Tooth Whitening Flashcards
What are extrinsic causes of tooth discolouration ?
Smoking.
Tannins - tea, coffee, red wine, Guinness.
Chromogenic bacteria.
Chlorhexidine.
Iron supplements.
What are intrinsic causes of tooth discolouration ?
Fluorosis.
Tetracycline antibiotics.
Non-vitality.
Physiological age changes.
Dental materials - amalgam, root filling materials.
Medical conditions - porphyria, cystic fibrosis, thalassemia, sickle cell anaemia, hyperbilirubinemia.
Porphyria - what tooth colour is this condition associated with ?
Red primary teeth.
CF - what tooth colour is this condition associated with ?
Grey teeth.
Thalassemia - what tooth colour is this condition associated with ?
Blue, green or brown teeth.
Sickle cell anaemia - what tooth colour is this condition associated with ?
Blue, green or brown teeth.
Hyperbilirubinemia - what tooth colour is this condition associated with ?
Green teeth.
What circumstances should teeth bleaching be considered ?
Age related discolouration.
Mild fluorosis.
Post-smoking cessation.
Tetracycline staining.
What discolouration does teeth whitening work best for ?
Yellow or orange (compared to blue/grey).
When should external bleaching be carried out vs. internal ?
External - tooth vitality.
Internal - tooth non-vital.
What causes discolouration of teeth ?
Formation of chemically stable, chromogenic products (long chain organic molecules) within tooth substance.
How does external bleaching work ?
Hydrogen peroxide oxidises long chain organic molecules into smaller molecules (which are not pigmented) and ionic exchange in metallic molecules (leads to lighter colour).
What are the components of bleaching gel ?
Carbamide peroxide.
Carbopol.
Urea.
Surfactant.
Pigment dispersers.
Preservatives.
Flavour.
Potassium nitrate.
Calcium phosphate.
Fluoride.
What is the function of carbamide peroxide in bleaching gel ?
Active agent - breaks down to produce hydrogen peroxide and urea.
What is the function of carbopol in bleaching gel ?
Thickening agent - slows release of oxygen, increases viscosity, slow diffusion in enamel.
What is the function of urea in bleaching gel ?
Raises pH and stabilises hydrogen peroxide.
What is the function of surfactant in bleaching gel ?
Allows gel to wet tooth surface.
What is the function of potassium nitrate and calcium phosphate in bleaching gel ?
Tooth desensitising agents.
What is the function of adding fluoride to bleaching gel ?
Prevents erosion.
Desensitising effect.
What are 4 factors which will affect bleaching ?
Time - more time, more effect.
Cleanliness of tooth surface - cleaner, better.
Concentration of solution - higher concentration, more and quicker effect.
Temperature - higher, quicker.
What warnings should be given to patient before undergoing external bleaching treatment ?
Sensitivity. Relapse. Restoration colour. Allergy. Might not work. Compliance with regime.
What problems come with external bleaching treatment ?
Sensitivity. Wears off. Cytotoxicity. Gingival irritation. Tooth damage. Damage to restoration. Problems with bonding to tooth in future.
Why does external bleaching pose problems to bonding to tooth in future ?
Remaining oxygen in enamel structure for hydrogen peroxide.
What advice should be given to a patient regarding sensitivity post-external bleaching treatment ?
Resolves after 2-3 days.
Likely if pre-existing sensitivity, high conc. of bleaching agent, frequency of change, bleaching method and gingival recession.
What percentage of external bleaching gel is given for home treatment ?
10-15% carbamide peroxide gel.
What is the maximum legal strength of hydrogen peroxide allowed in external bleaching gels ?
16% hydrogen peroxide i.e. 16.7% carbamide peroxide.
How does non-vitality cause tooth discolouration ?
Pulpal necrosis causing bleeding into dentine.
Blood products diffuse and darken causing grey discolouration.
What are indications for internal non-vital tooth bleaching ?
Non-vital tooth.
Adequate RCT.
No apical pathology.
What are contraindications for internal non-vital tooth bleaching ?
Heavily restored tooth or staining due to amalgam.
What are the risks associated with internal non-vital tooth bleaching ?
External cervical resorption due to diffusion of H2O2 through dentine into PD tissues.
What % of carbamide peroxide gel is used in internal non-vital tooth bleaching ?
10%.
Describe the process of non-vital internal bleaching.
- Rubber dam.
- Remove filling from access cavity and GP from pulp chamber to 1mm below ACJ.
- Place 1mm RMGIC over GP to seal canal and prevent root resorption.
- Remove dark dentine.
- Etch internal surface of tooth with 37% phosphoric acid.
- Place 10% carbamide peroxide gel into cavity with cotton wool over it.
- Seal with GIC.
- Repeat weekly for 3-4 visits.
- Once shade achieved - restore palatally with white GP in pulp chamber and light shade of composite.
How often will tooth internally bleached require re-treatment ?
Every 4-5 years.
What is the function of micro-abrasion treatment alternative to internal non-vital bleaching ?
Remove discolouration limited to outer layers of enamel using combination of acid (erosion) and pumice (abrasion).
What are indications for micro-abrasion ?
Fluorosis.
Post-orthodontic demineralisation.
Demineralisation with staining.
Prior to veneering if dark staining present.
What are the advantages of micro-abrasion ?
Quick, easy, no long term pulpal damage, no caries risk.
What are the disadvantages of micro-abrasion ?
Acid, sensitivity, only superficial staining.
Describe micro-abrasion technique.
- Rubber dam with seal.
- Mix 18% HCl and pumice.
- Apply to all teeth and rub with prophy cup 5 seconds each tooth.
- Wash and repeat up to 10x.
- Polish teeth with fluoride prophy paste and apply fluoride varnish.
- Review 1x month.
What legislation is there in relation to tooth whitening ?
Cosmetic Products (Safety Amendment) Regulations 2012.
What are the 4 laws in tooth whitening ?
Cannot contain >6% hydrogen peroxide.
0.1-6% hydrogen peroxide cannot be used on <18s.
0.1% hydrogen peroxide products - toothpaste, mouth rinse - can be available on market.
0.1-6% hydrogen peroxide should not be available directly to customer, other than through treatment from a dentist.
What are the medical contraindications for tooth whitening ?
Glucose 6-phosphate dehydrogenase deficiency and actalasemia - neither groups can metabolise hydrogen peroxide.
