Tooth whitening Flashcards
What are the extrinsic causes of tooth discolouration?
Smoking
Tannins
- Tea
- Coffee
- Red wine
- Guinness
What are non extrinsic causes of tooth discolouration?
- Chromogenic Bacteria
- Chlorhexidine
- Iron supplements
What are some intrinsic causes of tooth discoloration?
- Fluorosis
- Tetracycline
- Non-vitality (blood products)
- Physiological (age changes)
Dental Materials - Amalgam
- Root filling materials
- Porphyria (red primary teeth)
- Cystic Fibrosis (grey teeth)
- Thalassemia, Sickle Cell anaemia (blue, green or brown teeth)
- Hyperbilirubinaemia (green teeth)
What is the first method of tooth whitening for extrinsic staining?
- Always HPT (Hydrogen peroxide)
What are the two types of tooth bleaching?
- External Vital bleaching
- Internal Non- Vital bleaching
- Can be used together in non-vital teeth*
How is discoloration caused?
- Caused by formation of chemically stable, chromogenic products within tooth substance
- They are long chain organic molecules
How does vital external bleaching chemically change the long chain organic molecules that cause discoloration?
- Bleaching oxidises the compounds
- Oxidation leads to smaller molecules which are not pigmented
- Oxidation can cause ionic exchange in metallic molecules leading to lighter colour
What is the active agent in Vital external bleaching?
- Hydrogen peroxide (H2O2)
What is hydrogen peroxide used for?
- Bleaching agent in industry
- Bleach hair
- Disinfectant
- Rarely in modern tooth bleaching products
How does hydrogen peroxide bleach things?
- Forms an acidic solution in water
- Breaks down to form water and oxygen
- Free radical per each hydroxyl (HO2) is formed which is the active oxidising agent
- Is a very fast oxidising agent
What are the constituents of tooth bleaching gel?
- Carbamide peroxide
- Carbopol
- Urea
- Surfactant
- Pigment dispersers
- Preservative
- Flavour
- Potassium Nitrate
- Calcium Phosphate
- Fluoride
What is carbamide peroxide used for in vital external bleaching?
- Active ingredient
- Breaks down to produce hydrogen peroxide and urea
- 10% carbamide peroxide leads to 3.6% H2O2 + 6.4% urea
- Urea increases pH
What is Carbopol used for in vital external bleaching?
- Thickening agent
- Slows release of oxygen
- Increases viscosity of gel so it stays where you put it (stays on teeth and on tray)
- Slows diffusion into enamel
What is urea used for in External tooth bleaching?
- Raises pH
- Stabilises hydrogen peroxide
What is surfactant used for in external tooth bleaching?
- Allows gel to wet the tooth surface
What is potassium nitrate and calcium phosphate used for in external tooth bleaching?
- Tooth desensitising agents
What is fluoride used for in external tooth bleaching?
- Prevents erosion
- Desensitising effect
What factors affect bleaching in external vital bleaching?
Time (more time = more effect)
Cleanliness of tooth surface (Cleaner = better)
Conc of solution (higher conc = more and quicker effect)
Temp (higher = quicker effect)
What is the first thing to check on a patient before you start external vital tooth bleaching?
- Check patient is dentally fit
- Any leakage around carious cavity margins will lead to pulpal damage
- Take shade and agree with patient and record in notes (Take photo with shade guide in pic)
What are some warning you should give patient for external vital tooth bleaching?
- Sensitivity
- Relapse
- Restoration colour
- Allergy
- Might not work
- Compliance with regime
What are the two ways to do vital external bleaching?
- Chair-side/in office
- Home
What are the two ways to do vital external bleaching?
- Chair-side/in office
- Home
What are the advantages to in office bleaching?
- Controlled by dentist
- Can use heat/light
- Quick results for patient
What are the disadvantages to in office bleaching?
- Time for dentist
- Can be uncomfortable
- Results tend to wear off quicker
- Expensive
What is the technique for in office external bleaching?
- Thorough cleaning of teeth
- Ideally rubber dam
- At least gingival mask
- Apply bleaching gel to tooth
- Apply heat/light
- Wash/dry/repeat
- Takes 30mins to an Hour
Are heat/light/laser really necessary for external bleaching?
