A influência de diferentes cromas na microdureza superficial e profunda de um cimento resinoso

Abstract

Objective: to perform in vitro comparison of surface and deep Vickers Microhardness (VM) of three different chromas of the same resin cement. Material and Method: 30 test bodies were divided into 6 groups (n=10/group) according to the surface and the chroma assessed: A1 (top and base); A3 (top and base); A4 (top and base) of a resin cement only in photo activated version (Variolink II® - IvoclarVivadent). Light curing of the samples was performed for 40s using the Ultraled® (DabiAtlante – Brazil) tool with a wavelength of 450 to 490nm. The samples were stored in a lightproof container, in dry conditions, at 370C for 24h. Four VM measurements were taken on each surface (top or base) of the tested specimens (50gf for 45s - Shimadzu HVM-2T®). The microhardness calculation of each sample was obtained from the mean of four indentations in each surface (top and base). Data was subjected to the student’s t, “F” (ANOVA) and Kruskal-wallis parametric tests and the Newman-Keuls multiple comparison test (signifi cance of 5%). Results: the mean and standard deviation values obtained were: A4T: 33.0350 (± 2.0087); A4B: 24.1627 (± 2.0260); A3T: 29.5225 (±1.5422); A3B: 23.8175 (±1.4944); A1T: 25.7725 (±2.2689) and A1B: 22.4625 (± 2.3691). There were statistically signifi cant differences between the VM values of the top and base surfaces for each of the chromas (p <0.05); and between each of the top surface values of the three groups (p <0.05). There was no difference between the base surface values of each of the three chroma groups (p = 0.2339). Conclusion: The distance from the light source to the surface of the resin cement, the composition, volume, type and size of the pigments infl uenced the VM of the cementing agent