The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high...

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-tungsten-halog...

OBJECTIVES To verify the effect of interposing different indirect restorative materials on degree of conversion (DC), hardness, and flexural strength of a dual-cure resin cement. METHODS Discs (2 mm-thick, n=5) of four indirect restorative materials were manufactured: a layered glass-ceramic (GC); a heat-pressed lithium disilicate-based glass-ceramic veneered with the layered glass-ceramic (L...

OBJECTIVE The aim of this study was to determine the effects of light intensity and type of light unit (quartztungsten-halogen [QTH] or light-emitting diode [LED]) on the hardening of various resin cements and a resin composite restorative. METHODS Disk specimens were prepared from 4 dual-cured resin cements (Variolink II, Calibra, Nexus 2 and RelyX ARC). Two QTH light-curing units (Visilux 2...

The aim of this study was to determine the effect of different types of composites (Filtek Z250, Esthet X and Filtek Supreme) and dentin thicknesses (0.5 or 1.0 mm) on the generation of heat during photoactivation by QTH (conventional halogen light), LED (light emitting diode), and PAC (xenon plasma light) light-curing units. Temperature changes were recorded with a thermocouple type K connecte...

BACKGROUND Light-emitting diode (LED) curing lights offer advantages over quartz-tungsten-halogen (QTH) lights, but the first-generation LED lights had some disadvantages. PURPOSE This study compared a second-generation LED light with a QTH light to determine which was better at photopolymerizing a variety of resin composites. METHODS The ability of a LED light used for 20 and 40 seconds to...

PURPOSE To compare the effect of reduced exposure times on the microhardness of resin composites cured with a "second-generation" light-emitting diode (LED) curing light and a quartz-tungsten-halogen (QTH) curing light. METHODS Ten composites were cured with a LED curing light for 50% of the manufacturers" recommended exposure time or a QTH light at the high power setting for 50% of the recom...