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BDS3 Restorative > Tooth whitening > Flashcards

Tooth whitening Flashcards

1
Q

What are the extrinsic causes of tooth discolouration?

A

Smoking
Tannins
- Tea
- Coffee
- Red wine
- Guinness

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2
Q

What are non extrinsic causes of tooth discolouration?

A
  • Chromogenic Bacteria
  • Chlorhexidine
  • Iron supplements
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3
Q

What are some intrinsic causes of tooth discoloration?

A
  • 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)
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4
Q

What is the first method of tooth whitening for extrinsic staining?

A
  • Always HPT (Hydrogen peroxide)
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5
Q

What are the two types of tooth bleaching?

A
  • External Vital bleaching
  • Internal Non- Vital bleaching
  • Can be used together in non-vital teeth*
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6
Q

How is discoloration caused?

A
  • Caused by formation of chemically stable, chromogenic products within tooth substance
  • They are long chain organic molecules
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7
Q

How does vital external bleaching chemically change the long chain organic molecules that cause discoloration?

A
  • 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
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8
Q

What is the active agent in Vital external bleaching?

A
  • Hydrogen peroxide (H2O2)
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9
Q

What is hydrogen peroxide used for?

A
  • Bleaching agent in industry
  • Bleach hair
  • Disinfectant
  • Rarely in modern tooth bleaching products
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10
Q

How does hydrogen peroxide bleach things?

A
  • 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
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11
Q

What are the constituents of tooth bleaching gel?

A
  • Carbamide peroxide
  • Carbopol
  • Urea
  • Surfactant
  • Pigment dispersers
  • Preservative
  • Flavour
  • Potassium Nitrate
  • Calcium Phosphate
  • Fluoride
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12
Q

What is carbamide peroxide used for in vital external bleaching?

A
  • Active ingredient
  • Breaks down to produce hydrogen peroxide and urea
  • 10% carbamide peroxide leads to 3.6% H2O2 + 6.4% urea
  • Urea increases pH
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13
Q

What is Carbopol used for in vital external bleaching?

A
  • 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
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14
Q

What is urea used for in External tooth bleaching?

A
  • Raises pH
  • Stabilises hydrogen peroxide
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15
Q

What is surfactant used for in external tooth bleaching?

A
  • Allows gel to wet the tooth surface
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16
Q

What is potassium nitrate and calcium phosphate used for in external tooth bleaching?

A
  • Tooth desensitising agents
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17
Q

What is fluoride used for in external tooth bleaching?

A
  • Prevents erosion
  • Desensitising effect
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18
Q

What factors affect bleaching in external vital bleaching?

A

Time (more time = more effect)
Cleanliness of tooth surface (Cleaner = better)
Conc of solution (higher conc = more and quicker effect)
Temp (higher = quicker effect)

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19
Q

What is the first thing to check on a patient before you start external vital tooth bleaching?

A
  • 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)
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20
Q

What are some warning you should give patient for external vital tooth bleaching?

A
  • Sensitivity
  • Relapse
  • Restoration colour
  • Allergy
  • Might not work
  • Compliance with regime
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21
Q

What are the two ways to do vital external bleaching?

A
  • Chair-side/in office
  • Home
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22
Q

What are the two ways to do vital external bleaching?

A
  • Chair-side/in office
  • Home
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23
Q

What are the advantages to in office bleaching?

A
  • Controlled by dentist
  • Can use heat/light
  • Quick results for patient
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24
Q

What are the disadvantages to in office bleaching?

A
  • Time for dentist
  • Can be uncomfortable
  • Results tend to wear off quicker
  • Expensive
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25
Q

What is the technique for in office external bleaching?

A
  • 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
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26
Q

Are heat/light/laser really necessary for external bleaching?

A
  • No evidence of better bleaching
  • Good heat sources
  • Mainly marketing technique
  • Good initial result due to dehydration but wears off quickly
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27
Q

What is an essential structure that should be protected for in office bleaching?

A
  • Protect the gingivae
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28
Q

What is the main constituent in home vital bleaching?

A
  • 10-15% carbamide peroxide gel
  • 16.7% = 6% hydrogen peroxide which is max strength of sol (anything more and illegal)
29
Q

What is the technique for at home bleaching?

A
  • 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
30
Q

What are the results likely to be for at home external bleaching?

A
  • Most see results 2-3days
  • Reach max 3-4 weeks
  • If no change in 2 weeks then not going to work
31
Q

When should you bleach?

A
  • 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

32
Q

What are some bleaching problems?

