Getting back an exquisitely matched restoration is one of the challenges of daily practice. At the heart of this frustration is gathering and sending the ceramist the information and records to help them do their best work. At the center of this information is shade selection. When I think about selecting a shade, I know that I am actually selecting three separate factors, Value, Chroma and Hue. Of the three, my experience is that matching the value is the critical piece, and the one least often communicated to the lab.
Value is an assessment of the reflectiveness of a tooth or restoration. We assess it as being light to dark, or white to black on a scale. There are many factors that influence the value of a restoration, and our goal is to give as much of that information to the lab, so they can create the result we are looking for. This is a combination of gathering the records and maximizing our ability to interpret it.
- Select Value separately from chroma and hue. Many of the new shade guide systems have value as one of the criteria. If you are using a Vita Classic shade system, reorder the tabs on one to reflect value order. B1, A1,B2,D2,A2,C1,D4,A3,D3,B3,A3.5,B4,C3,A4,C4
- Bright light makes value selection more difficult. Turn the dental light off the tooth. Turn off the overhead lights and close the blinds and then give your eyes about thirty seconds to accommodate to the lower light levels before you make your selection.
- Color information is dominant for our brains, and can make it more challenging to select color. Turning down the light in the room limits color information and makes selecting value easier. Take lots of photos, and alter some of these photos to black and white, which will make the value of the different teeth and areas of the teeth easier to determine.
- With all of the tabs in the guide compare the tabs directly to the teeth being matched. To avoid the natural error introduced by our brains storing information in memory we want to do a direct comparison between the object being matched and the guide. I orient my tabs incisal edge up and place them against the teeth incisal edge of tooth to incisal edge of the tab, slowly I move the guide from one end to the other until I have the tab that best matches the “brightness” or “reflectiveness” of the tooth end to end with the tooth.
- For posterior teeth where access is difficult I match the corresponding anterior tooth. Centrals and laterals match the value and color information of bicuspids in a natural dentition. Canines can be used to match the shade information of molars.
- Photographs are invaluable to the technician. Take photos and choose value prior to beginning any restorative procedures as dehydration will alter the shade characteristics of the teeth. Take lots of photos, alter the angle of the lens to the labial surface of the tooth, alter the exposure, and convert some to black and white. Send the photos to the technician either digitally or as prints. Take some of the photos with the tabs in them so the technician can see what you saw when you made the selection.
- Indicate value on the laboratory script separately from chroma and hue. Value = B3, Chroma = 2, Hue = A.