Physicomechanical properties of resin-based composites photo-polymerized using laser, polywave and quadwave curing lights.

OBJECTIVES

This study evaluated the fracture toughness (K), energy absorption E and Vickers hardness (VH) of resin-based composites (RBC) photo-polymerized with new light curing unit (LCU) technologies: one laser diode (Monet Laser - AMD Lasers), one polywave™ LED (PowerCure - Ivoclar) and one quadwave LED (PinkWave - Apex).

METHODS

Two conventional: Evo, Tetric EvoCeram (Ivoclar) and FS, Filtek Supreme (Solventum); and two bulk-fill: PF, PowerFill (Ivoclar) and AF, Admira Fusion x-tra (VOCO) were tested. The RBC specimens were photo-polymerized for 1 second with the Monet, 3 seconds with the PinkWave in the 3-second-high output mode, and the 10-second standard mode using the PowerCure light. The power (mW), irradiance (mW/cm), radiant exposure (J/cm), and emission spectrum (mW/cm/nm) were measured using a fiberoptic spectrometer attached to an integrating sphere. K (K, MPa·m) was obtained using an 8.2 mm diameter and 2.0 mm thick metal mold. After 24-hour storage at 37 °C, the K was measured in a universal testing machine at a rate of 0.5 mm/min. The energy absorption (E, N/mm) up to failure was calculated. The Vickers hardness (VH, Kg/mm) was measured at the bottom of the K specimen. Data were analyzed using a two-way analysis of variance followed by the Tukey multiple comparison test (α = 0.05).

RESULTS

Both the K and VH were significantly influenced by the light-curing unit/exposure time and by the RBC used (p < .001). The Monet emitted the highest power (1501.4 mW) but delivered the lowest radiant exposure (3.0 J/cm). In general, the K values did not differ when RBCs were photo-polymerized with PowerCure in the standard 10 s or 3 s modes, except for the Admira Fusion x-tra. The K, VH and energy absorption to failure values were higher for all RBCs when photo-polymerized with PowerCure in the Standard mode for 10 s and lowest with the Monet used for 1 s. Filtek Supreme had the highest VH values regardless of the curing light unit/exposure time. The VH was better at detecting differences between the LCUs/exposure time and the RBC.

SIGNIFICANCE

Short 1-3 s exposure times produce inferior physicomechanical properties in some RBCs compared to a 10 s exposure at a lower irradiance. Clinicians should understand how much energy the manufacturers of the RBCs are recommending should be delivered to their RBC.