- No evidence of better bleaching
- Good heat sources
- Mainly marketing technique
- Good initial result due to dehydration but wears off quickly
What is an essential structure that should be protected for in office bleaching?
- Protect the gingivae
What is the main constituent in home vital bleaching?
- 10-15% carbamide peroxide gel
- 16.7% = 6% hydrogen peroxide which is max strength of sol (anything more and illegal)
What is the technique for at home bleaching?
- Custom made set of mouth guards required
- Alginate impressions
- 0.5mm thick soft, acrylic, vacuum formed soft splint made
- Should stop 1mm short of gingival margin
- Buccal spacer to allow for placement of gel
In Surgery - Full mouth cleaning/polishing of teeth in surgery
- Fit trays and check extension/comfort
- Instruction in use
At Home - Brush and floss teeth
- Load tray
- 1mm^2 dot buccally on each tooth
- Fit tray in mouth
- Requires to be in place for at least 2 hrs
- Preferably overnight
- Clear written instructions
- Review at 1 week
What are the results likely to be for at home external bleaching?
- Most see results 2-3days
- Reach max 3-4 weeks
- If no change in 2 weeks then not going to work
When should you bleach?
- Age related darkening/discolouration
(Teeth with yellow/orange discolouration respond better than those with bluish/grey discolouration) - Mild fluorosis
- Post smoking cessation (Don’t bleach smokers it is a waste of time)
Tetracyclin staining?
- Prolonged treatment
- Better with yellow and brown than grey
- Can take months
What are some bleaching problems?
- Sensitivity
- Wears off
- Cytotoxicity/Mutagenicity
- Gingival irritation
- Tooth damage
- Damage to restorations
- Problems with bonding to tooth
What are the predictors of sensibility?
- Pre-existing sensitivity
- High concentration of Bleaching agent
- Frequency of change
- Bleaching method
- Gingival recession
What advice can you give patient about sensitivity?
- Common for 60%
- Worse initially
- Resolves over 2-3days post bleaching
What advice can you give about the bleaching wearing off?
- Oxidised chromogens gradually reduce with time
- Retreatment 1-3 years, varies
Why does gingival irritation occur?
- Related to conc
- Must check tray extension correct
Is damage to restorations likely to happen after bleaching?
- Probably not
- Teeth bleach, composite doesn’t.
- Patients must be aware of this before treatment starts
- If you change the restorations to match the bleached teeth continued bleaching will be required or fillings will be too light in colour
What are the problems with bonding after bleaching?
- Residual oxygen from peroxide remains within enamel structure initially
- Gradually dissipates over time
- Delay restorative procedures for 24hrs post bleaching
- Better to delay for a week
Why Should you never use Chlorine dioxide?
- Never
- Has pH of 3 and softens tooth surface
- Strip enamel
- As result teeth more prone to re-staining, develop rough surface and become extremely sensitive
What are the causes of internal non-vital discoloration?
- Dead pulp leads to bleeding into dentine
- Blood products diffuse and darken
- Grey discoloration
What are the indications of internal non-vital bleaching?
- Non-vital tooth
- Adequate RCT
- No apical path
What are the contraindications of internal non-vital bleaching?
- Heavily restored tooth (is easier with crown or veneer)
- Staining due to amalgam
What are the limitations of internal non-vital bleaching?
- Doesn’t always work but worth a go
What are some advantages of internal non-vital bleaching?
- Easy
- Conservative
- Patient satisfaction
What are some risks associated with internal non-vital bleaching?
External cervical resorption
- Due to diffusion of H202 through dentine into periodontal tissues
- High conc H202 and heat
- Trauma important
What is the technique for internal non-vital bleaching?
- Record shade
- Prophylaxis
- Rubber dam
- Remove filling from access cavity
- Remove GP from pulp chamber and 1mm below amelo-cemental junction
- Place 1mm RMGIC over GP to seal canal (Seals dentine and prevents root resorption)
- Remove any very dark dentine
- Etch the internal surface of the tooth with 37% phosphoric acid
- Place 10% carbamide peroxide gel in cavity
- Cotton wool over this
- Seal with GIC
- Repeat procedure at weekly intervals
How many times should internal non-vital bleaching happen?
