Joe Blaes, DDS
In the August issue of Dental Economics, Dr. Jeff Dalin touched upon the attributes of color and how the surrounding conditions can come into play with human color perception. This month, I'd like to focus more on the drastic improvements in shade-matching technology.
Blending the science of dentistry with the art of color poses significant challenges. With a cosmetic-minded society striving for optimal aesthetics, new systems and devices must be considered. The human eye is one of the best color devices in the world, a true marvel of bioengineering. However, it does have its limitations; new technology is helping both dentists and the labs ensure the accuracy and aesthetic quality of their patients' restorations. Additionally, by improving communication between the dentist and the lab and minimizing the number of remakes, new shade-matching technology is resulting in an increase in the dental practice's profitability.
Nearly every detail involving color that we encounter in our daily lives - from magazines to automobiles to food products - uses advanced technology to quantify shade for consistency, accuracy and time efficiency. Until recently, this technology was not available in dentistry.
The cosmetic dentistry explosion has mandated that dentists combine their science with an art form. Dentists have been ready and waiting for technology that can cut down the remake rate, increase dentist/lab communications, and ensure the aesthetic accuracy of their patients' restorations.
Today's cosmetic-savvy patients are demanding the highest-quality aesthetic dentistry. Patients perceive an attractive smile as an important social asset, and a poorly matched shade does not fit their cosmetic ideals. The color and shade of a tooth is unique to each patient, and, when the color is off even slightly, the mistake can be glaring. Accurately matching the color and shade of a restoration is difficult with the obvious limitations of the human eye, and those limitations are compounded when using traditional shade tabs. The subjective analysis of traditional shade tabs/guides can be affected by retinal fatigue, the light source, background effects, age, and poor color memory. This often makes accurate color assessment problematic and the pursuit for the "perfect match" unattainable.
With the addition of today's advanced technology, the qualitative and quantitative reliability of shade matching has become increasingly more accurate. Today, there are three main technological categories that can help provide an accurate shade reading and streamline the communication between the dentist and the lab:
•Digital cameras/RGB devices: Digital cameras and RGB devices represent the most basic approach to electronic shade taking. With RGB devices, dentists take a digital shot of the surrounding teeth and use the information from the image to determine the shade of a tooth. The downside to these systems is that they are not color measuring devices, but image comparison devices. They still involve some degree of subjective shade selection with the human eye. Essentially, RGB devices are computer programs that compare information from two digital images to determine how close an object looks to another object. Digital photography primarily enhances the communication between the dentist and the lab and works in conjunction with traditional shade tab readings.
•Spectrophotometers. Spectrophotometers provide the most colorimetric information possible and are commonly used for spot measuring in industrial applications. Many different types of spectrophotometers are available, from those that measure small areas of an object to those that measure entire objects at once. However, all spectrophotometers measure multiple individual wavelengths of visible light (between 380n-720n); they have no correlation to human vision. The extensive data obtained from spectrophotometers must be manipulated and a data reduction strategy employed to translate the data into a useful form.
•Colorimeters: Colorimeters are engineered to measure color as perceived by a human eye. A colorimeter filters light in three areas of the visible spectrum to determine the spectral response based on this data. Some colorimeters are handheld and offer the convenience of portability. With a colorimeter, all tooth detail is captured as if seen by a perfect human eye with ideal illumination. Properly designed colorimeters can provide greater data efficiency since they store only the needed three data points of hue, value, and chroma instead of the more basic 16-plus data points of reflectance. While a colorimeter can deliver accuracy similar to spectrophotometers, it reduces the data load time by determining "if a human being cannot see it, it is not important to measure or store."
Proper color assessment requires control of light, the object, its surroundings, and a healthy, trained observer. Unless these ideal conditions are met, shade measurement can be negatively impacted. Ideal shade taking conditions are next to impossible and, with the rise of new digital color measurement options, electronic shade taking devices will soon become the standard.
