The Science of Color, Light
and Shade Selection
Presented by
Lisa Fedor James D.D.S.
Outline
• Light and Color
– Description of Light
• Quality of light
– Description of Color
• Hue, Chroma, Value
• Munsell Color System
– Factors influencing perception
• The eye (rods and cones)
• Deceptive color perception
• Color Blindness
• Shade selection
– Techniques for determining shade / Shade guides
– Shade mapping
Visible electromagnetic energy whose
wavelength is measured in nanometers (nm)
Without Light Color Does Not Exist
A yellow object
absorbs all
lightwaves of all
colors, but
reflects yellow
Color
Influenced by three main factors
1. Physical properties of the object
2. Assessment of the observer
3. Nature of incident light
– Relationship to other colored objects
Light
•Part of the electromagnetic spectrum
•The eye is only sensitive to the visible portion
of the spectrum (380 – 750nm)
•Different wavelengths constitute the different
colors we perceive
Pure White Light
• Relatively equal quantities of electromagnetic
energy over the VLS
+
+
+
+
+
+
=
• When passed through a prism we see component
colors of white light
• Shorter
wavelengths bend
more than longer
wavelengths
380nm
750nm
Quality of Light / 3 Types
1. Incandescent Light
2. Fluorescent Light
3. Natural Daylight
Most dental offices are outfitted with incandescent
and fluorescent lights
1. Incandescent Light
• Emits high concentration of yellow waves
• Not suitable for shade matching
• Low Color Rendering Index (CRI)
2. Fluorescent Light
• Emits high concentration of blue waves
• Not suitable for shade matching
• CRI =(50-80)
3. Natural Daylight
• Northern daylight considered the best
• Closest to emitting the full spectrum of
white light
• Used as the standard by which to judge
other light sources
• CRI close to 100
Color Rendering Index
• CRI = (0-100)
• Indicates how well a light source renders color as
compared to a standard source (N. Daylight)
• Northern daylight (hence CRI) can be affected by
–
–
–
–
Time of day
Cloud cover
Humidity
Pollution
CRI and Time of Day
• Morning and evening
– Shorter wavelengths scatter
before penetrating atmosphere
– Daylight rich in yellow/orange,
lacks blue/green
• Mid-day
– Hours around noon = ideal
– Incident daylight is most
balanced within VLS
– Full spectrum of colors visible
Color Temperature
• Another light source reference standard
• Related to the color standard black body when
heated
• Reported in degrees Kelvin (°K)
–
–
–
–
–
1000K – red
2000K – yellow
5555K – white
6500K – northern daylight
8000K – pale blue
• Dependent on four factors which influence CRI
Color
The quality of an object or substance with
respect to light reflected by the object,
usually determined visually by
measurement of hue, chroma and value
Color
Influenced by three main factors
1. Physical properties of the object
2. Assessment of the observer
3. Nature of incident light
– Relationship to other colored objects
Subtractive Color
• These are the colors associated with the subtraction of
light
• Used in pigments for making paints, inks, fabrics etc.
• The primary subtractive colors are Red, Yellow, and Blue
• The secondary subtractive colors
are Green, Purple and Orange
• When subtractive primary colors
are combined they produce black
Additive Color
• These are the color obtained by emitted light
• Associated with television and computer displays
• The primary additive colors are
Red, Blue and Green
• The secondary colors are
Cyan, Yellow and Magenta
• When additive primary
colors are combined they
produce white
Complimentary Colors
Three Attributes of Color
1. Hue
2. Chroma
3. Value
Hue
• Variety of color (red, green, yellow, etc.)
• Determined by wavelength of observed
light within the VLS
• Reflected wavelength determines hue
Chroma
The intensity or saturation of a hue
Low Chroma
High Chroma
Value
• The relative darkness or lightness of a color, or
brightness of an object
– Range = 0-10 (0=black, 10 = white)
• Amount of light energy an object reflects or
transmits
• Objects of different hues / chroma can be identical
value
• Restorations too high in value are easily detected
Low Value
High Value
Objects of different
chroma / hue can be identical
value
Value
Chroma
Objects of different
chroma can be identical value
- Equal in Chroma / Variation in Value
- Variation in Chroma / Equal in Value
Objects of different
chroma / hue can be identical value
Perception of Color
Color Perception
• Rods
– Scotopic (gray scale) vision, interpret brightness
– Interpret brightness, not color
– Highest concentration on
peripheral retina
• Cones
–
–
–
–
Photopic (color) vision
Interpret color
More active under high light
Highest concentration on central retina (macula),
most color perceptive area of eye
Color Adaptation
• Color vision decreases rapidly as object is
observed
• Color viewed dulls, while its compliment
increases in intensity
– Fatigue
• Viewing a pale blue or gray surface
between shade matching will restore color
vision
Metamerism
Two colors that appear to be a match under a
given lighting condition but have different
spectral reflectance = metamers, the
phenomenon is metamerism.
Single Light Source
Light Source #1
Light Source #2
Light Source #3
Metamerism
Color Blindness
• Defect in color vision
– 8% males
– 0.5% females
• Several variations exist
– Achromatism – complete lack of hue sensitivity
– Dichromatism – sensitivity to two primary hues
– Anomalous Trichromatism – sensitivity to all three
hues, with abnormality in retinal cones affecting one
of primary pigments
Dentists should have their color vision evaluated.
If any deficiency is detected, a dentist should seek
assistance when selecting tooth shades.
