Instrumental/Digital Shade Selection

Digital color measuring devices were introduced to eliminate the subjectivity of visual color analysis, thereby reducing the chances of error in shade determination and permitting the fabrication of aesthetic restorations by dental laboratory technicians.^1,60 Digital shade-matching tools can identify approximately 100,000 dental shades while the human eye can only identify 1% of these shades.⁴⁷ They are easy to use and can store shade information digitally, which can be easily transmitted to the laboratory.³⁸ Several clinical studies have reported that shade selection using digital tools takes less time and is as accurate as the conventional shade determination process.^38,62,63 However, digital shade determination systems are more expensive compared to conventional shade determination systems.³⁸ Additionally, shade-matching accuracy is influenced by factors such as the type of lighting used, the condition of the teeth (including the presence of stains or restorations), and the operator’s experience and techniques.²⁴

Digital shade determination instruments usually contain 3 key elements: a detector, signal conditioner, and software that processes the signal in a manner that makes the data usable in the dental operatory or laboratory.²⁸ Digital shade selection devices may be classified into two types based on the type of measurement: instruments that perform spot measurements and instruments that perform complete tooth measurements.¹ Spot measurement devices measure a small area of the tooth surface.¹ The size of these instruments is generally small, as a result, they cannot be used to create a whole image of the tooth.¹ They record three points of reference on a tooth surface.^1,35 This not only leads to errors but also increases the time for shade information data capture.¹ Therefore spot measurement should not be the sole method of shade determination but used as an adjunct to the visual shade-matching process. Examples of spot measurement devices are the Vita EasyShade Compact (Vita Zahnfabrik, Bad säckingen, Germany) (Fig. 32) and Shade-X (X-Rite, Grandville, MI).¹

Fig. 32 - Vita Easyshade Spectrophotometer

Image: https://www.vita-zahnfabrik.com/pdb_GG2G50G200_en-US.html_us

Devices that perform complete tooth measurement record the entire tooth surface, thereby generating a complete shade map of the tooth.¹ They provide all the information in one image.¹ They provide more consistent and reproducible information of the tooth surface.¹ They are larger compared to the spot-measuring devices, hence, their use is limited to the anterior teeth.¹ Examples of these devices are the CrystalEye (Olympus, Tokyo, Japan) (Fig. 33) and SpectroShade (MHT Optic Research, Niederhasli, Switzerland).¹

Fig. 33 - Olympus CrystalEye Spectrophotometer

Image: https://www.olympus.co.jp/jp/news/2006b/nr061113crystalj.html

Another classification system categorizes the shade-matching instruments into 3 basic types spectrometers, colorimeters, and digital imaging systems.¹

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