Science of Color

Question 1

What is visible electromagnetic energy whose wavelength is measured in nanometers?

Answer 1

Light

Question 2

What is the range of the electromagnetic spectrum?

Answer 2

380-750nm

Question 3

What factors influence color?

Answer 3

1. Object, physical properties
2. Observer, assesment
3. Light, nature of incident to which object is exposed

Question 4

What factors should be considered when selecting a light source?

Answer 4

1. Color Rendering Index (CRI)
2. Color temperature

Question 5

What indicated how well a light source renders color as compared to a standard source?

Answer 5

CRI (0-100)

Question 6

What can CRI be affected by?

Answer 6

• Time of day
• Cloud cover
• Humidity
• Pollution

Question 7

What CRI is recommended for lights used in shade matching?

Answer 7

Greater than 90 CRI

Question 8

What factors influence color temperature?

Answer 8

1. Time of day
2. Cloud cover
3. Humidity
4. Pollution

Question 9

What are the 3 types of light?

Answer 9

1. Incandescent
2. Fluorescent
3. Natural

Question 10

What kind of lights are most dental offices outfitted with?

Answer 10

Incandescent and fluorescent lights

Question 11

Which type of light emits higher concentrations of yellow light waves?

Answer 11

Incandescent

Question 12

What is the normal CRI for fluorescent light?

Answer 12

50-80 CRI

Not suitable for shade matching

Question 13

What 2 systems describe color?

Answer 13

1. Munsell color order system (visually descriptive system)
2. CIELAB color system (quantitative system - 3D)

Question 14

What colors when combined produce black, and which colors when combined produce white?

Answer 14

• Black
  
  • Secondary subtractive colors (Green, Purple, Orange)
• White
  
  • Secondary additive colors (Cyan, Yellow, Magenta)

Question 15

What word describes the variety of color, and where is it found on the color wheel (Munsell system)?

Answer 15

Hue

Arranged around the wheel

Question 16

What word describes the intensity or saturation of a color and where is it found along the color wheel?

Answer 16

Chroma

From inside to outside of the wheel

Question 17

What word describes the relative darkness or lightness of a color, or brightness of an object?

Answer 17

Value

(0=black, 10=white)

Question 18

What value do natural teeth have?

Answer 18

5.5 - 8.5

Question 19

A restoration too high in ______ is easily detected by an observer and a common mistake in ___________ prothodontics?

Answer 19

• Value
• Metal-ceramic

Question 20

How does the CIELAB color system define color space?

Answer 20

By 3 coordinates:

• L* - lightness variable
• a* - red-purple/blue-green axis
• b* - yellow/purple-blue axis

Question 21

What is scotopic vision vs photopic vision?

Answer 21

• Scotopic - rods used (low light conditions)
• Photopic - cones - color (higher light conditions)

Question 22

What is the phenomenon occuring when the color of two objects appears to match under one lighting source but not under a different source?

Answer 22

Metamerism

Question 23

What are some variations of color blindness?

Answer 23

• Achromatism - complete lack of hue sensitivity
• Dichromatism - sensitivity to two primary hues
• Anamalous Trichromatism - sensitivity to all 3 hues, with abnormality in retinal cones affecting one of primary pigments

Question 24

What is the sequence of selecting a shade under the Vita Classic Shade Guide?

Answer 24

1. Hue
2. Chroma
3. Value

Question 25

What is the sequence for selecting a shade with the Vita-3D shade guide?

Answer 25

1. Value
2. Chroma
3. Hue