Effect of Light‐Curing Method and Cement Activation Mode on Resin Cement Knoop Hardness

Abstract

To evaluate the Knoop hardness (KHN) of the resin cement Enforce activated by chemical/physical mode or physical mode solely; light-cured directly or through a 1.5 mm thick ceramic disc (HeraCeram) on shade DD2. Light-curing was carried out using a conventional quartz tungsten halogen light (QTH) (XL2500) for 40 seconds at 700 mW/cm(2); light-emitting diodes (LED) (Ultrablue Is) for 40 seconds at 440 mW/cm(2); and Xenon plasma arc (PAC) (Apollo 95E) for 3 seconds at 1600 mW/cm(2). Bovine incisors had their buccal faces flattened and hybridized. A mold was seated on these surfaces and filled with cement. A disc of the acid-etched and silanized veneering material was seated over this set for light-curing. After dry storage (24 hours at 37 degrees C), specimens (n= 10) were sectioned for KHN measurements performed in a microhardness tester (50 gf load for 15 seconds). Data were submitted to ANOVA and Tukey's test (alpha= 0.05). The highest KHN values were obtained with LED, for both dual-cured and light-cured cement. The lowest KHN value was obtained with light-cured PAC. Light-curing with QTH resulted in hardness values similar to PAC in dual-cured groups. Light-curing through HeraCeram can influence resin cement hardness.