Tooth Whitening Flashcards
What are some extrinsic causes of tooth discolouration?
Smoking, tannins, chromogenic bacteria, chlorohexidine, iron supplements
What are some intrinsic causes of tooth disocolouration?
Fluorosis
Tetracycline
Non-vitality
Amalgam
Age changes
Porphyria (red primary teeth)
What is the molecular action of external vital bleaching?
Oxidisation of long chain organic molecules, resulting in smaller molecules which are often not pigmented
What is the active agent in external vital bleaching?
Hydrogen peroxide (free radical per hydroxyl)
Often in bleaching solution as carbamate peroxide -breaks down to give hydrogen and urea (less acidic)
4 factors affecting external bleaching?
Time, cleanliness of tooth, concentration of solution , temperature
6 warnings for patient before external bleaching
Sensitivity
Relapse
Restoration colour will not change
Allergy
Might not work
Compliance with regime is important
Procedure of in office external vital bleaching
Clean teeth
Record initial shade
Place rubber dam/ gingival mask
Apply bleach to tooth
Apply heat/ light (speeds up reaction)
Wash/ dry/ repeat
Takes 30 mins/ 1 hour
What is the maximum percentage hydrogen peroxide in home vital bleaching?
6%
Describe the process of at home bleaching?
Alguna te impression
0.5mm thick soft splint, stopping 1mm of gingival margin with buccal spacer
Brush and floss teeth
Load tray 1mm dot buccal
Wear for 2hours/ overnight
If no results after what period of time should bleaching be stopped?
2 weeks
Why does external bleaching wear off?
Oxidised chromogens gradually reduce with time
How long should restoration placement be delayed post bleaching?
24 hours/ a week
Why is chlorine dioxide not used?
Has a ph of 3, strips enamel
More prone to re staining
Extreme sensitivity
What are some indications and contraindications for internal bleaching?
Non-vital tooth
Adequate RCT
No apical pathology
Contraindications- heavily restored tooth/ amalgam staining
What is a risk of internal bleaching and the cause of this?
External cervical resorption - due to diffusion of hydrogen peroxide through dentine into periodontal tissues
More common in trauma
Can also be due to heat during bleaching
Process of internal bleaching
Record shade
Clean tooth externally
Rubber dam
Remove filling from access cavity
Remove GP from pulp chamber and 1mm below ADJ
place 1mm RMBIC over GP to seal canal
Remove darkened dentine
Etch with 37% phosphoric acid
Place 10% carbamide peroxide gel in cavity
Place cotton wool over this
Seal with GIC
Repeat weekly until required shade is achieved (normally takes 3-4 visits)
Once final shade obtained- place white GP in pulp chamber and restore with light shade of composite
How often should internal bleaching be repeated?
4-5 years
What is combination bleaching?
Remove GP and cover with RMGIC
make bleaching tray with palatial reservoir
Bleach placed in tray and replaced frequently over a week
Need to wear tray full time
What is microabrasion
Combination of erosion and abrasion (acid and pumice) to remove outer layer of enamel
Used in superficial staining - fluoride, post ortho demineralisation, prior to veneer
Microabrasion procedure
Clean teeth
Rubber dam
18% HCl and pumice applied to teeth (or 37% phosphoric acid)
Gently rub with prophy cup 5 sec per tooth
Wash
Repeat up to 10x
Remove dam and polish with fluoride prophy paste
Apply fluoride gel/ varnish
Review in a month
What is resin infiltration?
Hydrophilic resin impregnating of the porous enamel in the white area,
Changes the refractive index of the white area, making it look like surrounding enamel.
What concentration of hydrogen peroxide products are only available through registered dentist?
0.1-6%
Excess of 6% is prohibited - will be prosecuted by Trading standards, face fitness to practice and prosecuted by GDC
What percentage of pts experience sensitivity after bleaching?
60%
What are some predictors of pt sensitivity post bleaching?
Concentration of hydrogen peroxide
Previous sensitivity
Gingival recession
