Color match of ultra-translucency multilayer zirconia restorations with different designs and backgrounds

The purpose of this in vitro study was to assess the color match of ultra-translucency multilayer zirconia restorations with different designs and backgrounds.

Thirty ultra-translucency multilayer zirconia crown specimens were made in VITA classical shade B2 for a prepared maxillary central incisor. The specimens were divided into three groups based on the restoration design: veneered zirconia with a trestle design (VZT), veneered zirconia with a dentin core design (VZD), and full-contour zirconia (FCZ). In the groups VZT and VZD, the zirconia specimens were layered with a feldspathic veneering ceramic. The specimens were seated on five different backgrounds: shade B2 composite resin, shade B2 zirconia, copper-colored metal alloy, silver-colored metal alloy, and the prepared central incisor. CIELab values of the labial middle sections of the crown specimens were measured with a spectrophotometer. Color differences between the specimens and a shade B2 VITA classical tab (as a control) were calculated from the ΔE^* _ab formula and compared with an acceptability threshold (ΔE^* _ab = 3.7) to be clinically explicated.

Mean ΔE^* _ab values ranged between 1.17 and 8.48. The restoration design, the background type, and their interaction affected the ΔE^* _ab (p < 0.001). The mean ΔE^* _ab values for VZT with all backgrounds and for VZD with the silver-colored metal background were greater than the threshold (p < 0.001), whereas the mean ΔE^* _ab values for VZD with the other backgrounds and FCZ with all backgrounds were less than the threshold (p = 1).

Restoration design and background type affected the color match of ultra-translucency multilayer zirconia restorations. VZT restorations on all backgrounds and VZD restorations on a silver-colored metal background showed color mismatches. However, VZD restorations on the other backgrounds and FCZ restorations on all backgrounds demonstrated color matches.