Visual shade matching is the most common method, in which a color standard from a commercially available dental shade guide is compared to and matched with the target tooth. However, several factors can contribute to perception errors including: different lighting variables, multiple shade systems available in the market with lack of standardization in color systems and corresponding porcelain systems, individual human variables in color perception and lack of understanding of color science.
Therefore, in order to eliminate the uncontrolled variables during the color matching process, instrumental methods have been developed. Spectrophotometric measurement methods employing computer calculations, based on color science and theories, allow quantitative evaluation which is objective and appears to be more accurate. However, extremely high costs, relatively low performance with respect to agreements of the computer-aided devices, and edge loss error make it less acceptable.
One of the most powerful tools in communicating with both patients and dental ceramists is digital photography. Hence, this study is designed to explore the possibilities of a novel approach to shade management (eLABor\_aid) utilizing a photocolorimetric (PCM) method and subsequent shade formulation without the use of stock shade guides in comparison to well-known visual and instrumental methods.
The aim of the study is to evaluate the accuracy of digital photography combined with shade analyzing software (eLAB) in optimizing shade matching when compared to conventional and instrumental methods of shade selection.
A Null Hypothesis is suggested where no significant difference regarding shade selection between eLAB protocol, conventional and instrumental methods will be found.
Age range of the patients from 20-50 years old; able to read and sign the informed consent document.
Patients able physically and psychologically to tolerate conventional restorative procedures.
Patients with no active periodontal or pulpal diseases, having teeth with good restorations.
Patients with teeth problems indicated for full coverage restoration (e.g. moderate discoloration, coronal fracture where partial coverage would lack retention, mal-posed or malformed teeth, esthetics enhancement of previously placed crown) where the contralateral/adjacent tooth is present.
Patients with poor oral hygiene and motivation.
Patients with teeth with increased incisal translucency.
Patients with severe discolored teeth.
Patients with smoking habits.
Crossover
Digital photography combined with eLABor_aid shade analyzing software
DeviceELABor\_aid is a new approach to objective shade communication and shade reproduction in dentistry, based on numeric quantification obtained from standardized RGB (red-green-blue) images, and the formulation of a patient personal shade recipe using trichromatic subtractive color mixing laws, thus abandoning the use of visual assessment and shade guides entirely. This approach is currently enjoying increasing popularity for its ease of use, reliability as well as for its practically oriented features like its imaging ability or the digital try-in.
Spectrophotometer
DeviceSpectrophotometric measurement methods employing computer calculations, based on color science and theories, allow quantitative evaluation which is objective and appears to be more accurate.
Conventional visual shade matching
DeviceVisual shade matching is the most common method, in which a color standard from a commercially available dental shade guide is compared to and matched with the target tooth.
Color difference (Delta E) calculated using calibrated images on photoshop software
Photoshop combined with dental photography using Delta E formula. Standardized images will be taken using a standardized protocol and a grey card to calibrate the produced images to ensure standard exposure in all photos. Delta E will be calculated using photoshop software. Delta E (ΔE) = \[(L1 - L2)² + (a1 - a2)² + (b1 - b2)²\]1/2
Shade match using modified USPHS criteria
Alpha (Excellent): ideal. Bravo (Acceptable): less than ideal but no modifications required Charlie (Acceptable but modifications needed): staining or other shade modifications required. Delta (Unacceptable): remake.
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