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BDS3 CLINICAL FLASHCARDS > Tooth Whitening > Flashcards

Tooth Whitening Flashcards

1
Q

What are some extrinsic causes of tooth discolouration?

A
  • smoking
  • tannins = tea/coffee/red wine/guinness
  • chromogenic bacteria
  • chlorohexidine
  • iron supplements
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2
Q

who are chromogenic bacteria more common in?

A

child patients
- causes black staining

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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
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4
Q

what is porphyria?

A

red primary teeth

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5
Q

what colour might the teeth of a cystic fibrosis patient be?

A

grey teeth

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6
Q

what colour will the teeth of a patient be with hyperbilirubinaemia?

A

green teeth

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7
Q

what does fluorosis present as?

A

white/brown patches on teeth

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8
Q

what should the first method of tooth whitening for extrinsic staining be?

A

PMPR scaling

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9
Q

what are the types of tooth bleaching?

A
  • external vital bleaching
  • internal non vital bleaching
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10
Q

what causes teeth to discolour?

A

the formation of chemically stable, chromogenic products within the tooth surface

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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

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12
Q

what is the active agent in the bleaching agents used?

A

Hydrogen peroxide (H2O2)
- from carbamide peroxide

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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
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14
Q

what are the constituents of bleaching gel?

A
  • carbamide peroxide
  • carbopol
  • urea
  • surfactant
  • pigment dispersers
  • preservative
  • flavour
  • potassium nitrate
  • calcium phosphate
  • fluoride
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15
Q

what forms the hydrogen peroxide in bleaching agents?

A

Carbamide peroxide

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16
Q

what is carbamide peroxide?

A

Active ingredient in bleach solutions
- breaks down to form hydrogen peroxide & urea

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17
Q

what does 10% carbamide peroxide break down to form?

A

3.6% H2O2 + 6.4% Urea

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18
Q

what is carbopol?

A
  • thickening agent
  • slows the release of oxygen
  • increases viscosity of gel
  • slows diffusion into enamel
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19
Q

why is carbopol needed in bleaching agents?

A

Increased viscosity of gel helps it to
- stay on teeth
- stay in tray

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20
Q

what is the purpose of Urea in bleaching agents?

A
  • raises pH
  • stabilises hydrogen peroxide
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21
Q

what is the purpose of surfactant in bleaching agents?

A

allows gel to wet the tooth surface

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22
Q

what is the purpose of potassium nitrate/calcium phosphate in bleaching agents?

A

tooth desensitising agents

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23
Q

what is the purpose of fluoride in bleaching agents?

A
  • prevents erosion
  • desensitising agent
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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
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25
Q

what does a higher temperature cause when performing external vital bleaching?

A

higher temp —> quicker bleaching effect

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26
Q

what must you ensure before performing external vital bleaching on a patient?

A

Patient is dentally fit!
- any leakage around carious cavity margins will lead to pulpal damage

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27
Q

What warnings must be given to the patient before performing external vital bleaching?

A
  • sensitivity
  • relapse
  • restoration don’t change colour
  • allergy
  • might not work
  • compliance with regime
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28
Q

what are the two types of vital external bleaching?

A
  • chair side
  • home
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29
Q

what are the advantages of in office bleaching?

A
  • controlled by dentist
  • can use heat/light
  • quick results for patient
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30
Q

what are the disadvantages of in office bleaching?

A
  • time for dentist
  • can be uncomfortable
  • results tend to wear off quicker
  • expensive
31
Q

what are the steps of in-office bleaching techniques?

A
  • 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
Q

why does laser lightening often give a good initial result when bleaching?

A
  • mainly due to dehydration
  • this wears off quickly
33
Q

how are gingiva protected when performing in-house bleaching?

A

?

34
Q

what is used for home vital bleaching?

A

10-15% carbamide peroxide gel

35
Q

what is the maximum strength of hydrogen peroxide allowed for teeth whitening?

A

6% !

36
Q

what strength of Carbamide Peroxide equates to the maximum strength of hydrogen peroxide allowed?

A

16.7%

37
Q

How is home vital bleaching performed?

A
  • 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
Q

how are custom mouth guards provided to patients?

A
  • alginate impressions of teeth taken
  • ask for 0.5mm thick soft, acrylic, vacuumed formed soft splint
39
Q

what are the requirements of the custom made mouth guards used in at-home bleaching?

A
  • should stop short of gingival margin by 1mm
  • buccal spacer to allow for gel placement
40
Q

If a patient is doing at-home bleaching, when should a review appointment be carried out? what should you explain to the patient?

A
  • review appt at 1 week
  • if no change in 2 weeks its not going to work
41
Q

when are results reached with at-home bleaching roughly?

