Tooth Whitening Flashcards
(73 cards)
1
Q
What are some extrinsic causes of tooth discolouration?
A
- smoking
- tannins = tea/coffee/red wine/guinness
- chromogenic bacteria
- chlorohexidine
- iron supplements
2
Q
who are chromogenic bacteria more common in?
A
child patients
- causes black staining
3
Q
what are examples of intrinsic tooth discolouration?
A
- fluorosis
- tetracycline antibiotics (used to be common)
- non-vitality
- physiological (age changes)
- dental materials
- porphyria
- cystic fibrosis
- thalassemia/sickle cell anaemia
- hyperbilirubinaemia
4
Q
what is porphyria?
A
red primary teeth
5
Q
what colour might the teeth of a cystic fibrosis patient be?
A
grey teeth
6
Q
what colour will the teeth of a patient be with hyperbilirubinaemia?
A
green teeth
7
Q
what does fluorosis present as?
A
white/brown patches on teeth
8
Q
what should the first method of tooth whitening for extrinsic staining be?
A
PMPR scaling
9
Q
what are the types of tooth bleaching?
A
- external vital bleaching
- internal non vital bleaching
10
Q
what causes teeth to discolour?
A
the formation of chemically stable, chromogenic products within the tooth surface
11
Q
how does vital external bleaching work?
A
Bleaching oxidises the long chain organic molecules found in teeth that cause discolouration
- leads to smaller, non pigmented molecules
12
Q
what is the active agent in the bleaching agents used?
A
Hydrogen peroxide (H2O2)
- from carbamide peroxide
13
Q
How does hydrogen peroxide bleach teeth?
A
- forms acidic solution in water
- breaks down to form water & oxygen
- free radical HO2 is formed which is the ACTIVE OXIDISING AGENT
14
Q
what are the constituents of bleaching gel?
A
- carbamide peroxide
- carbopol
- urea
- surfactant
- pigment dispersers
- preservative
- flavour
- potassium nitrate
- calcium phosphate
- fluoride
15
Q
what forms the hydrogen peroxide in bleaching agents?
A
Carbamide peroxide
16
Q
what is carbamide peroxide?
A
Active ingredient in bleach solutions
- breaks down to form hydrogen peroxide & urea
17
Q
what does 10% carbamide peroxide break down to form?
A
3.6% H2O2 + 6.4% Urea
18
Q
what is carbopol?
A
- thickening agent
- slows the release of oxygen
- increases viscosity of gel
- slows diffusion into enamel
19
Q
why is carbopol needed in bleaching agents?
A
Increased viscosity of gel helps it to
- stay on teeth
- stay in tray
20
Q
what is the purpose of Urea in bleaching agents?
A
- raises pH
- stabilises hydrogen peroxide
21
Q
what is the purpose of surfactant in bleaching agents?
A
allows gel to wet the tooth surface
22
Q
what is the purpose of potassium nitrate/calcium phosphate in bleaching agents?
A
tooth desensitising agents
23
Q
what is the purpose of fluoride in bleaching agents?
A
- prevents erosion
- desensitising agent
24
Q
When performing external vital bleaching, what factors affect the bleaching?
A
- time (longer time on tooth —> whiter)
- cleanliness of tooth
- concentration of solution
- temperature
25
what does a higher temperature cause when performing external vital bleaching?
higher temp —> quicker bleaching effect
26
what must you ensure before performing external vital bleaching on a patient?
Patient is dentally fit!
- any leakage around carious cavity margins will lead to pulpal damage
27
What warnings must be given to the patient before performing external vital bleaching?
- sensitivity
- relapse
- restoration don’t change colour
- allergy
- might not work
- compliance with regime
28
what are the two types of vital external bleaching?
- chair side
- home
29
what are the advantages of in office bleaching?
- controlled by dentist
- can use heat/light
- quick results for patient
30
what are the disadvantages of in office bleaching?
- time for dentist
- can be uncomfortable
- results tend to wear off quicker
- expensive
31
what are the steps of in-office bleaching techniques?
- thorough cleaning of teeth
- ideally rubber dam
- at least gingival mask
- apply bleaching gel to tooth
- apply heat/light
- wash/dry/repeat
- takes 30 mins to an hou r
32
why does laser lightening often give a good initial result when bleaching?
- mainly due to dehydration
- this wears off quickly
33
how are gingiva protected when performing in-house bleaching?
?
34
what is used for home vital bleaching?
10-15% carbamide peroxide gel
35
what is the maximum strength of hydrogen peroxide allowed for teeth whitening?
6% !
36
what strength of Carbamide Peroxide equates to the maximum strength of hydrogen peroxide allowed?
16.7%
37
How is home vital bleaching performed?
- brush & floss teeth
- patient uses custom made tray
- load tray with carbamide peroxide
- fit tray in mouth for at least 2 hours but preferably overnight
38
how are custom mouth guards provided to patients?
- alginate impressions of teeth taken
- ask for 0.5mm thick soft, acrylic, vacuumed formed soft splint
39
what are the requirements of the custom made mouth guards used in at-home bleaching?
