W7. TOOTH SHADE DETERMINATION Flashcards
What are the 2 steps of tooth shade determination?
I. Comparison method with Shade guides
II. Measurement - Instruments for color measurement
What is the Classical shade guide: practical experience?
A-orange
B-yellow orange
C-grey orange
D-brown orange
What are the 5 shade selection keys?
- Use correct environment and lightning
- Select shade at the beginning of appointment
- Patient sitting upright
- Patient’s teeth/dentist’s eyes at same level
- Look for variance between gingival ,middle and incisal thirds of teeth
- gingival -higher chroma
- middle -higher value
- incisal -higher translucency
How should we control the environment for tooth shade determination?
- Must surround teeth with colour that aids color perception
- Use neutral colors in operatory
- Window light-daylight
- No lipstick
- Always use a bib
- Cover brightly-colored clothing
- Natural teeth-orange/compliment of orange is blue
- Use gray patient bibs
What is value? (Grassmann/ Munsell)
- Degree of lightness or darkness of a
color relative to a series of grays
What is chroma? (Grassmann/ Munsell)
It is the difference between the color and a gray having the same brightness
What is hue? (Grassmann/ Munsell)
-physical wavelength of light, represented as an angle ranging from 0° to 360°.
Are there any limitations in classical shade guides?
YES!!
* Not uniformly positioned throughout tooth color space
* No standard difference between adjacent shades
* In-between shades (eg.”A2.5” ) are inaccurate
Are there any limitations in classical shade guides?
YES!!
* Not uniformly positioned throughout tooth color space
* No standard difference between adjacent shades
* In-between shades (eg.”A2.5” ) are inaccurate
What are the characteristics of 3D Master tooth guide?
Systematic precision of shade matching :
- 5 Value Groups (1-5) left to right
- Chroma represented by a number (1- 3)within each value group: pale to intensive
- Hue represented by L,M, R left to right
How do we determine shade selection?
1st step: Value level from the five value groups (levels 1 - 5) that is closest to the value of the tooth to be compared
2nd step: Chroma (levels 1 2,3) is determined, color sample of the selected M group that is closest to the tooth to be compared.
3rd step: Hue (L, M, R) is determined,whether the natural tooth displays a “more yellowish” (L) or “more reddish” {R) shade than M-group
What are the features of digital color determination?
- Technological shade systems
- Measurement data analyzed by computers
- Color quantified using numerical values
- Objective, consistent, reproducible color measurement
- Printing house-press
- Textile industry
- Interior decorators
- Paintwork on cars
What are the features of Digital Tooth Shade Determination?
- RGB devices
- Colorimeter
- Spectrophotometer
How do we place the probe tip correctly? ( Digital Tooth Shade Determination)
A. Correct placement: (probe tip perpendicular and flush on tooth surface)
How should lab communication be in Digital Tooth Shade Determination?
Tooth color: BASIC SHADE and :
* Tooth surface
* Bluish, whitish, greyish incisal edge
* Inclusion of perykimata
* Glossy, matt surface
* Mamelons
* Longitudional and transverese lines
* Hairline cracks and stains
* Transparency zones trans/appearance
* Translucency trans/lucence
* Individual characteristics
* Anatomic differences
