Estimation of visual shade matching errors with 2 shade guides

Objective: To compare the interobserver difference in visual shade matching and estimate the precision of color discrimination. Method and Materials: Visual shade matching of a maxillary central incisor of 33 subjects was performed by 2 prosthodontists independently in a chair under ceiling daylight-corrected fluorescent lighting, using the Vitapan Classical and the Vitapan 3D Master shade guides (Vita Zahnfabrik). The 3 closest shade tabs were selected and ranked in order of best, second best, and third best matches. Interobserver agreement was found by comparing the best shade and the common shade for each subject by the 2 clinicians. The CIE Lab color difference, ΔE*, between the best shade and the common shade selected by the clinicians was calculated for each subject. A t test (α = .05) was performed to find clinician differences of the means of the best shade and the common shade for both shade guides. Results: Interobserver agreement was 30% when matching the best shade; however, the ratio increased to over 85% for the common shade (a significant difference at the .05 level). No significant differences were found between the 2 shade guides by means of the mean color differences between the best shade match and the common shade match, while the Vitapan 3D Master shade guide was superior to the Vitapan Classical shade guide in reducing the interobserver color differences from 0.8 to 0.2. Conclusion: Visual shade matching of teeth gave better agreement using the Vitapan 3D Master shade guide when selecting the common shade from among the closest 3 shades chosen by multiple observers. Keywords: best shade, CIE Lab color difference, common shade, interobserver agreement or disagreement, visual shade matching