Mechanical behavior of water-aged nano-filled hybrid composite restoratives

AbstractThe purpose of this study was to examine the mechanical behavior of water-aged nano-filled hybrid dental composites at four time intervals.Three nano-filled hybrid composites were tested; 20 specimens of each were fabricated, calibrated and transferred to desiccators at 37°C for dryness. Dry weights of the specimens were measured after 24 and 48h. Additionally, all specimens were weighted, while being stored in distilled water at 37°C, at the following time intervals: 1, 3, 7 and 14days. The specimens were then subjected to the applied force for measuring the flexural strength and elastic modulus using a universal testing machine. The loss tangent (δ) was also measured using the same test, in a trial to describe some of the viscoelastic parameters of the investigated materials. Data were analyzed and compared using one-way analysis of variance (ANOVA) at P=0.05. Tukey Post Hoc test was also conducted in order to compare the difference among these materials.For the flexural strength test, Filtek Supreme XT showed significance differences among all the experimental intervals, while, there were no significant differences between Tetric EvoCeram and Grandio. For the modulus of elasticity test, Tetric EvoCeram showed significant differences at different storage time intervals. In contrast, the modulus values did not significantly differ with other tested composite materials. The elastic deformation; loss tangent, tan(δ) of Tetric Evo Ceram was the lowest, while Filtek Supreme XT had the highest value among the different storage intervals.While aging in water, all the tested materials showed relatively stable elastic and mechanical behaviors. Additionally, it could be concluded that the tested nano-filled hybrid resin materials had similar behavior while ageing in water