Comparison of the color of natural teeth measured by a colorimeter and Shade Vision System

Abstract

Objectives. The objectives were to measure the difference in the color and color parameters of natural teeth measured by a tristimulus colorimeter (CM, used as a reference) and Shade Vision System (SV), and to determine the influence of color parameters on the color difference between the values measured by two instruments. Method. Color of 12 maxillary and mandibular anterior teeth was measured by CM and SV for 47 volunteers (number of teeth = 564). Color parameters such as CIE L*, a* and b* values, chroma and hue angle measured by two instruments were compared. Chroma was calculated as C∗ab = (a∗2 + b∗2)1/2, and hue angle was calculated as h◦ = arctan(b*/a*). The influence of color parameters measured by CM on the color difference ( E∗ab) between the values measured by two instruments was analyzed with multiple regression analysis (˛ = 0.01). Results. Mean E∗ab value between the values measured by two instruments was 21.7 (±3.7), and the mean difference in lightness (CIE L*) and chroma was 16.2 (±3.9) and 13.2 (±3.0), respectively. Difference in hue angle was high as 132.7 (±53.3)◦. Except for the hue angle, all the color parameters showed significant correlations and the coefficient of determination (r2) was in the range of 0.089–0.478. Based on multiple regression analysis, the standardized partial correlation coefficient (ˇ) of the included predictors for the color difference was −0.710 for CIE L* and −0.300 for C∗ab (p < 0.01). Conclusion. All the color parameters showed significant but weak correlations except for hue angle. When lightness and chroma of teeth were high, color difference between the values measured by two instruments was small. Clinical accuracy of two instruments should be investigated further.