Mechanical properties and wear behavior of light-cured packable composite resins

Objectives: Determination of flexural strength, flexural modulus, fracture toughness and wear resistance of three packable composites (Solitaire, Surefil, ALERT) and a packable ormocer (Definite) in comparison with an advanced hybrid composite (Tetric Ceram) and an ion-releasing composite (Ariston pHc). Methods: Flexural strength, flexural modulus and fracture toughness of each material were determined in three-point bending (each test n=10). Single-edge notched-bend specimens were used to evaluate the fracture toughness (KIC). Wear of the materials (n=8) was determined in a pin-on-block-design with a spherical Degusit antagonist at 50 N vertical load and quantified by a replica technique using a 3D-laser scanner. Replicas were made after 6000, 10000, 30000 and 50000 load cycles. The mean wear rate (MWR (μm3 cycle−1)) was obtained by a linear regression analysis in the steady-state of the time–wear-curve. All results were statistically analyzed with ANOVA and post hoc Tukey HSD tests ( p<0.05). Results: ALERT exhibited the highest flexural modulus (12.5±2.1 GPa) and KIC (2.3±0.2 MN m−3/2), but the lowest wear resistance (8275 μm3 cycle−1). Solitaire presented the highest wear resistance (1591 μm3 cycle−1), but significantly lower flexural strength (81.6±10.0 MPa), flexural modulus (4.4±0.3 GPa), and KIC (1.4±0.2 MN m−3/2) than all other materials. Surefil revealed a significantly higher flexural modulus (9.3±0.9 GPa) and wear resistance (3028 μm3 cycle−1) than Tetric Ceram (6.8±0.5 GPa; 5417 μm3 cycle−1) and Ariston pHc (7.3±0.8 GPa; 7194 μm3 cycle−1). Significance: The tested packable composite resins differed significantly in their mechanical properties. This study suggested that fracture and wear behavior of the composite resins are highly influenced by the filler system. Overall, Surefil demonstrated good fracture mechanics parameters and a low wear rate.