OPTEC- Tooth whitening

Question 1

What has caused this staining?

Answer 1

Smoking

Question 2

What has caused this staining?

Answer 2

Chlorohexidine.

Question 3

What has caused this staining?

Answer 3

Iron supplements.

Question 4

WHat can cause extrinsic tooth discoloration?

Answer 4

Smoking

Tanins (e.g. coffee, tea, red wine, guiness)

Chromogenic bacteria.

chlorohexidine

Iron supplements.

Question 5

What has caused this tooth staining?

Answer 5

Fluorosis

Question 6

What has caused this tooth staining?

Answer 6

Porphyria causing red stained primary teeth

Question 7

What has caused this tooth staining?

Answer 7

These green teeth are caused by hyperbilirubinaemia .

Question 8

What has caused this tooth staining?

Answer 8

The use of tetracycline during tooth formation which has caused bands of staining on the teeth

Question 9

What can cause intrinsic tooth discoloration?

Answer 9

• Non-vitality (the dead pulp causes bleeding itno the dentine. These blood products diffuse and darken causing grey discoloration.
• Physiological- teeth get more stained with age
• Dental materials (amalgam/ root filling materials)
• Cystic fibrosis (causing grey teeth)

Question 10

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

Answer 10

Hygiene phase therapy.

Question 11

What causes the discoloration of teeth?

Answer 11

The formation of long chain organic molecules within the tooth.

Question 12

How does bleaching work?

Answer 12

Reduces the molecular size and pigmentation of the long chain molecules.

It also causes ionic exchange in the metallic molecules leading to a lighter colour.

Question 13

What is the chemical reaction that occurs in tooth whitening?

Answer 13

H₂O₂ -> hO₂ + water + O₂

This forms hydrogen peroxide (hO₂) which is the active oxidising agent that breaks down the chemicals.

Question 14

Why do we use carbamide peroxide in modern tooth whitening?

Answer 14

As it is less acidic than hyrogen peroxide and it breaks down to produce hydrogen peroxide and urea.

Question 15

What other components do we find in a tooth bleaching gel?

Answer 15

DeSensitising agents (pottasium nitrate and calcium phosphate)

Carbopol- This slows the release of oxyegn in order to thicken the gel (so the gel stays where you put it)

Surfactant (allows the gel to wet the tooth surface)

Fluoride (to prevent eroision)

Pigment dispersers

Preservatives

Flavour

Question 16

Discuss the factors that affect external bleaching?

Answer 16

Concentration- higher conc increases effect

Time- longer bleaching increases effect

Higher temperature- quicker effect

Cleanliness- the cleaner the better.

Question 17

What do you need to do before a patient has external vital bleaching?

Answer 17

Clinical check up to check they are dentally fit.

Take an initial shade and record it in the patient notes.

Warn the patient.

Question 18

What do you warn the patient of before tooth whitening?

Answer 18

Sensitivity

Relaspe

The whitening not working.

Restorations (the composite doesn’t whiten)

Compliance

Allergies.

Question 19

Compare the two types of External tooth whitening

Answer 19

In chair- The dentist whitens and washed off your teeth multiple times in the chair.

Adv- controlled by the dentist, can use heat/ light and provides quick results for the patient.

Disadv- expensive (as dentist time is required) and alot of the initial whiteness is from dehydration of the tooth. Quick results but they wear off quicker.

At home- the patient has a custom made tray to use the solution at home.

Adv- Easy for the dentist and patient.

Disadv- Down to patient compliance. THis also requires more reviews (see the patient a week later)

Question 20

What are the indications for external bleaching?

Answer 20

Mild Fluorosis

Age related darkening or discoloration

AFTER smoking cessation.

Tetracycline staining.

Question 21

Discuss sensitivity as a result of bleaching?

Answer 21

>60% of patients will get tooth sensitivity after bleaching but this should wear off in 2-3 days.

Higher concentrations and pre-existing sensitivity make it more likely.

Question 22

Discuss the tooth whitening wearing off?

Answer 22

It will eventually wear off as the oxidised chain molecules reduce with time.

Re-treatment is needed every 1-3 years.

Question 23

Discuss the problem of cytotoxicity and gingival irritation

Answer 23

This is dependent on the concentration used.

Question 24

What is the probem posed by restorations when tooth whitening.

Answer 24

Restorations do not whiten.

Therefore, we need to redo the restorations to match the whitened shade of the teeth. This also means it is vital to keep up with the tooth whitening otherwise the restorations will be too white compared to the natural teeth.

Question 25

How does tooth whitening impact restorative procedures?

Answer 25

You need to wait a week after whitening to complete restorative procedures as the leftover oxygen from carbamide peroxide makes affects bonding to the tooth.

Question 26

Why do we not use chlorine dioxide?

Answer 26

it is too acidic so causes softening and stripping of the enamel from the tooth surface. This causes a bumpy surface making staining more likely. and also makes teeth extremely sensitive.

Question 27

What do we need to use internal non-vital bleaching?

Answer 27

Non vital teeth Adequate RCT No apical pathology.

Question 28

what are the contraindications for internal non-vital bleeding?

Answer 28

Heavily restored tooth (better of with a veneer) Staining due to amalgam.

Question 29

What are the disadvantages of internal non-vital bleaching?

Answer 29

Risk of external cervical resorption because the H₂O₂ diffuses through the dentine into the PDl tissues (this is more common in teeth affected by trauma)

Question 30

How is internal bleaching completed?

Answer 30

Carbamide peroxide is placed in the cavity and sealed in for a week. Every week we add more.

Question 31

Discuss combination bleaching?

Answer 31

This is when we add bleach into to the cavity but leave the cavity open at the back. We then add carbmaide peroxide to the trays providing a palatal reservoir for the carbamide peroxide. But the patient has to wear the tray at all times.

Question 32

What is micro-abrasion?

Answer 32

This removes discoloration related to the outer layers of enamel through a combination of erosion (acid) and abrasion (pumice)

Question 33

Discuss the advantages and disadvantages of microabrasion?

Answer 33

Adv- quick/ easy and does not damage the pulp Disadv- Uses acid. causes sensitivity and only works for superficial stains.

Question 34

Why can't we reguarily repeat micro-abrasion.

Answer 34

It can lead to tooth yellowing as the dentine shows through as well as permanent sensitivity.

Question 35

What is resin infiltration?

Answer 35

The white area of the tooth is infiltrated with resin to change the refractive index of the area. This masks the white area making it look like the surrounding enamel.

Question 36

What are we looking for in a pre-whitening dental examination?

Answer 36

* Any pathology * Any diseases that make the patient unable to metabolise hydrogen peroxide. * Glucose 6-phosphate dehydrogenase deficiency * Acatalesemia

Question 37

What are the laws for tooth whitening?

Answer 37

* Products cannot be used on under 18s unless for the prevention of disease * only dentists can sell tooth whitening products. * A percentage of 0.1-6% hydrogen peroxide can be used. * The first cycle must be supervised.