Avaliação da resistência de união de reparos em resinas bulk fill após diferentes protocolos de adesão

Abstract

Objective: To evaluate the microtensile bond strength of repairs performed on bulk fill and conventional composite resins subjected to aging, after different adhesion protocols. Materials and methods: 42 specimens (8x8x4 mm3 ) of each of the following materials were prepared in shade A1: a microhybrid composite (Filtek Z250 XT-3M ESPE, St. Paul, MN, USA) and a high-viscosity bulk fill composite (Filtek Bulk Fill - 3M ESPE, St. Paul, MN, USA). These specimens were aged by storage in artificial saliva at 37 ° C for 30 days. After, they received a mechanical surface treatment by means of abrasion with a diamond bur 4138F, followed by the division in six groups, according to the adhesion protocol employed: FSA - etching with 35% phosphoric acid + silane + etch-and-rinse adhesive (Adper Single Bond 2 - 3M ESPE, St. Paul, MN, USA); SA - silane + etch-and-rinse adhesive; FA - etching with 35% phosphoric acid + etch-and-rinse adhesive; A - etch-and-rinse adhesive; FU - 35% phosphoric acid + universal adhesive (Universal Bond Single - 3M ESPE, St. Paul, MN, USA); U - universal adhesive. The repairs were performed with Z250 XT composite, in shade B3, to differentiate them from the base materials. The repaired resin blocks were cut into sticks (8x1x1 mm3 ) and submitted to microtensile test. Fractured specimens were evaluated by macrophotography to determine the type of fracture (adhesive or cohesive). In order to analyze the differences among the adhesion protocols and composite types, two-way ANOVA statistical test was used, with a significance level of 5%. Results: No statistically significant differences were found in bond strength values among the adhesion protocols and among the composite resins repaired, as well as no interaction between these variables. Conclusion: For the aging pattern adopted in this study, repair bond strength of a bulk fill composite was similar to that found in a conventional microhybrid composite, with no distinction among several adhesion protocols.