Resistência de união por microtração entre materiais autoadesivos e dentina

Abstract

Restorative composites denominated self-adhesive dispense adhesive systems. This study aimed to evaluate the bond strength of dentin adhesive materials. The hypotheses for the study were: 1) self-adhesive materials have lower bond strength to adhesive systems of fourth and fifth generation, 2) pressure grouting is able to increase the bond strength of adhesive materials. Fifty healthy human third molars teeth were stored in distilled water, embedded in acrylic resin, sectioned to expose flat surface of dentin and randomly divided into five groups: TE (Control 1) Adhesive system of total etching; SE - (Control 2) - adhesive system; UC - self-adhesive resin cements; VE - composite resin flow self-adhesive, and UCP - UC with static pressure of 1Kg for 5 min. Teeth were restored with composite resin (Opallis / FGM color A2) at 6 mm of height. Teeth were sectioned to obtain samples in the form of sticks with 1mm2 cross sectional area, resulting in two sticks from each tooth (n = 20), that were submitted to microtensile bond test in a universal testing machine (EMIC DL 2000) until fracture occurs (v = 0.5 mm / min). Data were evaluated by ANOVA / Tukey (α = 0.05). The fractured samples were examined under an optical microscope (OM) with 40x magnification in order to classify its into cohesive or adhesive. It was concluded that UC and VE developed lower bond strength than TE and SE, used as controls, confirming H1. Cement pressure was not able to increase bond strength values of UCP, when compared with UC, rejecting H2. OM showed predominance of adhesive failures in all the groups