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restorative > tooth whitening (3rd year) > Flashcards

tooth whitening (3rd year) Flashcards

1
Q

extrinsic causes of tooth discolouration

A 
smoking
tannins - tea, coffee, red wine, Guiness
chromogenic bacteria - bacteria within plaque
 - brown stain (not usually decay)
 - green stain (linked to decay)
CHX
Fe supplements
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2
Q

intrinsic causes of tooth discolouration

A 
fluorosis
tetracycline
non-vitality (blood products)
physiological (age changes)
dental materials
 - amalgam
 - root filling materials
porphyria (red primary teeth)
CF (grey teeth)
thalassaemia, sickle cell anaemia (blue, green or brown teeth)
hyperbilirubinaemia (green teeth)
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3
Q

tetracycline

A

not so common now, may see historic use in older pts
preferentially taken up by calcified tissues
if stop taking bone will return to normal colour due to bone turnover but teeth won’t
might see in teenagers being txed for acne - not on already erupted teeth but maybe when you extract their 8s

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4
Q

what should the first method for extrinsic staining always be?

A

HPT

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5
Q

types of bleaching

A

external vital

internal non-vital

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6
Q

what cause of discolouration does vital external bleaching treat?

A

discolouration caused by formation of chemically stable, chromogenic products within the tooth substance - teeth slightly porous
long chain organic molecules

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7
Q

how does vital external bleaching work?

A

oxidises the long chain organic compounds (high MW)
oxidation leads to smaller molecules which are often not pigmented (smaller MW)
oxidation can cause ionic exchange in metallic molecules leading to lighter colour

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8
Q

what is the active agent in bleaching (once broken down)?

A

hydrogen peroxide

rarely an ingredient in modern tooth bleaching products

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9
Q

how does hydrogen peroxide work - chemistry?

A

forms acidic solution in water
breaks down to form water and oxygen
free radical per hydroxyl (HO2) is formed - active oxidising agent
fast reactive oxidising agent

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10
Q

vital external bleaching constituents of bleaching gel

A 
carbamide peroxide
carbopol
urea
surfactant
pigment dispersers
preservative
flavour
potassium nitrate
calcium phosphate
F
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11
Q

carbopol

A

thickening agent
slows the release of O2
increases the viscosity of the gel - stays where you put it - stays on teeth and in tray
slows diffusion into enamel
makes bleach work over a longer time more slowly

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12
Q

surfactant

A

allows the gel to wet the tooth surface

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13
Q

fluoride

A

prevents erosion

desensitising agent

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14
Q

carbamide peroxide

A

active ingredient

breaks down to produce hydrogen peroxide and urea

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15
Q

what does 10% carbamide peroxide break down to form?

A
  1. 6% H2O2

6. 4% urea

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16
Q

urea

A

raises pH
stabilises H2O2
slows down reaction - H2O2 liberated over a longer period

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17
Q

potassium nitrate, calcium phosphate

A

tooth desensitising agents

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18
Q

factors affecting bleaching (chemical reaction)

A

time - more time = more effect
cleanliness of tooth surface - cleaner = better
conc of solution - higher conc = more and quicker effect
temp - higher = quicker effect

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19
Q

prior to external vital bleaching

A

check pt dentally fit
- don’t bleach on top of caries or leaking fillings
- any leakage around carious cavity margins will lead to pulpal damage
take initial shade, agree it with pt and record in notes - if possible take photo with a shade guide included in the picture - so can show pt there has been a difference

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20
Q

vital external bleaching warnings for pt

A 
sensitivity
relapse
restoration colour
allergy - vvv rare
might not work
 - some people have more porous teeth than others
 - if teeth similar colour to when they erupted i.e. young won't work as well
compliance with regime
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21
Q

types of external vital bleaching

A

chairside/in office

home

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22
Q

advantages of in office bleaching

A

controlled by dentist
can use heat/light (speeds it up)
quick results for pt

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23
Q

disadvantages of in office bleaching

A 
time for dentist
can be uncomfortable
results tend to wear off quicker
 - a lot of the effect is dehydration - tooth whiter when dry. will look good when leave dentist but won't last long
£££
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24
Q

in office vital external bleaching technique

A 
thorough cleaning of teeth
ideally rubber dam - protection of gingivae essential
at least gingival mask
apply bleaching gel to tooth
apply heat/light
wash/dry/repeat
takes 30mins-1hr
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25
Q

heat/light/laser

A

often used with in-office bleaching
mainly a marketing technique
no evidence of better bleaching with these additional procedures
light and laser are really just heat sources
often a good initial result
- mainly due to dehydration
- wears off quickly

