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

To investigate the influence of colored zirconia frameworks on the overall color match of zirconia-veneered restorations.

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.

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).

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.