* Focused Lec Quiz 3/30 Color Science and Dental restoration (same as above?) Flashcards
How are rays of light colored?
They are not
Factors affecting color perception:
stimulus, receptor, interpretation
Psychophysical perception of color:
receptor
physical quantity affecting color:
stimulus
psychological aspect of color perception:
interpretation
Pictorial representation of radiant power emitted by a light source:
spectral power distribution
Visible region of electromagnetic spectrum:
360-770nm
Light source w the most to least amt of yellow:
warm white fluorescent, cool white fluorescent, natural light, vita-lite fluorescent
Color at the 700nm:
red
Light source w most to least blue:
natural, vita, cool white fl, warm white fl
Natural light source:
yellow, green, red, blue, gray, near-UV white, mid-UV white
spectral power distribution of light source affects:
ability to render colors “naturally”
Are all SPD curves the same for different manufactured light sources?
no
Metamerism is based on:
differences in spectral power distribution
Theory of Photochemical process (Young-Helmholtz theory)
trichromatic color vision
Photoreceptors, cones or rods?
cones
How do cone cell differ?
each sensitive to a certain range of WV
What type of light mixture is theorized to occur in the photochemical process?
additive mixture of lights
3 parts of color interpretation:
signal pwys, visual cortex, color memory
Hue, value, chroma, axis for each?
x: chroma, y: value, z: hue
this is the vertical, achromatic axis:
value
Enables differentiation bw color families:
hue
Enables differentiation bw pale and strong:
chroma
Most universally accepted color wheel system:
Munsell, non-uniform color space
Color system, differential color measurement:
CIELAB
CIELAB, uniform or non color space?
uniform
What does it mean to have a uniform color space?
equal distances represent equally perceived color difference
does the relative change in wavelength correlate to the relative change in perception?
Dimensional units for CIELAB:
L, a, b*
Which are generally higher, perceptible or acceptable thresholds?
acceptable
Bench top assessment of imperceptible, DE is:
<1
Bench top assessment of perceptible, DE is:
> 2
Acceptability range via intraoral assessment:
DE=2.75 - 3.3
What varies the most in teeth, hue value or chroma?
value
Requirements for color guide:
logical arrangement, adequate distribution in color space
Main grouping in Vita Classic shade guide:
Hue: A to D
What varies within each group?
higher N^0, Cinc, Ldec
check
of tabs in Vitapan 3d master guide:
26, uniformly positioned throughout color space
4 types of shade guides:
3D, Vita Classic, Chromascope, Bioform
Shade guide least uniformly distributed in space:
Bioform?
of groups for Vitapan 3d master guide::
5 + bleaching group
Groups in the Vitapan 3d master guide are based on:
Value (hue for Vitapan Classic)
The groups are arranged this way horizontally for Vitapan 3d master guide:
Hue horizontal
How are the groups in Vitapan 3d master guide arranged vertically?
chroma
2 methods of shade selection:
Visual, instrumental
5 factors affecting visual shade selection:
light, pt position, tooth hydration, timing (daylight), sequence
What can affect light during visual shade selection?
operatory colors, pt w vivid color clothing or lipstick
Ideal distance to be from pt when choosing tooth shade;
25-35cm, arms length
Shade tab positioning of colors, apical to incisal:
red, green, blue
How to hold shade guide while choosing:
arms length, next to tooth, matches and aligned so light reflects in a similar manner off both, eye at tooth level, single trial 5-7s, neutral gray bib, different light sources, full mouth photo
When w/in appt to test shade:
beginning
Is the Vita Easyshade V more accurate or reliable?
reliable
