Shade taking Flashcards
What are the 3 components of colour?
- Hue
- Value
- Chroma
What is hue?
The specific wave length of light, any of the primary colours individually or blended together. (A,B,C,D)
What is value?
The lightness or darkness of a colour.
What is chroma?
The intensity of a colour/saturation due to the concentration of a pigment (number).
Describe the VITA shade guide.
Divided into hue groups:
- A: reddish brown
- B: reddish yellow
- C: grey
- D: reddish grey
Divided into chroma (intensity of pigment):
- 1 = low chroma
- 4 = high chroma
Can be arranged by value (lightest to darkest, top image) or arranged by hue group (bottom image).
What tips should you remember for shade taking in practice?
- Have a neutral-coloured environment
- Remove bright lipstick
- Drape patient in neutral cloth if wearing bright clothing
- Make intial shade choice in daylight and check under different light sources if possible
- Check hue group first, then decide chroma
- Compare results with a shade guide
- Assess shade using the middle third of the shade tab
- Use canines as a reference as they have the highest chroma and most dominant hue
- Assess incisal edge separately
- Take shade at beginning of appointment (cones of eye fatigue within 20 seconds)
- Look at blue card between appointments
How do you chart tooth shade on a lab prescription?
- Tooth divided into 9 sections
- Central square decides the body colour
- Incisal edge shade: write ‘en’ so technician knows it is the enamel colour
- Draw line to show where body colour and enamel colour transition (solid = harsh transition, dotted = faded)
What can be added to a crown or veneer to better match a patient’s natural tooth?
Stain
- Replicate natural tooth staining using stain guides
Why may a restoration shade not match?
- Thickness of shade guide, VITA shade guide tabs are 5mm thick, for a crown the enamel will be 1mm thick or less so the colour will be different
- Mixing of prescriptions- if you are doing all ceramic crowns and some metal ceramic crowns, the all ceramic crowns will always look better
- Design of metalwork (metal substructure dictates how much room you have for ceramic on top)
- Black line at margins for metal ceramic crowns
- Prepare teeth as pairs wherever possible e.g. 4 anterior teeth: do the 2 laterals together and the 2 centrals together