Characterization of nanofilled compared to universal and microfilled composites.

OBJECTIVES: The purpose of this study was to compare the inorganic fraction and the mechanical properties of three nanofilled composites with four universal hybrid and two microfilled composites. The degrees of conversion of the materials photopolymerized using halogen and LED units were also investigated. METHODS: Three nanofilled (Supreme, Grandio and Grandio Flow), four universal hybrid (Point-4, Tetric Ceram, Venus, Z 100) and two microfilled (A 110, Durafill VS) composites were used in this study. Their filler weight content was measured by thermogravimetric analysis. The morphology of the filler particles was determined using scanning-electron microscopy (SEM). Mechanical properties were measured: dynamic and static elastic moduli, flexural strength and Vickers microhardness. The degree of conversion in relation with the depth of polymerization of every material tested was evaluated using Raman spectrophotometry. RESULTS: Nanofilled resin composites show higher elastic moduli than those of universal and microfilled composites, except for the Z-100. The microfilled composites exhibit by far the lowest mechanical properties. The flexural strength does not appear as a discriminating factor in this study. The degrees of polymerization obtained with the halogen lamp are higher than those obtained with the LED lamp. SIGNIFICANCE: Nanofilled resin composites show mechanical properties at least as good as those of universal hybrids and could thus be used for the same clinical indications as well as for anterior restorations due to their high aesthetic properties