Color stability of CAD/CAM Zirconia ceramics following exposure to acidic and staining drinks

Background: The aim of this in vitro study was to evaluate the color stability of CAD/CAM Zirconia ceramics
following exposure to acidic drink (Coca Cola) and after exposure to staining solution (coffee).
Material and Methods: All the samples were immersed in different staining solutions over a 28-day test period. A
colorimetric evaluation according to the CIE L*a*b* system was performed by a blind trained operator at 7, 14, 21,
28 days of the staining process. Shapiro Wilk test and Kruskal-Wallis ANOVA were applied to assess significant differences
among restorative materials. Paired t-test was applied to test which CIE L*a*b* parameters significantly
changed after immersion in staining solutions.
Results: One week immersion in acidic drink did not cause a perceivable discoloration for all restorative materials
(ΔE < 3.3). Subsequent immersion in coffee affected color stability of all Zirconia samples, even if Kruskal-Wallis
ANOVA found significant differences among the various restorative materials.
Conclusions: The ΔEs of CAD/CAM Zirconia ceramics after immersion in coffee varied among the products, but
color integrity is not affected by contact with acidic drinks.