Efeito da aplicação de extrato de chá verde após clareamento dental na resistência de união entre esmalte e resina composta

Abstract

This in vitro study evaluated the effect of applying 10% green tea on the bond strength between bleached enamel and composite resin. The buccal enamel of 30 crowns of bovine incisors was smoothed to obtain a flat area of 1cm2. Teeth were randomly divided into 5 groups (n=6): GCtrl-control, without tooth bleaching or antioxidant application; GSc–bleached only; and GAtx5, GAtx10, GAtx15–groups submitted to bleaching and antioxidant application for 5, 10, and 15 min, respectively. Hydrogen peroxide at 35% was applied to the enamel and removed with air-water jets, followed by etching with phosphoric acid and application of adhesive. The composite resin was applied over the crown in increments to form a 1x1x0.3 cm restoration. The samples were sectioned under water cooling (250rpm) in the form of 6mm long sticks with 1mm2 cross-sectional area. The specimens were joined to a microtensile device and subjected to a gradual force (0.5 mm/min) in a universal testing machine. The force (N) at the moment of failure was recorded and the calculated bond strength (MPa). Statistical analysis was performed using the Kruskal Wallis test at a significance level of 5%. The GAtx5, GAtx10 and GAtx15 groups were equivalent to the GCrtl group and superior to the GSc group, showing that the application of 10% Green Tea positively interferes with the bond strength between composite resin and freshly bleached enamel, regardless of the antioxidant application time.