Colour correspondence of a ceramic system in two different shade guides

Objectives: The aim of this study was to test by means of a clinical spectrophotometer the ability of a ceramic system to correctly reproduce the selected shade with reference to two available shade guides. 

Methods: One shade for each guide of Vita Omega 900 ceramic system (Vita Zahnfabrik, Germany) was selected: A3 for the system based on Vitapan Classical; 2M3 for the system based on Vitapan 3D Master. Fifteen discs were fabricated for each ceramic using a proprietary steel mould that allowed to control the thickness of each layer. The total thickness of the specimen was 1.6 mm. The thickness of the metal base disc was 0.3 mm, while opaque was layered in 0.15 mm. Dentin opaque (0.25-0.45 mm), dentin (0.5-0.7 mm), and enamel (0.1-0.3 mm) were then layered following manufacturer's patterns. Each layer thickness was checked after firing. Easyshade (Vita Zahnfabrik, Germany) clinical spectrophotometer was used for colour comparison. "Restoration" mode was selected using A3 and 2M3 shades as comparison. The obtained ΔE values were statistically analyzed with the Two-Way Analysis of Variance and the Tukey Test. 

Results: A closer colour correspondence resulted for the ceramic based on Vitapan 3D Master (ΔE = 1.80 ± 0.42) than for Omega 900 in Vitapan Classical (ΔE = 2.94 ± 0.12) (p < 0.001). 

Conclusions: The shade matching ability of the VITA 3D-Master Tooth Guide was found to be more reliable than that of the VITA Classical Shade Guide for Omega 900.