Color Stability of Hybrid Ionomers After Accelerated Aging

PURPOSE: The color stability and surface roughness of three commercial hybrid ionomers were determined in vitro after accelerated aging. Three shades of each hybrid ionomer prepared in light-cured and dark-cured conditions were tested. MATERIALS AND METHODS: Samples were aged in an artificial aging chamber by subjecting them to total ultraviolet light irradiation of 150 kJ/m2 over a period of 77 hours. Color (CIE LAB system) was measured before and after aging on a reflection spectrophotometer. Surface roughness was measured with a profilometer. RESULTS: After accelerated aging, all samples became lighter. Photac-Fil Aplicap (ESPE-Premier, Norristown, PA) and Fuji II LC (GC America, Chicago, IL) also became less chromatic (less red and less yellow). Among the light-cured samples, Fuji II LC had the greatest change in color followed by Photac-Fil Aplicap and Vitremer (3M Dental Products, St Paul, MN). For the dark-cured samples, Fuji II LC had the greatest change in color followed by Vitremer and Photac-Fil Aplicap. There were no differences in delta E* between the two lightest shades, but the darker shades of each product showed the greatest changes in color. All samples became significantly rougher after aging. CONCLUSIONS: Hybrid ionomers changed color significantly and perceptibly after in vitro accelerated aging. Surfaces became significantly rougher and showed evidence of cracking and degradation.