Resinas compostas bulk fill envelhecidas em soluções ácidas – análise da microdureza superficial

Abstract

The objective was to compare in vitro the superficial microhardness of different Bulk fill composites after immersion in different solutions. Composite resins (RC) Bulk fill, Bulk filaments and a nanoparticulate RC were stored in four different solutions (n = 10) and measured in three times. The specimens (CP) were made with dimensions of 6 mm in diameter by 2 mm in height for the group of RC nanoparticulate and 6 mm in diameter by 4 mm in height for the other RC. The CPs were kept in an oven at 37ºC for 24 hours in distilled water and after being submitted to the Knoop microhardness test (KHN). The following solutions were stored in those solutions: AD - Distilled water; EA - Ethanol-water solution (75%), AC- 0.02N citric acid and AN- 0,02N Nitric Acid. The CPs were immersed in each solution at 37oC for 7.30 and 60 days, for each of these periods the KNH test was performed. The results were analyzed using the Shapiro-Wilk, Kruskall Wallis and Dunn tests, p <0.05.Nevertheless, according to the results obtained it was possible to verify that the Z350 composite resin was the resin that presented the highest values of superficial microhardness in the majority of the evaluations, though, for the condensable Bulk fill resins the Aura Bulk Fill resin presented the lowest values of microhardness in the evaluations. For Bulk Fill Flow resins, the resin with the lowest values was Filtek Bulk Fill flow, among all comparisons. The water / alcohol solution showed the greatest reduction in surface microhardness after being storage during a while, and SDI Aura Bulk Fill showed no change in its surface microhardness after immersion in the different solutions and whiles evaluated.