Effect of accelerated artificial aging on color stability of CAD-CAM materials

Abstract Objective: The purpose of this study was to compare the effect of accelerated artificial aging using weathering process on color stability of computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Four CAD-CAM materials were tested; Nano hybrid CAD-CAM composite (Tetric CAD “TC”) , hybrid ceramic (Vita Enamic “VE”), Advanced Lithium disilicate (CEREC Tessera “CT”) and Lithium disilicate (IPS e.max CAD “EM”) . Each group material contains nine samples (n=9). Color measurements of the four materials were assessed before and after accelerated aging in weathering machine for 300 hours using a spectrophotometer based on CIE L*a*b* relative to the standard illumination D65. Color difference was obtained using the formula ∆E=[(∆L*)2+(∆a*) 2+(∆b*) 2]½. Statistical analysis was done using one - way ANOVA and Kruskal-Wallis tests (a=0.05). Results: There was a statistically significant difference between ΔE of CAD-CAM materials. TC showed the highest mean ∆E (4.29) while there was no statistical significance difference between ∆E of VE, CT and EM (3.02, 3 and 2.94 respectively). Conclusions: Artificial accelerated aging caused clinically unacceptable color changes in TC, while it caused perceptible but clinically acceptable color changes in VE, CT, and EM. Chemical composition could influence the change in color of the material. Clinical Significance: When color stability with weathering process is considered; advanced lithium disilicate, lithium disilicate and hybrid ceramic with high color stability may be a better choice than nano hybrid CAD/CAM composite, especially when being used in the anterior esthetic zone.