Chu Color Textbook

Question 1

43. What Viewer-Associated Effects can impact perception of color?

Answer 1

1. Color deficiency (weakness/absence of one or more of the three types of photosensitive pigments/cones for red, green, blue)
2. Age (cornea/lens become yellowed at age 30, hard to differ white/yellow. Worse at 50, then 60 where blues/purples are hard to perceive)
3. Fatigue (stimulation of one color affects the other pair - blue-yellow, red-green, and black-white)
4. Light/dark adaptation
5. Nutrition (Vit A supply
6. Emotions
7. Medications
8. Binocular difference

Question 2

4.58 How do people’s tooth structure and color change as they age?

Answer 2

Dentin becomes more exposed and there is wear on the incisal edge, causing tooth to become more tapered and triangular. Surface texture becomes shinier and smoother (due to abrasion/attrition).

1. Dentin more visible through thinner, more translucent enamel
2. Calcification increases, resulting in lower enamel translucency
3. Diffusion of light through dentin decreases, color goes from opaque light to translucent dark
4. High-value whitish color of youth changes to low-value orange and then low-value brownish

Question 3

4.58 How does tooth whitening affect tooth color (chroma, hue, lightness)? What’s the actual most appropriate term instead of whitening?

Answer 3

Chroma, then lightness then hue. “Desaturation” is most appropriate term. Tooth whitening’s decrease in chroma combined with increase in lightness causes desaturation.

Teeth become lighter, less chromatic, higher hue angle. Decreases a* red and b* yellow.

Question 4

4.60 What four factors give gingiva its color?

Answer 4

Thickness of epithelium, degree of keratinization, pigmentation, underlying vascularity

Question 5

4.61 2015 Ho et al study: How does gingiva’s color change as we age?

How does male compare to female?

Which ethnicity has the darkest gingiva?

Answer 5

Becomes lighter, less red, less yellow with age

Males: Darker, redder, less yellow then females

African Americans: Darkest, yet least red and yellow.

Question 6

4.72 What are the Vita classical A1-D4 shade guides arranged according to? What are the four?

Answer 6

Hue

A: Reddish-brown
B: Reddish-yellow
C: Grayish
D: Reddish-gray

Question 7

4.72 Going from A1 to A4 indicates what?

Answer 7

1. Least chromatic with highest value
2. Most chromatic with lowest value (ie the darker and most chromatic)

Question 8

What do the three numbers in VITA 3D-Master tabs mean? (eg 3M2)

Answer 8

3: Value (Six groups: Goes 0/bleach to 5/dark)
M: Hue (“L”Left for yellow, “M”middle for middle hue, and “R” for right/reddish
2: Chroma (1: low, 2: medium, 3: high)

Question 9

80. What are optimal shade matching conditions for lighting/environment, distance/position, and timing/duration?

Answer 9

1. Lighting/environment: color-corrected lighting with ideal color temp of 5500 to 6500 K
2. Distance/position: clinician’s eye at tooth level, 10 to 14 inches away
3. Timing/duration: Beginning of appointment (to avoid dehydration - teeth get lighter and less chromatic, and avoid eye fatigue)