Estabilidade de cor e translucidez de facetas diretas de resina composta – estudo laboratorial

Abstract

One of the major challenges concerning direct anterior restorations with resin composite is the mimicking of the patient's natural teeth and his/her aesthetic pattern. Thus, the choice of the material should be based on optical properties so that success may be achieved by choosing the correct color and translucency of the restorative material. Moreover, the stability of these properties must be observed and studied, since it is a determinant factor in the aesthetics and durability of the restoration. Hence, the aim of this study was to evaluate the optical properties of resin composites with different opacities compared to dentin and enamel, simulating the preparation of a direct veneer, as well as the alteration of these properties after storage in distilled water. In this study, samples were prepared involving dentin and/or enamel substrates only, resin composites for dentin and enamel restoration only, as well as the combination between dental substrates and resin composites. In total, 50 samples were evaluated for color and translucency using a digital spectrophotometer (Easyshade; VITA) and the CIEL*a*b* color system. All samples were immersed in distilled water for 120 days, and their color and translucency were evaluated at baseline and after 1, 30 and 120 days of storage. The surface wettability and visual appearance of the samples were also evaluated. The data were analyzed by the Friedman method and the post hoc test of Student-Newman-Keuls (α=5%). The samples that have most changed their color after water storage were those combining dentin and enamel, followed by samples consisting only of enamel or dentin, which did not differ statistically from each other (p=0.273). The samples prepared with dentin or enamel resins composite showed the least changes in color over time. After 120 days of storage, all samples changed color at ΔE* values greater than the threshold of 3.3. Dentin samples and those prepared solely with enamel resins composite were the most translucent of the study (p<0.001), although they have not differed from each other (p=0.213); on the other hand, the samples prepared by combining dentin resin with any dental substrate presented the lowest translucency values of the study. Regarding wettability, the samples prepared with resin composite presented similar wettability to the dental substrates, except for the pure enamel. In conclusion, the optical properties of dentin and enamel are difficult to fully mimic using resin composites, since the color and translucency characteristics were not properly reestablished between the substrates and materials tested.