Methods: IPS e.max, IPS Classic, Gradia and Sinfony materials were tested, both unpolished (as-cast) and polished. Coffee, tea, red wine and distilled water (blank) were used as staining drinks. Disk-shaped samples were soaked in the staining drinks for up to 5 days. Color was measured by a colorimeter. Fluorescence was recorded using a spectrofluorimeter, in the front-face geometry. Time-resolved fluorescence spectra were recorded used a laser nanosecond spectrofluorimeter.
Results: The exposure of examined dental materials to staining drinks caused changes in color of the composites and ceramics, with the polished samples exhibiting significantly lower color changes as compared to unpolished samples. The materials with lower color stability were the composites , while those with higher color stability were the ceramic materials. Water also caused perceptible color changes in most materials. All materials demonstrated significantly different luminescence intensities., Upon exposure to staining drinks, luminescence became weaker by up to 40%, dependent on the drink and the material. Time-resolved luminescence spectra exhibited some red shift of the emission band at longer times, with the lifetimes in the range of dozens of nanoseconds.
Conclusions: Unpolished materials with a more developed surface have lower color stability. Samples stored in water develop some changes in their visual appearance. It is important to improve the color and luminescence stability of dental materials. The presently proposed methods are effective in evaluating the luminescence of dental materials. Luminescence needs to be tested in addition to color, as the two characteristics are uncorrelated.