- Repeat until required shade achieved
- Or no change
- Normally takes 3-4 visits
- If no change after 4 visits it’s not going to work and consider crown/veneer/composite build up
What is the technique of internal non-vital bleaching once final shade is obtained?
- Once shade obtained restore pulp cavity
- Place white GP or similar in pulp chamber
- Restore with light shade composite
- Will gradually darken again
- Retreat every 4-5years but this is variable
What is combination bleaching?
- Inside -outside bleaching
- Remove GP and cover with RMGIC
- Make bleaching tray with palatal not buccal reservoir
- Bleach placed in access cavity and tray
- Replaced frequently over a week
- Tricky for patient as they must wear tray whole time
What is microabrasion?
- Removes discolouration limited to outer layers of enamel
- Combo of erosion (acid) and abrasion (pumice)
What are some indications for micro-abrasion?
- Fluorosis
- Post orthodontic demineralisation
- Demineralisation with staining
- Prior to veneering if dark staining is present
What is the technique for micro-abrasion?
- Clean teeth thoroughly
- Rubber dam (seal is very important)
- Mix 18% HCl and pumice
- Apply to teeth
- Gently rub with prophy cup 5 seconds/tooth
- Wash
- Repeat up to 10X
- Remove rubber dam
- Polish teeth with fluoride prophy paste
- Apply fluoride gel or varnish
- Review after one month
Why is fluoride gel applied in micro-abrasion technique?
- Fluoride to help reharden the surface and decrease sensitivity
What can too much micro-abrasion lead to?
- Yellowing of tooth as dentine begins to show
- Permanent sensitivity
What are the advantages of micro-abrasion?
- Quick
- Easy
- No long term problems like caries or pulpal damage
What are the disadvantages of micro-abrasion?
- Acid
- Sensitivity
- Only works for superficial staining
- Works better for brown staining than white marks
What other acid can be used in micro-abrasion rather than HCL?
- 37% phosphoric acid
- HCL removes 100microns
- Phosphoric acid only removes 10microns
- Etch with phosphoric acid and for longer 30s prior to pumice
- Not as effective but readily available in GDP
What is resin infiltration?
- Doesn’t remove surface layer
- Infiltrates white area with resin
- Changes refractive index of white area
- Masks it and makes it look like surrounding enamel
What is resin infiltration used for?
- Treatment of white spot lesions
- Hydrophilic resin impregnation of porous enamel surface in white area
What is a negative of resin infiltration?
- Appears to have immediate masking effect
- But durability of aesthetic requires longer term study due to potential staining and the aging of low viscosity resins used
When did the Cosmetic Products (safety amendment) regulations 2012 come into place?
- October 2012
In the UK what are tooth bleaching products considered as compared to rest of world?
- Cosmetic
- Everywhere else is medical device
What is the legal limit of hydrogen peroxide in tooth whitening products?
- 6% hydrogen peroxide is max for itself or any products that release this supplied for cosmetic puproses
At what age can 0.1%-6% hydrogen peroxide be used?
- Any product containing or releasing hydrogen peroxide can’t be used on person under 18 years
- Unless for sole purpose of preventing disease
What 0.1% hydrogen peroxide products are safe?
- Mouth rinse, tooth paste, tooth whitening and bleaching
How can products containing 0.1-6% hydrogen peroxide be available to consumer?
- Only available through registered dentist, dental hygienist, dental therapist or clinical dental technicians working to a dentist’s prescription
- Breach of these regulations is criminal offence
- Enforced through trading standards
What are the legal aspects of 0.1-6% hyrdogen peroxide?
- Exposure should be limited
- Only available through dentist prescription
- Whitening products sold only by dental practitioners
- First cycle must be supervised after this can be used by consumer
- Conc exceeding 6% prohibited
- Criminal offence to breach guidelines
What will happen if dentist is found using over 6% hydrogen peroxide?
- Prosecuted by trading standards
- Face fitness to practice proceedings
- Non registrants providing tooth whitening prosecuted by GDC under Dentists Act 1984 for illegal practice of dentistry