Shade Selection
• Subjective evaluation with considerable
variation
• Subtle variations can exist without causing
disharmony in smile
– Restoration contour
– Value of restoration
• Process improved by applying principles of
light and color
Principles of Shade Selection
1. Teeth to be matched must be clean
2. Remove bright colors from field of view
- makeup / tinted eye glasses
- bright gloves
- neutral operatory walls
3. View patient at eye level
4. Evaluate shade under multiple light sources
5. Make shade comparisons at beginning of
appointment
6. Shade comparisons should be made quickly to
avoid eye fatigue
Commercial Shade Guides
• Most convenient and common method of
making shade selections
• Guides consist of shade tabs
– Metal backing
– Opaque porcelain
– Neck, body, and incisal color
• Select tab with the most natural
intraoral appearance
Commercial Shade Guides
• Vita Classic
• Vitapan 3D –Master
• Extended Range Shade Guides
Vita Classic Shade Guide
• Very popular shade guide
• Tabs of similar hue are clustered into letter
groups
A
B
C D
–
–
–
–
A (red-yellow)
B (yellow)
C (grey)
D (red-yellow-gray)
• Chroma is designated
with numerical values
• A3 = hue of red-yellow, chroma of 3
Red/Yellow
Yellow
Grey
Grey
Red/Yellow
Vita Classic Shade Guide
Manufacturer recommended sequence for
shade matching
1. Hue Selection
2. Chroma Selection
3. Value Selection
4. Final Check / Revision
Vita Classic – Step 1
(Hue Selection)
• Four categories representing hue
–
–
–
–
A, yellow-red
B, yellow
C, gray
D, red-yellow-gray
• Operator should select hue closest to that of
natural tooth
• Use area of tooth highest in chroma for hue
selection
– Difficult to select hue for teeth low in chroma
Vita Classic – Step 2
(Chroma Selection)
• Hue selection has been made (B)
• Chroma is selected from gradations within
the B tabs
– B1, B2, B3, B4
• Several comparisons should be made
– Avoid retinal fatigue
– Rest eyes between comparisons (blue-gray)
Vita Classic – Step 3
(Value Selection)
• Use of second, value ordered shade guide is
recommended
• Value oriented shade guide
– B1, A1, B2, D2, A2, C1, C2, D4, A3,
D3, B3, A3.5, B4, C3, A4, C4,
• Value best determined by squinting with
comparisons made at arms length
– Decreases light
– Diminishes cone sensitivity, increases rod sensitivity
– Tooth fading first has a lower value
Vita Classic – Step 4
(Final Check / Revision)
• Potential Problem
– Following value selection, tabs selected for
hue and chroma may not coincide with shade
tab selected for value
Vita Classic – Step 4
(Final Check / Revision)
• Possible Findings / Solutions
– Value of shade tab < natural teeth
• Select new shade tab with higher value
• Cannot increase value of restoration with extrinsic
staining
• Will only increase opacity, light transmisison
– Value of shade tab > natural teeth
• Select new shade tab with lower value
(or)
• Bridge difference with intrinsic or extrinsic staining
VITAPAN 3D-MASTER Shade
Guide
Vita-3D – Step 1
• Determine the lightness
level (value)
• Hold shade guide to
patient’s mouth at arms
length
• Start with darkest group
moving right to left
• Select Value group
1, 2, 3, 4, or 5
Vita-3D – Step 2
• Select the chroma
• From your selected Value
group, remove the middle
tab (M) and spread the
samples out like a fan
• Select one of the three
shade samples to
determine chroma
Vita-3D – Step 3
• Determine the hue
• Check whether the
natural tooth is more
yellowish or more
reddish than the
shade sample
selected
Vita-3D – Step 4
• For more precise shade, intermediate
levels for hue, value, and chroma can be
given
– 2.5M2 = value between 2M2 and 3m2
– 3M1.5 = chroma between 3M1 and 3M2
– 3M2 / 3L2.5 = hue between 3M2 and 3L2.5
Vita-3D – Value Modification
• For more precise shade, intermediate
levels for value, chroma, and hue can be
given
– 2.5M2 = value between 2M2 and 3M2
Vita-3D – Chroma Modification
• For more precise shade, intermediate
levels for value, chroma and hue can be
given
– 3M1.5 = chroma between 3M1 and 3M2
Vita-3D – Hue Modification
• For more precise shade, intermediate
Intermediate
values
shouldand
be hue
noted
onbe
the
levels for value,
chroma
can
givenlaboratory communication form
– 3M2 / 3L2.5 = hue between 3M2 and 3L2.5
2.5
Extended Range Shade Guides
• Most shade guides do not cover all the
colors in the natural dentition
• Some porcelain systems extend the typical
range
• Bleached shades
• Dentin shades
• Custom shade guides
Shade Mapping
• Recommended even when good custom shade
match exists
• Tooth is divided into
– Three regions
– Nine segments
• Each region is matched independently
• Further characterizations are sketched
on diagram, may include…
–
–
–
–
Craze lines
Hypocalcifications
Proximal discolorations
Translucency
Summary
• An understanding of the science of color and color perception is
crucial to the success in the ever expanding field of esthetic
restorative dentistry.
• Although limitations in materials and techniques may make a perfect
color match impossible, a harmonious color match impossible, a
harmonious restoration can almost be achieved.
• Shade selection should be approached in a methodical and
organized manner.
• This will enable the practitioner to make the best choice and
communicate it accurately to the laboratory.
Thank You