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3 Operative Dentistry > Tooth Whitening > Flashcards

Tooth Whitening Flashcards

1
Q

What are the extrinsic causes of tooth discolouration?

A

Smoking
Tannins - tea, coffee, red wine, Guinness
Chromogenic bacteria
Chlorhexidine
Iron supplements

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2
Q

What are the intrinsic causes of tooth whitening?

A

Fluorosis
Tetracycline
Non-vitality
Physiological (age changes)
Dental materials - amalgam
Porphyria (red primary teeth)
Cystic fibrosis (grey teeth)
Thalassaemia, sickle cell anaemia (blue, green or brown teeth)
Hyperbilirubinaemia (green teeth)

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3
Q

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

A

PMPR

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4
Q

What are the types of tooth bleaching?

A

Externa vital bleaching
Internal non-vital bleaching

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5
Q

How does vital external bleaching work?

A

Discolouration is caused by the formation of chromogenic products within the tooth substance
Bleaching oxidises these compounds
Oxidation leads to smaller molecules which are often not pigmented
Oxidation can cause ionic exchange in metallic molecules leading to lighter colour

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6
Q

What is used for vital external bleaching and why is it used?

A

Hydrogen peroxide (H2O2)
It forms an acidic solution in water, breaking down to form the free radical HO2

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7
Q

What are the constituents of bleaching gel?

A

Carbamide peroxide
Carbopol
Urea
Surfactant
Potassium nitrate
Calcium phosphate
Fluoride

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8
Q

What factors affect external vital bleaching?

A

Time
Cleanliness of tooth surface
Concentration of solution
Temperature

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9
Q

What should you do before external vital bleaching?

A

Check patient is dentally fit - any leakage around cavity margins will lead to pulpal damage
Take an initial shade, agree it with patient and record it in notes - clinical photo with shade guide is even better

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10
Q

What are the patient warnings for external vital bleaching?

A

Sensitivity
Relapse
Restorations won’t change colour
Allergy
Might not work
Requires compliance

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11
Q

What are the advantages of in office bleaching?

A

Controlled by dentist
Can use heat/light
Quick results for patient

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12
Q

What are the disadvantages of in office bleaching?

A

Time consuming
Can be uncomfortable for patient
Results wear off quicker
Expensive

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13
Q

Describe technique for in office bleaching

A

Thorough cleaning of teeth
Ideally rubber dam used but at least gingival mask
Apply bleaching gel to tooth
Apply heat/light
Wash/dry/repeat
Takes 30 minutes to an hour

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14
Q

How does a light affect teeth whitening?

A

Mainly a marketing technique
No evidence of better bleaching
Just heat sources
Often a good initial result due to dehydration but wears off quickly

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15
Q

Describe home vital bleaching

A

Commonest technique
10-15% carbamide peroxide gel
Patient uses solution at home with custom made tray
Bleaches slowly over several weeks
Easy for dentist and patient

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16
Q

Describe the technique for at home vital bleaching

A

Alginate impression of teeth
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

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17
Q

What are the possible results of at home vital bleaching?

A

Most patients see a result within 2-3 days
Normally reached max by 3-4 weeks
If no change in 2 weeks - it’s not going to work

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18
Q

When should bleaching be carried out?

A

Age related darkening/discolouration
Mild fluorosis
Post smoking cessation - don’t bleach smokers, waste of time
Tetracyclin staining

19
Q

What are the problems with bleaching?

A

Sensitivity
Wears off
Cytotoxic/mutagenicity
Gingival irritation
Tooth damage
Damage to restorations
Problems with bonding to tooth

20
Q

Describe sensitivity after bleaching

A

Found in 60% of patients
Worse initially but resolves over 2-3 days

21
Q

What are the problems with bonding with bleaching and what does this mean?

A

Residual oxygen from the peroxide remains within the enamel structure initially - this gradually dissipates over a short time
Delay any restorative procedures for at least 24 hours post bleaching - better to delay for a week

22
Q

Why should chlorine dioxide never be used for bleaching?

A

It has a pH of 3 and will soften the tooth surface
Teeth are then more prone to re-staining, develop a rough surface and become very sensitive

23
Q

What causes a tooth to need internal non-vital bleaching?

A

Dead pulp causing bleeding into dentine
The blood products darken causing grey discolouration

24
Q

What are the indications for internal non-vital bleaching?

A

Non-vital tooth with an adequate RCT and no apical pathology

25
Q

What are the contraindications to internal non-vital bleaching?

A

Heavily restored teeth - use crown or veneer
Staining due to amalgam

26
Q

What are the limitations to internal non-vital bleaching?

A

Doesn’t always work but generally worth a go

27
Q

What are the advantages of internal non-vital bleaching?

A

Easy
Conservative
Patient satisfaction

28
Q

What are the risks of internal non-vital bleaching?

A

External cervical resorption - due to diffusion of H2O2 through dentine into periodontal tissues

29
Q

Describe technique for internal non-vital bleaching

A

Record shade
Remove filling from access cavity, remove GP from pulp chamber and 1mm below ACJ
Place 1mm RMGIC over GP to seal canal
Remove any very dark dentine
Etch internal surface with 37% phosphoric acid
Place 10% carbamide peroxide gel in cavity
Cotton wool over this
Seal with GIC
Repeat procedure at weekly intervals

30
Q

How long does internal non-vital bleaching take?

A

Normally 3-4 visits
If no change after 4 visits it is not going to work and consider crown/veneer/composite build up

31
Q

How is internal non-vital bleaching maintained?

A

Once final shade obtained, place white GP in pulp chamber and restore with light shade of composite
Will gradually darken again so retreat every 4-5 years

32
Q

What is combination bleaching?

A

GP is removed and covered with RMGIC
Make bleaching tray with palatal reservoir
Bleach placed in access cavity and tray
Replaced frequently over about a week
Tricky for patient as must wear tray the whole time

33
Q

What is microabrasion?

A

Removes discolouration limited to the outer layers of enamel
A combination of erosion (acid) and abrasion (pumice)

34
Q

What are the indications for microabrasion?

A

Fluorosis
Post orthodontic demineralisation
Demineralisation with staining
Prior to veneering if dark staining is present

35
Q

Describe microabrasion technique

A

Clean teeth thoroughly
Rubber dam (seal is very important)
Mix 18% HCl and pumice
Apply to teeth
Gently rub with prophy cup for 5s per tooth
Wash
Repeat up to 10 times

36
Q

What is the alternative option for microabrasion?

A

Using 37% phosphoric acid rather than HCl
HCl removes 100 microns, phosphoric acid only removes 10
Not as effective but readily available to GDP

37
Q

What is resin infiltration?

A

Doesn’t remove the surface layer
Infiltrate the white area with resin, changing its refractive index
This masks it and makes it look like the surrounding enamel

38
Q

When is resin infiltration used?

A

For treatment of white spot lesions

39
Q

What is the maximum level of H2O2 that can be found in tooth whitening products?

A

6%

40
Q

At what age can H2O2 products be used?

A

18 and over
0.1-6%

41
Q

At what percentage of H2O2 are products available?

A

0.1% mouthrinses, toothpastes and tooth whitening products are available on the market
Tooth whitening products between 0.1 and 6% must only be obtained through a registered dentist

42
Q

How should tooth whitening treatment be supervised?

A

The first cycle of treatment must be supervised by a dental practitioner
After the first cycle, the product may be provided for use by the consumer

43
Q

How can concentrations exceeding 6% H2O2 be used?

A

Only if being used wholly for the prevention of disease

3 Operative Dentistry (9 decks)

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