A

maximum 3-4 weeks

42
Q

teeth with what type of discolouration respond better to treatment?

A

yellow/orange better than bluish/grey

43
Q

what problems can arise from bleaching?

A
  • sensitivity
  • wears off
  • cytotoxicity/mutagenicity
  • gingival irritation
  • tooth damage
  • damage to restorations
  • problems with bonding to tooth
44
Q

how common is post-bleaching sensitivity?

A

60% +

45
Q

how long does post-bleaching sensitivity last?

A

usually resolves after 2-3 days

46
Q

what are predictors of a patient experiencing post-bleaching sensitivity?

A
  • pre existing sensitivity
  • high concentration of bleaching agent
  • frequency of change
  • bleaching method
  • gingival recession
47
Q

what is gingival irritation after bleaching as a result of?

A

due to concentration of solution used
- check tray extension is correct ( 1mm )

48
Q

how long should restorative procedures be delayed for after bleaching? why is this?

A
  • at least 24hrs but better to delay for a week
  • residual oxygen from the peroxide remains within the enamel structure initially
49
Q

what substance should NEVER be used for teeth bleaching? why?

A

CHLORINE DIOXIDE (pH of 3)
- softens and strips enamel from tooth surface

50
Q

what are some causes for need of internal non-vital bleaching?

A
  • dead pulp
  • blood products diffuse and darken tooth
  • grey discolouration
51
Q

what are the indications for internal non-vital bleaching?

A
  • non-vital tooth
  • adequate RCT
  • no apical path
52
Q

what are contraindications for internal non-vital bleaching?

A
  • heavily restored tooth
  • staining due to amalgam
53
Q

what are the advantages of internal non-vital bleaching?

A
  • easy
  • conservative
  • usually patient satisfaction
54
Q

what are the risks of internal non-vital bleaching?

A

EXTERNAL CERVICAL RESORPTION
- due to diffusion of H2O2 through dentine into periodontal tissues
- high conc H2O2 and heat
- trauma important

55
Q

what are the technical steps of internal non-vital bleaching?

A
  • 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
Q

what is used to etch the internal surface of the tooth during internal bleaching?

A

37% phosphoric acid

57
Q

what % of carbamide peroxide gel is used in internal non-vital bleaching?

A

10%

58
Q

how many visits does internal non-vital bleaching normally take?

A

3-4 visits

59
Q

what is combination bleaching?

A

inside-outside bleaching

60
Q

what is micro-abrasion?

A
  • removes discolouration limited to the outer layers of enamel
  • combination of erosion (acid) and abrasion (pumice)
61
Q

what are indications for micro-abrasion?

A
  • fluorosis
  • post-orthodontic demineralisation
  • demineralisation with staining
  • prior to veneering if dark staining present
62
Q

what are the technical steps of performing micro abrasion?

A
  • 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
Q

what should be done after performing microabrasion on teeth?

A
  • polish teeth with fluoride prophy paste
  • apply fluoride gel or varnish to help re harden surface
  • review after 1 month
64
Q

what are the advantages of micro-abrasion?

A
  • quick
  • easy
  • no long term problems such as pulpal damage or caries
65
Q

what are the disadvantages of micro-abrasion?

A
  • acid leads to sensitivity
  • only works for superficial staining
  • works better on brown staining rather than white marks
66
Q

what can be used for micro-abrasion if you dont have any hydrochloric acid in practise?

A

Phosphoric acid
- etch teeth 30secs prior to using pumice

67
Q

what is resin infiltration?

A

NO removal of surface layer
- infiltrate white staining with resin
- changes refractive index of white area to make it look like surrounding enamel

68
Q

what is typically used for Resin Infiltration?

A

ICON

69
Q

is tooth bleaching medical or cosmetic?

A

UK = cosmetic
USA (and most of rest of world) = medical

70
Q

what are medical contraindications for tooth whitening?

A
  • Glucose-6-Phophate dehydrogenase deficiency
  • Acatalasemia
    (NEITHER ABLE TO METABOLISE HYDROGEN PEROXIDE)
71
Q

what is the minimum age for tooth whitening done in practise?

A

18 years old

72
Q

Is it illegal to buy/sell tooth whitening products containing or releasing 0.1%-6% hydrogen peroxide online/not from dentist?

A

YES ILLEGAL
- criminal offence

73
Q

what will occur if a dentist is caught supplying bleaching products in excess of 6% hydrogen peroxide?

A
  • prosecuted by trading standards
  • fitness to practise meetings
  • prosecution by GDC

BDS3 CLINICAL FLASHCARDS (7 decks)

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