Effect of Varying Thickness and Number of Coloring Liquid Applications on the Color of Anatomic Contour Monolithic Zirconia Ceramics

Statement of the problem: there is not enough information available about the effect of thickness reduction and the coloring method on the color of new mono-lithic zirconia ceramic system. purpose: this study aimed to evaluate the effect of varying thickness reductions and number of coloring liquid applications on the final color of anatomic contour monolithic zirconia ceramics. materials and method: in this experimental in-vitro study, 48 disk-shaped mono-lithic zirconia specimens (10×2mm) were divided into three groups (group i to iii) according to the number of a2 -coloring liquid applications (n=16). each group was then divided into 4 subgroups (n=4) by reducing the thickness of 2 to 0.5 mm in increments of 0.5 mm on the colored surface. color measurement was done through cielab (l*, a*, b*) on a reflection spectrophotometer on five differ-ent areas of each specimen. color differences (δe) were calculated. data were analyzed by using two-way anova and tukey’s hsd test (α=0.05). results: the number of coloring liquid applications and reducing the thickness of monolithic zirconia disks had significant effects on cie l* a* and b* values. the ciel*, a* and b* values increased as the thickness decreased (p< 0.05), whereas, increasing the number of coloring liquid applications resulted in decreased cie l* value and increased cie a* and b* values (p< 0.05). conclusion: decreasing the thickness of monolithic zirconia increases the light-ness and reddish, yellowish appearance. meanwhile, increasing the number of coloring liquid applications reduces the lightness and makes it seem more reddish and yellowish.