Tooth Whitening Flashcards
What are the extrinsic factors of tooth discolouration?
- Smoking
- Tannins (Tea, coffee, red wine)
- Chromogenic bacteria
- Chlorhexadine
- Iron supplements
What are the intrinsic causes of tooth discolouration?
- Fluorisis
- Tetracycline
- Non-vitality
- Dental materials
- Cystic fibrosis
- Thalassemia
What is the first stage of whitening for extrinsic tooth staining?
PMPR (HPT - hygiene phase therapy)
What is the mechanism by which vital tooth staining occurs?
Discolouration is caused by formation of chromogenic products. These are long chain organic molecules.
What is the mechanism by which vital tooth bleaching can occur?
Bleaching oxidises the long chain organic molecules, leading to smaller molecules which are often no longer pigmented.
Oxidation can also cause ionic exchange in metallic molecules leading to a lighter colour.
How does hydrogen peroxide cause tooth whitening?
- Forms an acidic solution in water
- Breaks down to form hydroxyl
- Hydroxyl is an oxidising free radical
Note that it is often not used as a bleaching agent for teeth.
What is the purpose of carbamide peroxide in bleaching gel?
- Active ingredient
- Breaks down to produce hydrogen peroxide and urea
- Urea increases and stabilises pH
- Hydrogen peroxide creates hydroxyl (the oxidising agent)
What is the purpose of carbopol in bleaching gel?
- Thickening agent
- Slows release of oxygen
- Increases viscosity of gel, causing it to stay on the tooth
What factors impact the effect of external vital bleaching?
- Time (more time, better effect)
- Cleanliness (the cleaner the better)
- Concentration (higher conc, quicker effect)
- Temperature (higher temp, quicker effect)
What factors should you check before starting external vital bleaching?
- Check patient is dentally fit
- Carious leakage may lead to pulpal damage
- Take an initial shade, ask patient if they agree, make a note of it.
- Consider clinical pictures
What advice would you give to the patient about the bleaching process?
- Sensitivity
- Relapse
- Restoration colour
- Allergy
- Might not work
- Requires compliance with regime
- Can cause gingival irriation
- Problems with bonding to teeth
What are the disadvantages of chair-side vital external bleaching?
- Takes time
- Can be uncomfortable
- Results wear off quicker
- Expensive
What is the process of chair-side vital external bleaching?
- Thorough cleaning
- Rubber dam
- Bleaching gel
- Apply heat/light
- Wash/dry/repeat
- Takes 30-60mins
What are the effects of heat/light/laser to bleaching?
- Mainly a marketing technique
- No evidence of better bleaching
- Often good initial result due to dehydration, but this wears of quickly
What is the typical strength of a bleaching agent?
10-15% carbamide peroxide gel.
What is the process of home vital external bleaching?
Patient sent home with custom made tray, and applies gel as per manufacturers guide.
Bleaches slowly over time, but requires patient compliance.
What do you tell the patient if their teeth are not whiter within 2 weeks?
Whitening is most likely not going to work.
What are the indications for tooth bleaching?
- Age related discolouration
- Mild fluorosis
- Post-smoking cessation
- Tetracyclin staining
How often is bleaching re-treatment required?
Every 1-3 years but this varies.
Is there evidence that bleaching can damage teeth long term?
No evidence over 15+ years.
How does bleaching affect boding?
Residual oxygen from the peroxide remains within enamel structure, but dissipates over a short time.
This can interfere with bonding, so it is advisable to delay restorative procedures for 24 hours after bleaching. (Better to delay for a week)
What can cause internal non-vital discolouration?
- Dead pulp, bleeding into dentine
- Blood products darken and diffuse
- Causes grey discolouration.
What are the contraindications for internal non-vital bleaching?
- Heavily restored teeth
- Staining due to amalgam
What are the limitations of internal non-vital bleaching?
Doesn’t always work, but generally worth a go.
What are the advantages to internal non-vital bleaching?
- Easy
- Conservative
- Patient satisfaction
What are the risks of internal non-vital bleaching?
- External cervical resorption
- Caused by diffusion of peroxide through dentine into periodontal tissues
What is the technique for internal non-vital bleaching?
- Record shade
- Prophylaxis
- Rubber dam
- Remove filling
- Remove GP from pulp chamber and 1mm below ACJ
- Place 1mm RMGIC over GP to seal canal (prevents root resorption)
- Remove very dark dentine
- Etch internal surface
- Place 10% carbamide gel
- Cotton wool over this
- Seal with GIC
- Repeat at weekly intervals
How often should internal non-vital bleaching be performed?
Every week until desired shade achieved. Normally takes 3-4 visits.
If no change after 4 visits, consider crown/veneer/composite build up.
How often does non-vital bleaching need to be repeated?
Typically every 4-5 years, but this is variable.
What can micro-abrasion be done with?
Acid (erosion) or pumice (abrasion).
What are the indications for micro-abrasion?
- Fluorosis
- Orthodontic related demoralisation
- Demoralisation with staining
- Prior to veneering if dark staining is present
What is the maximum legal limit of hydrogen peroxide release, in a bleaching agent?
6% is the maximum, any more than it is a criminal offence to apply it to a patient.
Who can apply tooth bleaching to a patient?
Only those legally registered with the GDC to perform such treatment.
What are the indications for internal non-vital bleaching?
- Non-vital tooth
- Adequate RCT
- No apical pathology
What are the advantages of chair-side vital external bleaching?
- Controlled by professional
- Can use heat and light
- Quick results for patient
