Shade selection/ academy laser dentistry

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

THE MEANING OF SHADE SELECTION
COLOUR Energy wave of specific wave length
Shade Matching Matching two objects that reflect similar
wave lengths of electromagnetic
spectrum

Wave lengths of electromagnetic spectrum perceived by human eye
-Visible light
• Ultraviolet rays
• x-rays
• gamma rays
• Infrared
• Microwaves
• Television &
Radio waves
380 760

An understanding of the nature of light & how the eye perceives
& the brain interprets light as colour is important for successful
shade selection

Perception of colour
3 types of cones- sensitive to : Blue (short)
green (Medium)
Red(long)
Ultimate colour depends on the relative amount of stimulation of the
three receptors www.indiandentalacademy.com

Seeing colours is possible ,
since all objects absorb certain
parts of the light, while
reflecting or transmitting other
parts
A surface appears to be of a
particular colour when it
reflects that wave length and
absorbs all others
With out light there is no colourwww.indiandentalacademy.com

•A surface appears white when it reflects the entire spectrum of
wavelengths.
•A surface appears black when it absorbs all light rays
•A surface appears grey when all the wave lengths of light
are reflected and absorbed in equal measure

Additive and Subtractive Colours
Additive Colours =light mixture system
Primary colours
•Red
•Green
• Blue
Secondary Colour
•Yellow
•Cyan
•magenta

Additive and Subtractive Colours
Subtractive Colours

Dimensions of colour
Hue
The name of the color
– Could be red, green, yellow
• This would depend on the wave length of
the reflected light.
• Short wave length = Violet Hue
• Long wave length = Red Hue
• Studies show that most natural teeth fall
in a Hue range between yellow and
yellow-red – 6YR-9.3YR

Value
Amount of Gray in the Hue
• Most important factor in tooth shade
matching.
– Tooth with high value looks vital (alive)
– Tooth with low value looks gray
(lifeless)
• Is a direct consequence of the amount of
light energy an object reflects or transmits.
• Studies have shown most teeth fall in a
range from 4-8

Chroma
Saturation of the Hue
• High Chroma = High amount of Hue
with little dilution
• Low Chroma = Small amount of Hue
with large amount of dilution
– Studies have shown that teeth have a
Chroma range of 0-7
– An achromatic shade would then have a
Chroma number near 0

Maverick:
•Defined as any color or colors located in dentin but not directly responsible for hue.
•They are called maverick colors because they are strewn throughout the dentin
without organization.
•Found in dentin of most teeth.
•Formed from chemical reactions between organic and inorganic materials contained
in dentin. External tooth environment, including saliva and occlusion, together with
diet, blood and nerve supply to tooth are sufficient to cause interactions.
•They combine with hue, chroma and are projected through enamel to be perceived as
composite tooth colour.

Munsells colour system
Value : along long axis
Hue : along rim of the wheel
Chroma: increases from center to periphery

Munsells colour system -Hue
•Ten basic hues; 5 principal hues & 5 intermediate
•Each hue segment-10 major segments- further 100 fractions
•Total of 10,000hues

Munsells colour system -Value
•Ten basic values: pure black at bottom
pure white at the top
•Each further divided into 100 segments
•Total of 1000 values

Munsells colour system -Chroma
•Purest colour arranged towards
periphery
•Degree of possible saturation of
a hue is variable for each level
of value
-irregular shape of munsell
solid

Munsells Notation
•The designation of any particular color located in the Munsell color
solid is given by the notation
HV/C
H-hue
V-value
C-chroma
•Color of natural tooth is in the range of 6YR4/10 - 9.3Y8/7

CIE L*A*B
•In this system all the colors are arranged in one plane on which
the lightness values can be changed vertically
•L* (vertical axis) defines brightness or darkness of color = value in
Munsell system
• a*b* represent chromacity

CIE L*A*B
•The color difference between two colors can be calculated as
∆E= ∆ L 2
* + ∆ a 2
* + ∆ b 2
*
•The of advantage this system over
the Munsell system is equally
arranged gradations in color space
•Any colour is represented by a
unique point in space denoted
by numerical representation of
the coordinates
L*a*b color chart

Colour temperature

Translucency & opacity
Transparent translucent opaque

With increasing opacity of teeth the grey scale value decreases and the brightness
value increases.The Higher the brightness values,the lower the transparency
becomes.The more transparent a tooth the more grey it appears

B &C -Translucent areas of the teeth appear grey
A B C
A-opaque incisal edge appears white

The opal effect
Fine particles in enamel (hydroxyapatite crystals) responsible for opal effect
Fine particles reflect short wave lengths and allow longer wave lengths to pass through
-hence tooth shows •Bluish areas in reflected light
•Orange red areas in transmitted areas
In reflected light In transmitted light