A
  • Sensitivity
  • Wears off
  • Cytotoxicity/Mutagenicity
  • Gingival irritation
  • Tooth damage
  • Damage to restorations
  • Problems with bonding to tooth
33
Q

What are the predictors of sensibility?

A
  • Pre-existing sensitivity
  • High concentration of Bleaching agent
  • Frequency of change
  • Bleaching method
  • Gingival recession
34
Q

What advice can you give patient about sensitivity?

A
  • Common for 60%
  • Worse initially
  • Resolves over 2-3days post bleaching
35
Q

What advice can you give about the bleaching wearing off?

A
  • Oxidised chromogens gradually reduce with time
  • Retreatment 1-3 years, varies
36
Q

Why does gingival irritation occur?

A
  • Related to conc
  • Must check tray extension correct
37
Q

Is damage to restorations likely to happen after bleaching?

A
  • 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
38
Q

What are the problems with bonding after bleaching?

A
  • 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
39
Q

Why Should you never use Chlorine dioxide?

A
  • 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
40
Q

What are the causes of internal non-vital discoloration?

A
  • Dead pulp leads to bleeding into dentine
  • Blood products diffuse and darken
  • Grey discoloration
41
Q

What are the indications of internal non-vital bleaching?

A
  • Non-vital tooth
  • Adequate RCT
  • No apical path
42
Q

What are the contraindications of internal non-vital bleaching?

A
  • Heavily restored tooth (is easier with crown or veneer)
  • Staining due to amalgam
43
Q

What are the limitations of internal non-vital bleaching?

A
  • Doesn’t always work but worth a go
44
Q

What are some advantages of internal non-vital bleaching?

A
  • Easy
  • Conservative
  • Patient satisfaction
45
Q

What are some risks associated with internal non-vital bleaching?

A

External cervical resorption
- Due to diffusion of H202 through dentine into periodontal tissues
- High conc H202 and heat
- Trauma important

46
Q

What is the technique for internal non-vital bleaching?

A
  • 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
47
Q

How many times should internal non-vital bleaching happen?

A
  • 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
48
Q

What is the technique of internal non-vital bleaching once final shade is obtained?

A
  • 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
49
Q

What is combination bleaching?

A
  • 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
50
Q

What is microabrasion?

A
  • Removes discolouration limited to outer layers of enamel
  • Combo of erosion (acid) and abrasion (pumice)
51
Q

What are some indications for micro-abrasion?

A
  • Fluorosis
  • Post orthodontic demineralisation
  • Demineralisation with staining
  • Prior to veneering if dark staining is present
52
Q

What is the technique for micro-abrasion?

A
  • 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
53
Q

Why is fluoride gel applied in micro-abrasion technique?

A
  • Fluoride to help reharden the surface and decrease sensitivity
54
Q

What can too much micro-abrasion lead to?

A
  • Yellowing of tooth as dentine begins to show
  • Permanent sensitivity
55
Q

What are the advantages of micro-abrasion?

A
  • Quick
  • Easy
  • No long term problems like caries or pulpal damage
56
Q

What are the disadvantages of micro-abrasion?

A
  • Acid
  • Sensitivity
  • Only works for superficial staining
  • Works better for brown staining than white marks
57
Q

What other acid can be used in micro-abrasion rather than HCL?

A
  • 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
58
Q

What is resin infiltration?

A
  • 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
59
Q

What is resin infiltration used for?

A
  • Treatment of white spot lesions
  • Hydrophilic resin impregnation of porous enamel surface in white area
60
Q

What is a negative of resin infiltration?

A
  • 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
61
Q

When did the Cosmetic Products (safety amendment) regulations 2012 come into place?

A
  • October 2012
62
Q

In the UK what are tooth bleaching products considered as compared to rest of world?

A
  • Cosmetic
  • Everywhere else is medical device
63
Q

What is the legal limit of hydrogen peroxide in tooth whitening products?

A
  • 6% hydrogen peroxide is max for itself or any products that release this supplied for cosmetic puproses
64
Q

At what age can 0.1%-6% hydrogen peroxide be used?

A
  • Any product containing or releasing hydrogen peroxide can’t be used on person under 18 years
  • Unless for sole purpose of preventing disease
65
Q

What 0.1% hydrogen peroxide products are safe?

A
  • Mouth rinse, tooth paste, tooth whitening and bleaching
66
Q

How can products containing 0.1-6% hydrogen peroxide be available to consumer?

A
  • 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
67
Q

What are the legal aspects of 0.1-6% hyrdogen peroxide?

A
  • 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
68
Q

What will happen if dentist is found using over 6% hydrogen peroxide?

A
  • 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

BDS3 Restorative (4 decks)

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