Effect of the Increase of Energy Density on Knoop Hardness of Dental Composites Light-Cured by Conventional QTH, LED and Xenon Plasma Arc

Abstract

The aim of this study was to evaluate the effect of the increase of energy density on Knoop hardness of Z250 and Esthet-X composite resins. Cylindrical cavities (3 mm in diameter X 3 mm in depth) were prepared on the buccal surface of 144 bovine incisors. The composite resins were bulk-inserted and polymerized using different light-curing units and times: conventional QTH (quartz-tungstenhalogen; 700 mW/cm 2 ; 20 s, 30 s and 40 s); LED (light-emitting diode; 440 mW/cm 2 ; 20 s, 30 s and 40 s); PAC (xenon plas…