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BDS3 OPERATIVE TECHNIQUES > 4 - Tooth whitening > Flashcards

4 - Tooth whitening Flashcards

1
Q

What are the extrinsic causes of tooth discolouration?

A
  • smoking
  • tannins
  • chromogenic bacteria
  • chlorohexadine
  • iron supplements
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2
Q

What are intrinsic causes of tooth discolouration? (9)

A
  • fluorosis
  • tertracycline (old antibiotic)
  • loss of vitality
  • age
  • dental materials
  • porphyria
  • CF
  • thalassemia, sickle cell anaemia
  • hyperbilirubinaemia
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3
Q

What discolouration does porphyria cause?

A

Red primary teeth

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4
Q

What discolouration does CF cause?

A

Grey

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5
Q

What discolouration does thalassemia or sickle cell disease cause?

A

Blue, green or brown

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6
Q

What discolouration does hyperbilirubinaemia cause?

A

Green

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7
Q

What are the different types of tooth bleaching?

A
  • external vital
  • internal non-vital
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8
Q

Describe external vital bleaching.

A
  • good for discolouration caused by chromogenic products
  • bleaching oxides organic molecules, the smaller molecules are less pigmented
  • hydrogen peroxide is the active agent
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9
Q

Describe how hydrogen peroxide acts as the active bleaching agent.

A
  • forms acidic solution in water
  • free radical is formed (hydroxyl) which is the active oxidising agent
  • oxidises long organic molecules to breakdown into smaller molecules which are less pigmented
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10
Q

What are the constituents of external bleaching gel?

A
  • carbamide peroxide
  • carbopol
  • urea
  • surfactant
  • pigment dispersers
  • preservative
  • flavour
  • potassium nitrate
  • calcium phosphate
  • fluoride
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11
Q

What is carbamide peroxide?

A
  • active ingredient
  • breakdowns to produce urea and hydrogen peroxide
  • maximum 16.7% carbamide peroxide in gel
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12
Q

What is carbopol?

A
  • thickening agent, increases viscosity to keep gel where placed
  • slow release of oxygen
  • diffuses slowly into enamel
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13
Q

What is urea?

A
  • raises pH of gel
  • stabilises hydrogen peroxide and slows reaction
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14
Q

What is surfactant?

A

Allows gel to wet the tooth surface

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15
Q

What factors affect the bleaching result?

A
  • time increases effect
  • cleanliness of tooth surfaces increases effect
  • concentration increases effect
  • higher temperature increases speed of effect
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16
Q

What should you warn your patient of before beginning external bleaching?

A
  • sensitivity
  • relapse
  • colour of restoration won’t change
  • allergy
  • may not work
  • compliance is key
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17
Q

What are the advantages of in office bleaching?

A
  • controlled by dentist
  • can use heat/light as catalyst
  • quick results
18
Q

What are the disadvantages of in office bleaching?

A
  • increased time in chair
  • can be uncomfortable
  • results wear off quicker
  • expensive
19
Q

Describe the process of in office bleaching.

A
  • thorough cleaning of teeth
  • rubber dam placed with gingival mask
  • bleaching gel applied
  • apply heat or light
  • wash/dry/repeat
  • 30-60 mins
20
Q

Describe the process of at home bleaching.

A
  • custom tray made (0.5mm thick, soft acrylic)
  • patient prescribed carbamide peroxide gel 10-15%
  • patient wears trays overnight ideally
  • bleaching occurs slowly over several weeks
21
Q

When is it appropriate to using external bleaching?

A
  • age related discolouration (yellow/orange responds best)
  • mild fluorosis
  • post smoking cessation
  • tetracycline staining if prolonged treatment
22
Q

What are the problems associated with external bleaching?

A
  • sensitivity
  • wears off
  • gingival irritation
  • tooth damage
  • damage to restorations
  • can impact effectiveness of bonding to teeth
  • cytotoxicity
23
Q

What are predictors of sensitivity post-bleaching?

A
  • preexisting sensitivity
  • high concentration agent
  • frequency
  • bleaching method
  • gingival recession
24
Q

How do you combat problems with bonding to newly bleaching teeth?

A
  • wait at least 24 hours
  • a week is best
25
Q

What is chlorine dioxide?

A
  • used to whiten teeth by some beauty salons and cruise liners
  • pH of 3 softens enamel
  • teeth become more prone to staining and develop roughened appearance
  • teeth become extremely sensitive
26
Q

What are the indications for internal non-vital bleaching?

A
  • non-vital tooth
  • adequate RCT
  • no apical pathology
27
Q

What are the contra-indications for internal non-vital bleaching?

A
  • heavily restored tooth (crown or veneer instead)
  • staining caused by amalgam
28
Q

What are the advantages associated with internal beaching?

A
  • easy
  • conservative
  • good patient satisfaction
29
Q

What are the risks associated with internal bleaching?

A
  • external cervical resorption
  • due to diffusion of hydrogen peroxide through dentine into periodontal tissues
  • theoretical problem
30
Q

Describe the process of internal bleaching.

A
  • record shade
  • place rubber dam
  • remove restoration from access cavity
  • remove GP from pulp chamber and 1mm below ACJ
  • place RMGIC over GP to seal canal
  • remove dark dentine
  • etch internal surface with 37% phosphoric acid
  • place 10% carbamide peroxide gel
  • place cotton wool over this
  • seal with GIC
  • repeat at weekly intervals
  • restore tooth with white GP after no further change
31
Q

What is combination bleaching?

A
  • internal and external bleaching
  • prepare cavity as with internal bleaching
  • custom tray with palatal reservoir for 24 hour wear
  • carbamide peroxide gel placed in reservoir and within cavity for around a week, topping up as necessary
32
Q

What is mircoabrasion?

A
  • combination of erosion using acid, and abrasion using pumice
  • removes discolouration which is limited to the outer layers of enamel
33
Q

What are the indications for microabrasion?

A
  • superficial fluorosis
  • post orthodontic demineralisation
  • demineralisation with staining
  • prior to veneer preparation if dark staining
34
Q

What is the technique for microabrasion?

A
  • clean teeth thoroughly
  • rubber dam placed
  • 18% HCl and pumice mix applied to teeth
  • prophy cup used for 5s/tooth
  • washed
  • repeat up to 10x
  • remove dam
  • polish teeth with fluoride paste
  • apply fluoride gel/varnish
  • review at 1 month
35
Q

What are the advantages of microabrasion?

A
  • quick
  • easy
  • no long term problems
36
Q

What are the disadvantages of microabrasion?

A
  • acid
  • sensitivity
  • only works for superficial staining
  • works better on brown stains that white
37
Q

What is resin infiltration?

A
  • surface layer is not removed
  • area is infiltrated with resin
  • changes the refraction index of the white area
  • masks the area (more porous enamel) to make it look like the surrounding areas
38
Q

What are the indications for resin infiltration?

A
  • white spot lesions
  • arresting very early caries
39
Q

What are medical contra-indications for tooth bleaching?

A
  • glucose-6-phosphate dehydrogenase deficiency (v rare)
  • acatalasemia (low levels of catalase enzyme)
  • neither group can metabolise hydrogen peroxide
40
Q

What is the maximum strength of hydrogen peroxide that can be used in tooth bleaching products?

A

16.7% carbamide peroxide which equates to 6% hydrogen peroxide

41
Q

At what age can you conduct tooth bleaching?

A
  • over 18s
  • under 18s can only bleach their teeth if it is wholly intended for the purpose of preventing disease

BDS3 OPERATIVE TECHNIQUES (7 decks)

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