OPTEC- Tooth whitening Flashcards
What has caused this staining?
Smoking
What has caused this staining?
Chlorohexidine.
What has caused this staining?
Iron supplements.
WHat can cause extrinsic tooth discoloration?
Smoking
Tanins (e.g. coffee, tea, red wine, guiness)
Chromogenic bacteria.
chlorohexidine
Iron supplements.
What has caused this tooth staining?
Fluorosis
What has caused this tooth staining?
Porphyria causing red stained primary teeth
What has caused this tooth staining?
These green teeth are caused by hyperbilirubinaemia .
What has caused this tooth staining?
The use of tetracycline during tooth formation which has caused bands of staining on the teeth
What can cause intrinsic tooth discoloration?
- 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)
What is the first method of tooth whitening for extrinsic staining?
Hygiene phase therapy.
What causes the discoloration of teeth?
The formation of long chain organic molecules within the tooth.
How does bleaching work?
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.
What is the chemical reaction that occurs in tooth whitening?
H2O2 -> hO2 + water + O2
This forms hydrogen peroxide (hO2) which is the active oxidising agent that breaks down the chemicals.
Why do we use carbamide peroxide in modern tooth whitening?
As it is less acidic than hyrogen peroxide and it breaks down to produce hydrogen peroxide and urea.
What other components do we find in a tooth bleaching gel?
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
Discuss the factors that affect external bleaching?
Concentration- higher conc increases effect
Time- longer bleaching increases effect
Higher temperature- quicker effect
Cleanliness- the cleaner the better.
What do you need to do before a patient has external vital bleaching?
Clinical check up to check they are dentally fit.
Take an initial shade and record it in the patient notes.
Warn the patient.
What do you warn the patient of before tooth whitening?
Sensitivity
Relaspe
The whitening not working.
Restorations (the composite doesn’t whiten)
Compliance
Allergies.
Compare the two types of External tooth whitening
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)
What are the indications for external bleaching?
Mild Fluorosis
Age related darkening or discoloration
AFTER smoking cessation.
Tetracycline staining.
Discuss sensitivity as a result of bleaching?
>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.
Discuss the tooth whitening wearing off?
It will eventually wear off as the oxidised chain molecules reduce with time.
Re-treatment is needed every 1-3 years.
Discuss the problem of cytotoxicity and gingival irritation
This is dependent on the concentration used.
What is the probem posed by restorations when tooth whitening.
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.
How does tooth whitening impact restorative procedures?
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.
Why do we not use chlorine dioxide?
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.
What do we need to use internal non-vital bleaching?
Non vital teeth
Adequate RCT
No apical pathology.
what are the contraindications for internal non-vital bleeding?
Heavily restored tooth (better of with a veneer)
Staining due to amalgam.
What are the disadvantages of internal non-vital bleaching?
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)
How is internal bleaching completed?
Carbamide peroxide is placed in the cavity and sealed in for a week. Every week we add more.
Discuss combination bleaching?
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.
What is micro-abrasion?
This removes discoloration related to the outer layers of enamel through a combination of erosion (acid) and abrasion (pumice)
Discuss the advantages and disadvantages of microabrasion?
Adv- quick/ easy and does not damage the pulp
Disadv- Uses acid. causes sensitivity and only works for superficial stains.
Why can’t we reguarily repeat micro-abrasion.
It can lead to tooth yellowing as the dentine shows through as well as permanent sensitivity.
What is resin infiltration?
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.
What are we looking for in a pre-whitening dental examination?
- Any pathology
- Any diseases that make the patient unable to metabolise hydrogen peroxide.
- Glucose 6-phosphate dehydrogenase deficiency
- Acatalesemia
What are the laws for tooth whitening?
- 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.
