Currently the growing demand for aesthetic procedures and significant improvement on physical and mechanical properties of composite resins, these materials are increasingly used to anterior and posterior fillings. However, these materials also promote significant biofilm accumulation on its surface. Many changes have been done to improve this characteristic of composite resins, among the major changes made in the composition for this purpose, the use of nanoparticles with antimicrobial properties has excelled. However, the incorporation of nanoparticles and modification of the composition can affect the properties of composite resins and little is known about this aspect. The objective of this study will be to evaluate the influence of TiO2 nanoparticles with different concentrations (1.0, 5.0 and 10%) over properties of a nanoparticulated composite resin FiltekTM Z350 XT, by degree of conversion(DC), sorption and solubility. The specimens will be made using a metal mould(4mmx 2mm for DC and 10mm x 1mm for sorption and solubility) and photoactivated with a LED Radii Plus (SDI, 1500 mW/cm²) for 40 seconds. For DC (%), the specimens will be pulverized, pressed with KBr and analyzed by FT-IR spectrophotometer (Nexus-470). For sorption and solubility tests, the specimens will be stored in dry mean at 37ºC (±1ºC) until to show constant mass. Then, the samples will be immersed in 5mL of artificial saliva, with a weekly changing, and kept in dry mean at 37ºC (±1ºC), and weighed after 24, 48 and 72 hours, 7, 14, 21, 30, 60 and 90 days. The specimens will be then reconditioned to obtain constant mass. In order to evaluate the surface degradation will be performed scanning electron microscopy (SEM) evaluation of one specimen per Group (JSM 5310, JEOL Ltd.., Tokyo, Japan). If the assumptions of normality and homoscedasticity will be met, data will be submitted to analysis of Variance (ANOVA) and multiple comparison will be used by the post-Tukey test, with significance level of 5%, otherwise it will be used a nonparametric test. For images of scanning electron microscopy will be used descriptive analysis.
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