Color matching in prosthodontic and restorative therapy is a very significant task as it influences the esthetic outcome of dental restorations. Both shade evaluation and communication are crucial to fabricating a lifelike realistic restoration. Color is an extraordinary type of psychophysical sensation in the eye caused by visible light.1 Current methods for selecting shades can be influenced by both objective and subjective variables that can greatly affect the quality of the final prosthesis. These variables include light source, surrounding environment, and the clinicians'/technicians' perception of color. The light source and environment can easily be changed by using color-corrected lights and by using light, neutral background colors during shade selection. Human factors are trickier to balance for, as color perception differs due to age, eye fatigue, and neural-color receptors in the eye.2 To at least partially offset these variables, excellent communication must exist between the dentist and laboratory technician.
There are two color matching methods in dentistry: visual (conventional) and instrumental. Visual shade determination, when comparing to patient’s tooth with color standard, is the most frequently applied method in clinical dentistry.3 However, visual shade matching is unreliable, inconsistent and considered highly subjective. This is the result of multiple factors such as individual’s physiological and psychological responses to radiant energy stimulation, aging,fatigue, emotions, lighting conditions, object and illumination position, previous eye exposure and metamerism.4,5 Furthermore, human eye can detect very small differences in color, the range of available shades in the shade guides is inadequate and it is not possible to translate results into CIE color specifications. Technology-based color matching has been developed to minimize color mismatches during visual color estimation.6,7 Most often used instruments are: tristimulus colorimeters, spectroradiometers, digital cameras and spectrophotometers.8
Shade verification systems promise to take the guesswork out of shades. The systems claim to negate color-matching difficulties, such as the differences in individual technicians’ perception because of age, eye fatigue and neural color receptors in the eye. Most systems do this by scanning an image and converting hue, value and chroma information it receives into a shade map or shade recommendation, similar to shade verification systems in the auto industry. Accurately selecting a shade is a critical step in the fabrication of any esthetic prosthodontic appliance. If an incorrect shade is chosen, the prosthesis must either be modified with colorants( i.e., stains) or remade.
However, according to van der Burgt et al. there are three distinct disadvantages with the use of shade guides for colour assessment.9
First- the range of available colours in the shade guides is insufficient and the colour
samples are not logically...