Influence of framework color and layering technique on the final color of zirconia veneered restorations

Objective: To investigate the influence of colored zirconia frameworks on the overall color match of zirconia- veneered restorations.
Method and Materials: Identical natural and colored zirconia frameworks (Cercon Base, Degudent) were layered using a veneer ceramic (IPS e.max Ceram Dentin, Ivoclar Vivadent) applied either directly on the frameworks, over a thin layer of a masking liner (IPS e.max ZirLiner 1), or over a layer of a deep chroma dentin (IPS e.max Deep Dentin) of the required target color, A1. Color parameters were obtained using a spectrophotometer (Spectro Shade Micro, MHT) and were used to calculate color difference value with the preselected required color (A1 tab according to Vita Classical shade guide). Color difference value < 2.2 was considered a clinically acceptable color match.
Results: Only three combinations of tested variables had an acceptable color match compared with the target color: colored zirconia frameworks with liner material or deep chroma dentin and white zirconia frameworks directly layered with the veneer ceramic (P < .001), all tested against a black background. The combination of yellow zirconia with deep chroma dentin over a white background produced a yellowish color shift, while white zirconia frameworks with either liner or deep chroma dentin were brighter and less yellow than the target color (A1).
Conclusions: When properly veneered, colored zirconia frameworks could produce clinically acceptable color match and have the capacity to mask a dark background such as a dark tooth or core buildup material.