color and shade selection

lecture given 3/2/2026

visible color spectrum

color red, orange, yellow, green, indigo, and violet

due to different wavelengths and frequency, the individual waves pass through the prism at different speeds and are separated

how many different colors can the human eye distinguish?

about 10 million

cone cells

color, high light

photoreceptors for medium and high light color vision

sensitivity peaks in short (420-440), middle (530-540) and long (560-580) wavelengths

rod cells

white, grey, black, low light

low light monochromatic night vision receptor, with peak sensitivity at 490-495

color perception

objects appear colored due to the way they reflect light

reflected light represents out perception of color

when white light shines on the plumage of a parrot, only the blue rays in the light are reflected and we perceive the plumage as blue

the same color can appear different due to…

light sources, background differences, viewing angle, angle of incident light

color space

munsell 1905 color space

CIE 1931 RGB color space

CIE 1931 XYZ color space

hunter lab space 1940

lab color space (CEILAB1976)

dental color system LC*h (luma/chroma/hue model)

I have no clue what the point of any of this slide is

3D color system

value- lightness, eye value (rods)

chroma- saturation, eye chroma (cones)

hue- tone, eye hue (cones)

in the CIE L*a*b system, what does L* stand for?

value

in the CIE L*a*b system, what does a* stand for?

red (+) to green (-)

in the CIE L*a*b system, what does b* stand for?

yellow (+) to blue (-)

what is the algebraic distanein color space?

deltaE = [(L*1 - L*2)² + (a*1 + a*2)² + (b*2 - b*3)²] ^1/2

what value of deltaE is discernable?

deltaE* = 4

what value of deltaE is not discernable?

deltaE* = 2

value

enables differentiation between the light and the dark colors

vertical, achromatic axis

hue

enables differentiation between color families

hues are placed in a closed hue circle

chroma

enables differentiation between pale and strong colors, the distance from the vertical axis

opacity

impenetrable by light, neither transparent nor translucent

transparency

capable of transmitting light so that objects or images can be seen as though there were no intervening material

translucency

diffuse light transmission

metamerism

the same object, without changing color, may appear different in color under different lighting conditions

what factors (besides lighting) help to determine a proper shade match?

characterization, surface texture, incisal shape

opalescence

sub micron crystals reflect light of different wavelengths depending upon the angle that the radiation strikes the object

fluorescence

light emission that is caused by the absoprtion of radiation at one wavelength followed by re-radiation usually at a different wavelength

5% of all dental restorations are returned to the lab, what % of that is due to shade mismatch?

80%

vita shade guide

first shade guide produced in 1927

24 shade tab guide with 4 color ordered groups that are estbalished with increasing chromatic intensity

vita classical lumin vac

classical 16x tab shade guide

what are modern developments in vita?

1998 3D master shade guide

2003 easy shade

easyshade V

shade guides

most are not evenly distributed in color space- value, hue, and chroma all change

vita 3D master

value based, evenly distributed, natural tooth color space

26 shades accurately cover known tooth colors

uniformly positioned throughout tooth color space

systematically organized for easy, accurate shade taking

vita classical A

reddish-brownish

vita classical B

reddish-yellowish

vita classical C

greyish

vita classical D

greyish-reddish

how should you arange your vita classical guides?

by value! to assess shade quicker and more accurately

(for example, shades C2 and D4 are actually lighter than A3)

where do tooth shades fall in visual space?

a banana shaped area, approx 1000 measurable dental shades

of these 1000, only 100 variations are visually noticable

what are the problems with classic guides?

gaps/clusters- not evenly distributed

complex mixing- simultaneous changes in hue, chroma, and value

not systematic

what is the criteria of distribution for tooth colors within tooth color space?

distances of tooth colors within the tooth color space (deltaE)- shades are distinguishable

absolute position within the tooth color space- the right positioning of shade guide tooth colors should cover the whole range of natural tooth colors

quantity of tooth colors- the whole tooth color space should be covered nearly complete (best matching probability), arrangement should include groups of the same lightness, saturation, hue (selection after colormetric order principle to meet human sense, fast/systematic selection)

if using the VITAPAN 3D master, what does the code 3M2 mean?

value of 3 (scaled from 1-5)

hue M (L, M, R)

chroma 2 (scaled 1-3 w/ 0.5)

how should you use a VITAPAN 3D master guide?

