AVALIAÇÃO DA RESISTÊNCIA DE UNIÃO, NANOINFILTRAÇÃO E CARACTERÍSTICAS MORFOLÓGICAS DA INTERFACE DENTE-RESINA EM DENTINA EROSIONADA SUBMETIDA A TRATAMENTO DE DESPROTEINIZAÇÃO

Abstract

The purpose of this "in vitro" study was to evaluate the effect of the deproteinization of the eroded dentin in bond strength, nanoleakage and morphology of the hybrid layer using three different adhesive systems. The sample consisted of 45 human molars. The teeth had their occlusal surfaces exposed to mid coronal dentin. After the standardization of smear layer and the induction of the dentin erosion, they were randomly divided into 3 groups (n=15), according to the adhesive system used: GS1 - Adper Single Bond™ 2 (3M-ESPE™) - 2 steps simplified adhesive system; GS2- AdheSE® (Ivoclar/Vivadent) - 2 steps self-etch adhesive system; GS3- Single Bond Universal™ (3M-ESPE) - 1 step adhesive system. Previously to the application of the adhesive system, each group was divided into 3 subgroups (n=5), according to the treatment of the dentin: A1– Sound Dentin (control), A2- eroded dentine and A3- eroded dentine + deproteinized with NaOCl ( 5.2% ) for 40 sec. After the application of the adhesive systems according to the manufacturer's instructions, the teeth were restored with composite resin and sectioned to obtain “sticks-like” resin specimens (0.8 mm2). The microtensile bond strength test (TBS) was performed after 24h storage in water at 37 ºC at a rate of 1 mm/min. Before the microtensile test, 4 “sticks” of each experimental condition were randomly assigned for micromorphological analysis (formation of the resin tags and nanoleakage - NI) by SEM. The TBS and NI data were analyzed by 2 way ANOVA complemented by Tukey's test (α=0.05). The group treated with Single Bond Universal and deproteinization showed the highest μ-TBS (41.86 ± 5.80 MPa). The lowest μ-TBS mean was observed for AdheSE® after erosion without deproteinization (14.04 ± 7.28 MPa). The higher NI mean (%) was observed for AdheSE® after erosion without deproteinization (69.40 ± 8.73) and Single Bond Universal had the lowest NI mean (%) for the deproteinized group (14.48 ± 5.47). The photomicrographs of sound dentin and deproteinized dentin for all adhesive systems showed the presence of longer resin tags in the hybrid layer compared to the eroded dentin only The dentin deproteinization resulted in increased TBS in the eroded substrate for the groups in which self-etch adhesive systems were applied.. For the NI, the best conditions were obtained for the Single Bond Universal adhesive system.