Evaluation of the Color of Zirconia in Different Substrates of Osseointegrated Implants, Thickness of Materials and Types of Resin Cements.

Abstract

Objectives: To evaluate the impact of surface conditioning of titanium, zirconia thickness, and cement type on the final color of zirconia luted to the titanium. Methods: A total of 192 grade 5 titanium specimens with the final dimensions 10 mm × 10 mm × 2 mm were fabricated and subjected to four different surface conditioning including, that is, sandblasting, etching, and anodization. In addition, 192 zirconia specimens with the same dimensions as the titanium specimens but altered thicknesses of 0.7 (n = 96) and 1.0 (n = 96) mm were fabricated using 5Y-TZP zirconia. Color as expressed by L ^∗ (lightness), a ^∗ (red-green axis), and b ^∗ (blue-yellow axis) of titanium and zirconia specimens as well as the joined titanium-zirconia complex, total assembly (Panavia V5 clear, PC; opaque, PO, each n = 96) were determined under standardized conditions using a spectroradiometer (SpectraScan P-650). Color differences were calculated using the ΔE ₀₀ formula. ANOVA supplemented with post hoc Tukey test for group comparisons was compiled to estimate possible effects of titanium conditioning, zirconia thickness, and type of cement used on the final zirconia color (SPSS Ver. 28; α = 0.05). Results: All investigated factors affected the zirconia color of the total assembly (p  < 0.001). Using PO mean values of all groups were still close to baseline colors (ΔE ₀₀ between 5.5 and 6.2). When using PC, the final color was significantly altered, irrespective of the other parameters. Specimens luted with PO appeared lighter, less reddish (a ^∗ was affected predominately by sample thickness), and more bluish, while luting with PC resulted in reduced lightness combined with large shifts along the red and yellow axes. Significance: Color changes of zirconia luted to titanium are primarily affected by the color of the substrate if a translucent cement was used. Vice versa, the application of an opaque cement effectively masked the dark substrate color. Substrate color and choice of cement have to be taken into consideration when performing shade selection.