Dental shade determination – The science of color
Dental shade involves Value Chroma and Hue and that is the order you choose them (nice definitions here). Human eye much better at value because rod cells detect and we have 120 million vs. 7 million cone cells that detect hue.
- Educate yourself and staff on the science of color. Scadent has a free course and Chad Anderson has a nice article. Lane has a great course on dentaltown. Education is proven to improve shade determination. Clary 2016 JPD
- Ensure you are not color blind or deficient EnChroma has a nice test here
- Always pick the value first and then squint to help you pick the proper value.
- Pick several that are close and take iphone photo in Mono or take a photo using polar eyes.
- For Hue look at canine as it has highest Chroma for the arch
- Stare at something blue before choosing (blue fatigue makes eyes more perceptive to yellow).
- Two second rule means look no longer than two seconds before get yellow fatigue.
- Use a gray card with a single tooth cut out so other teeth do not influence your selection
- Get the value based shade guide =Linearguide 3D Master
- Utilize light sources like Rite-Lite 2 and SmileLite Clary 2016 JPD
How good is your color IQ?
X-rite has a nice test but hard to tell where you actually compare to others and also hard to tell if your score is good or not. Here are my results, I apparently have a color IQ or color acuity of 20.
Tricks if unsure of dental shade
- Pick higher value if unsure (can not increase value)
- Choose lower chroma if unsure (can raise chroma)
- More reflection makes look brighter (higher value)
- Tech toys listed below.
- Ott Lite gives true color 5500K
- Gray card to isolate tooth to eliminate impact the perception of nearby teeth have on the one you want to match
- Take photos using polar eyes and send them to the lab. This eliminates specular highlights that hide details.
Watch how the color seems to change as the cut section of the shade tab moves from high value/low chroma to low value/high chroma
Tricks to alter dental shade if already made
- You can lower value by using a complementary color tint (can’t increase=why pick higher if unsure)
- In dentistry, Violet (complementary of yellow) most effective reduce value also increase translucency
- For translucency gray is nice. Can use mixture of violet and gray
Tricks for staining under a restoration
- An underlying white opaque cement may bring value up if using a translucent material.
- Pink opaque over metal or dark tooth
Dental shade guide information
Traditional guide is hue based A=reddish brown, B=reddish yellow, C=gray, and D=reddish gray. 3D Master is value based with M=standard hue L=yellow and R=red
If using older shade guide organize by yellow-red hue and then yellow hue in decreasing value SO
A1, A2, A3, D3, A3.5, C3, A4, C4, B1, B2, D2, C1, C2, D4, B3, B4
Dentists use RGB devices, colorimeters, and spectrophotometers, but spectrophotometers are the best. Spectrophotometers measure reflected light in 20 nm intervals from 380-720 nm. Easyshade Compact, SpectroShade Micro, Shade Pilot are all examples of spectrophotometers. Kim-Pusateri JPD 2009 found them to be similar in accuracy and Doziac JP 2007 found EasyShade did well.
Another option is software route. Shadewave is an example and finally the cloud version of this is the Clear Match system. In conclusion this seems like this is the best method.
What is the best lighting for shade determination?
Lighting should be full spectrum balanced light at 5500K, CRI of >90, and about 200 footcandles of intensity. However, any light that is 5,200K-6,000K with a high CRI, preferably in the 90’s, will help. One common light aid is the 5,500K handheld light Rite-lite by AdDent.
Brighter L Darker
Red a Green
Yellow b Blue