Mechanical properties of new composite restorative materials

Determination of flexural strength, flexural modulus, fracture toughness, Vickers hardness, and wear resistance of condensable composites (Solitaire, Surefil, Alert) and an ormocer (Definite) in comparison with a hybrid composite (Tetric Ceram) and an ion-releasing composite (Ariston pHc).

Flexural strength, flexural modulus, and fracture toughness were determined in 3-point bending. Single-edge notched-bend specimens were used to evaluate fracture toughness. Microhardness was measured with a Vickers indenter. Wear was determined in a pin-on-block-design with a Degusit antagonist at 50 N load and quantified by a replica technique after 6000, 10000, 30000, and 50000 load cycles using a 3D-laser scanner. All results were statistically analyzed with ANOVA and post hoc Tukey HSD tests.

Alert exhibited the highest flexural modulus, K(IC), and hardness, but lowest wear resistance. Solitaire presented the highest wear resistance, but significantly lower flexural strength, flexural modulus, K(IC), and hardness than all other materials. No significant correlation could be detected between hardness and wear of the tested composites with Pearson's correlation coefficient.

The condensable composites differed significantly in their mechanical properties. This study suggested that, besides the filler content level and filler size, other factors like matrix-filler interactions highly influence the fracture and wear behavior of the materials.