Photoluminenescence : fluorescence & phosphorescence
Phosphorescence : continue to emit
visible light after being struck by U-V
light
Fluorescence: emit visible light only as
U-V rays strike them
•Human enamel is fluorescent
•Takes place even under day light conditions but usually goes unnoticed
•Becomes pronounced under high energy U-V light environment eg. Discos
•Lack or abundance of fluorescing agents in restorations may produce undesirable
effects

Tooth colors are situated in the upper lightness area of the color
space, well defined as yellow-red color tones. The shape of this tooth
color space resembles a banana in an upright position.
This signifies that all tooth shades - regardless of perception - can be
clearly defined. Knowing the position of the color space of natural teeth
provides the basis for reliable and accurate shade determination and
allows for aesthetically perfect tooth reproduction.
The tooth color space

studies of tooth shades
have shown: the
distribution of natural
tooth shades - just like
all "populations" in
nature - comes close to
a normal distribution.
That is, certain tooth
shades - defined by the
parameters of value,
chroma and hue - occur
more frequently whereas
other - more extreme -
kinds of shades are
found quite rarely.

Factors that influences the shade
perception

Cone color perception decreases the longer an object is looked at.
– The Hue range gets less and less (Gets grayer)
– This suggests that one should not stare at a
tooth but look briefly and then look away
When looking away, you should look at a
neutral or gray background to allow cone
sensitivity to return
Factors Affecting Color Perception
Color Adaptation:

Complementary Colors affect each other:
• When placed side-by-side they may
appear to increase Chroma
• Hue and Chroma selection may be
affected by the color of lipstick or make-up
the patient is wearing.
Deceptive Color Perception:

Affects about 8% of the male population
– Very few cannot see color at all, most have an inability to detect the
differences in Chroma - This is called monochromatism
– Requires then an alternate method of shade selection.
Color Blindness:
• Use of office staff
• Special training to overcome or adapt
Colour vision test plate
You should be able to see the no.

Factors that influences the color of
an object?
• The physical properties of the
object
• The nature of the incident light in
which the object is viewed
• The relationship or close
association to other colored objects
• The color background of the
viewer

The nature of the incident light in which the object is viewed
Colours of two objects appear to match under one set of viewing
conditions but differ under different light conditions - metamerism

The nature of the incident light in which the object is viewed
Clinical significance :tooth & restorative material of a
differing shade may appear matched under certain light
conditions , but may show discrepancy in day light
tooth
restorative
Appear Matched
mismatch

Ideally light source for shade matching:
•Should have complete colour content
•Enough intensity
•Comfortable to the eye
•Standard- unchanging in quality & quantity
Northern exposure sunlight at mid day with slightly overcast
sky considered ideal- equal blend of all wave lengths of light
Unfortunately all clinics may not have access to natural sunlight
and even if available,may not have adequate intensity .

Most common lighting is
either:
– Incandescent
– Fluorescent
• Neither is pure white light
– Incandescent is higher
in yellow than blue
– Fluorescent is higher in
blue waves
Light in the Dental Office
Chair light is not recommended for colour matching as it is over
powering and interferes with fine discrimination of three
dimensions of colour

The concept of Colour Rendering Index (CRI):
•Capacity of artificial light to reproduce natural light
•White light has CRI of 100- is constituted of equal energies
from all the three primaries of the spectrum ie. Red , blue,
green.
•Artificial sources with CRI 90 are adequate
Warm white fluorescent –CRI 56
Cool white fluorescent –CRI 68
Colour corrected fluorescent CRI –above 90

Amount & location of lighting
Ideal amount of light –1500 lux
-This over comes influence of ambient room light
-not so intense that slight colour differences are
overcome or washed out
Location of light
•All luminous ceiling
Surrounding environment
Bright coloured environment
Interfere with proper colour match
Light grey –ideal background

Selection should be made when subject tooth and adjacent teeth are
clean.
Principles of Shade Selection
Selection should be made at the start of the appointment
before operator’s eyes get tired
Cosmetics
should be
removed and
bright colored
clothes
covered

The shade tab should be Held as close to the subject tooth as
possible.This lets the incident light hit both at the same angle

A blinder of neutral grey may be used to separate the tooth
from its surrounding - hence no near by colour can
interfere in judgment

• Use multiple light sources or have an operatory of
color corrected lights
• View the subject tooth quickly
– Do not stare at the tooth-eye accommodates and becomes
biased
– Move your eyes away and look at a neutral color
(light blue or grey)to readapt vision to orange – yellow
portion of spectrum