- should stop short of gingival margin by 1mm
- buccal spacer to allow for gel placement
40
If a patient is doing at-home bleaching, when should a review appointment be carried out? what should you explain to the patient?
- review appt at 1 week
- if no change in 2 weeks its not going to work
41
when are results reached with at-home bleaching roughly?
maximum 3-4 weeks
42
teeth with what type of discolouration respond better to treatment?
yellow/orange better than bluish/grey
43
what problems can arise from bleaching?
- sensitivity
- wears off
- cytotoxicity/mutagenicity
- gingival irritation
- tooth damage
- damage to restorations
- problems with bonding to tooth
44
how common is post-bleaching sensitivity?
60% +
45
how long does post-bleaching sensitivity last?
usually resolves after 2-3 days
46
what are predictors of a patient experiencing post-bleaching sensitivity?
- pre existing sensitivity
- high concentration of bleaching agent
- frequency of change
- bleaching method
- gingival recession
47
what is gingival irritation after bleaching as a result of?
due to concentration of solution used
- check tray extension is correct ( 1mm )
48
how long should restorative procedures be delayed for after bleaching? why is this?
- at least 24hrs but better to delay for a week
- residual oxygen from the peroxide remains within the enamel structure initially
49
what substance should NEVER be used for teeth bleaching? why?
CHLORINE DIOXIDE (pH of 3)
- softens and strips enamel from tooth surface
50
what are some causes for need of internal non-vital bleaching?
- dead pulp
- blood products diffuse and darken tooth
- grey discolouration
51
what are the indications for internal non-vital bleaching?
- non-vital tooth
- adequate RCT
- no apical path
52
what are contraindications for internal non-vital bleaching?
- heavily restored tooth
- staining due to amalgam
53
what are the advantages of internal non-vital bleaching?
- easy
- conservative
- usually patient satisfaction
54
what are the risks of internal non-vital bleaching?
EXTERNAL CERVICAL RESORPTION
- due to diffusion of H2O2 through dentine into periodontal tissues
- high conc H2O2 and heat
- trauma important
55
what are the technical steps of internal non-vital bleaching?
- remove filling from access cavity
- remove GP from pulp chamber & 1mm below ACJ
- place 1mm RMGIC over GP to seal canal
- remove any very dark dentine
- etch the internal surface of the tooth
- place carbamide peroxide gel in cavity
- cotton wool over this
- seal with GIC
- repeat at weekly intervals
- once final shade obtained restore palatal cavity, place white GP in pulp chamber, restore with light shade of composite
56
what is used to etch the internal surface of the tooth during internal bleaching?
37% phosphoric acid
57
what % of carbamide peroxide gel is used in internal non-vital bleaching?
10%
58
how many visits does internal non-vital bleaching normally take?
3-4 visits
59
what is combination bleaching?
inside-outside bleaching
60
what is micro-abrasion?
- removes discolouration limited to the outer layers of enamel
- combination of erosion (acid) and abrasion (pumice)
61
what are indications for micro-abrasion?
- fluorosis
- post-orthodontic demineralisation
- demineralisation with staining
- prior to veneering if dark staining present
62
what are the technical steps of performing micro abrasion?
- clean teeth thoroughly
- rubber dam (seal is SO important with this)
- mix 18% HCl and pumice
- apply to teeth
- gently rub on teeth with prophy cup for 5 seconds/tooth
- wash
- repeat up to 10x
63
what should be done after performing microabrasion on teeth?
- polish teeth with fluoride prophy paste
- apply fluoride gel or varnish to help re harden surface
- review after 1 month
64
what are the advantages of micro-abrasion?
- quick
- easy
- no long term problems such as pulpal damage or caries
65
what are the disadvantages of micro-abrasion?
- acid leads to sensitivity
- only works for superficial staining
- works better on brown staining rather than white marks
66
what can be used for micro-abrasion if you dont have any hydrochloric acid in practise?
Phosphoric acid
- etch teeth 30secs prior to using pumice
67
what is resin infiltration?
NO removal of surface layer
- infiltrate white staining with resin
- changes refractive index of white area to make it look like surrounding enamel
68
what is typically used for Resin Infiltration?
ICON
69
is tooth bleaching medical or cosmetic?
UK = cosmetic
USA (and most of rest of world) = medical
70
what are medical contraindications for tooth whitening?
- Glucose-6-Phophate dehydrogenase deficiency
- Acatalasemia
(NEITHER ABLE TO METABOLISE HYDROGEN PEROXIDE)
71
what is the minimum age for tooth whitening done in practise?
18 years old
72
Is it illegal to buy/sell tooth whitening products containing or releasing 0.1%-6% hydrogen peroxide online/not from dentist?
YES ILLEGAL
- criminal offence
73
what will occur if a dentist is caught supplying bleaching products in excess of 6% hydrogen peroxide?
- prosecuted by trading standards
- fitness to practise meetings
- prosecution by GDC
