Tooth Whitening Flashcards
What are some extrinsic causes of tooth discolouration?
- smoking
- tannins = tea/coffee/red wine/guinness
- chromogenic bacteria
- chlorohexidine
- iron supplements
who are chromogenic bacteria more common in?
child patients
- causes black staining
what are examples of intrinsic tooth discolouration?
- fluorosis
- tetracycline antibiotics (used to be common)
- non-vitality
- physiological (age changes)
- dental materials
- porphyria
- cystic fibrosis
- thalassemia/sickle cell anaemia
- hyperbilirubinaemia
what is porphyria?
red primary teeth
what colour might the teeth of a cystic fibrosis patient be?
grey teeth
what colour will the teeth of a patient be with hyperbilirubinaemia?
green teeth
what does fluorosis present as?
white/brown patches on teeth
what should the first method of tooth whitening for extrinsic staining be?
PMPR scaling
what are the types of tooth bleaching?
- external vital bleaching
- internal non vital bleaching
what causes teeth to discolour?
the formation of chemically stable, chromogenic products within the tooth surface
how does vital external bleaching work?
Bleaching oxidises the long chain organic molecules found in teeth that cause discolouration
- leads to smaller, non pigmented molecules
what is the active agent in the bleaching agents used?
Hydrogen peroxide (H2O2)
- from carbamide peroxide
How does hydrogen peroxide bleach teeth?
- forms acidic solution in water
- breaks down to form water & oxygen
- free radical HO2 is formed which is the ACTIVE OXIDISING AGENT
what are the constituents of bleaching gel?
- carbamide peroxide
- carbopol
- urea
- surfactant
- pigment dispersers
- preservative
- flavour
- potassium nitrate
- calcium phosphate
- fluoride
what forms the hydrogen peroxide in bleaching agents?
Carbamide peroxide
what is carbamide peroxide?
Active ingredient in bleach solutions
- breaks down to form hydrogen peroxide & urea
what does 10% carbamide peroxide break down to form?
3.6% H2O2 + 6.4% Urea
what is carbopol?
- thickening agent
- slows the release of oxygen
- increases viscosity of gel
- slows diffusion into enamel
why is carbopol needed in bleaching agents?
Increased viscosity of gel helps it to
- stay on teeth
- stay in tray
what is the purpose of Urea in bleaching agents?
- raises pH
- stabilises hydrogen peroxide
what is the purpose of surfactant in bleaching agents?
allows gel to wet the tooth surface
what is the purpose of potassium nitrate/calcium phosphate in bleaching agents?
tooth desensitising agents
what is the purpose of fluoride in bleaching agents?
- prevents erosion
- desensitising agent
When performing external vital bleaching, what factors affect the bleaching?
- time (longer time on tooth —> whiter)
- cleanliness of tooth
- concentration of solution
- temperature
what does a higher temperature cause when performing external vital bleaching?
higher temp —> quicker bleaching effect
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
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
what are the two types of vital external bleaching?
- chair side
- home
what are the advantages of in office bleaching?
- controlled by dentist
- can use heat/light
- quick results for patient
what are the disadvantages of in office bleaching?
- time for dentist
- can be uncomfortable
- results tend to wear off quicker
- expensive
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
why does laser lightening often give a good initial result when bleaching?
- mainly due to dehydration
- this wears off quickly
how are gingiva protected when performing in-house bleaching?
?
what is used for home vital bleaching?
10-15% carbamide peroxide gel
what is the maximum strength of hydrogen peroxide allowed for teeth whitening?
6% !
what strength of Carbamide Peroxide equates to the maximum strength of hydrogen peroxide allowed?
16.7%
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
how are custom mouth guards provided to patients?
- alginate impressions of teeth taken
- ask for 0.5mm thick soft, acrylic, vacuumed formed soft splint
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
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
when are results reached with at-home bleaching roughly?
maximum 3-4 weeks
teeth with what type of discolouration respond better to treatment?
yellow/orange better than bluish/grey
what problems can arise from bleaching?
- sensitivity
- wears off
- cytotoxicity/mutagenicity
- gingival irritation
- tooth damage
- damage to restorations
- problems with bonding to tooth
how common is post-bleaching sensitivity?
60% +
how long does post-bleaching sensitivity last?
usually resolves after 2-3 days
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
what is gingival irritation after bleaching as a result of?
due to concentration of solution used
- check tray extension is correct ( 1mm )
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
what substance should NEVER be used for teeth bleaching? why?
CHLORINE DIOXIDE (pH of 3)
- softens and strips enamel from tooth surface
what are some causes for need of internal non-vital bleaching?
- dead pulp
- blood products diffuse and darken tooth
- grey discolouration
what are the indications for internal non-vital bleaching?
- non-vital tooth
- adequate RCT
- no apical path
what are contraindications for internal non-vital bleaching?
- heavily restored tooth
- staining due to amalgam
what are the advantages of internal non-vital bleaching?
- easy
- conservative
- usually patient satisfaction
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
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
what is used to etch the internal surface of the tooth during internal bleaching?
37% phosphoric acid
what % of carbamide peroxide gel is used in internal non-vital bleaching?
10%
how many visits does internal non-vital bleaching normally take?
3-4 visits
what is combination bleaching?
inside-outside bleaching
what is micro-abrasion?
- removes discolouration limited to the outer layers of enamel
- combination of erosion (acid) and abrasion (pumice)
what are indications for micro-abrasion?
- fluorosis
- post-orthodontic demineralisation
- demineralisation with staining
- prior to veneering if dark staining present
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
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
what are the advantages of micro-abrasion?
- quick
- easy
- no long term problems such as pulpal damage or caries
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
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
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
what is typically used for Resin Infiltration?
ICON
is tooth bleaching medical or cosmetic?
UK = cosmetic
USA (and most of rest of world) = medical
what are medical contraindications for tooth whitening?
- Glucose-6-Phophate dehydrogenase deficiency
- Acatalasemia
(NEITHER ABLE TO METABOLISE HYDROGEN PEROXIDE)
what is the minimum age for tooth whitening done in practise?
18 years old
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
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
