This document summarizes a presentation on color science and optics given by several professors and doctors. It covers topics like the description of color, Munsell and CIELAB color systems, shade matching, human vision, metamerism, fluorescence, opalescence, shade selection systems, guidelines for shade matching, instrumental color analysis, basic shades, and the Cercon ceram kiss shade selection system. The presentation contained information on light and color perception, various color ordering systems, factors that influence shade matching, and techniques and technologies used in shade selection.

1. Color Science and Optics
Convened by:
Prof. Dr. R. K. Singh
Dr. Pramita Suwal
Dr. Prakash Kumar Parajuli
Dr. Pragya Shrestha
Dr. Arati Sharma
Dr. Indra Kumar Limbu
Presenter:
Rahul Gupta
Junior Resident
Department of Prosthodontics
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2. Contents:
1. Introduction
2. Description of color
3. Munsell color order system
4. CIELAB color system
5. Shade matching
6. Human vision
7. Metamerism
8. Fluorescence
9. Opalescence
10. Shade selection system
11. Guidelines for visual shade matching
12. Instrument color analysis
13. Basic shades
14. Cercon ceram kiss
15. Conclusion
16. References
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3. Introduction:
 Light is an electromagnetic radiation.
 Eye is sensitive to wavelengths from approximately 400 to 700 nm.
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4. The basics… 4

5. 5
Seeing Around….

6. 6
What if the incident light has no red component???
Color perception:

7. Description of color
1. Munsell color order system
2. CIELAB color system
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8. Munsell color order system:
 Devised in 1905 by A. H munsell
 3- dimension : Hue , Value , Chroma
 Hue : That quality by which we distinguish one color family from
another, as red from yellow from blue or purple.
 Value : Value relates a color brightness to the specific area on the
black-white scale. (Squinting maneuver, rods function)
 Chroma : that quality by which we distinguish a
strong color from a weak one.
 Munsell notation : H V/C Eg . 5R 5/8
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9.  Sproull determined the volume of natural tooth shades in Munsell color space
Hue: 7.5 YR - 2.7 Y
Value: 5.8–8.5
Chroma: 1.5–5.6
Relative clinical importance of hue, value and chroma :
 Color matching authorities state that hue differences are easiest to detect and value differences the most
difficult.
 The authors have approached clinical color matching of teeth with the opinion that value differences are
most important, and hue differences the least
 Hue differences may well be recognized most easily, but a slight mismatch in hue may not be as
objectionable as a slight value mismatch.
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10. CIELAB color system:
 Introduced in 1976 and recommended by international commission
on illumination.
 Used exclusively in color research in dentistry around the world.
 Equal distances across the CIELAB color space represents
approximately uniform steps in human color perception.
 Defines color space in three coordinates as L*a*b
L = proportional to value of munsell system
a = red-purple/ blue-green axis
b = yellow/ purple-blue axis
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11.  The color difference ∆E between two colors can be calculated from the sum of squares
difference among three coordinates.
 The system is so arranged that a color difference of 1 is perceptible by 50% of observer with
normal color vision
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12. Shade-matching:
 Occurs in dentist office.
visual shade matching
 Quality / Quantity of light source:
o Light source with color temperature close to 5500 K
o Color rendering index > 90
o Light intensity in dental operatory : 18-28 lux
o Light intensity for dental laboratory : 28 lux
 If ambient lighting in dental operatory is not ideal in terms of quality and quantity for visual
shade matching, the use of auxiliary lighting is recommended. Its been recommended that
the ratio of task (shade matching ) to ambient light should not exceed 3:1
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13. Shade matching environment:
 Following may influence the shade selection :
 Color of dental operatory
 Clothing of dentist and dental assistant
 The patient’s clothing
 The dental drape
 Recommendations :
1. Wall , staff clothing, patient drape and shade matching environment have a Chroma of 4
munsell units or less, which are pastel or ideal neutral gray tone.
2. Ceiling have a munsell value of 9
3. All other major reflectors (E.g. cabinets, wall )should present a munsell value of 7 and
Chroma of no more than 4.
4. Countertops not within the working area can have a Chroma of up to 6 and munsell value
retained at 7 or greater.
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14. Human vision:
 Light from any object enters the eye and acts on receptors in the retina (rods and cones )
 Impulses then pass to optical center of brain, where an interpretation is made : subjective
 Scotopic vision : Under low light conditions only rods are used, Allow only interpretation
of brightness. Rods are most sensitive to blue-green objects
 Photopic vision: dependent on cones and are dependent on high lighting conditions
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15. Color adaptation:
 Color vision decreases rapidly as a person stares at an
object. The original color appears to become less and
less saturated until it appears almost gray.
Deceptive color perception:
 Colors is influenced by surrounding colors, particularly
complementary ones.
 When blue and yellow are placed side by side their
Chroma may appear to be increased.
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16. Metamerism:
 Two colors that appear to be a match under given lighting condition but have different
spectral reflectance are called metamers and the phenomena is known as metamerism.
 Yellow objects normally reflect yellow light and hence appear yellow
 Some may actually absorb yellow light and reflect orange and green which to an observer
appears yellow.
 The problem of metamerism can be avoided by selecting a shade and confirming it under
different light conditions.
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17. Fluorescence:
 Fluorescent material such as tooth enamel, absorb near UV radiations (300-400 nm )
and then re-emit radiant energy at a lower frequency than it is absorbed
 Tooth becomes a source of light and emits in wavelength 400-450 nm (blue- white
region )
 Fluorescence makes a definite contribution to vital appearance of a tooth
 Ceramic crowns and ceramic agent that lack a fluorescent agent appear as missing
teeth when viewed in black light.
 In theory a mismatch can occur if a mismatch occurs if dental restoration had
different fluorescence than the natural tooth.
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18. Opalescence:
 Natural tooth particularly at incisal edges exhibit a light scattering effect that creates the
appearance of bluish white color as the teeth are seen at different angles
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19. Shade selection system
Vita lumin vacuum shade guide:
 A1, A2, A3, A3.5, A4
 B1, B2, B3, B4
 C1, C2, C3, C4
 D2, D3, D4
 Hue selection
 Chroma selection
 Value selection
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20. Vitapan 3D master shade guide
 manufacturers claim that this system cover the entire tooth
color space.
 Shade samples are grouped into six lightness level.
 Shade guide spacing
4 CIELAB units in lightness dimension
2 CIELAB units in hue and Chroma dimension
 Because the guides are evenly spaced intermediate shades
can be predictably formulated
 Manufacturers recommend selection in value, chroma and hue
sequence .
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21. Custom shade guide:
 Certain teeth may be impossible to match to commercial shade samples .
 One approach to this problem is to extend the concept of commercial shade guide by
making custom shade guide
 Time comsuming and generally confined to speciality practice.
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22. Guidelines for visual shade matching:
 Balanced lighting and appropriate shade matching environment
 Anything on patient that influences shade matching including brightly colored clothes be
draped and lipsticks removed.
 Teeth to be matched should be cleaned / prophylaxis done
 Shade matching should be done at the beginning of patients visit.
 Cheek retractors be used to provide an unhindered intra-oral shade matching area
 The patient should be viewed at eye level. A viewing working distance of 25cm be adopted
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23.  If tooth and shade tab have different surface characteristics, wetting the surface helps
remove the difference
 Shade matching should be made quickly (less than 5 seconds)
 Dentist should rest his/her eyes between viewing by focusing on a neutral gray surface.
 Select appropriate value by squinting
 Shade selection be confirmed at one or two other visits / confirmed with an auxillary staff
member / under different light settings
 If exact match cannot be selected , a shade tab with lower chroma and higher value should
be selected
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24. Instrumental color analysis
 Spectrophotometer / spectroradiometer /colorimeters/ digital color analyzer
 Spectrophotometer and spectroradiometer measure light reflectance at wavelengths
interval over the visible spectrum to measure the color
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25. Basic shades
 Shade A:
 Shade in A group are frequently encountered in young individual and account for
atleast 65% of the porcelain sales .
 Hue is well centered in the natural tooth color space.
 Being closest yellow hues to orange they allow color diversification into orange color
space.
 Shade B:
 Closer to pure yellow compared to shades in A group.
 Rarely encountered in natural dentition : because they are located at one extreme of natural tooth
color space
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26.  Shade C:
 Considered a sub group of B family
 Comparable hue but a lower value to B family
 Middle-aged and older individuals or in patients with tetracycline stained teeth
 Shade D
 Considered a sub group of A family
 Comparable hue but lower value to A family
 Shades C and D represent only isolated examples of lower value of a given hue of the B and
A groups, and as such do not automatically provide the expected value when an A or B tab
of lower value is desired.
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Cercon ceram kiss

