tooth whitening (3rd year) Flashcards
extrinsic causes of tooth discolouration
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
intrinsic causes of tooth discolouration
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)
tetracycline
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
what should the first method for extrinsic staining always be?
HPT
types of bleaching
external vital
internal non-vital
what cause of discolouration does vital external bleaching treat?
discolouration caused by formation of chemically stable, chromogenic products within the tooth substance - teeth slightly porous
long chain organic molecules
how does vital external bleaching work?
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
what is the active agent in bleaching (once broken down)?
hydrogen peroxide
rarely an ingredient in modern tooth bleaching products
how does hydrogen peroxide work - chemistry?
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
vital external bleaching constituents of bleaching gel
carbamide peroxide carbopol urea surfactant pigment dispersers preservative flavour potassium nitrate calcium phosphate F
carbopol
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
surfactant
allows the gel to wet the tooth surface
fluoride
prevents erosion
desensitising agent
carbamide peroxide
active ingredient
breaks down to produce hydrogen peroxide and urea
what does 10% carbamide peroxide break down to form?
- 6% H2O2
6. 4% urea
urea
raises pH
stabilises H2O2
slows down reaction - H2O2 liberated over a longer period
potassium nitrate, calcium phosphate
tooth desensitising agents
factors affecting bleaching (chemical reaction)
time - more time = more effect
cleanliness of tooth surface - cleaner = better
conc of solution - higher conc = more and quicker effect
temp - higher = quicker effect
prior to external vital bleaching
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
vital external bleaching warnings for pt
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
types of external vital bleaching
chairside/in office
home
advantages of in office bleaching
controlled by dentist
can use heat/light (speeds it up)
quick results for pt
disadvantages of in office bleaching
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 £££
in office vital external bleaching technique
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
heat/light/laser
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
home vital bleaching
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
what does 16.7% carbamide peroxide gel equate to?
6% hydrogen peroxide
max legal strength of solution
home vital bleaching - trays
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
home vital bleaching - surgery
full mouth cleaning/polishing of teeth
fit trays and check extension/comfort
instruction in use - written too
home vital bleaching - at home
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
review and results of home vital bleaching
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
when to bleach?
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
bleaching problems
sensitivity wears off cytotoxicity/mutagenicity gingival irritation tooth damage damage to restorations problems with bonding to teeth
prevalence of sensitivity
60+%
how does sensitivity start to resolve?
worse initially
resolves over 2-3 days post-bleaching
predictors of sensitivity
pre-existing sensitivity high conc of bleaching agent freq of change bleaching method (more likely with in-office) gingival recession - exposed root
bleaching wears off
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)
cytotoxicity/mutagenicity
no evidence for 10% carbamide peroxide
high conc H2O2 can cause problems
gingival irritation
related to conc
must check tray extension correct
tooth damage
no evidence over 15+ years
damage to restorations
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
why should you never use chlorine dioxide?
highly acidic and will take all E off
problems with bonding
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
internal non-vital bleaching - discolouration in a non-vital tooth
dead pulp - bleeding into dentine
blood products diffuse and darken
grey discolouration
indications for non-vital bleaching
non-vital tooth
adequate RCT - can redo first if not
no apical pathology
limitations of non-vital bleaching
doesn’t always work but generally worth a go
contraindications for non-vital bleaching
heavily restored tooth - better with crown or veneer
staining due to amalgam
advantages of non-vital bleaching
easy
conservative
pt satisfaction
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 - susceptible to external resorption anyway
combination bleaching
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
internal non-vital bleaching technique
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
review and repeat of internal non-vital bleaching
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
microabrasion
remove discolouration limited to outer layers of enamel
- remove surface layer of E
combination of erosion (acid) and abrasion (pumice)
indications for microabrasion
fluorosis
post-ortho demineralisation
demineralisation with staining
prior to veneering if dark staining is present
technique for microabrasion
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
repeating microabrasion
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
advantages of microabrasion
quick
easy
no long term problems - pulpal damage, caries
disadvantages of microabrasion
acid
sensitivity
only works for superficial staining
works much better for brown staining than for white marks
using phosphoric acid rather than HCl for microabrasion
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
what legislation governs whitening?
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
what must be carried out before bleaching?
clinical exam - free of dental pathology medical contraindications (v rare) - glucose-6-phosphate dehydrogenase deficiency - acatalasemia - neither group can metabolise H2O2
U18s
products containing/releasing 0.1-6% H2O2 cant be used on U18s except where wholly for the purpose of preventing disease
products containing 0.1% H2O2
inc mouth rinse, toothpaste and tooth whitening/bleaching products
safe and continue to be available on the market
products containing 0.1-6% H2O2
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
cycles of whitening
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
conc exceeding 6% H2O2
prohibited unless wholly for the purpose of prevention of disease
criminal offence to breach guidelines
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
