4 - Tooth whitening Flashcards
(41 cards)
1
Q
What are the extrinsic causes of tooth discolouration?
A
- smoking
- tannins
- chromogenic bacteria
- chlorohexadine
- iron supplements
2
Q
What are intrinsic causes of tooth discolouration? (9)
A
- fluorosis
- tertracycline (old antibiotic)
- loss of vitality
- age
- dental materials
- porphyria
- CF
- thalassemia, sickle cell anaemia
- hyperbilirubinaemia
3
Q
What discolouration does porphyria cause?
A
Red primary teeth
4
Q
What discolouration does CF cause?
A
Grey
5
Q
What discolouration does thalassemia or sickle cell disease cause?
A
Blue, green or brown
6
Q
What discolouration does hyperbilirubinaemia cause?
A
Green
7
Q
What are the different types of tooth bleaching?
A
- external vital
- internal non-vital
8
Q
Describe external vital bleaching.
A
- good for discolouration caused by chromogenic products
- bleaching oxides organic molecules, the smaller molecules are less pigmented
- hydrogen peroxide is the active agent
9
Q
Describe how hydrogen peroxide acts as the active bleaching agent.
A
- forms acidic solution in water
- free radical is formed (hydroxyl) which is the active oxidising agent
- oxidises long organic molecules to breakdown into smaller molecules which are less pigmented
10
Q
What are the constituents of external bleaching gel?
A
- carbamide peroxide
- carbopol
- urea
- surfactant
- pigment dispersers
- preservative
- flavour
- potassium nitrate
- calcium phosphate
- fluoride
11
Q
What is carbamide peroxide?
A
- active ingredient
- breakdowns to produce urea and hydrogen peroxide
- maximum 16.7% carbamide peroxide in gel
12
Q
What is carbopol?
A
- thickening agent, increases viscosity to keep gel where placed
- slow release of oxygen
- diffuses slowly into enamel
13
Q
What is urea?
A
- raises pH of gel
- stabilises hydrogen peroxide and slows reaction
14
Q
What is surfactant?
A
Allows gel to wet the tooth surface
15
Q
What factors affect the bleaching result?
A
- time increases effect
- cleanliness of tooth surfaces increases effect
- concentration increases effect
- higher temperature increases speed of effect
16
Q
What should you warn your patient of before beginning external bleaching?
A
- sensitivity
- relapse
- colour of restoration won’t change
- allergy
- may not work
- compliance is key
17
Q
What are the advantages of in office bleaching?
A
- controlled by dentist
- can use heat/light as catalyst
- quick results
18
Q
What are the disadvantages of in office bleaching?
A
- increased time in chair
- can be uncomfortable
- results wear off quicker
- expensive
19
Q
Describe the process of in office bleaching.
A
- thorough cleaning of teeth
- rubber dam placed with gingival mask
- bleaching gel applied
- apply heat or light
- wash/dry/repeat
- 30-60 mins
20
Q
Describe the process of at home bleaching.
A
- custom tray made (0.5mm thick, soft acrylic)
- patient prescribed carbamide peroxide gel 10-15%
- patient wears trays overnight ideally
- bleaching occurs slowly over several weeks
21
Q
When is it appropriate to using external bleaching?
A
- age related discolouration (yellow/orange responds best)
- mild fluorosis
- post smoking cessation
- tetracycline staining if prolonged treatment
22
Q
What are the problems associated with external bleaching?
A
- sensitivity
- wears off
- gingival irritation
- tooth damage
- damage to restorations
- can impact effectiveness of bonding to teeth
- cytotoxicity
23
Q
What are predictors of sensitivity post-bleaching?
A
- preexisting sensitivity
- high concentration agent
- frequency
- bleaching method
- gingival recession
24
Q
How do you combat problems with bonding to newly bleaching teeth?
A
- wait at least 24 hours
- a week is best
25
What is chlorine dioxide?
- used to whiten teeth by some beauty salons and cruise liners
- pH of 3 softens enamel
- teeth become more prone to staining and develop roughened appearance
- teeth become extremely sensitive
26
What are the indications for internal non-vital bleaching?
- non-vital tooth
- adequate RCT
- no apical pathology
27
What are the contra-indications for internal non-vital bleaching?
- heavily restored tooth (crown or veneer instead)
- staining caused by amalgam
28
What are the advantages associated with internal beaching?
- easy
- conservative
- good patient satisfaction
29
What are the risks associated with internal bleaching?
- external cervical resorption
- due to diffusion of hydrogen peroxide through dentine into periodontal tissues
- theoretical problem
30
Describe the process of internal bleaching.
- record shade
- place rubber dam
- remove restoration from access cavity
- remove GP from pulp chamber and 1mm below ACJ
- place RMGIC over GP to seal canal
- remove dark dentine
- etch internal surface with 37% phosphoric acid
- place 10% carbamide peroxide gel
- place cotton wool over this
- seal with GIC
- repeat at weekly intervals
- restore tooth with white GP after no further change
31
What is combination bleaching?
- internal and external bleaching
- prepare cavity as with internal bleaching
- custom tray with palatal reservoir for 24 hour wear
- carbamide peroxide gel placed in reservoir and within cavity for around a week, topping up as necessary
32
What is mircoabrasion?
- combination of erosion using acid, and abrasion using pumice
- removes discolouration which is limited to the outer layers of enamel
33
What are the indications for microabrasion?
- superficial fluorosis
- post orthodontic demineralisation
- demineralisation with staining
- prior to veneer preparation if dark staining
34
What is the technique for microabrasion?
- clean teeth thoroughly
- rubber dam placed
- 18% HCl and pumice mix applied to teeth
- prophy cup used for 5s/tooth
- washed
- repeat up to 10x
- remove dam
- polish teeth with fluoride paste
- apply fluoride gel/varnish
- review at 1 month
35
What are the advantages of microabrasion?
- quick
- easy
- no long term problems
36
What are the disadvantages of microabrasion?
- acid
- sensitivity
- only works for superficial staining
- works better on brown stains that white
37
What is resin infiltration?
- surface layer is not removed
- area is infiltrated with resin
- changes the refraction index of the white area
- masks the area (more porous enamel) to make it look like the surrounding areas
38
What are the indications for resin infiltration?
- white spot lesions
- arresting very early caries
39
What are medical contra-indications for tooth bleaching?
- glucose-6-phosphate dehydrogenase deficiency (v rare)
- acatalasemia (low levels of catalase enzyme)
- neither group can metabolise hydrogen peroxide
40
What is the maximum strength of hydrogen peroxide that can be used in tooth bleaching products?
16.7% carbamide peroxide which equates to 6% hydrogen peroxide
41
At what age can you conduct tooth bleaching?
- over 18s
- under 18s can only bleach their teeth if it is wholly intended for the purpose of preventing disease
