Principles of Color Science in Dentistry and dental ceramic restorations

Question 1

What factors are important for the appearance of teeth and restorations

Answer 1

Size
Shape
Interactions of illumination

Question 2

What are the interactions of illumination?

Answer 2

Gloss
Translucency
Color

Question 3

Gloss

Answer 3

The amount of light reflected at the surface of material; with consideration also of the dispersion or scattering of the reflected light from the specular angle of refletion

Question 4

T/F - instruments are available to measure gloss

Answer 4

True - but most instruments do not precisely cover the entire range of possible gloss values

Question 5

What are the ways to recommend gloss for clinical evaluation?

Answer 5

Know the shape of the illuminant
Assess the quantity of reflected light
Assess the quality of reflected light

Question 6

What are the 3 levels of translucency?

Answer 6

Opaque
Translucent
Transparent

Question 7

Opaque

Answer 7

Light cannot pass through the material

Material masks any underlying color

Question 8

Translucent

Answer 8

Light, and therefore color, pass through the material, but is partly absorbed, scattered, or both

Question 9

Transparent

Answer 9

Light and color pass through the material unaltered

Question 10

Translucency of human enamel

Answer 10

Light tries to travel through, but the curvature of the tooth can reflect light

Question 11

What are the 3 components of color observation?

Answer 11

Illuminant
Object
Observer

Question 12

Spectrum of light

Answer 12

Illuminant, the object, and the light entering the eye are each spectral, comprising energy at every visible wavelength
The visible wavelengths extend from 380 nm (just above UV) to 780 nm (just below infrared)

Question 13

Any light below 380 nm or 780 nm is perceived as what?

Answer 13

Black

Question 14

Observer

Answer 14

Although the light entering the eye is spectral, the 3 different types of cones of the eye simplify this spectrum into 3 aspects, or 3 dimensions of color

Question 15

What are the 3 dimensions of color?

Answer 15

Lightness/Value

Two dimensions of chromaticity (hue and chroma)

Question 16

Lightness/Value

Answer 16

What we consider to be the ‘color’

Question 17

Chroma

Answer 17

The spectrum that goes from gray to a more vivid color

Question 18

What color change value is perceivable?

Answer 18

For tooth colors, the limit of perceptibility is ~2 CIELAB units

Question 19

What color change value is acceptable?

Answer 19

In dentistry, a CIELAB color difference of less than 3-5

Question 20

What are some examples of color temperature?

Answer 20

1,800K = Red-orange
3,000K = Yellow
5,555K = White
25,000K = Bluish-white

Question 21

Rendering Index

Answer 21

Describes how the colors of objects under the illuminant differ from the colors of the same objects under a standard (daylight) illuminant
The closer to 100, the more the colors of objects look like they do under daylight

Question 22

Metamerism

Answer 22

Two objects
No (or negligible) color difference under some illuminant
Color difference under other illuminant

Question 23

What does scattering cause?

Answer 23

A change in direction of the light

Eventually the light scatters so much, the direction of the light reverses

Question 24

What does absorption cause?

Answer 24

A lowering in the intensity of the light

Chormatic pigements have absorption which is highly dependent on wavelength

Question 25

High ratio of absorption/scattering causes what?

Answer 25

Low lightness (dark)

Question 26

Low ratio of absorption/scattering causes what?

Answer 26

High lightness (bright)

Question 27

T/F - Absorption and scattering are each spectral

Answer 27

True

Question 28

High absorption and/or scattering leads to what?

Answer 28

Low translucency (High opacity)

Question 29

Low absorption AND scattering leads to what

Answer 29

High translucency