Avaliação da microdureza superficial de resinas compostas à base de metacrilato e silorano fotopolimerizadas com fontes de luz halógena e LED, em diferentes profundidades

Abstract

The enhanced mechanical properties of composites, as well as superior curing units, allowed the use of such restorative materials with more predictable results. However, it is known that the success of esthetic restorations depends on many factors such the amount and depth of polymerization, the type of curing unit used, the light intensity and the properties of the composite. Thus, this study aimed to evaluate the surface microhardness of methacrylate and silorane based composites (Filtek Z250 and Filtek P90, respectively) cured with halogen lamps or LED (Optilux 401 and Radii) at the depths of 0, 2 and 4 mm. Samples (n=120) were obtained using a silicone matrix containing pits of 2 or 4 millimeters and 5 millimeters wide, which were filled with the tested composites and cured with halogen lamp or LED units for 40 seconds. The samples were included in acrylic resin and polished, being stored for 24 hours at room temperature in black, opaque containers before the microhardness test. A Vickers microhardness tester was used with a load of 200 gf for 10 seconds. Statistical analysis showed higher microhardness values obtained by Filtek Z250 when compared to Filtek P90 (P<0,001). When curing units were compared, LED-based units showed higher hardness that halogen lamp based-units, except for the FILTEK P90 resin, which showed similar values of microhardness (P> 0.05), at depths of 2 and 4 mm. The depth of polymerization was also determinant in microhardness values (P<0,001), showing an inversely proportion pattern.