Effect of Coloring of Zirconia Framework and Ceramic Veneer on Adhesion of Interfacial Surfaces Determined Using Three-Point Flexural Bonding Strength: An In Vitro Study

Purpose: The aim of this study was to investigate the effect of coloring on the interfacial surface adhesion between a zirconia framework and ceramic veneer using three-point flexural bonding strength. Materials and Methods: A total of 40 zirconia bars (Zirlux ST1; DE Healthcare) were cut and divided into two groups of 20 (Groups 1 and 2). The two groups were then further split and divided into four groups of 10 each (Groups 1a, 1b, 2a, and 2b). Groups 1a and 1b tested adhesion of uncolored zirconia and two different shades of ceramic veneer, and Groups 2a and 2b tested adhesion of zirconia colored with two different coloring liquids and one shade of ceramic veneer. Results: Some coloring liquids used to color zirconia can significantly affect the bond strength between zirconia and the veneer, whereas ceramic veneer shades do not influence adhesion. Conclusion: Bonding strength between zirconia framework and ceramic veneer is affected by the coloring of the zirconia.