RESUMO
OBJECTIVE: The aim of this study was to assess the performance of three bonding agents in preventing microleakage of class V cavities prepared and treated by Er:YAG laser associating with acid etching. BACKGROUND DATA: There has been very little research comparing the efficiency of single-component and self-etching adhesive systems in preventing microleakage of cavities prepared and conditioned with Er:YAG laser. MATERIALS AND METHODS: Thirty cavities - with occlusal margin in enamel and cervical in dentin/cementum - were prepared in sound human third molars using a short pulsed Er:YAG laser (500 mJ/5 Hz) The enamel and dentin surfaces were conditioned for 30 sec using lower dosimetries (120 mJ/4 Hz), and the samples were randomly assigned into three groups, according to the adhesive system: (I) Bond-1; (II) Prime & Bond NT; and (III) Etch & Prime 3.0. Groups I and II were acid-etched for 15 sec, and group III did not receive any acid treatment once a self-etching system was employed. Cavities were restored with a light-cured composite resin (JEK-Z250 Filtek-250), and after finishing, the samples were thermocycled, isolated with epoxy resin and nail varnish, immersed in a 0.2% Rhodamine B solution for 24 h, and sectioned longitudinally. The sections obtained were analyzed for leakage using an optical microscope connected to a computer and a video camera. We digitized the images using a special software program that allowed a quantitative evaluation of microleakage in millimeters. RESULTS: Statistical analysis using the Kruskal-Wallis test showed statistically significant difference between both margins, and the occlusal region presented better marginal sealing. Comparing the three resin bonding systems, Prime & Bond NT entirely sealed both margins, while Etch & Prime 3.0 provided the poorest overall results, showing a statistically significant difference (p < 0.01). CONCLUSION: It may be concluded that, for all the tested materials, microleakage values were higher in cervical (dentin/cementum) margins. Additionally, Prime & Bond NT provided a complete elimination of marginal infiltration at both margins, after treating the dental surface with laser irradiation associated with a sequent acid-etching.