Effect of High-Power Curing on Polymerization Shrinkage and Microhardness of Composite Resins

The polymerization shrinkage (PS) and microhardness of dental composite resins, are known to be significantly influenced by the intensity of the curing light and the thickness of the material. However, the specific effect of high-power curing mode on composite resins has not been fully clarified. This study investigated the effect of the curing mode using high-power curing unit (VALO) on the volumetric shrinkage and microhardness of nanohybrid composites. SonicFill 3 and OptiShade were polymerized using standard and high-power curing modes with the VALO Cordless. A total of 60 specimens were prepared using Teflon molds with a diameter of 8 mm and a thicknesses of 2 mm and 4 mm. The microhardness values were measured using a Vickers hardness tester (Innovatest,Maastricht,Holland). Forty specimens were prepared for volumetric shrinkage ratios. PS was measured using a video imaging device (Acuvol Volumetric Shrinkage Analyzer; Bisco Inc., Schaumburg, IL, USA). The curing mode affected the microhardness of each composite material. Pertaining to microhardness of the nanohybrid composite materials, there were significant differences between thicknesses and light-curing modes (p