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Operative Dentistry > Tooth Whitening > Flashcards

Tooth Whitening Flashcards

1
Q

List some extrinsic causes of tooth discolouration (5)

A
  1. Smoking
  2. Tannins
    - Tea
    - Coffee
    - Red wine
    - Guinness
  3. Chromogenic bacteria
    - Common in children
  4. Chlorrhexidine
  5. Iron supplements
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2
Q

List some intrinsic causes of tooth discolouration (7)

A
  1. Fluorosis
  2. Tetracycline
  3. Non vitality
    - Blood products
    - Tooth dies becomes darker over time as pulp dies and products leach into dentine
  4. Physiological
    - Age changes
  5. Dental materials
    - Amalgam
    - Root filling materials
  6. Porphyria
    - Red primary teeth
  7. Cystic fibrosis
    - Grey teeth
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3
Q

Whats the 1st method of tooth whitening for extrinsic staining?

A

HPT

- scaling etc

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4
Q

What are the 2 types of tooth bleaching?

A
  1. External vital bleaching

2. Internal non-vital bleaching

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5
Q

When is external vital bleaching used? (2)

A
  • Discolouration forms chemically stable, chromogenic products within the tooth surface
  • Bleaching oxidises these compounds and leads to smaller molecules that are not pigmented
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6
Q

Active ingredient for vital external bleaching

A

Hydrogen peroxide

  • Forms an acidic solution in water
  • Breaks down to form water + o2
  • Free radical per hydroxyl (HO2) is formed (the active oxidising agent)
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7
Q

What are the constituents of bleaching gel? (9)

A
  1. Carbamide peroxide
  2. Carbopol
  3. Urea
  4. Surfactant
  5. Pigment dispersers
  6. Preservative
  7. Potassium nitrate
  8. Calcium phosphate
  9. Fluoride
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8
Q

What does carbamide peroxide break down to produce?

A

Hydrogen peroxide + urea

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9
Q

Function of carbopol (3)

A
  1. Thickening agent
  2. Slows the release of o2 and diffusion into enamel
  3. Increases viscosity of gel so it stays where you put it
    - Teeth
    - Tray
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10
Q

Function of urea (2)

A
  1. Raises pH
  2. Stabilises Hydrogen peroxide
    - Slows down the reaction
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11
Q

Function of surfactant

A

Allows gel to wet the tooth surface

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12
Q

Function of potassium nitrate/calcium phosphate

A

Desensitising agent

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13
Q

Function of fluoride

A

Prevents erosion

Desensitising agent

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14
Q

List factors that affect bleaching (4)

A
  1. Time
    More time = more effect
  2. Cleanliness of tooth surface
    Cleaner = better
  3. Concentration of solution
    Higher conc = more+quicker effect
  4. Temperature
    Higher = quicker effect
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15
Q

What must you check before starting bleaching?

A

Patient is dentally fit
Any leakage around carious cavity margins will lead to pulpal damage

  • Take an initial shade
  • Agree with patient + record in their notes
  • Take a phoot with shade guide included in the picutre
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16
Q

Warnings for patient about external vital bleaching (6)

A
  1. Sensitivity
  2. Relapse
  3. Restoration colour
  4. Allergy
  5. Might not work
  6. Compliance with regime
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17
Q

What are the 2 types of vital external bleaching we can offer?

A
  1. Chairside

2. Home bleaching

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18
Q

Advantages of in office bleaching (3)

A
  1. Controlled by dentist
  2. Can use heat/light
  3. Quick results for patient
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19
Q

Disadvantages of in office bleaching (4)

A
  1. Time for dentist
  2. Can be uncomfortable
  3. Results tend to wear off quicker
  4. Expensive
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20
Q

Talk through the in-office bleaching technique (6)

A
  1. Thorough cleaning of teeth
  2. Ideally rubber dam, but atleast gingival mask
  3. Apply bleaching gel to tooth
  4. Apply heat/light
  5. Wash/dry repeat
  6. Takes 30 mins to an hour
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21
Q

Talk through the home vital bleaching technique (4)

A
  1. 10-15% carbamide peroxide gel
  2. Patient uses solution at home with a custom made mouthguard tray
  3. Bleaches slowly, over several weeks
  4. Easy for dentist + patient
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22
Q

What doest 16.7% carbamide peroxide equate to?

A

6% of hydrogen peroxide = max strength of solution

Anything stronger = illegal

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23
Q

How are mouth guards made? (4)

A
  1. Alginate impressions of teeth
  2. 0.5mm thick soft splint made
  3. Should stop 1mm short of gingival margin
  4. Buccal spacer to allow placement of gel
24
Q

How long should a whitening tray be placed at home?

A

Atleast 2 hours

Preferably overnight

25
Q

How quickly do patients see a result from tooth whitening

26
Q

When should teeth be bleached? (4)

A
  1. Age related darkening/discolouration
    - Teeth with yellow/orange discolouration respond better than ones with bluish/grey discolouration
  2. Mild fluorosis
  3. Post smoking cessation
    - Don’t bleach smokers as its a waste of time
  4. Tetracyclin staining
    - Can work if prolonged tx
    - Works better with yellow over grey
    - Can take months
27
Q

What are some issues revolving bleaching teeth? (5)

A
  1. Sensitivity
  2. Wears off
  3. Cyotoxicity
  4. Gingival irritation
  5. Problems with bonding to tooth
28
Q

How long does sensitivity take to resolve?

