A tooth shade guide is a commonly used reference tool which divides tooth color into four basic shade range as A-reddish brown, B-reddish yellow, C-gray, and D-reddish gray.
This article will help you know the pointers that you need to keep in mind while choosing a shade for your teeth.
Commercial tooth shade guide
Commercial tooth shade guide is the most common and convenient method of shade selection. Components of shade guide consist of –
- Metal backing
- Opaque porcelain
- Neck, body and incisal color
Most commonly used shade guides are –
- Vita Classic (2)
- Vitapan 3D-Master
- Extended range shade guides
Vita classic is a very popular shade guide. There are four different range in the shade guide – A (reddish brown), B (reddish yellow), C (gray), D (reddish gray).
Numerical values are used to denote chroma. For example, shade A3 means hue of reddish brown and chroma of 3.
Steps for selection of tooth shade
The operator should select hue closest to the natural tooth. Use the area of tooth highest in chroma. When chroma is low, selecting hue for the tooth is difficult.
Suppose the hue selected is B. The B hue has a range of chroma from B1-B4 and chroma is chosen from these four tabs. Make several comparisons and care has to be taken to avoid retinal fatigue. Give adequate rest to eyes between comparisons.
A value-oriented tooth shade guide is used. The arrangement of the guide is in the order –
Value is selected best at arm’s length and by squinting eyes to help
- Decrease light
- Diminish cone sensitivity and increase rod sensitivity.
- The tooth which fades first has a low value
The value tab may be different from the hue and chroma tab. There are two approaches to solve this problem.
If the value of shade tab is less than natural teeth then select new shade tab with higher value since you cannot increase the value of restoration with extrinsic stains.
If the operator tries to manage by increasing value with extrinsic stain, then the opacity will increase, due to a decrease in light transmission.
If the value of the shade tab is higher than natural teeth then select new shade tab with lower value or bridge the difference with extrinsic or extrinsic staining.
The color of human teeth
Albert Munsell described three dimensions of color as hue, chroma, and value. Dr. E B Clark described the color of teeth where –
- Hue ranges from 6YR to 9.3Y (YR= yellow-red, Y=yellow)
- Value ranges from 4 to 8
- Chroma ranges from 0 to 7
Guidelines for tooth shade selection
Standard daylight is the best source of light while performing work involving color. But this is not available always. Commonly used artificial light sources are –
- Daylight fluorescent – CRI- 75
- Warm white fluorescent – CRI- 56
- Cool white fluorescent – CRI- 68
*CRI= color rendering index
The use of dental operating light is not advised during shade selection as it is overpowering and interferes with the discrimination of the three dimensions of color.
Select shade before the start of the procedure. Allow sufficient time for the process. Don’t stare for a prolonged period instead stare for 5 seconds with a period of rest in between. Some people recommend staring at a blue or gray card while resting your eyes.
The patient should be in an upright position during shade selection so that the dentist views teeth under the same conditions under which others will see the teeth.
The patient should be upright with teeth at the eye level of the operator, back of the chair adjusted such that light doesn’t reflect off the surface in a distracting manner.
The patient should never be in a supine position while the dentist goes for shade selection.
Before undergoing any dental treatment, the patient should get a round of scaling done. Stains on the tooth surface will misguide both the dentist and patient during shade selection.
The operator should maintain a distance of about the length of a forearm. A greater distance of around 3 feet from the oral cavity will be even better while evaluating the shade.
If it takes considerable visual study and close inspection for another person to determine a crown, then the color match is considered good.
Digital images are useful in showing the laboratory technician the extent of translucency and the magnitude and location of surface characteristics like enamel craze lines, pigmented areas, etc.
The shade tab should be held above the mandibular tooth or below the maxillary tooth and aligned close to the plane of orientation of the facial surface of the tooth which the operator wants to match.
Holding the shade tab over the tooth gives a false impression of color as then the tooth shade is chosen against the background of shade tab instead of the oral cavity.
Over to you
The process of shade selection is a combination of art and science. The scientific phase involves serious study along with clinical application whereas artistic phase requires years of practice.
If you are going for teeth whitening, then a shade difference of two or three will change your smile. Also, if you are going for the crown, then it is better to match the color of the crown with the shade of your natural teeth to give it a natural look.
Also, take care of your oral hygiene, don’t miss your dental appointments and avoid food that can stain your crown or teeth. Doing this will make the effect of treatment last longer. (2)