STATEMENT OF PROBLEM: Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. PURPOSE: The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). CONCLUSIONS: The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.
STATEMENT OF PROBLEM: Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. PURPOSE: The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). CONCLUSIONS: The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.