Tooth Whitening Flashcards
Extrinsic causes of tooth discolouration
- smoking
- tannins e.g. tea, coffee
- chromogenic bacteria
- chlorohexidine
- iron supplements
intrinsic causes of tooth discolouration
- fluorosis
- tetracycline
- non-vitality
- amalgam
- cystic fibrosis - grey teeth
- sickle cell anaemia
Two types of tooth bleaching
- external vital bleaching
- internal non-vital bleaching
briefly describe how vital external bleaching works
- discolouration caused by formation of chemically stable, chromogenic products within tooth substance
- bleaching oxides compounds into smaller molecules which are often not pigmented
- oxidation can cause ionic exchange in metallic molecules = lighter colour
active agent in vital external bleaching
hydrogen peroxide or carbamide peroxide
What are the products of the breakdown of carbamide peroxide?
hydrogen peroxide and urea (urea increases pH)
function of carbopol in bleaching gel
- thickening agent
- slows release of oxygen
- increases viscosity of gel so it stays on teeth and in tray
- slows diffusion into enamel
function of urea in external tooth bleaching
- raises pH
- stabilises hydrogen peroxide
function of surfactant in external tooth bleaching
allows gel to wet the tooth surface
function of fluoride in external bleaching
- desensitising effect
- prevents erosion
factors affecting external tooth bleaching
- time
- cleanliness of tooth surface
- concentration of solution
- temperature
external vital bleaching - warnings to patients
- sensitivity
- relapse
- won’t bleach restorations
- allergy
- might not work
- compliance with regime
Advantages of in office bleaching
- controlled by dentist
- can use heat/light
- quick results for patient
disadvantages of in office bleaching
- time for dentist
- can be uncomfortable
- expensive
- results tend to wear off quicker
in office bleaching technique
- thorough clean of teeth
- rubber dam or at least gingival mask
- apply bleaching gel to tooth
- apply heat and light
- wash, dry and repeat
- takes 30 mins to an hour
home vital bleaching technique
- requires custom made tray
- bleaches slowly, over several weeks
internal non-vital bleaching Indications
- non-vital tooth
- adequate RCT
- no apical pathology
internal non-vital bleaching contraindications
- heavily restored tooth
- staining due to amalgam
internal non-vital bleaching advantages
- easy
- conservative
- patient satisfaction
internal non-vital bleaching - risks
external cervical resorption
- due to diffusion of H202 through dentine into periodontal tissues
- high conc H202 and heat
Internal non-vital bleaching technique
record shade
prophylaxis
rubber dam
remove filling from access cavity
remove gp from pulp chamber and 1mm below ACJ
place 1mmm RMGIC over GP to seal canal
- seals dentine and prevents root resorption
remove any very dark dentine
etch internal surface of the tooth
place carbamide peroxide gel in cavity
cotton wool over this
seal with GIC
Repeat procedure at regular intervals
What concentration phosphoric acid is used to etch the internal surface of the tooth?
37%
what percentage of carbide peroxide os used in non vital internal bleaching?
10%
How many times do you repeat the technique for internal non-vital bleaching?
until required shade achieved or there is no change
- usually takes 3-4 visits
After 4 visits, if internal bleaching not worked, what other options do you have?
crown
veneer
composite build up
Non-vital internal bleaching - what do you do when final shade is obtained?
restore palatal cavity
place white GP or similar in pulp chamber
restore with light shade of composite
will gradually darken again - pretreatment every 4-5 years?
What is micorabrasion?
combination of erosion (acid) and abrasion (pumice)
- to remove discolouration limited to outer layers of enamel
Microabrasion - indications
fluorosis
post orthodontic demineralisation
demineralisation with staining
prior to veneering if dark staining present
micro abrasion technique
clean teeth thoroughly
rubber dam - seal very important
mic 19% HCL and pumice
apply to teeth
gently rub with prophy cup 5 seconds per tooth
wash
repeat up to 10x
remove rubber dam
polish teeth with proxy paste
apply fluoride varnish or gel
- regarded surface and decreases sensitivity
review after one month
micro abrasion advantages
quick
easy
no long term problems
micro-abrasion disadvantages
- acid
- sensitivity
- only works for superficial staining
- works better for brown staining than white marks
