Written by Todd C. Snyder, DDS Sunday, 31 May 2009 19:00
The cosmetic dental industry grows more and more every year with billions of dollars being spent by consumers to have dazzling white teeth. The over-the-counter market is driven by savvy manufacturers capitalizing on this trend with catchy marketing and clever claims of dramatic results in the number of shade changes in tooth whiteness. The consumer unfortunately is sometimes left with less-than-anticipated levels of whiteness because of claims that they will see 8 to 12 shades of improvement in tooth whiteness.
SHADE GUIDES VARY
Figure 1. An example of a printed shade guide. These are included with most professional- and consumer-grade whitening products and used by the patient to determine shade changes.
|Figures 2 to 4. Examples of shade guides that composite manufacturers include with their products.|
The number of shade changes that visibly occur depends on how many shade tabs are available in any particular shade guide to cover the gamut of whiteness. Most shade tabs are not fabricated based on science and are also not equally spaced between adjacent shade tabs. Rather, they are made as arbitrary standalone shades selected by manufacturers with no statistical relevance to coverage or being spaced equal distance apart. The typical shade guides used for take-home and in-office whitening poorly relate shade changes due to their lack of available shades (which are based only on hue and chroma) and uneven shade distribution between each shade tab. However, to interpret shade changes a shade guide must be implemented and used as a standard for assessment of tooth whitening. Just as the everyday consumer tries to use a shade guide, so does the dental practitioner on a daily basis for whitening and restorative shade analysis.
There are numerous shade guides prevalent in the dental industry for use by dental professionals, their team, and even consumers. Most professional- and consumer-grade whitening products have printed shade guides that are used by the patient to determine shade changes (Figure 1). Composite manufacturers also typically have shade guides included with their product showing the colors available in their system (Figures 2 to 4). Ceramic manufacturers include a few different shade guides with each of their kits, various types for the dental technician, and usually one for the dentist to use for better communication (Figure 5). It is obvious for anyone to see that many shade guides are lacking in colors available, and some shade guides have too many shade tabs so close together in their color representation that it is difficult to see any difference between them.
A REVIEW OF HUE, CHROMA, AND VALUE
Shade guides most often assess and characterize shades of teeth based on hue and chroma, however, value typically has no representation in the formula. The hue of a tooth is that component of its appearance often referred to in normal discussions of a physical object’s appearance known as color (or the family of colors). For example, a tomato has a red hue, or in laymen terms, one would say it has a red color. Chroma is the level of saturation (intensity) of any particular hue. For example, the traditional VITA shade guide (Vident) has the B group where they all possess the same hue but have increasing levels of saturation or chroma. The third component of color is value. Value is the level of brightness from black to white and is typically not represented at all in the shade selection process. However, value is the most important component when describing the shade of a restoration. Oftentimes if the value is correct, then the chroma and hue can be off slightly with no visual discrepancies to the eye. Whereas, if the value is not correct for a restoration it does not matter how accurate the hue or chroma are, as they will not make up for the deficit in the overall shade.
When a shade guide has shade tabs where their color representation is not spread out enough to visually perceive a difference between them, it becomes difficult to utilize the shade guide for restorative dentistry, teeth whitening assessment, or anything else because of the confusion caused by too many shades looking like possible matches. However, when utilized for teeth whitening it becomes beneficial for manufacturers to be able to make claims that their product has more tooth color shade changes which makes the appearance of a whitening procedure that much more dramatic in its final results.
Unfortunately, shade guides cannot typically relate color between competing manufacturers’ products unless they have been licensed to do so and given the chemistry behind its color composition. For this reason, when selecting a shade for a restorative material, it is best to use the manufacturer’s shade guide for that particular restorative material. Additionally, the best shade guides used for restorative dentistry are made from the actual restorative material to provide the most accurate example of the colors available.
Figure 5. Ceramic manufacturers include a few different shade guides with each of their kits, including various types for the dental technician.
Figure 6. The Vitapan Classical (Vident) shade guide (with 16 variably spaced shades) had its origin in the 1920s and was based on subjective observation of teeth.
|Figure 7. The scientifically developed 3D-Master Shade Guide (Vident) became available in 1997, offering 29 equally distanced shades.||Figure 8. The most recent guide to be fabricated from the same research (still based on value) is the VITA Bleachedguide 3D-Master [Vident]).|
The typical shade guide used in dentistry, the VITA Lumin Vacuum (Vident), with 16 variably spaced shades, was originally created for dentists based on subjective observation of teeth for the fabrication of denture teeth. This shade selection device’s origin stems back to the 1920s with no research based in color science. This went on to be the standard shade guide for more than 50 years. Since 1956, the VITA “Lumin-Vac” guide quickly became known as the “gold standard”; today it is known as the Vitapan Classical guide (Vident [Figure 6]). It has done a very good job for selecting denture teeth, fabrication of direct/indirect resin restorations, ceramics, and even shade documentation for whitening.
