Tooth Whitening Flashcards
1
Q
Extrinsic causes of tooth discolouration
A
- smoking
- tannins e.g. tea, coffee
- chromogenic bacteria
- chlorohexidine
- iron supplements
2
Q
intrinsic causes of tooth discolouration
A
- fluorosis
- tetracycline
- non-vitality
- amalgam
- cystic fibrosis - grey teeth
- sickle cell anaemia
3
Q
Two types of tooth bleaching
A
- external vital bleaching
- internal non-vital bleaching
4
Q
briefly describe how vital external bleaching works
A
- discolouration caused by formation of chemically stable, chromogenic products within tooth substance
- bleaching oxidises compounds into smaller molecules which are often not pigmented
- oxidation can cause ionic exchange in metallic molecules = lighter colour
5
Q
active agent in vital external bleaching
A
hydrogen peroxide or carbamide peroxide
6
Q
What are the products of the breakdown of carbamide peroxide?
A
hydrogen peroxide and urea (urea increases pH)
7
Q
function of carbopol in bleaching gel
A
- thickening agent
- slows release of oxygen
- increases viscosity of gel so it stays on teeth and in tray
- slows diffusion into enamel
8
Q
function of urea in external tooth bleaching
A
- raises pH
- stabilises hydrogen peroxide
9
Q
function of surfactant in external tooth bleaching
A
allows gel to wet the tooth surface
10
Q
function of fluoride in external bleaching
A
- desensitising effect
- prevents erosion
11
Q
factors affecting external tooth bleaching
A
- time
- cleanliness of tooth surface
- concentration of solution
- temperature
12
Q
external vital bleaching - warnings to patients
A
- sensitivity
- relapse
- won’t bleach restorations
- allergy
- might not work
- compliance with regime
13
Q
Advantages of in office bleaching
A
- controlled by dentist
- can use heat/light
- quick results for patient
14
Q
disadvantages of in office bleaching
A
- time for dentist
- can be uncomfortable
- expensive
- results tend to wear off quicker
15
Q
in office bleaching technique
A
- thorough clean of teeth
- rubber dam or at least gingival mask
- apply bleaching gel to tooth
- apply heat and light
- wash, dry and repeat
- takes 30 mins to an hour
