Effect of Pre-Colored Zirconia Copings on the Final Color of Zirconia Veneered Restorations: An In vitro Study
Delaram Ghaemi
Department of Prosthodontics, Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Iran.
Mohammadreza Nakhaei
Department of Prosthodontics, Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Iran.
Minoo Naderzadeh
Department of Prosthodontics, Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Iran.
Zahra Soroush *
Department of Prosthodontics, Dental Materials Research Center, School of Dentistry, Mashhad University of Medical Sciences, Iran.
*Author to whom correspondence should be addressed.
Abstract
Background: This study aimed to investigate the effect of different zirconia coping shades on the color and translucency of zirconia-based restorations.
Materials and Methods: Zirconia core plates were fabricated from the non-shaded and pre-shaded translucent zirconia materials and were divided into four groups (n=11) according to their shade: Bleach (B), A2, A3, and A4. Next, they underwent porcelain veneering and glazed. The CIELab color measurements were performed before and after porcelain veneering by a colorimeter against white and black backgrounds. Color difference (∆E) between the groups and translucency parameter (TP) were calculated. ∆E values were compared with perceptibility (∆E=2.6) and acceptability (∆E=5.5) thresholds. Data were analyzed by paired t-test, one-way analysis of variance, and Tukey’s Honest Significant Difference post hoc tests (P < 0.05).
Results: The TP and ∆E of the samples significantly decreased in all groups after porcelain veneering compared with baseline (P<0.001). Against a black background, the ∆E of all groups was below the perceptible threshold after porcelain application (P<0.001). Against a white background, ∆E of all groups decreased to a level lower than the perceptible threshold after porcelain veneering except for groups B-A3 (∆E=3.02±0.73) and B-A4 (∆E=4.10±0.70), in which ∆E was between the perceptible and acceptable thresholds (P<0.001).
Conclusions: Porcelain veneering reduces ∆E between two samples more efficiently than pre-colored zirconia copings, especially against a dark background.
Keywords: Ceramics, color, colorimetry, Zirconium oxide