Color in Zirconia-Based Restorations and Related Factors: A Literature Review.

Zirconia ceramic is a popular trend in esthetic and restorative dentistry. Computer-aided design/computer-aided manufacturing (CAD/CAM) systems have been well developed to fabricate zirconia frameworks and restorations with acceptable mechanical properties. Zirconia ceramics have excellent optical characteristics; however, achieving optimal esthetic outcomes with zirconia-based restorations is still challenging due to multiple effective factors on the final color. These factors are different layers of a zirconia-based restoration and its underlying structures including: dental substrate, cement, zirconia coping, veneering ceramic, and glaze. Moreover, the laboratory procedure of these restorations' fabrication is another effective factor on the resultant color. Unpredictable esthetic results may be obtained without estimation of the role of each factor and its effect on the final color. This review discussed the color aspect of zirconia-based restorations according to these factors and based on the literature. In the past decade, investigators have been concerned with the shade reproduction with zirconia-based restorations; however, there are no sufficient clinical guidelines on how to reproduce the appearance of natural teeth with these restorations. Zirconia-based restorations have presented a new chance for accomplishing optimum esthetics. Nonetheless further investigations are needed on these restorations to establish clinical guidelines on esthetics.