Lab Tribune U.S. Edition, November 2010, Vol. 1, No. 61

LAB TRIBUNE The World’s Dental Lab Newspaper · U.S. Edition By Kevin Kim As a technical advisor, I see a lot of extremes. Complicated full- mouth reconstruction cases with huge numbers of variables and challenges to solve aren’t uncom- mon to see several times a week. By the time I see the case, I’ve already spoken with the dentist, planned the case, and I know what to expect. Difficult at times, but also fairly routine. It’s the cases that seem extreme- ly straight-forward and easy on the outside that can have the tendency to throw me for a loop. And to be honest, if I had to choose, I’d prob- ably choose the full-mouth recon- struction over a single unit central incisor any day of the week. Why? Shade. What makes matching a shade so difficult? It’s the one physical property of a tooth that’s loaded with subjectivity. The rest of the physical properties are very objec- tive and easier to match; length, width, and contour are all right there on the study model and are plain as day. Shade can be difficult because everyone’s eyes perceive color, shade, hue and value slightly dif- ferently. What looks like a per- fect match to one person could look a little “off” to another. And with cases like single-unit central incisors that demand vital, lifelike esthetics, a shade match that isn’t perfect can mean one redo after another, and a lot of unhappy peo- ple. This isn’t new news to most of us, though. The majority of cases that come in are bundled with lots of quality information about the case and patient, including pho- tos to communicate shade and other subtle details such as inci- sal translucency, surface texture, craze lines, demarcation lines and calcification. But photos can be a double-edged sword. If they’re taken well, a photo can speed the shading process and eliminate lots of guesswork. On the other hand, a photo that doesn’t How to eliminate shade-taking variables November 2010 www.dental-tribune.com vol. 1, No. 6 g LT page 2D CAD/CAM a central topic at IDS 2011 Show to focus on current developments in technology Digital high-technology processes increasingly determine the day-to- day work in dental practice and the laboratory. This is especially true where the precise design and produc- tion of classic or implant-supported dentures are concerned. In the case of high-value full- ceramic restorations, the number of cases since the beginning of this mil- lennium is in the high tens of millions — undoubtedly a success for modern CAD/CAM technology. “Today, this scientific and tech- nological progress incorporates all of the disciplines of dental medicine. The importance of digital processes for the opportunities of the team of dentists and dental technicians can be characterized without exaggeration as revolutionary,” said Dr. Martin Rickert, chairman of the Association of German Dental Manufacturers (VDDI). Today, users have available digital methods that enable the precisely fit- ting and economic design and manu- facture of crown and bridge frame- works up to and including complex implant-supported superstructures. ThecontinueddevelopmentofCAD/ CAM technology has been accom- plished by years of intensive research and development work on the part of science and the dental industry. In the meantime, digital design and manufacturing processes have firmly established themselves in most practices and laboratories and have leant important momentum to the disciplines of prosthetics and implan- tology in particular. Dentists, dental g LT page 3D The Canon 40-D with 100 mm macro lens and ring flash is perfect for taking shade photos to send to our doctors. (Photo/Provided by Dave Crone) take certain variables into consid- eration can put the process back at square one and increase the chances that the shade won’t be perfect. Just like any other job, using the right tools can make all the differ- ence. And in this case, the right tools can help eliminate many of the vari- ables that can throw the accuracy of a shade-matching photo off. The toughest variable to control in this case is light and the way it affects your subject. The amount, type, and temperature of light can alter the out- come of a photo. A perfect example is a photo with subjects that have turned a bluish hue from fluorescent lights or an orangish hue from incan- descent lights. Here are some tips you can offer the dentists you work with on how to master the light and control the subject in your office to yield the most accurate color in your photos: • Use color-corrected office light- ing. At Keating Dental Arts, every fluorescent light is calibrated to 6,700 degrees Kelvin. It’s very close to the temperature of natural daylight and helps us eliminate light as a variable for achieving accurate shades. • Consider your backdrop. Seafoam green operatory walls may match the dentist office’s color scheme, but it can throw off the accuracy of photos. Colored walls reflect ambient light and can impact the color of a photo. A room or wall with a neutral color like white, off-white or light gray usually generates the best results. • Consider your patient’s cloth- ing. Just like the surrounding walls, brightly colored clothing can reflect ambient light and change the quality of your photo. Using a neutral colored drape or smock will help minimize or eliminate that chance. • Calibrate your camera’s white balance. If your camera “knows” how absolute white should appear, then you can be more certain that the rest of the colors will be accurate and life- like. Consult your user’s manual for this step. • Determine shade at or near the beginning of the appointment. The longer you and your patient are look- ing at and comparing shade tabs, the more likely you are to suffer from ocular fatigue. A tired pair of eyes has a tougher time determining shade. • Have your patient remove lipstick or other makeup. This is really about minimizing distractions and making it easier to determine a patient’s over- all tone. Tech advisor: Shade matching can be difficult because everyones’ eyes perceive color, shade, hue and value slightly differently International Dental Show (IDS) takes place in Cologne, Germany, from March 22–26, 2011.