Polymerization efficiency of high-intensity LEDs with different exposure times.

This study compared two high-intensity light-emitting diode (LED) appliances to a quartz-halogen-tungsten (QTH) appliance and measured their ability to polymerize resin composite efficiently. Eighty-four test specimens (2 mm x 5 mm) were made of resin composite and exposed to one of the two LED appliances for 10, 20, or 40 seconds; the QTH appliance was used as a control group for 40 seconds. It was concluded that using the high-intensity LEDs for 20 seconds produced microhardness similar to that produced by using the QTH appliance for 40 seconds, but the high intensity LEDs did not improve depth of cure.