RESUMO
Aim: Evaluating the resin-dentin bond strength of Class II conventional and bulk-fill composite restorations, using different cavity sizes before and after aging. Methods: Seventy-five human molars were distributed into groups according to the buccolingual width of the cavities, conservative (n=25) and extended (n=50). They were divided according to the restorative material: conventional (Z100/control group) or bulk-fill resin composites (Filtek Bulk Fill/FBF; Tetric N Ceram Bulk Fill/TNCBF; Filtek Bulk Fill Flow/FBFF; Surefill SDR flow/SDR). The restored teeth were sectioned on sticks (n=50 per restorative materials + width cavities group), half were stored in Water/Ethanol 75% for 30 days and the other half were submitted to the immediate microtensile bond strength (µTBS) test. Data were analyzed applying the Three-Way Analysis of Variance (ANOVA), Bonferroni test, test t, and Weibull analyses (p<0.05). Results: SDR and FBF presented lower µTBSvalues for extended preparation when compared to the conservative preparation, before aging. After aging, only for the FBFF, a decrease in the µTBSvalues was observed. Comparing the µTBSvalues, before and after aging, the SDR demonstrated lower µTBSvalues after aging when the conservative cavity was used. A decrease in the µTBSvalues was observed for the Z100, the FBF and, the FBFF, after aging, when the extended cavity was used. Conclusion: The effect of cavity preparation and aging on the resin-dentin of Class II is material dependent. Most of the bulk-fill resin composites evaluated presented a similar performance to the conventional resin composites for all the conditions of this study