Shade taking

Question 1

What are the 3 components of colour?

Answer 1

• Hue
• Value
• Chroma

Question 2

What is hue?

Answer 2

The specific wave length of light, any of the primary colours individually or blended together. (A,B,C,D)

Question 3

What is value?

Answer 3

The lightness or darkness of a colour.

Question 4

What is chroma?

Answer 4

The intensity of a colour/saturation due to the concentration of a pigment (number).

Question 5

Describe the VITA shade guide.

Answer 5

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).

Question 6

What tips should you remember for shade taking in practice?

Answer 6

• 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

Question 7

How do you chart tooth shade on a lab prescription?

Answer 7

• 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)

Question 8

What can be added to a crown or veneer to better match a patient’s natural tooth?

Answer 8

Stain
- Replicate natural tooth staining using stain guides

Question 9

Why may a restoration shade not match?

Answer 9

• 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