Color of Zirconia-Based Posterior Crowns

Objective: The objective of this study was to determine the effect of a color of an underlying structure on the overall color of zirconia-based all-ceramic posterior crowns.Methods: Twenty-one posterior crowns were made for twenty subjects, using the CAD-CAM technique for a zirconia core ceramic and conventional condensation and sintering methods for a veneering ceramic. (ZENO®, WIELAND Dental and Technik, Germany, and IPS e. max Ceram, Ivoclar Vivadent AG, Liechtenstein) Seven premolar crowns and six molar crowns were cemented onto abutments with a metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and a composite core built-up. The thicknesses of each core and core plus veneering were measured three times at buccal and occlusal surfaces. The color measurements of all crowns were made using a shade measurement device before try-in, before and after cementation using the CIE-Lab parameters. A repeated measure ANOVA was used for statistical analysis. Results: The means thickness of the core ceramics were 0.6- 0.7 mm for all crowns. L*, a*, and b* values did not show a significant change when compared the values obtained before try-in, before and after cementation for all ceramic crowns. (p>0.05) However, L* values of ceramic crowns with metal cast post and core appeared to be decreased and a* was increased when comparing between before try-in and before cementation. No notable change of the L* values in the third group was observed, but a*and b* were increased when comparing between before try-in and before cementation. Conclusions: Slight shade differences were observed for all-ceramic crowns before try-in, before and after cementation. These results indicated that color of an underlying structure had a minor effect on the overall color of zirconia-based posterior crown.