Comparison of two color-difference formulas using the Bland-Altman approach based on natural tooth color space.

STATEMENT OF PROBLEM Several formulas to measure color differences have been proposed to improve the correlation between color measurements and visual perception. Despite the progress obtained, equating between formulas is complex, rendering the exchange of information in scientific papers difficult. PURPOSE The purpose of this study was to determine the relationship between the results provided by classic CIELab (ΔEab∗) and the CIEDE2000 (ΔE00) formulas in the natural tooth color space using the Bland and Altman limits of agreement, to use this relationship to establish the equivalences between the tooth color thresholds of acceptability and perceptibility of both formulas, and to evaluate whether the relationship between ΔEab∗ and ΔE00 is modified depending on the axis on which the changes occur. MATERIAL AND METHODS The L∗, a∗, and b∗ means coordinates in the 26 shade tabs of the Toothguide 3D Master were used, and color differences were calculated in 325 pairs of shade tabs using the CIELab (ΔE∗ab) and CIEDE2000 (ΔE00) color difference formulas. The results obtained with these formulas were compared, and the limits of agreement after a logarithmic transformation of the data were obtained. RESULTS The linear relationship between both formulas was ΔE00 =0.66ΔE∗ab. The results obtained with the CIELab formula were between 1.15 (95% confidence interval 1.11 to 1.18) and 2.09 (95% confidence interval 2.03 to 2.15) times higher than those obtained with the CIEDE2000 formula. CONCLUSIONS In the natural tooth color space, the scale factor between CIEDE2000 and CIELab values changes from 0.46 to 0.90, such that providing an accurate scale factor between both values is difficult. Furthermore, the ΔE00/ΔE∗ab ratio increases with the increase in ΔL∗ and the decrease in Δb∗. The pairs for which the ratio is highest are those in which the difference in color is mainly due to changes in lightness, whereas the pairs for which the ratio is the smallest are those in which the difference in color is mainly due to changes on the blue-yellow axis.

[1]  Delwin T Lindsey,et al.  Use of a porcelain color discrimination test to evaluate color difference formulas. , 2007, The Journal of prosthetic dentistry.

[2]  C. Gómez-Polo,et al.  Study of natural teeth color according to toothguide 3d master through cluster analysis , 2016 .

[3]  C. Gómez-Polo,et al.  3D Master Toothguide according to L*, C*, and h* coordinates , 2015 .

[4]  M. Bravo,et al.  Impact of prosthodontic status on oral wellbeing: a cross-sectional cohort study. , 2009, Journal of oral rehabilitation.

[5]  R Duane Douglas,et al.  Intraoral determination of the tolerance of dentists for perceptibility and acceptability of shade mismatch. , 2007, The Journal of prosthetic dentistry.

[6]  W M Johnston,et al.  Assessment of Appearance Match by Visual Observation and Clinical Colorimetry , 1989, Journal of dental research.

[7]  William M. Johnston,et al.  Color acceptance of direct dental restorative materials by human observers , 2000 .

[8]  D. Altman,et al.  Applying the right statistics: analyses of measurement studies , 2003, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[9]  Gregory L Polyzois,et al.  Repeatability and interdevice reliability of two portable color selection devices in matching and measuring tooth color. , 2009, The Journal of prosthetic dentistry.

[10]  J M Bland,et al.  Statistical methods for assessing agreement between two methods of clinical measurement , 1986 .

[11]  Ana Yebra,et al.  Color difference thresholds in dental ceramics. , 2010, Journal of dentistry.

[12]  M. M. Pérez,et al.  Study of the Variation between CIELAB ΔE* and CIEDE2000 Color-differences of Resin Composites , 2007 .

[13]  C. Gómez-Polo,et al.  Differences between the human eye and the spectrophotometer in the shade matching of tooth colour. , 2014, Journal of dentistry.

[14]  P. Robinson,et al.  The impact of dental appearance on the appraisal of personal characteristics. , 2003, The International journal of prosthodontics.

[15]  Rade D Paravina,et al.  Performance assessment of dental shade guides. , 2009, Journal of dentistry.

[16]  A Baltzer,et al.  Shading of ceramic crowns using digital tooth shade matching devices. , 2005, International journal of computerized dentistry.

[17]  M. M. Pérez,et al.  Study of the variation between CIELAB delta E* and CIEDE2000 color-differences of resin composites. , 2007, Dental materials journal.

[18]  D. Altman,et al.  Measuring agreement in method comparison studies , 1999, Statistical methods in medical research.

[19]  Alma Dozic,et al.  Perceptibility and acceptability thresholds for colour differences in dentistry. , 2014, Journal of dentistry.

[20]  Yong-Keun Lee,et al.  Comparison of CIELAB DeltaE(*) and CIEDE2000 color-differences after polymerization and thermocycling of resin composites. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[21]  S. Kawaguchi,et al.  Color and translucency of in vivo natural central incisors. , 2000, The Journal of prosthetic dentistry.

[22]  A. Yoshida,et al.  Clinical evaluation of perceptibility of color differences between natural teeth and all-ceramic crowns. , 2009, Journal of dentistry.

[23]  M. Melgosa,et al.  Sensitivity differences in Chroma, Hue, and Lightness from several classical threshold datasets , 1995 .

[24]  Y. N. Wang,et al.  Applicability of CIELAB/CIEDE2000 formula in visual color assessments of metal ceramic restorations. , 2012, Journal of dentistry.

[25]  Miguel Gómez-Polo,et al.  A clinical study relating CIELCH coordinates to the color dimensions of the 3D-Master System in a Spanish population. , 2015, The Journal of prosthetic dentistry.

[26]  D. M. Williams,et al.  The influence of tooth colour on the perceptions of personal characteristics among female dental patients: comparisons of unmodified, decayed and 'whitened' teeth , 2008, BDJ.

[27]  Antony Preston,et al.  Assessment of perceptibility and acceptability of color difference of denture teeth. , 2012, Journal of dentistry.

[28]  Wencheng Wu,et al.  The CIEDE2000 color-difference formula: Implementation notes, supplementary test data, and mathematical observations , 2005 .

[29]  R. D. Douglas,et al.  Acceptability of shade differences in metal ceramic crowns. , 1998, The Journal of prosthetic dentistry.

[30]  M. Melgosa,et al.  Chromaticity-discrimination thresholds with aperture and object colors: experimental results and predictions of some recent color-difference formulas. , 1996, Applied optics.

[31]  M. Luo,et al.  The development of the CIE 2000 Colour Difference Formula , 2001 .

[32]  Yong-Keun Lee,et al.  Correlations between color differences based on three color-difference formulas using dental shade guide tabs. , 2009, Journal of prosthodontics : official journal of the American College of Prosthodontists.

[33]  Jin-Soo Ahn,et al.  Color distribution of a shade guide in the value, chroma, and hue scale. , 2008, The Journal of prosthetic dentistry.

[34]  R J Goodkind,et al.  Use of a fiber-optic colorimeter for in vivo color measurements of 2830 anterior teeth. , 1987, The Journal of prosthetic dentistry.

[35]  R. Paravina,et al.  Evaluation of polymerization-dependent changes in color and translucency of resin composites using two formulae , 2005, Odontology.