A

Resolves over 2-3 days post bleaching

29
Q

What are some predictors of sensitivity (5)

A
  1. Pre-existing sensitivity
  2. High conc of bleaching agent
  3. Frequency of change
  4. Bleaching method
  5. Gingival recession
30
Q

Why does tooth whitening wear off? (2)

A
  1. Oxidised chromogens gradually decrease with time

2. Retx 1-3yrs varies

31
Q

What causes the cytotoxicity?

A

High conc of Hydrogen Peroxide

No evidence for 10% carbamine peroxide

32
Q

What is gingival irritation related to?

A

Concentration of bleach

Must check tray extension is correct
- Don’t want it extending onto the gingivae

33
Q

How can problems with bonding occur from tooth whitening?

A

Residual O2 from the peroxide remains within the enamel structure

Gradually dissipates over a short time

  • Delay resto procedures for at least 24hrs post bleaching
  • Preferable a week
34
Q

Why are beauty salon whitening txs bad?

A

Very acidic

Softens and strips enamel on the surface of the tooth

35
Q

List some causes for internal non-vital bleaching

A
  1. Dead pulp
    - Bleeding into dentine
  2. Blood products diffuse and darken
  3. Grey discolouration
36
Q

Indications for internal non vital bleaching (3)

A
  1. Non-vital tooth
  2. Adequate RCT
  3. No apical path
37
Q

Contraindications for internal non vital bleaching (2)

A
  1. Heavily restored tooth
    - Better with crown or veneer
  2. Staining due to amalgam
38
Q

Advantages of Internal non-vital bleaching (3)

A
  1. Easy
  2. Conservative
  3. Patient
39
Q

Risk of Internal non-vital bleaching

A
  1. External cervical resorption
    - Due to diffusion of hydrogen peroxide through dentine into periodontal tissues

Low conc hydrogen perxodie + heat = less trauma risk

40
Q

Talk through the technique for internal non-vital bleaching - RCT first (6)

A
  1. Record shade
  2. Prophylaxis
  3. Rubber dam
  4. Remove filling from acess cavity (where RCT was)
  5. Remove GP from pulp chamber and 1mm below ACJ
  6. Place 1mm RMGIC over GP to seal canal
    - Seals dentine + prevents root resorption
41
Q

Talk though the technique for internal non-vital bleaching after the RCT has been fixed (6)

A
  1. Remove any very dark dentine
  2. Etch the internal surface of the tooth with 37% phosphoric acid
  3. Place 10% carbamide peroxide gel in cavity
  4. Cotton wool over this
  5. Seal with GIC
  6. Repeat procedure at weekly intervals
42
Q

How many visits needed for internal non vital bleaching?

A

3-4

If not change after 4 visits consider crown/veneer/comp build up

43
Q

What do we do once final shade is obtained?

A
  1. Place white GP in pulp chamber
  2. Restore with light shade of composite
  3. Will gradually darken again
44
Q

What is combination bleaching (5)

A

Inside-outside bleaching

  1. Remove GP as before and cover with RMGIC
  2. Make bleaching tray
    - Palatal not buccal reservoir
  3. Bleach placed in access cavity + in tray
  4. Replaced frequently over about a week
  5. Tricky for patient as they must wear the tray for whole time
45
Q

Function of micro-abrasion

A

Removes discolouration limited to outer layers of enamel

Its a combo of erosion (acid) + abrasion (pumice)
- It is like giving the patient toothwear

46
Q

Indications for micro-abrasion (4)

A
  1. Fluorosis
  2. Post orthodontic demineralisation
  3. Demineralisation with staining
  4. Prior to veneer if dark staining is present
47
Q

Technique for microabrasion

A
  1. Clean tooth thoroughly
  2. Rubber dam
  3. 18% HCL and pumice mixed
  4. Gently rub for 5 seconds
  5. Wash
  6. Repeat up to 10x
48
Q

Technique for microabrasion after you remove the rubber dam

A
  1. Polish teeth with fluoride prophy paste
  2. Apply fluoride gel or varnish
    - Fluoride to help reharden the surface + decrease sensitivity
  3. Review after 1 month
49
Q

Why should we avoid repeating microabrasion too regularly? (2)

A
  1. Too much can lead to yellowing of the tooth as dentine begins to show through
  2. Will lead to permanent sensitivity
50
Q

Advantages of micro-abrasion (3)

A
  1. Quick
  2. Easy
  3. No long term problems
    - Pulpal damage
    - Caries
51
Q

Disadvantages of microabrasion (4)

A
  1. Acid
  2. Sensitivity
  3. Only works for superficial staining
  4. Works much better for brown staining than white marks
52
Q

What solution is used for microabrasion?

A

37% phosphoric acid rather than HCl

53
Q

Why would you rather use phosphoric acid over HCl?

A

Phosphoric acid only removes 10 microns

HCl removes 100 microns

54
Q

What is resin infiltration

A

When you don’t remove the surface layer

Infiltrate with resin instead

55
Q

What is resin infiltration used to tx?

A

White spot lesions

56
Q

What act relates to tooth whitening?

A

The Cosmetic Products (Safety Amendment) Regulations 2012

57
Q

List some medio-legal issues revolving around tooth whitening

A
  1. Illegal for tooth whitening products to contain more than 6% hydrogen peroxide
  2. Tooth whitening products containing or releasing up to 6% hydrogen peroxide should not be made directly available to the consumer (other than through tx by dentist/dental hygienists/dental therapist)

Operative Dentistry (6 decks)

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