tooth whitening (3rd year)

Question 1

extrinsic causes of tooth discolouration

Answer 1

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

Question 2

intrinsic causes of tooth discolouration

Answer 2

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)

Question 3

tetracycline

Answer 3

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

Question 4

what should the first method for extrinsic staining always be?

Answer 4

HPT

Question 5

types of bleaching

Answer 5

external vital

internal non-vital

Question 6

what cause of discolouration does vital external bleaching treat?

Answer 6

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

Question 7

how does vital external bleaching work?

Answer 7

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

Question 8

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

Answer 8

hydrogen peroxide

rarely an ingredient in modern tooth bleaching products

Question 9

how does hydrogen peroxide work - chemistry?

Answer 9

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

Question 10

vital external bleaching constituents of bleaching gel

Answer 10

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

Question 11

carbopol

Answer 11

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

Question 12

surfactant

Answer 12

allows the gel to wet the tooth surface

Question 13

fluoride

Answer 13

prevents erosion

desensitising agent

Question 14

carbamide peroxide

Answer 14

active ingredient

breaks down to produce hydrogen peroxide and urea

Question 15

what does 10% carbamide peroxide break down to form?

Answer 15

3. 6% H2O2

6. 4% urea

Question 16

urea

Answer 16

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

Question 17

potassium nitrate, calcium phosphate

Answer 17

tooth desensitising agents

Question 18

factors affecting bleaching (chemical reaction)

Answer 18

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

Question 19

prior to external vital bleaching

Answer 19

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

Question 20

vital external bleaching warnings for pt

Answer 20

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

Question 21

types of external vital bleaching

Answer 21

chairside/in office

home

Question 22

advantages of in office bleaching

Answer 22

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

Question 23

disadvantages of in office bleaching

Answer 23

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
£££

Question 24

in office vital external bleaching technique

Answer 24

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

Question 25

heat/light/laser

Answer 25

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

Question 26

home vital bleaching

Answer 26

``` 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 ```

Question 27

what does 16.7% carbamide peroxide gel equate to?

Answer 27

6% hydrogen peroxide | max legal strength of solution

Question 28

home vital bleaching - trays

Answer 28

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

Question 29

home vital bleaching - surgery

Answer 29

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

Question 30

home vital bleaching - at home

Answer 30

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

Question 31

review and results of home vital bleaching

Answer 31

``` 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 ```

Question 32

when to bleach?

Answer 32

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

Question 33

bleaching problems

Answer 33

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

Question 34

prevalence of sensitivity

Answer 34

60+%

Question 35

how does sensitivity start to resolve?

Answer 35

worse initially | resolves over 2-3 days post-bleaching

Question 36

predictors of sensitivity

Answer 36

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

Question 37

bleaching wears off

Answer 37

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)

Question 38

cytotoxicity/mutagenicity

Answer 38

no evidence for 10% carbamide peroxide | high conc H2O2 can cause problems

Question 39

gingival irritation

Answer 39

related to conc | must check tray extension correct

Question 40

tooth damage

Answer 40

no evidence over 15+ years

Question 41

damage to restorations

Answer 41

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

Question 42

why should you never use chlorine dioxide?

Answer 42

highly acidic and will take all E off

Question 43

problems with bonding

Answer 43

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

Question 44

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

Answer 44

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

Question 45

indications for non-vital bleaching

Answer 45

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

Question 46

limitations of non-vital bleaching

Answer 46

doesn't always work but generally worth a go

Question 47

contraindications for non-vital bleaching

Answer 47

heavily restored tooth - better with crown or veneer | staining due to amalgam

Question 48

advantages of non-vital bleaching

Answer 48

easy conservative pt satisfaction

Question 49

risks of internal non-vital bleaching

Answer 49

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

Question 50

combination bleaching

Answer 50

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

Question 51

internal non-vital bleaching technique

Answer 51

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

Question 52

review and repeat of internal non-vital bleaching

Answer 52

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

Question 53

microabrasion

Answer 53

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

Question 54

indications for microabrasion

Answer 54

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

Question 55

technique for microabrasion

Answer 55

``` 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 ```

Question 56

repeating microabrasion

Answer 56

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

Question 57

advantages of microabrasion

Answer 57

quick easy no long term problems - pulpal damage, caries

Question 58

disadvantages of microabrasion

Answer 58

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

Question 59

using phosphoric acid rather than HCl for microabrasion

Answer 59

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

Question 60

what legislation governs whitening?

Answer 60

``` 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 ```

Question 61

what must be carried out before bleaching?

Answer 61

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

Question 62

U18s

Answer 62

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

Question 63

products containing 0.1% H2O2

Answer 63

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

Question 64

products containing 0.1-6% H2O2

Answer 64

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

Question 65

cycles of whitening

Answer 65

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

Question 66

conc exceeding 6% H2O2

Answer 66

prohibited unless wholly for the purpose of prevention of disease

Question 67

criminal offence to breach guidelines

Answer 67

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