Shade selection

Question 1

Why is shade selection so important?

Answer 1

• Selection of the correct shade is the foundation for superior aesthetics
• To provide an aesthetic restorations, the dentist must have a full understanding of the science of colour and colour perception.
• Matching the correct shade satisfies both the dentist and patient and gives a pleasing appearance to the patient

Question 2

what are the 3 variables used to characterize the perception of light reflected from the tooth surface?

Answer 2

• hue
• value
• chroma.

Question 3

what colour system is most commonly used in dentistry?

Answer 3

munsell color system

Question 4

what 3 things is munsell color system divided into?

Answer 4

value
hue
chroma

Question 5

what is value?

Answer 5

lightness

Question 6

what is hue?

Answer 6

colour

Question 7

what is chroma?

Answer 7

the intensity of the colour

Question 8

Define Hue of a tooth in terms of the vita shade guide

Answer 8

Describes the dominant shade of the tooth (more yellowish or reddish)
colour- name of colour- in Vita Guide

Question 9

What hue is A on the vita shade guide?

Answer 9

red-yellow

Question 10

What hue is B on the vita shade guide?

Answer 10

yellow

Question 11

What hue is C on the vita shade guide?

Answer 11

grey

Question 12

What hue is D on the vita shade guide?

Answer 12

red-yellow- grey

Question 13

what is meant by chroma on the vita shade guide?

Question 14

what is chroma respresented by on the vita shade guide?

Answer 14

numbers

Question 15

A3 - what does this mean on a shade guide?

Answer 15

hue A - red-yellow
chroma 3 - intesity of 3

Question 16

what is meant by value on a Vita shade guide?

Answer 16

Is the lightness or darkness of the tooth shade measured independently of the hue

how white/black/grey tooth is

Question 17

out of the tooth layers, which does the value represent/ is dependent on?

Answer 17

enamel layer

Question 18

Something that is missing from shade guides but must NOT be missed is translucency

Answer 19

by arranging the vita

Question 20

what are the limitations of a shade guide?

Answer 20

1- The colours in shade guides differ for each manufacturing company
2- Shade guides are not universal for all types of colour restorations, variations can be observed between shades for resin composites, porcelain and denture teeth
3- It is key to ensure that you are using the same shade guide used by the lab for indirect restorations (dentures, crowns etc)

Question 21

list the clinical factors that influence the shade

Answer 21

• the object (pt)
• the observer (dentist)
• illumiation

Question 22

the way we perceive an object is the way the light hits that object

what are the 3 ways in which light hits an object?

Answer 22

• reflected
• absorbed
• transmitted
• or a combo of all three

Question 23

what determines the colour of an object in terms of light?

Answer 23

Question 24

the rougher the surface the increased/decreased the scattering of light from the surface

Answer 24

Question 25

comment on the scatter/reflection of a polished surface

Answer 25

have a lot of reflection

Question 26

comment on the scatter/reflection of a rough surface

Answer 26

have a lot of scatter

Question 27

Question 28

what is the ability of the teeth to transmit light through called?

Answer 28

translucency

Question 29

it is important to distinguish between the light source and the illuminant what is the light source?

Answer 29

Physical emitter of light eg candle, lamp, sun

Question 30

it is important to distinguish between the light source and the illuminant what is the illuminant?

Answer 30

Standard light source defined by its specific spectral power distribution

Question 31

in terms of the light source, what is the most important one when evaluating the shade of teeth?

Answer 31

daylight

Question 32

what is daylight a combination of?

Answer 32

sunlight + skylight

Question 33

which spectrum of light are we interested in when providing illumination for shade selection?

Answer 33

blue light - this is visible to the eye

Question 34

When it comes to the observers eyes, it is affected by the level of light. what cells in the eye are activated when there is low light?

Answer 34

rod cells

Question 35

what kind of perception do rod cells provide?

Answer 35

monochromatic light/dark

Question 36

when is full sensitivity of rod cells reached?

Answer 36

30 mins

Question 37

what type of vision do we use when viewing low light levels?

Answer 37

scotopic

Question 38

When it comes to the observers eyes, it is affected by the level of light. what cells in the eye are activated when there is medium/high light?

Answer 38

cone cells

Question 39

what type of vision do cone cells privde?

Answer 39

full colour

Question 40

what type of vision do we use when viewing medium/high light levels?

Answer 40

photopic

Question 41

what time of day should shade selection be performed?

Answer 41

morning - eye fatigue finimal

Question 42

what is the ideal distance away from the oral cavity for shade selection to be performed?

Answer 42

61 cm (2 feet) to 183 cm (6 feet) distance

Question 43

what level should the patients teeth be at during shade selection

Answer 43

level of the operators eyes - so pt should sit in the chair

Question 44

the environment - what colour of surroundings should be avoided when shade matching?

Answer 44

bright colours

Question 45

what can we use in clinic to mask undesirable colours in patient's clothing when shade matching?

Answer 45

a drape

Question 46

what is the ideal background colour for shade matching?

Answer 46

light gray

Question 47

why should surface with high gloss be avoided?

Answer 47

provide disturbing glares

Question 48

lipstick should be removed before colour matching so it doesn't affect colour perception

Question 49

describe the condition the teeth should be in for shade matching

Answer 49

- free of plaque, deposits, surface stains - moist with saliva

Question 50

why should teeth be moist for colour matching?

Answer 50

dehydration results in whiter appearance

Question 51

what are further clinical tips

Answer 51

- photos with a shade tag sent to technician to evaluate (indirect) - apply composite to the tooth to assess the shade of the restoration (direct) - take clinical photographs - u can convert it to black and white to see the value, or inc intensity to evaluate the chroma

Question 52

it is important to take a stump shade guide for actual core of tooth. why is this important when communicate with the technicians?

Answer 52

indicates core shade of crown on top of the overall shade

Question 53

list the various devices that can aid in shade selection