Comparative evaluation of secondary heat treatment and a high intensity light source for the improvement of properties of prosthetic composites.

This study determined the hardness and water solubility of two prosthetic composites polymerized with three curing modes for the purpose of evaluating the influence of secondary heating and a high intensity light source on resulting material properties. Two prosthetic composite materials (Artglass and Dentacolor) were cured with the following methods: (1) exposure by means of a photo-curing unit with a xenon stroboscopic light source (Dentacolor XS) for 120 s; (2) exposure with the xenon unit for 120 s, followed by heating in an oven (KL 100) at 100 degrees C for 15 min; and (3) exposure by means of a photo-curing unit with two metal halide lamps (Hyper LII) for 120 s. Knoop hardness and water solubility were determined according to standardized testing methods. Although post-cure heat treatment considerably elevated the Knoop hardness number for both materials, the greatest hardness number was generated with the use of the metal halide unit. Water solubility of the Dentacolor material was lowest when the material was cured with the metal halide unit, followed by the secondary heated group, whereas, solubility of the Artglass material was unaffected by the curing modes. This suggests that the use of a high intensity light source is more effective than the application of secondary heating for improving the post-curing properties of composites.