Teeth whitening

Question 1

What are some extrinsic causes of tooth discolouration?

Answer 1

Smoking
Tannins - tea, coffee, red wine, Guinness
Chromogenic bacteria
Chlorhexidine
Iron supplements
Tetracycline - in medication to treat bacterial infections.

Question 2

What are some intrinsic causes of tooth discolouration?

Answer 2

Fluorosis
Tetracycline
Non-vitality (blood products)
Physiological (age changes)
Dental Materials (amalgam, root filling materials)

Question 3

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

Answer 3

Hygiene phase therapy

Question 4

What are the 2 types of tooth bleaching?

Answer 4

External vital bleaching
Internal non-vital bleaching

Question 5

What is discolouration caused by?

Answer 5

Chemically stable, chromogenic products within the tooth substance

Question 6

How does bleaching lighten pigment?

Answer 6

Bleaching oxidises the long chain organic molecules.
Oxidation leads to smaller molecules which are often not pigmented.
Oxidation can cause ionic exchange in metallic molecules leading to lighter colour.

Question 7

What is the active component in external bleaching?

Answer 7

Hydrogen peroxide (H2O2)

Question 8

What are some factors affecting bleaching?

Answer 8

Time
Cleanliness of the tooth surface (cleaner = better)
Concentration of solution
Temperature (higher - quicker effect)
Degree of discolouration

Question 9

What should a patient be warned of for external vital bleaching?

Answer 9

Sensitivity
Relapse
Restoration colour
Allergy
Might not work
Compliance with regime

Question 10

What are some problems with bleaching?

Answer 10

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

Question 11

What should never be used for tooth whitening and why?

Answer 11

Chlorine dioxide
Has a pH of around 3 - will soften tooth surface
Teeth are more prone to re-staining, develop a rough surface and become extremely sensitive.

Question 12

What are some indications for internal, non-vital bleaching?

Answer 12

Non-vital tooth
Adequate RCT
No apical pathology

Question 13

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

Answer 13

Heavily restored tooth
Staining due to amalgam

Question 14

What is a risk of internal non-vital bleaching and why does it occur?

Answer 14

External cervical resorption
Due to diffusion of H2O2 through dentine to periodontal tissues

Question 15

After how many visits with internal bleaching, if it did not work would you stop treatment?

Answer 15

If no change after 4 visits its not going to work.

Question 16

What are some indications for micro-abrasion?

Answer 16

Fluorosis
Post-orthodontic demineralisation
Demineralisation with staining
Prior to veneer if dark staining present

Question 17

How does micro-abrasion work?

Answer 17

Removes discolouration limited to the outer layers of enamel

Question 18

What are some advantages of micro-abrasion?

Answer 18

Quick
Easy
Doesn’t affect bonding to tooth
Lesser degree of sensitivity

Question 19

What are some disadvantages of micro-abrasion?

Answer 19

Sensitivity
Only works for superficial staining
Works much better for brown staining than white marks

Question 20

What is the maximum legal % of hydrogen peroxide any tooth whitening product can contain?

Answer 20

It’s illegal for any tooth whitening product to contain more then 6% Hydrogen peroxide or any products that release greater then 6% hydrogen peroxide to be supplied for cosmetic purposes.

Question 21

What is the max % of hydrogen peroxide in a tooth whitening product that is available over the counter?

Answer 21

0.1%
Between 0.1 and 6% has to be prescribed by a dentist or HC professional

Question 22

What would happen if a dentist was found to be supplying bleaching products greater than 6%?

Answer 22

Will be prosecuted by trading standards and face fitness to practice proceedings.
ILLEGAL