Color related to ceramic and zirconia restorations: A review

Statement of problem Many color specification systems and color differences have been proposed to improve the correlation between color measurement and visual perception. Although color differences can be quantified using either the CIELab formula (ΔE* ab ) or the recently introduced CIEDE2000 formula (ΔE00), which captures the perceived color difference better is unknown. Purpose The purpose of this study was to evaluate the CIELab and CIEDE2000 formulas to determine which best reflects the difference in color perception and whether color perception differs by sex. Material and methods Forty participants grouped 18 dental resin disks (color range: from 73.6 to 87.5 for L*; from −1.6 to 3.4 for a*; from 18.1 to 36.6 for b*), the only requirement being that each group was formed of disks with chromatically indistinguishable colors. Each participant was free to choose the number and composition of the groups. With the results obtained, a dissimilarity matrix was generated, and nonmetric multidimensional scaling (MDS) was applied to it to obtain the coordinates of the disks within a Euclidean space. Results The linear correlation coefficient between the interpoint distances of the MDS configuration (MDS_total sample) and the color differences with the CIELab formula (ΔE* ab ) was 0.176 ( P =.029), whereas with the CIEDE2000 formula (ΔE00) it was 0.289 ( P P =.004), and the CIEDE2000 color difference was 0.328 ( P Conclusions Within the limitations of this study, the CIEDE2000 formula reflected the color differences perceived by the human eye better than the CIELab formula (ΔE* ab ). In addition, women were confirmed to be more sensitive than men to color differences.

Comparison of the CIELab and CIEDE2000 color difference formulas

Visual and instrumental shade matching using CIELAB and CIEDE2000 color difference formulas

Shade matching quality among dental students using visual and instrumental methods.

Objective
The aim of this investigation was to evaluate intrarater and inter-rater reliability of visual and instrumental shade matching.

Materials and Methods
Forty individuals with normal color perception participated in this study. The right maxillary central incisor of a teaching model was prepared and restored with 10 feldspathic all-ceramic crowns of different shades. A shade matching session consisted of the observer (rater) visually selecting the best match by using VITA classical A1-D4 (VC) and VITA Toothguide 3D Master (3D) shade guides and the VITA Easyshade Advance intraoral spectrophotometer (ES) to obtain both VC and 3D matches. Three shade matching sessions were held with 4 to 6 weeks between sessions. Intrarater reliability was assessed based on the percentage of agreement for the three sessions for the same observer, whereas the inter-rater reliability was calculated as mean percentage of agreement between different observers. The Fleiss' Kappa statistical analysis was used to evaluate visual inter-rater reliability.

Results
The mean intrarater reliability for the visual shade selection was 64(11) for VC and 48(10) for 3D. The corresponding ES values were 96(4) for both VC and 3D. The percentages of observers who matched the same shade with VC and 3D were 55(10) and 43(12), respectively, while corresponding ES values were 88(8) for VC and 92(4) for 3D.

Conclusions
The results for visual shade matching exhibited a high to moderate level of inconsistency for both intrarater and inter-rater comparisons. The VITA Easyshade Advance intraoral spectrophotometer exhibited significantly better reliability compared with visual shade selection.

CLINICAL SIGNIFICANCE
This study evaluates the ability of observers to consistently match the same shade visually and with a dental spectrophotometer in different sessions. The intrarater and inter-rater reliability (agreement of repeated shade matching) of visual and instrumental tooth color matching strongly suggest the use of color matching instruments as a supplementary tool in everyday dental practice to enhance the esthetic outcome.

Herbert Dumfahrt

Papers

Does gender and experience influence shade matching quality