Effect of coping thickness and background type on the masking ability of a zirconia ceramic
Available online 5 May 2017
Abstract
Statement of problem
The masking ability of zirconia ceramics as copings is unclear.
Purpose
The
purpose of this in vitro study was to evaluate the effect of coping
thickness and background type on the masking ability of a zirconia
ceramic and to determine zirconia coping thickness cut offs for masking
the backgrounds investigated.
Material and methods
Thirty
zirconia disks in 3 thickness groups of 0.4, 0.6, and 0.8 mm were
placed on 9 backgrounds to measure CIELab color attributes using a
spectrophotometer. The backgrounds included A1, A2, and A3.5 shade
composite resin, A3 shade zirconia, nickel-chromium alloy, nonprecious
gold-colored alloy, amalgam, black, and white. ΔE values were measured
to determine color differences between the specimens on the A2 shade
composite resin background and the same specimens on the other
backgrounds. The color change (ΔE) values were compared with threshold
values for acceptability (ΔE=5.5) and perceptibility (ΔE=2.6). Repeated
measures ANOVA, the Bonferroni test, and 1-sample t tests were used to analyze data (α=.05).
Results
Mean
ΔE values ranged between 1.44 and 7.88. The zirconia coping thickness,
the background type, and their interaction affected the CIELab and ΔE
values (P<.001).
Conclusions
To
achieve ideal masking, the minimum thickness of a zirconia coping
should be 0.4 mm for A1 and A3.5 shade composite resin, A3 shade
zirconia, and nonprecious gold-colored alloy, 0.6 mm for amalgam, and
0.8 mm for nickel-chromium alloy.
Comments