Influence of thermocycling on the optical properties of laboratory resin composites and an all-ceramic material.

The purposes were to determine the difference of color and translucency of dental laboratory resin composites and an all-ceramic material, and to compare the changes in optical properties after thermocycling. Three shades for enamel appearance of two laboratory resin composites (ART; Artglass, TES; Tescera) and all-ceramic material (EMP; Empress 2) were chosen, and three disk specimens for each shade and thickness (0.8, 1.3 and 1.8 mm) were made. Color and spectral reflectance were measured before and after thermocycling over white and black backgrounds. Contrast ratio (CR) and translucency parameter (TP) were calculated. Before and after thermocycling, CR of 1.8 mm specimens did not differ between the materials. After thermocycling, CR and TP of TES were not changed significantly; however, ART and EMP showed increased CR and decreased TP in some shades (p = 0.05). Color change of three materials after thermocycling was not significant. CR increased in inverse proportion to TP (r = - 0.93, p < 0.01). In TES, change of translucency after thermocycling was lower than those of other materials regardless of the specimen thickness. TES seemed to yield more predictable curing performance.