Aesthetics and Shade Selection

Question 1

What are the parameters of dental aesthetics?

Answer 1

• Shape
• Colour
• Position
• Proportion
• Symmetry

Question 2

What should you check in terms of smile analysis?

Answer 2

• Incisal occlusal plane (follows curve of spee)
• Midline position and inclination
• Axial inclination
• Proportion of central incisors
• Gold proportion ratio
• Gingival height and contours
• Gingival zenith
• Gradation, buccal corridor continuity
• Tooth size, shape texture

Question 3

What is the ratio between canine: lateral: central width?

Answer 3

0.618: 1.0: 1.618 in that order when viewed from the front

Question 4

Define hue, value, chroma

Answer 4

Hue: basic colour group (red, white, pink, etc.)
Value: How light or dark the observed object is (brightness), higher value the lighter/brighter it is (0% value is always black)
Chroma: Degree of colourisation (saturation), higher value=more intense/greater saturation

Question 5

Define metamerism

Answer 5

When a particular colour appears different when viewed under different lighting–> do shade selection in natural light

Question 6

What colours are associated with each shade group (A, B, C, D)?

Answer 6

A= yellow-brown
B= Yellow
C=Yellow-grey
D= Pink-grey

Question 7

In what order of hue, value, chroma should you select a shade?

Answer 7

-Value (1-5), chroma (1, 1.5, 2, 2.5, 3), hue (LMR ranges from yellow to red)

Question 8

What are the steps for shade selection?

Answer 8

• Sit patient upright
• Cover bright clothing and colour distractors (e.g. lipstick)
• Remove dental light, ensure tooth is moist
• Hold shade guide close to tooth and view it from approximately 30cm away
• Do not view for more than 5-10 seconds
• Select value, chroma, hue + translucency and other surface characteristics

NB: better to pick higher value, low chroma

Question 9

What are the important zones for tooth colour shade prescription?

Answer 9

• Incisal 1/3
• Labial face (middle 1/3)
• Cervical 1/3
• Inicsal edge
• Occlusal surface

Question 10

What options do you have to modify shade of porcelain? What are some limitations?

Answer 10

Surface stains

• Can only slightly alter porcelain shade
• Not as longer lasting as intrinsic stains as not incorporated into ceramics
• However works well for surface characterisation