Shade selection for resin composites
•Standard shade guides e.g.. Vita &
use corresponding shade of
composite material
•Shade guides supplied by the
respective manufacturers
•Custom shade tabs

(Esthtet x )

Translucent bodies demonstrate the property of changing their
colour with increased thickness.Colours become darker and
more intense

Conversion chart
Composite materials usually carry
Shade information in one system
(e.g..A3, i.e..vita)
However if the clinician does not
have the same shade guide a
conversion chart may be used

Types of Shade Guides
Hue – Chroma shade guide
Allow an approximate Colour shade to be given
Eg. Vita Lumin vaccum – 15 shade tabs
Mass shade guide
Allow an more accurate shade matching
Eg. Vita 3D master- 26 shade tabs

Vita lumin
Four basic hues of Vita Shade guide
A Brownish tones
B Yellowish tones
C Greyish tones
D Reddish tones
A1, A2, A3,A3.5,A4 represent
increasing chroma

Vita lumin
The following arrangement of shade tabs indicates decreasing value
B1*A1*B2*D2*C1*C2*D4*A3*D3*A3.5*B4*C3*A4* C4*
Brightest Darkest
• Begin by selecting hue.Maximum
chromas of hue are selected-
A4,B4,C4,D4 and compared against the
teeth.
•After basic hue has been determined
chroma is chosen
Sequence of Shade Selection

The tooth colors of conventional shade
systems do not feature systematic
colorimetric distribution in the tooth color
space.
Shade guides – Vitapan 3D Master
VITAPAN 3D-MASTER provides a systematic
uniform and complete colormetric coverage of
the tooth color space.

Shade guides – Vitapan 3D Master
Tolerance cloud
Rationale: The most frequent tooth Colours are located in the middle
Human eye can tolerate greater variation in value than in
chroma or hue

In the first step of the shade taking procedure the value
(lightness) is determined. Select the value level from the five
value groups (levels 1 - 5) that is closest to the value of the tooth
to be compared.
Vitapan 3D Master

Pull out the medium shade sample (M) from the selected value group.
Then the chroma (levels 1 2,3) is determined. Select the color sample of
the selected M group that is closest to the tooth to be compared.
Vitapan 3D Master

In the third step the hue (L, M,
R) is determined. Check
whether the natural tooth
displays a "more yellowish" (L)
or "more reddish" {R) shade
than the color sample of the M-
group that has been selected in
the second step. Now the best
matching shade sample is
determined and the information
is recorded in the color
communication form.
Vitapan 3D Master

2 L 1.5
Value Hue Chroma
Color communication form

Chromascop
Based on the concept that tooth shade blends in with overall
appearance of individuals.

Chromascop
According to this concept individuals can be classified into two types
•Amber reflectors
Spring type , autumn type
•Grey reflectors
Summer type ,Winter type
Tooth shade is in harmony with the colour of the skin,hair, eyes & teethwww.indiandentalacademy.com

Spring types
•200 shade group
•Golden to medium blond hair
•Light grey eyes
•Pink pale skin

Autumn types
•(300 shade group)
•Medium blonde- red hair
•Dark blue eyes to green – blue eyes
•Pale reddish skin

Summer types
•100 shade group
•Ash grey to medium brown hair
•Slightly pink to pale skin
•Grey-blue eyes

Winter types
•400 & 500 shade group
•Dark brown to black hair
•Icy blue/green eyes
•Amber skin
Dark skinned individuals -Asians allocated to this type

The Noritake Shade Guide
The Noritake Shade Guide has.
a) Intermediate shades (NP1.5 , NP2.5)
These two shades are often seen in natural teeth:
NP1.5: The chroma is between A1 and A2 shedes - the hue
corresponds to the slightly reddish shades.
NP2.5: The chroma is between A2 and A3 shades - the hue
corresponds to the slightly reddish shades.

Shade matching in Glass ionomer
Vita shade
Biochromatic shade

Shade selection Acrylics
•Standard shade guides

Shade distribution chart
•Tooth divided into 3 regions
•Each region matched independently
•Individual characterstics marked

Colour measuring devices
They remove the subjectivity out of the colour matching process
Shade vision system
Vita easy shade
•Still in their infancy
lack the ability to
match the shade of the
tiny, fine details

An understanding of the science of colour and colour
perception is important if success is to be attained in the
ever expanding field of esthetic restorative dentistry.
Although limitations in materials and techniques may
make a perfect colour match impossible, a harmonious
restoration can almost always be achieved . Shade
selection should be done in a methodical and and
organised manner. This will enable the practitioner to
make the best choice and communicate it accurately to the
laboratory
Conclusion

Thank you
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Shade selection/ academy laser dentistry

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