# Color characteristics of various computerized machinable ceramics veneered to yttria-stabilized tetragonal zirconia polycrystalline upon different hybridized techniques

## TL;DR

This study explores how different ceramic materials and hybridization techniques affect the color properties of zirconia used in dental restorations.

## Contribution

The study identifies how specific ceramics and hybridization methods influence translucency, opalescence, and color alteration in zirconia veneers.

## Key findings

- Vm and Em ceramics showed better translucency and opalescence with less color alteration compared to Vs and Cd.
- CAD-fused hybridization reduced translucency and increased color alteration due to t→m transformation.
- Color characteristics of ceramic veneered zirconia are significantly affected by both material and hybridization technique.

## Abstract

Hybridization technique impacted color of ceramic veneered zirconia. This study examined color characteristics of different ceramics veneered zirconia upon different hybridized techniques.

120 zirconia specimens (0.8 mm thickness, 12 mm diameter) were prepared from 3-yttria-stabilized tetragonal zirconia polycrystalline and unintentionally veneered with Vitabloc Mark-II (Vm), IPS e.max CAD (Em), Vita-Suprinity (Vs), and Celtra-Duo (Cd), by CAD-bonded (Cb) versus CAD-fused (Cf) hybridization (n=15/group). CIE-L*a*b* color characteristics were determined for translucency parameter (TP), contrast ratio (CR), opalescence parameter (OP), and color difference (ΔEdiff). Microstructures were investigated with SEM and XRD. Analysis of Variance and Bonferroni comparisons were determined for significant differences (p<0.05).

TP and OP were significantly higher, but lower CR and ΔEdiff for Vm and Em than Cd and VS. Cf hybridized technique significantly decreased TP and OP but increased CR and ΔEdiff than Cb, which amplified color alteration. Better TP and OP, with less CR and ΔEdiff, were achieved for zirconia veneering with either Vm or Em, compared to Vs or Cd, whether hybridized with Cb or Cf technique.

Different veneering ceramics and hybridized techniques significantly altered color characteristics of ceramic veneered zirconia. Zirconia veneering with either Vm or Em appeared to produce better translucence and opalescence, with less contrast and color alteration than veneering with either Vs or Cd. CAD-fused decreased translucency, opalescence, and intensified color alteration due to t→m transformation. Nevertheless, the color alteration of ceramics veneered zirconia still rendered an acceptable limit, except for both Vs and Cd upon Cf hybridization.

Key words:CAD/CAM, color, contrast, hybridized technique, opalescence, translucency.