The Effect of two Shading Techniques on Value of Zirconia-Based Crowns

STATEMENT OF THE PROBLEM: By introducing the coloring liquids, it is claimed that it is possible to make the color of frameworks fabricated from zirconium oxide extremely close to the natural tooth color. PURPOSE: The purpose of this research was to evaluate the effect of two staining techniques on value changing in zirconia crowns. MATERIALS AND METHOD: Three groups A, B, and C, each containing ten zirconia crowns, were used. The zirconium cores samples were fabricated by a CAD/CAM device. Group A was left uncolored, Groups B was submerged for two minutes in A2 coloring liquid and Group C was stained with brush. Then all cores were sintered and the porcelain was applied by using the layering technique. Ultimately, the crowns color was determined using a spectrophotometer. Their color changing (∆E) and value changing (∆L) in relation to A2 color were also assessed. The data were analyzed with one-sample t-test, post-hoc Tukey, and one-way ANOVA tests with significant level set at 0.05. RESULTS: The mean value in all groups was higher than the value obtained from A2 color samples (p= 0.001). The highest mean value was 78.31±1.22 belonging to group C (staining with brush) and the lowest mean value was 76.99±0.65 belonging to group B (submerging). The results of post-hoc Tukey regarding both ∆E and ∆L variables showed a significant difference between groups A (uncolored) and C (staining with brush) with P(∆E)=0.006 and P(∆L)=0.039, respectively. A significant difference between group B (submerging technique) and C (staining with brush) were shown when these two variables were compared (P(∆E)=0.001, P(∆L)=0.015). CONCLUSION: Due to the higher value increase in surface staining (brush), it is recommended to use the submerging technique for staining zirconia cores.