Effects of different polishing procedures on the color stability of recent resin composites

Purpose: To evaluate different polishing methods' effects on the color stability of recent resin composites. Methods: 160 samples for color stability evaluation and 40 samples for the degree of conversion evaluation were prepared with four different resin composites [Harmonize (H), Filtek Universal (F), Omnichroma (O), Essentia Universal (E)] and light cured. For color stability evaluation, samples prepared from each resin composite were divided into four groups: three polishing procedures and a control group. The Delta E-00 was calculated between initial, and after immersion in coffee solution for 12 days. The degree of conversion was evaluated with Fourier Transform Infrared Spectroscopy. The statistical analysis of Delta E-00 values was made with the two-way ANOVA, Tukey HSD, and Tamhane's T2 tests. One-way ANOVA and Tukey HSD tests were used to compare the degree of conversion values (P<0.05). Results: in all composite groups, mylar (control) groups had the highest Delta E-00, and no differences between other polishing procedures. According to the polishing procedures, Omnichroma showed the highest Delta E-00 values (on mylar groups 0 vs F, P<0.001; O vs H, P<0.001; 0 vs E, P<0.001). There was a significant difference between the composite groups in terms of the degree of monomer conversion (P<0.05). Omnichroma showed, significantly, the highest discoloration.