SCIENCE-BASED SHADE GUIDES DEVELOPED
In 1997, the scientifically developed 3D-Master Shade Guide (Vident) (Figure 7) became available. It offers 29 equally-distanced shades to better define tooth colors and make it easier to see the shade changes. This was the first shade guide fabricated based on research done on naturally occurring shades in teeth. Additionally, the shade guide was fabricated utilizing the most important component of color, value, as the foundation for the selection process.
The most recent guide to be fabricated from the same research (still based on value) is the VITA Bleachedguide 3D-Master [Vident]) (Figure 8). This guide, for use with bleaching procedures, addresses the dilemma of misinformation with 15 equally-distanced shades. Developed especially for the observation and monitoring of the patient’s tooth whitening process, it simplifies the selection process and classifies it more accurately due to the equidistance of the shade tabs. The new system has almost double the actual color space coverage to have a larger deviation of selectable shades.
When it comes to documenting shade changes with any office-based whitening product, the VITA Bleachedguide 3D-Master is the only linearly-aligned shade guide that has the ability to properly document the changes systematically. Due to the equal-distanced shade tabs, it is easy to perceive color shifts and accurately depict equal shade shifts between each shade tab. Shade guides typically are not scientifically fabricated to have each of their shade tabs the same distance away from each other in 3-D color space. Some shade tabs look very similar to their neighboring shade tab, while others look drastically different. This deviation of color can be a drastic difference, or a very minor (almost undetectable) change between shade tabs. This can make the shade analysis and selection process very difficult.
TECHNICAL CONSIDERATIONS: COLOR DEVIATION
The color deviation between 2 shade tabs can be defined by their difference. This deviation distance is defined as Delta E. Delta E is based on the definition from the International Lighting Commission (Commission Internationale de l’Eclairage; CIE) from 1976 and is the common measure for color variations in industrial practice. The smaller the Delta E, the better the match of 2 colors. However, shade guides with shade tabs that are too close together in their Delta E difference can make it extremely difficult for the eye to discern a difference. This is because the eye can only typically perceive differences of 2 Delta E or larger, unless one has a very well-trained eye—then it is said to be able to see changes as low as a 1 Delta E.
The Vitapan Classical shade guide range has a total coverage rated at 17 Delta E divergence, compared to the 34 Delta E representations from the 15 shade tabs in the VITA Bleachedguide; which is also the same as the full 29 shades of the VITA 3D-Master shade guide. The VITA Bleachedguide can be used to standardize the shade selection process for teeth whitening in the dental office and with dental office take-home kits. Implementation of this guide allows the dentist and the patient to be able to visualize and discuss shade changes with the same terminology. It offers a more consistent way to quantify and define the results.
VARIABLES CAN CAUSE ERRORS
In any shade selection process, there are variables that will influence potential errors in the shade selection process that may be different from one location to the next. These variables include: lighting, perception, the eyes, the color of the walls and other surrounding colors. Dehydration of the teeth (enamel) can also play a big role in selection of the right shade. The slightest amount of enamel dehydration can cause a tooth to appear higher in value. In an attempt to eliminate this problem, there have been advances in documentation of shade change with cameras and shade taking devices that utilize camera-based systems, colorimeters, spectrophotometers, and computer software. These technologies were all developed with the goal of interpreting the colors of teeth.
The VITA Bleachedguide can be used in the practice every day to provide a consistently better shade analysis in place of existing shade guides. This can be implemented without the additional cost of a high-priced shade analysis tool for the selection of composites and ceramic restorative materials. The only disadvantage is that other manufacturers do not currently have the licensing and shade information to fabricate various restorative materials using this evolved shade guide system. Until there is some communication and agreement between the dental manufacturers, this excellent tool for restorative materials can only be accurately used for composite and ceramic restorative materials manufactured by Vident. However, it can be used very effectively for evaluation and monitoring of the bleaching process.
Disclosure: Dr. Snyder reports no conflict of interest.
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