Evaluation of mechanical properties on three nanofilled composites.

The purpose of this study was to evaluate the mechanical behavior of three composites with nanoparticles Filtek Z350 XT (3M ESPE), Esthet X (Dentsply), Grandio (Voco) in enamel and body shades (A2) trough nanohardness, elastic modulus, compressive strength test, flexural strength test, diametral tensile strength, flexural modulus, weight filler content and Knoop microhardness. One sample of each material was submitted to nanohardness and elastic modulus. Five values of ten indentations were considered valids inside confidence intereval. Ten samples of each material were submitted to compressive strength, flexural strength and diametral tensile strength test at universal testing machine. The flexural modulus test was calculated based on flexural strength results. Ten samples of each group were submitted to knoop microhardness test. The results were submitted to ANOVA and Tukey statistical tests. The highest inorganic weight filler content for Grandio was registered after the organic mould decomposition. After statistical analysis Grandio showed the highest averages for nanohardness, elastic modulus, flexural modulus and knoop microhardness. For diametral tensile strength Grandio and Filtek Z350 XT obtained the highest averages. The tested composite resins ranged similar medias statistically for compressive strength. For flexural strength Filtek Z350 XT and Esthet X showed the highest averages. The results suggest that the weight filler content, the filler size and shape and the contact surface between nanofillers and organic phase has direct relation with composite resins with nanoparticles mechanical properties. Further studies should be carried out to improve the knowledge of composites with nanoparticles mechanical behavior.

Evaluation of diametral tensile strength and Knoop microhardness of five nanofilled composites in dentin and enamel shades.

The purpose of this study was to evaluate and compare the mechanical behavior of five nanofilled composites with dentin and enamel shades trough diametral tensile strength and knoop microhardness. 4 Seasons (Ivoclar Vivadent), Esthet X improved (Dentsply), Filtek Supreme (3M), Grandio (Voco) and Palfique Estelite (Tokuyama Dental Corp.) were used in this research. Twenty samples (6 mm diameter and 3 mm thickness) of each material were used. Ten samples were submitted to knoop microhardness and the others to diametral tensile strength examinations. The results were submitted to ANOVA and Tukey statistical tests (a=0.05). There were significant differences between the tested groups (p<0.05). The diametral tensile strength ranged from 36.08 (4 Seansons dentin) to 49.24 (Grandio enamel). The knoop microhardness ranged from 54.45 (Esthet X improved enamel) to 123.90 (Grandio dentin). A great variability in the mechanical behavior of the nanofilled composites was observed. However it was not recorded with dentin and enamel shades with the exception of Grandio.