Application of a digital technique in evaluating the reliability of shade guides

• Published in: Journal of oral rehabilitation Vol. 31; no. 5; pp. 483 - 491
• Main Authors: Cal, E., Sonugelen, M., Guneri, P., Kesercioglu, A., Kose, T.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.05.2004
• Subjects: aesthetic dentistry; Color - standards; colour analysis; Computer-Aided Design; Dental Prosthesis Design - methods; Dentistry; digital analysis; Esthetics, Dental; Humans; L and RGB values; Lighting; metamerism; Photography; Prosthesis Coloring; Reproducibility of Results; shade guides; Software; Tooth
• ISSN: 0305-182X; 1365-2842
• DOI: 10.1111/j.1365-2842.2004.01197.x

summary  There appears to be a need for a reliable method for quantification of tooth colour and analysis of shade. Therefore, the primary objective of this study was to show the applicability of graphic software in colour analysis and secondly to investigate the reliability of commercial shade guides produced by the same manufacturer, using this digital technique. After confirming the reliability and reproducibility of the digital method by using self‐assessed coloured images, three shade guides of the same manufacturer were photographed in daylight and in studio environments with a digital camera and saved in tagged image file format (TIFF) format. Colour analysis of each photograph was performed using the Adobe Photoshop 4·0 graphic program. Luminosity, and red, green, blue (L and RGB) values of each shade tab of each shade guide were measured and the data were subjected to statistical analysis using the repeated measure Anova test. The L and RGB values of the images taken in daylight differed significantly from those of the images taken in studio environment (P < 0·05). In both environments, the luminosity and red values of the shade tabs were significantly different from each other (P < 0·05). It was concluded that, when the environmental conditions were kept constant, the Adobe Photoshop 4·0 colour analysis program could be used to analyse the colour of images. On the other hand, the results revealed that the accuracy of shade tabs widely being used in colour matching should be readdressed.