Influence of light-curing units and indirect restorative material on the hardness and elastic modulus of two dual-cured resin cements

Abstract

The aim of this study will be to evaluate hardness and elasticity module of two dual-curing resin cements, photoactivated under indirect restorative materials, using different light-curing units through dynamic testing of ultra-microhardness. To obtain specimens will be used bovine incisors after prophylaxis, will be subject to cuts in amelo-cementary limit for the separation of the coronal portion on the metallographic cutter (Labcut, model 1010, Extec, Enfield, CT, USA). After addition, the samples are ground until the dentin exposed to polishing (Buehler, USA) for 30 seconds, to standardize the substrate. The teeth are randomly divided among the twelve experimental groups (n = 5). To simulate clinically indirect restorations will be made in advance in the laboratory, ceramic discs IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein) in the color corresponding to the A2 Vita (Vita, Germany) and indirect composite SR Adoro (Ivoclar Vivadent, Schaan, Liechtenstein), color A2. After cementation, the samples will be stored for 24 hours in distilled water at 37pC. Subsequently be sectioned with diamond disk (Isomet 1000, Buehler, Lake Bluff, IL, USA) at low speed and constant irrigation. Thus the entire row of cement will be exposed to evaluate the nanohardness. The specimen of the test piece shall be tested for nanohardness and modulus of elasticity, the ultra-microhardness tester (Shimadzu Dynamic Ultra Micro Hardness Tester, Tokyo, Japan). The cycle is applied for 1 min and the rate of application of force shall be 0.01 mN / msec. Will be held five nanoindentations in each specimen, with a distance of 10 mm between them, which means values of each surface. The results, expressed in number of Berkovich hardness, will undergo an exploratory analysis in order to verify that the same normal distribution and homogeneous. If so, will be submitted to ANOVA and Tukey's test. (AU)