APF) on the control of enamel erosion progression. DESIGN: Enamel slabs (4 mm x 4 mm x 2 mm) from bovine incisors were flattened, polished, and received a tape on their test surfaces, leaving a 4 mm x 1 mm area exposed. Specimens were eroded (10 min in 1% citric acid solution) and randomly assigned into 8 experimental groups (n = 10): Control (no treatment); F (APF gel, 1.23% F, pH 3.6-3.9); Er,Cr:YSGG laser irradiation (P1: 0.25 W, 20 Hz, 2.8 J/cm(2), 56 W/cm(2)); Er,Cr:YSGG laser irradiation (P2: 0.50 W, 20 Hz, 5.7 J/cm(2), 1136 W/cm(2)); Er,Cr:YSGG laser irradiation (P3: 0.75 W, 20 Hz, 8.5 J/cm(2), 1704 W/cm(2)); F + Laser P1; F + Laser P2; F + Laser P3. Specimens were then subjected to erosive cycling (5 min immersion in 0.3% citric acid solution, followed by immersion in artificial saliva for 60 min; 4x/day for 5 days). At the end of cycling, surface loss (SL, in mum) was determined with optical profilometry. Selected specimens were further evaluated by environmental scanning electron microscopy (n = 3). Data were analyzed using Kruskal-Wallis and Tukey tests (alpha = 0.05). RESULTS: Group F + Laser P2 had the lowest SL value, differing significantly from the control; however, with no significant difference from the other groups. All groups, except F + Laser P2, showed no significant difference in SL when compared with the control. An irregular and rough surface, suggestive of a melting action of laser, was observed on enamel in Laser P2 and F + Laser P2 groups. CONCLUSIONS: Association of the Er,Cr:YSGG laser in parameter 2 with fluoride was the only treatment capable of controlling the progression of enamel erosion.