RESUMO
PURPOSE: The purpose of this study was to evaluate the effect of pre-etching enamel with phosphoric acid on the bond strength of a 1-step self-etch adhesive system in primary and permanent teeth. METHODS: The enamel of 30 primary molars and 30 permanent molars was ground with wet 600-grit silicon carbide paper, and specimens were randomly assigned according to bonding approach (with or without acid-etching). Half of the teeth received preliminary acid etching with phosphoric acid for 15 seconds before applying the self-etch adhesive system Adper Easy Bond. Polyethylene tubes with an internal diameter of 0.76 mm were placed on the bonded area and filled up with Filtek Z250 resin composite. The microshear bond testing was performed after 24 hours of storage in water at 37°C. Failure mode was evaluated using a stereomicroscope (400X). The microshear bond strength means were analyzed by 2-way analysis of variance and Tukey's post hoc test (P<.05). RESULTS: Bond strength to the enamel of primary teeth was significantly lower compared to permanent teeth. Higher microshear bond strength values were obtained when the enamel was pre-etched with phosphoric acid. For all groups, adhesive/mixed failure prevailed. CONCLUSION: The preliminary etching of enamel increases the bonding effectiveness for the 1-step self-etch system, regardless of tooth type (primary or permanent).