Effect of different surface finishing/polishing procedures on color stability of esthetic restorative materials: A spectrophotometric evaluation

OBJECTIVE: To evaluate the color stability of different esthetic restorative materials after surface finishing/polishing with different procedures. MATERIALS AND METHODS: All materials were polymerized into silicone rubber rings to obtain specimens identical in size. Samples were randomly assigned into four groups (10 specimens of each composite for each group), and they were finished with different procedures: Control group (Group 1), three or two polishers interspersed with diamond grit (Groups 3 and 2, respectively), and one tungsten carbide bur + one polisher interspersed with diamond grit (Group 4). After staining process in coffee, a colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21, and 28 days. Shapiro-Wilk test and Kruskal-Wallis analysis of variance were applied to assess significant differences among restorative materials. Means of the different polishing/finishing groups were compared with Scheffe's multiple comparison test at the 0.05 level of significance. RESULTS: In control group, significant lower discolorations were recorded for Essentia, Admira Fusion, and Estelite. After finishing, Filtek Supreme XTE and Ceram.X Universal showed a significantly lower degree of staining. The finishing technique used for Group 4 produced higher color changes. CONCLUSIONS: Tungsten carbide burs produced the higher color variations; after finishing, the nanofilled composites showed lower discoloration than nanohybrid ones, and the time of exposure to the staining agent and the polishing/finishing technique influenced the color change.