A Compare Of Visual And Instrumtal Shade Selection

Objective: The CIE Lab colorimetric system was used to evaluate the differences between instrumentally measured color differences(ΔE) and human observer assessment of color differences between metal ceramic crowns and natural teeth.Methods: The shade of 40 left maxillary incisors were assessed visually by 5 observers and measured by a computer colorimeter. Corresponding metal ceramic crowns were fabricated according to the shades determined by visual and instrumental methods. The colors (CIE L~*a~*b~* coordinates) of crowns were measured by a spectrophotometers with a 45° /0° configuration. Repeated-measures analysis of variance was used to evaluate within-group differences between two shade selection methods for the total color difference(ΔE) and direction of the color parameters(ΔL, Δa and Δb).The Paired-Samples T Test was used for post-hoc analysis( α =0.05).Results: No significant difference was found in the mean AE between the two shade selecting methods (P>0.05).With the difficulty increasing in visual shade determining, a significant difference was found in the total color difference(AE) and direction of the color parameters(ΔL, Δa and Δb).Conclusion: Within the limitation of this study, the results suggest that ShadeEye NCC reliably measured the color of natural teeth, especial for the teeth which are not easy to select color by visual method.