Comparison of PAC and QTH light sources on polymerization of resin composites.

Purpose: To evaluate the polymerization shrinkage, Knoop hardness number (KHN) and compressive strength and to suggest a suitable time for irradiating resin composite restorations, when using a high-intensity light source.

Methods: Two restorative resin composites, UniFil F, and Clearfil AP-X were employed. A high-intensity light unit (more than 1000mW/cm2) with a xenon discharge lamp (Apollo 95E), which is generally called a plasma arc light-curing unit (PAC), was compared with a conventional light-curing unit fitted with a quartz-tungsten-halogen lamp (QTH) (GC Newlight VL2).