Effect Of Stain Firing On The Translucency And The Color Of All-ceramic CAD/CAM Restorations

Objective: To investigate the influence of repeated staining firings on the translucency and the color of all-ceramic CAD/CAM restorations.Materials and methods: 16 all-ceramic sample disks 20mm in diameter and 2mm in thickness were fabricated and fired for 5 times, including shades A1C and A3C 8 each. Color was measured both before and after stain firing using a colorimeter. Changes in translucency were evaluated by determining the contrast ratio, and changes in color were evaluated by determining color difference ΔE * ab, hue angle hab * and chroma Cab: ΔE * ab =[(ΔL * )2+(Δa * )2+(Δb * )2]1/2, hab * =tg-1b * /a * , Cab * =[(a * )2+(b * )2]1/2,L * presented brightness.Results: The translucency changes detected in the forth firings for both shades A1C and A3C all-ceramic restorations. A color difference of more than 1.4, a visually appreciable change, was found for shade A1C specimens. For shade A3C specimens, there were no detectable clinically relevant differences. After stain firing, L * and Cab values of all samples increased, the hab * of shade A1C increased, but no change of shade A3C samples was foundConclusion: Within the limitations of this study, the following conclusions could be made: the translucency of CAD/CAM all-ceramic restorations changes after stain firing, the color of the samples changed, the change of color was not concerned with the number of firing.