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26
Q

home vital bleaching

A 
commonest technique
10-15% carbamide peroxide gel
pt uses solution at home
custom made tray
bleaches slowly over several weeks
easy for pt and dentist
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27
Q

what does 16.7% carbamide peroxide gel equate to?

A

6% hydrogen peroxide

max legal strength of solution

28
Q

home vital bleaching - trays

A

alginate impressions
0.5mm thick, soft, acrylic, vacuum-formed splint
should stop short of and go round gingival margin (1mm)
Buccal spacer to allow for placement of gel

29
Q

home vital bleaching - surgery

A

full mouth cleaning/polishing of teeth
fit trays and check extension/comfort
instruction in use - written too

30
Q

home vital bleaching - at home

A

brush and floss teeth
load tray - 1mm2 dot buccally on each tooth
fit tray in mouth
in place for at least 2hrs, preferably overnight
clean trays in cold water with brush - boiling water makes it go flat

31
Q

review and results of home vital bleaching

A 
review at 1wk
results variable
 - most pts see a result within 2-3 days
 - normally reached max by 3-4wks
 - if no change in 2wks it is not going to work
32
Q

when to bleach?

A

age related darkening/discolouration
- teeth with yellow/orange discolouration respond better than those with bluish/grey discolouration

mild fluorosis

post-smoking cessation - don’t bleach smokers as waste of time

tetracycline staining?

  • prolonged tx
  • better with yellow and brown than grey
  • can take months
  • trying to bleach out of dentine as well as enamel so takes a lot longer
33
Q

bleaching problems

A 
sensitivity
wears off
cytotoxicity/mutagenicity
gingival irritation
tooth damage
damage to restorations
problems with bonding to teeth
34
Q

prevalence of sensitivity

A

60+%

35
Q

how does sensitivity start to resolve?

A

worse initially

resolves over 2-3 days post-bleaching

36
Q

predictors of sensitivity

A 
pre-existing sensitivity
high conc of bleaching agent
freq of change
bleaching method (more likely with in-office)
gingival recession - exposed root
37
Q

bleaching wears off

A

oxidised chromogens gradually reduce with time
- short chain molecules gradually reform into larger
retx 1-3years, varies
- doesn’t take as long (2-3 days)

38
Q

cytotoxicity/mutagenicity

A

no evidence for 10% carbamide peroxide

high conc H2O2 can cause problems

39
Q

gingival irritation

A

related to conc

must check tray extension correct

40
Q

tooth damage

A

no evidence over 15+ years

41
Q

damage to restorations

A

probably not
teeth bleach, composite doesnt
pts must be aware of this before tx starts
if you change the restorations to match the bleached teeth, continued bleaching will be required or fillings will be too light in colour - discuss replacement with pt

42
Q

why should you never use chlorine dioxide?

A

highly acidic and will take all E off

43
Q

problems with bonding

A

residual oxygen from the peroxide remains within E structure initially
gradually dissipates over a short time
- delay Rx procedures for at least 24hrs post-bleaching
- better to delay for a week
O2 inhibited layer of composite - doesn’t cure

44
Q

internal non-vital bleaching - discolouration in a non-vital tooth

A

dead pulp - bleeding into dentine
blood products diffuse and darken
grey discolouration

45
Q

indications for non-vital bleaching

A

non-vital tooth
adequate RCT - can redo first if not
no apical pathology

46
Q

limitations of non-vital bleaching

A

doesn’t always work but generally worth a go

47
Q

contraindications for non-vital bleaching

A

heavily restored tooth - better with crown or veneer

staining due to amalgam

48
Q

advantages of non-vital bleaching

A

easy
conservative
pt satisfaction

49
Q

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 - susceptible to external resorption anyway

