The Effect of an Opaque Coating on the Color of High Translucency Zirconia

Hypothesis and Objective: Clinically perceptible color differences are observed when titanium or gold-hue titanium abutment materials are used with high-translucency zirconia. The objective of this study was to evaluate the effectiveness of an opaque medium painted on high translucency monolithic zirconia in masking the underlying implant abutment material. Our null hypothesis is that there is no mean difference in the color difference value (ΔE00) for each abutment material group between the opaqued and non-opaqued groups. Methods: Zirconia, titanium, and gold-hue titanium discs were fabricated to emulate abutment materials (N=10). Telio discs were used as control group. E.max ZirCAD MT discs were used to emulate high translucency zirconia restorations. Half of the E.max ZirCAD MT discs were painted with an opaque medium. The different groups were cemented with either SpeedCem Plus transparent or opaque-shade cement. A calibrated reflectance spectrophotometer was used to measure color parameters for each of the samples (L*a*b* values of CIE L*a*b* color space). The ΔE00 was measured between the control group and test groups. The effect of an opaque medium, implant abutment material and luting cement on the color of high translucency zirconia was analyzed via a Two-way ANOVA. Results: There was a statistically significant mean difference between opaqued and non-opaqued samples on the color of high translucency zirconia for titanium and gold-hue-titanium abutments, p-values are < 0.001 and 0.045, respectively. However, there was no statistical difference between opaque and non-opaque when zirconia abutments were used, p-value = 0.254. With an opaque layer, luting cement color did not have a statistically significant effect on the color of high translucency zirconia in comparison to non-opaqued zirconia. Conclusions: An opaque layer improves the color match for all abutment materials in comparison to no opaque layer; however, titanium and gold-hue titanium abutments still result in a clinically unacceptable result.