chose the matching lightness level (start from the middle)

select the color stauration (start from the M group)

select the matching hue (reddish R or yellowish L)

what are the advantages of vita 3D master guide?

logical/better coverage

more reproducible

less adjustments and remakes?

besides the shade guide, how should you take shade measurements?

patient sitting in an upright angle- the angle at which light enters the mouth significantly influences how the shade is perceived

use color corrected 5500 degree K light bulbs or use digital shade taking

ALWAYS take the shade before prepping the tooth (teeth dry out quickly but take 24 hrs to rehydrate)

position the shade tab in the same position (maxillary or mandibular) as the tooth being measured

view the shade from both direct and slight indirect viewpoints

view the shade of the restoration under natural daylight, incandescent, and fluorscent light

always take a shade of the preparation when prescribing an all-ceramic restoration (stump shade)

select the higher value of tooth shade if undecided (easier to increase the chroma and/or lower the value)

do not stare at a shade for more than 5-10 seconds

if pt bleaches teeth, do not take the shade until a week after the last bleaching application

allow the pt to review the shade holding the mirror at arms length from their face

warm white

2700K

cool white

3000K

daylight

5000K

what are the automatic shade selection options?

shofu shadeeye, vita easyshade, cynovad shadescan, x rite shade x, digicolor, olympus

why should you use automatic shade selection devices?

confounding factors- lighting, surrounding colors, texture/morphology, angle of incidence

automatic systems- improved selection, quality control, reliability, reproducibility, more information, less adjustment / remakes

what factors (light related) may influence shade selection?

angle of view, lighting conditions, colors reflecting from walls/clothes, surrounding soft tissues, value vs chroma

spectrophotometer

measures transmitted / reflected light, measures may points to produce a color curve or spectrum

colorimeter

tristimulus- uses red, green, blue filters to measure color

cannot compensate for metamerism

software based shade selection

digital photo color analysis

what are the parts of the easyshade spectrophotometer?

detector fiber, spectral filters, semi conductor detectors, emission spectrum

is a human using a shade guide or digital shade guide more reproducible?

digital- matched shade 90% of the time

humans were only 50% of the time

what part of the eye is responsible for perception of hue and chroma?

a) rods

b) cones

c) pyramids

b) cones

what minimum difference in deltaE can be seen by most people?

a) about 2-4

b) about 4-6

c) about 1-2

a) about 2-4

a spectrophotometer shade selection is:

a) affected by ambient light source

b) is not affected by ambient light source

c) functions the same as a colorimeter

b) is not affected by ambient light source

when selecting a shade you should reset your yellow-orange color vision by?

a) looking at a red background

b) looking at a grey background

c) looking at an orange background

b) looking at a grey background

when selecting a sahde you should do this?

a) at the beginning of the appointment, before tooth preparation

b) at the end of the appointment, after tooth preparation

c) only in bright sunlight

a) at the beginning of the appointment, before tooth preparation

when selecting a shade you should?

a) always choose a lower value shade when unsure

b) always choose a higher value shade when unsure

c) always choose a higher chroma shade when unsure

b) always choose a higher value shade when unsure

t/f the value of a restoration can always be made higher (whiter/brighter)

false

a glossy surface on a restoration appears?

a) to have a higher value

b) to have a lower value

c) higher chroma

a) to have a higher value

if a restoration is not fluorscent, how will it appear in fluorescent lighting?
a) bright white

b) black

c) yellow

b) black

the color of an object is due to?

a) absorbed wavelengths of light

b) reflected wavelengths of light

c) diffracted and transmitted wavelengths of light

b) reflected wavelengths of light

the CIE L*a*b* system is a measure of an objects position color space, what is L?

a) value

b) chroma

c) hue

a) value

the CIE L*a*b* system is a measure of an objects position color space, what is a and b a measure of?

a) a= red/green, b= yellow/blue

b) a= yellow/blue, b= red/green

c) a= purple/red, b= blue/green

a) a= red/green, b= yellow/blue

many shade guides including vita classic have shade tabs that?

a) overlap in color space

b) are outside the range of normal tooth color

c) a and b

c) a and b

t/f spectrophotometers compensate for metamerism

true