Visual and instrumental evaluation of color match ability of 2 shade guides on a ceramic system

Abstract

There is limited information on the visual and instrumental evaluation of color match between a natural tooth and a ceramic crown. The purpose of this study was to evaluate the influence of 2 shade guides on color match, and to evaluate the relationship between color difference (ΔE) values and examiners' assessments of the color match in ceramic crowns. Thirty-three subjects were selected for a ceramic crown restoration of the maxillary central incisor. Two crowns were fabricated with selected shades from Vitapan Classical and Vita Toothguide 3D-Master shade guides for each subject. The color values of maxillary central incisors, selected shade tabs, and corresponding crowns were measured with a spectrophotometer. The ΔE values between the natural teeth and the crowns and between the selected shade tabs and the corresponding crowns were calculated for each subject and compared with the Student's t test (α=.05). In addition, 3 examiners visually evaluated the clinical acceptability of each crown on a scale from 1 to 6. The agreement among the examiners was assessed with the Kappa test. The scores of examiners for both shade guides were analyzed with the Wilcoxon signed rank test (α=.05). The results revealed that the color difference values between the teeth and the crowns fabricated with the selected shades from the Vita Toothguide 3D-Master shade guide were significantly smaller than those of the Vitapan Classical guide (P=.003). Similarly, the color difference values between the selected shade tabs from the Vita Toothguide 3D-Master guide and the corresponding crowns were significantly smaller than those of the Vitapan Classical guide (P=.001). However, the ΔE values obtained for both shade guides were within the clinically acceptable range (ΔE<3.7). The kappa values implied moderate agreement among the 3 examiners. The median value of the examiners' scores was 2, which denoted an acceptable color match. In addition, the recorded scores of the 3 examiners showed that there was no significant difference in terms of the color match between the crowns fabricated with either of the 2 shade guides. The ceramic crowns fabricated with the Vita Toothguide 3D-Master shade guide resulted in a closer color match to the natural teeth than those of the Vitapan Classical guide. However, the ΔE values and the examiners' scores were within the clinically acceptable range for both shade guides.