Effect of Nd:YAG/fluoride treatment on permeability of primary teeth enamel

Objectives: To evaluate the ability of Nd:YAG irradiation associated or not with topical acidulated phosphate fluoride gel or fluoride varnish in alteration of primary enamel permeability. Methods: twenty four human primary teeth were sectioned in buccolingual direction. The samples were isolated with nail varnish/wax, leaving an exposed area on the outer surface (9mm²), and randomly divided into 6 groups (n=8) according treatments: G1 (control): no treatment; G2: 1.23% acidulated fluoride gel (DFL ®); G3: acidulated fluoride gel + Nd:YAG at 0.5 W/10Hz contact mode; G4: 5% fluoride varnish (Duraphat ®); G5: fluoride varnish + Nd: YAG at 0.5 W/10Hz; G6: Nd:YAG at 0.5 W/10Hz. After the treatments, the samples were submitted to in vitro pH cycles (Dem/Rem). Specimens were subjected to a histochemical coloring method using cooper sulfate and dithiooxamide solutions. Three sections taken from the exposed area were imaged in an optical microscope. Permeability was measured in digitized images as the % of cooper penetration over the enamel thickness. Data were analysed using Kruskal-Wallis. Results: Control group (68.15%) showed the higher cooper penetration (p<0.05), differing statistically from G2 (22.42%), G3 (14.57%), G4 (32.67%), G5 (44.37%) and G6 (40.10%), which presented lower cooper penetration. Conclusion: Nd:YAG laser associated or not with fluoride gel/varnish reduced the enamel permeability. Supported by FAPESP (2009/07018-7).