Colour correspondence of ceramic systems in two different shade guides

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Objectives: The aim of this study was to compare the colour correspondence of two different ceramic system, based on two different colour shade guides by the use of a clinical spectrophotometer. Methods: one shade for each of the two ceramic systems was selected: A3 for Vita Omega 900 (Vita Zahnfabrik, Germany) based on Vitapan Classical Shade Guide, 2M3 for Vita Omega 900 (Vita Zahnfabrik, Germany) based on Vitapan 3D Master Shade Guide and 2M3 for Vita VM13 (Vita Zahnfabrik, Germany) based on Vitapan 3D Master Shade Guide. 15 disks were fabricated for each ceramic system using a proprietary steel mould allowing the control of the thickness of each layer. The total thickness of each specimen was 2.0mm. The thickness of the metal base disk was 0.7mm; Opaque was layered in 0.15mm. Dentin Opaque, Dentin and Enamel were then layered following manufacturer's patterns. To correlate with clinical conditions, Dentin Opaque (OD) was layered in a 0.25mm to 0.35mm range, Dentin (D) 0.55mm-0.65mm, Enamel (E) 0.20mm-0.30mm. Each layer thickness was checked after firing. Easyshade (Vita Zahnfabrik, Germany) clinical spectrophotometer was used for colour comparison. Results: The results are shown in Table 1. The independent samples t-test showed a statistical significant difference between the groups (p<0.001). Conclusions: The specimens manufactured with Vita Omega 900 Vitapan Classical shade guide(DE=2.94±0.12) showed a statistically significant lower color correspondence when compared with Vita Omega 900 in 3D-Master shade guide (DE=1.11±0.65) and and VM13 in 3D-Master shade guide system (DE=2.03±0.47). The direct comparison between two different ceramics based on the same shade guide (3D Master) did not reveal significant differences in color correspondence. The 3D Master showed to allow a better color correspondence irrespectively of the ceramic system used. This findings may be explained with the more systematic spatial distribution of 3D Master shade guide color values.