28. Power chroma:
 The six fluorescent power chromas can reproduce the bulk of
all cervical and mamelon effects
as well as increases in chroma.
 Simple 1:1 mixtures between these power chromas result in
an additional 15 intermediate shades.
 Even the smallest color gradients can be emulated
rapidly and in a systematic manner
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29. Custom incisals, opal effects and multifunctional Stand-
by:
 The Stand-by multifunctional material is a strongly transparent opal effect that is one of the
keystones of the Kiss system.
 It can be used by itself or mixed with any other materials.
 The three opal effects, Ocean, Sky and Fog, control value and opalescence in blueish and greyish
incisal regions
 Sunset and Sunrise are suitable for incisal characterization and for subdued transparent chroma
gradations in the body region
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30.  The individual incisals within the Kiss system allow the emulation of all natural opalescent and fluorescent
effects.
 Opal incisals 1 and 2 are intended for lighter (OS 1) and darker (OS 2) shades. For intermediate shades, the
two material are simply mixed at a 1 : 1 ratio.
 Flu Inside 1 and 2 are highly fluorescent materials designed for the inner layers, covering the liner even where
space is at a premium, while at the same time increasing value in the incisal area.
 White Surface (WS) is a whitish opalescent effect used to increase surface value (brightness).
Here, too, the effect can be attenuated by 50% by adding Stand-by.
 To reproduce the effect of teeth that have been bleached, Bleach Liner and Bleach Dentine are available
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32. Gingival materials:
 By mixing Gum 1 to Gum 4 with selected effects
(see chart), natural gingival effects can be emulated very closely and simply.
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33. Basic build up technique in anterior region:
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34. Custom build up technique in anterior region:
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35. Conclusion:
 A basic understanding of colors objectively, is a prime prerequisite for the color
replication process viz . Shade matching and shade duplication phase. Furthermore it
reduces the hovering confusion in communication between a dental clinic and the lab
assistant. Knowing colors its various dimension and factors which affect its perception
helps us to attain predictable success in cosmetic rehabilitation .
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36. References:
 Contemporary fixed prosthodontics , Rosenstiel, Land , Fujimoto, 4th edition
 Phillips’ science of dental material Kenneth J.Anusavice, 12th Edition
 Craig’s restorative dental material, Ronald L. Sakaguchi , John M. Powers, 13th edition
 Esthetics of anterior fixed Prosthodontics
 Fundamentals of fixed prosthodontics , Herbert T. Shillingburg , 3rd edition
 Cercon ceram kiss, product description and processing manual, Degudent , Adentsply
company
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