50
Q

combination bleaching

A

inside-outside bleaching
remove GP, as before, cover with RMGIC
make bleaching tray - palatal not buccal reservoir
bleach placed in access cavity and in tray
replaced frequently over about a week
tricky for pt, must wear tray whole time

51
Q

internal non-vital bleaching technique

A

record shade
prophylaxis
rubber dam
remove filling from access cavity
remove GP from pulp chambers and 1mm below ACJ
place 1mm RMGIC over GP to seal canal
- seals dentine and prevents root resorption
remove any v dark dentine
etch internal surface of tooth with 37% phosphoric acid
place 10% carbamide peroxide gel in cavity
cotton wool over this
seal with GIC

52
Q

review and repeat of internal non-vital bleaching

A

review in 1wk
repeat procedure at weekly intervals until required shade achieved/no change
normally takes 3-4 visits
if no change after 4 visits it is not going to work, consider crown/veneer/composite build up
once final shade obtained restore palatal cavity
place white GP or similar in pulp chamber
restore with light shade of composite
will gradually darken again
- retx every 4-5 yrs? - variable

53
Q

microabrasion

A

remove discolouration limited to outer layers of enamel
- remove surface layer of E
combination of erosion (acid) and abrasion (pumice)

54
Q

indications for microabrasion

A

fluorosis
post-ortho demineralisation
demineralisation with staining
prior to veneering if dark staining is present

55
Q

technique for microabrasion

A 
clean teeth thoroughly
rubber dam (seal is v important)
mix 18% HCl and pumice
apply to teeth
gently rub with prophy cup 5s/tooth
wash
repeat up to 10x
remove rubber dam
polish teeth with fluoride prophy paste
apply F gel/varnish - helps reharden the surface and decrease sensitivity
review after 1m
56
Q

repeating microabrasion

A

can be repeated
too much can lead to yellowing of the tooth as dentine can begin to show through
too much will lead to permanent sensitivity

57
Q

advantages of microabrasion

A

quick
easy
no long term problems - pulpal damage, caries

58
Q

disadvantages of microabrasion

A

acid
sensitivity
only works for superficial staining
works much better for brown staining than for white marks

59
Q

using phosphoric acid rather than HCl for microabrasion

A

37%
HCl removes 100microns, phosphoric acid only removes 10microns
etch first with H3PO4 and for longer
30s prior to using pumice
not as effective but this acid is readily available to GDP - may need to do more often

60
Q

what legislation governs whitening?

A 
Cosmetic Products (Safety Amendment) Regulations 2012
 - in UK tooth bleaching products are considered a cosmetic as opposed to USA and most of rest of world - medical device
61
Q

what must be carried out before bleaching?

A 
clinical exam - free of dental pathology
medical contraindications (v rare)
 - glucose-6-phosphate dehydrogenase deficiency
 - acatalasemia
- neither group can metabolise H2O2
62
Q

U18s

A

products containing/releasing 0.1-6% H2O2 cant be used on U18s except where wholly for the purpose of preventing disease

63
Q

products containing 0.1% H2O2

A

inc mouth rinse, toothpaste and tooth whitening/bleaching products
safe and continue to be available on the market

64
Q

products containing 0.1-6% H2O2

A

exposure limited to ensure only used in terms of freq and duration of application
should not be directly available to consumer, only through a dentist, hygienist, therapist or clinical dental technician
whitening products can only be sold by dental practitioners

65
Q

cycles of whitening

A

1st cycle of tx must be supervised
after the first cycle the product may be provided for use by the consumer
- after 1st cycle if they just want a top up you can sell them the gel

66
Q

conc exceeding 6% H2O2

A

prohibited unless wholly for the purpose of prevention of disease

67
Q

criminal offence to breach guidelines

A

if a dental professional is found to be using a product in excess of 6% for cosmetic purposes they will face fitness to practice proceedings
non-registrants providing tooth whitening will be prosecuted under the Dentists Act 1984 by the GDC for illegal practice of dentistry
non-dentists supplying bleaching products in excess of 6% will be prosecuted by Trading Standards

restorative (12 decks)

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