Properties of a new photo-activated composite polymerized with three different laboratory photo-curing units

This study determined the hardness, solubility and curing depth of a new photo-activated composite polymerized with three different laboratory photo-curing units for the purpose of evaluating the post-curing properties of the material. A new photo-activated composite material for both direct and indirect applications (DiamondCrown) was polymerized with three photo-curing units equipped with the following light sources: (i) two halogen lamps (DiamondLite-VL. Halogen Light Curing Booth); (ii) two metal halide lamps (Hyper LII) and (iii) two xenon stroboscopic tubes (UniXS II). Knoop hardness, water solubility and curing depth were determined for groups of five specimens according to standardized testing methods. All data were compared using analysis of variance (anova) and Scheffe's S intervals (P < 0.05). The Knoop hardness number (KHN) generated with the metal halide unit (63.3 +/- 2.4 KHN) was statistically (P < 0.05) greater than those produced by the other two curing units. Water solubility values for both the halogen unit (2.5 +/- 0.5 microg mm(-3)) and the metal halide unit (2.5 +/- 0.5 microg mm(-3)) were significantly (P < 0.05) lower than for the xenon unit (3.8 +/- 0.5 microg mm(-3)). Of the three photo-curing units, the metal halide curing-unit consistently exhibited the greatest depth of cure. The composite material appears to be reliable, although its post-curing properties were found to be influenced by the type of curing unit.