Journal of esthetic and restorative dentistry : official publication of the American Academy of Esthetic Dentistry ... [et al.] · 2026
Effect of Translucency and Thickness of Zirconia and Lithium Disilicate Veneered Frameworks in Different Shades on the Masking Ability of Discolored Substrates.
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Castillo Duvan Cala, Pilecco Rafaela Oliveira, Pereira Gabriel Kalil Rocha, Bacchi Ataís
Аннотация
PURPOSE: The aim of the present study was to assess the substrate masking ability of veneered zirconia and lithium disilicate ceramic frameworks in two shades and with different thicknesses and translucencies.
MATERIAL AND METHODS: Disc-shaped framework specimens (8 mm in diameter; 0.8 mm and 1.3 mm in thickness) were fabricated with lithium disilicate (LD) (from ingots of medium-opacity, MO and high-opacity, HO) and zirconia (3Y-TZP, sintered at 1350°C and 1550°C, to modulate translucency). Porcelain discs (0.4 mm dentin and 0.3 mm enamel) were produced as veneer layers. Specimens were produced in shades A1 and BL2. Lightness (L*), chroma (C*), and hue angle (h°) were measured. The translucency parameter (TP00) and whiteness index for dentistry (WID) were calculated. Color differences (∆E00) were assessed from data obtained from ceramic specimens placed over reference (A1) and discolored substrates (A4, C4, coppery and silvery metals). Data were analyzed with one-way ANOVA and the Tukey test (α = 0.05). ∆E00 values were compared with the perceptibility (PT = 0.81) and acceptability (AT = 1.77) thresholds. Pearson correlation analysis was performed for the outcomes of TP00 and ∆E00.
RESULTS: All outcomes of the study were significantly influenced by the different frameworks (p < 0.001). Specimens of 3Y-TZP sintered at 1350°C and LD-HO showed higher L* and C* and lower h°, WID, TP00, and ∆E00 values than the other groups, especially with thicker frameworks (p < 0.001); ∆E00 values below the PT and AT were obtained with the referred specimens over all discolored substrates for both A1 and bleach-shade ceramics. Specific groups of LD-MO and 3Y-TZP sintered at 1550°C showed ∆E00 values below the AT over A4 and copper-colored metal substrates. Thicker frameworks reduced TP00 and ∆E00 values of all ceramics. Outcomes of TP00 and ∆E00 showed a strong and positive correlation.
CONCLUSIONS: Masking of discolored substrates was achieved with veneered zirconia and lithium disilicate frameworks, depending on ceramic thickness and translucency relative to each substrate.
CLINICAL SIGNIFICANCE: Discolored substrates can be predictably masked by ceramic restorations produced with porcelain-veneered frameworks, especially those of 3Y-TZP zirconia sintered at lower temperatures and from lithium disilicate with high opacity. Such outcomes are obtained for both A1 and bleach-shade ceramics.
MATERIAL AND METHODS: Disc-shaped framework specimens (8 mm in diameter; 0.8 mm and 1.3 mm in thickness) were fabricated with lithium disilicate (LD) (from ingots of medium-opacity, MO and high-opacity, HO) and zirconia (3Y-TZP, sintered at 1350°C and 1550°C, to modulate translucency). Porcelain discs (0.4 mm dentin and 0.3 mm enamel) were produced as veneer layers. Specimens were produced in shades A1 and BL2. Lightness (L*), chroma (C*), and hue angle (h°) were measured. The translucency parameter (TP00) and whiteness index for dentistry (WID) were calculated. Color differences (∆E00) were assessed from data obtained from ceramic specimens placed over reference (A1) and discolored substrates (A4, C4, coppery and silvery metals). Data were analyzed with one-way ANOVA and the Tukey test (α = 0.05). ∆E00 values were compared with the perceptibility (PT = 0.81) and acceptability (AT = 1.77) thresholds. Pearson correlation analysis was performed for the outcomes of TP00 and ∆E00.
RESULTS: All outcomes of the study were significantly influenced by the different frameworks (p < 0.001). Specimens of 3Y-TZP sintered at 1350°C and LD-HO showed higher L* and C* and lower h°, WID, TP00, and ∆E00 values than the other groups, especially with thicker frameworks (p < 0.001); ∆E00 values below the PT and AT were obtained with the referred specimens over all discolored substrates for both A1 and bleach-shade ceramics. Specific groups of LD-MO and 3Y-TZP sintered at 1550°C showed ∆E00 values below the AT over A4 and copper-colored metal substrates. Thicker frameworks reduced TP00 and ∆E00 values of all ceramics. Outcomes of TP00 and ∆E00 showed a strong and positive correlation.
CONCLUSIONS: Masking of discolored substrates was achieved with veneered zirconia and lithium disilicate frameworks, depending on ceramic thickness and translucency relative to each substrate.
CLINICAL SIGNIFICANCE: Discolored substrates can be predictably masked by ceramic restorations produced with porcelain-veneered frameworks, especially those of 3Y-TZP zirconia sintered at lower temperatures and from lithium disilicate with high opacity. Such outcomes are obtained for both A1 and bleach-shade ceramics.