Color Of Ceramic Restorations Research Articles

Effects of Substrate and Cement Shade on the Translucency and Color of CAD/CAM Lithium-Disilicate and Zirconia Ceramic Materials.

The aim of this in vitro study was to evaluate the effects of substrate and cement shades on the translucency and color of lithium-disilicate and zirconia CAD/CAM materials. Two light-cured resin cements (RelyX Veneer Cement; 3M; Choice 2 Veneer Cement; Bisco Dental) with a standardized thickness (0.1 mm) were tested in combination with two different monolithic CAD/CAM materials (E-Max CAD (LI2SI2O5); Ivoclar Vivadent; Katana (ZrO2); Kuraray-Noritake Dental) on two different colored composite substrates used as a dentin (Filtek Supreme XTE; 3M); for a total of 12 combinations (n = 10). The specimens’ color was measured with a spectrophotometer (Spectroshade; MHT). Measurements were taken using the CIELAB color coordinate system (L*a*b*) against black and white backgrounds. L*a*b* values were statistically analyzed for the variables Substrate, Ceramic, and Cement by applying a Three-Way ANOVA followed by the Tukey Test for post-hoc comparison (p < 0.05). Translucency Parameter (TP) and Constant Ratio (CR) were assessed to evaluate translucency; acceptability and perceptibility thresholds (ΔE00 1.8 and 0.8) were used. Statistically significant influence was found for factors ceramic material, cement shade, and substrate color (p < 0.05). Unacceptable color differences were reported for Li2Si2O5. Opacity was significantly higher when white opaque cement shade was employed. Ceramic type and cement shade significantly influenced L*a*b* color coordinates. The final translucency and color of ceramic restorations can, therefore, be influenced by ceramic material, cement shade, and substrate color.

Effect of in vitro aging and acidic storage on color, translucency, and contrast ratio of monolithic zirconia and lithium disilicate ceramics

Statement of problemHow the translucency and color of ceramic restorations are affected by surface changes from the corrosive environment in the oral cavity and aging of materials is unclear. PurposeThe purpose of this in vitro study was to compare the impact of acidic exposure and aging on the color and translucency of monolithic zirconia and lithium disilicate ceramics. Material and methodsTwenty computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic zirconia specimens and 20 pressed lithium disilicate specimens were fabricated. Half of the specimens of each group were aged in an autoclave (7.5 hours, 134 °C, 0.2 MPa), and the rest were immersed in hydrochloric acid to simulate the acidic conditions in the oral cavity from gastric reflux. The color coordinates L∗, a∗, and b∗ were measured with an ultraviolet spectrophotometer before and after aging or acidic storage. The translucency parameters and contrast ratios were calculated, and the CIEDE2000 color difference formula was used to determine color differences before and after each treatment. ANOVA and ANCOVA test models were used for data analysis (α=.05), while differences of color parameters in respect to acceptability and perceptibility thresholds were evaluated with the 1-sample t test (α=.05). ResultsLithium disilicate presented a significantly higher translucency parameter and lower contrast ratio at baseline compared with monolithic zirconia specimens (P<.001). Acidic storage significantly impacted all parameters compared with aging, especially for the lithium disilicate group. Color differences were above the acceptability ΔΕ00 threshold for lithium disilicate after acidic storage (P=.001) and below for monolithic zirconia after acidic storage (P=.003). ConclusionsThe performance of lithium disilicate was slightly inferior compared with that of monolithic zirconia specimens, as they presented significant and clinically observable differences for the translucency parameter and ΔΕ00 after acidic storage and aging.

Main Factors Affecting the Final Color of Ceramic Restorations

Main Factors Affecting the Final Color of Ceramic Restorations

Effect of porcelain crown substructures on visually perceivable Value

Factors that will affect the potential color of ceramic restorations must be understood to control variables that exist. Clinical observations of porcelain restorations lead to the hypothesis that certain substructures tend to produce crowns with a lower than expected Value (brightness). This study was done to determine whether a visually perceivable difference could be detected between groups of ceramic crowns with different substructures. Two test groups of crown types with four different porcelain substructures were compared. In the first group, metal ceramic crowns made with either Galaxy or Rexillium III alloys were compared. In the second group, aluminous porcelain jacket crowns with and without a tin-plated, bonded platinum foil internally were compared. Visual analysis showed that (1) in the metal ceramic group, the crowns with the Rexillium III substructure were scored as more often having a lower significant Value, and (2) in the aluminous porcelain jacket group the crowns with the tin-plated, bonded platinum substructures were scored as more often having a lower significant Value.