CIE L*a*b*: comparison of digital images obtained photographically by manual and automatic modes

Fabiana Takatsui,Marcelo Ferrarezi De Andrade,Luiz Antônio Borelli Barros,Maximiliano Piero Neisser,Leonor De Castro Monteiro Loffredo

doi:10.1590/s1806-83242012005000025

Fabiana Takatsui, Marcelo Ferrarezi De Andrade + Show 3 more

Open Access

https://doi.org/10.1590/s1806-83242012005000025

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Abstract

The aim of this study was to analyze the color alterations performed by the CIE L*a*b* system in the digital imaging of shade guide tabs, which were obtained photographically according to the automatic and manual modes. This study also sought to examine the observers' agreement in quantifying the coordinates. Four Vita Lumin Vaccum shade guide tabs were used: A3.5, B1, B3 and C4. An EOS Canon digital camera was used to record the digital images of the shade tabs, and the images were processed using Adobe Photoshop software. A total of 80 observations (five replicates of each shade according to two observers in two modes, specifically, automatic and manual) were obtained, leading to color values of L*, a* and b*. The color difference (ΔE) between the modes was calculated and classified as either clinically acceptable or unacceptable. The results indicated that there was agreement between the two observers in obtaining the L*, a* and b* values related to all guides. However, the B1, B3, and C4 shade tabs had ΔE values classified as clinically acceptable (ΔE = 0.44, ΔE = 2.04 and ΔE = 2.69, respectively). The A3.5 shade tab had a ΔE value classified as clinically unacceptable (ΔE = 4.17), as it presented higher values for luminosity in the automatic mode (L* = 54.0) than in the manual mode (L* = 50.6). It was concluded that the B1, B3 and C4 shade tabs can be used at any of the modes in digital camera (manual or automatic), which was a different finding from that observed for the A3.5 shade tab.

Highlights

Aesthetic dentistry relies on the crafting of a restoration that properly integrates with the tooth structure in all aspects, including color
In a study by Rodrigues et al.,[2 60] dentists were interviewed, and, they all employed the method of visual color selection with a preference for the Vita shade guide as a standard, 75% reported experiencing difficulty in this measurement
Yap et al.[1], Dozic et al.,[6] and Mutlu-Sagesen et al.[7] have recommended the use of digital instruments, including the colorimeter and portable instruments of color and other digital imaging methods, which could help eliminate the subjectivity of visual assessment

Summary

Introduction

Aesthetic dentistry relies on the crafting of a restoration that properly integrates with the tooth structure in all aspects, including color. According to Yap et al.,[1] the lighting of the dental clinic and the dental laboratory can influence color selection in that different lighting sources may present different wavelengths. In this way, fluorescent light can acti-. In a study by Rodrigues et al.,[2 60] dentists were interviewed, and, they all employed the method of visual color selection with a preference for the Vita shade guide as a standard, 75% reported experiencing difficulty in this measurement. Yap et al.[1], Dozic et al.,[6] and Mutlu-Sagesen et al.[7] have recommended the use of digital instruments, including the colorimeter and portable instruments of color and other digital imaging methods, which could help eliminate the subjectivity of visual assessment

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