Masking ability of a zirconia ceramic on composite resin substrate shades

Farhad Tabatabaian, Sima Shabani, Mahshid Namdari, Koroush Sadeghpour


Background: Masking ability of a restorative material plays an important role to cover discolored
tooth structure; however, this ability has not yet been well understood in zirconia‑based restorations.
This study assessed the masking ability of a zirconia ceramic on composite resin substrates with
different shades.
Materials and Methods: Ten zirconia disc specimens, with 0.5 mm thickness and 10 mm
diameter, were fabricated by a computer‑aided design/computer‑aided manufacturing system.
A white substrate (control) and six composite resin substrates with different shades including
A1, A2, A3, B2, C2, and D3 were prepared. The substrates had a cylindrical shape with 10 mm
diameter and height. The specimens were placed onto the substrates for spectrophotometric
evaluation. A spectrophotometer measured the L*, a*, and b* values for the specimens. ΔE values
were calculated to determine the color differences between the groups and the control and
then were compared with a perceptional threshold (ΔE = 2.6). Repeated measures ANOVA and
Bonferroni tests were used for data analysis (P < 0.05).
Results: The mean and standard deviation of ΔE values for A1, A2, A3, B2, C2, and D3 groups
were 6.78 ± 1.59, 8.13 ± 1.66, 9.81 ± 2.64, 9.61 ± 1.38, 9.59 ± 2.63, and 8.13 ± 1.89, respectively.
A significant difference was found among the groups in the ΔE values (P = 0.006). The ΔE values
were more than the perceptional threshold in all the groups (P < 0.0001).
Conclusion: Within the limitations of this study, it can be concluded that the tested zirconia
ceramic could not thoroughly mask different shades of the composite resin substrates. Moreover,
color masking of zirconia depends on the shade of substrate.
Key Words: Color, spectrophotometry, visual perception, ceramic

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