‘the act or process of making or becoming white’

teeth whitening involves bleaching your teeth to make them lighter.

the chemical degradation of the chromogens within or on the tooth is termed as bleaching. 

it can’t make your teeth brilliant white, but it is a very effective way of lightening the existing colour by several shades without removing any of the tooth surface.

once the teeth are whitened, it is common to notice a facial radiance similar to having a suntan. 

this in turn creates a huge ‘feel good’ factor and boosts confidence. 

types of stain.

broadly there are two types of staining

extrinsic staining due to things like tea, coffee, red wine and smoking 

intrinsic staining caused by genetic conditions, certain antibiotics or hairline c

racks in the teeth that take up stain.

how does it work? – the science!

hydrogen peroxide is the active ingredient most commonly used in whitening products and is delivered as either hydrogen peroxide or carbamide peroxide. 

hydrogen peroxide is comparable to carbamide peroxide as it is released when the stable complex is in contact with water. 

as it diffuses into the tooth, it acts as an oxidising agent that breaks down to produce unstable free radicals. 

in the spaces between the inorganic salts in tooth enamel, these unstable free radicals attach to organic pigment molecules resulting in small, less heavily pigmented components. 

these smaller molecules reflect less light and hence create a “whitening effect”.

time exposure and the concentration of the bleaching compound, determines the tooth whitening endpoint.

types of whitening treatments

custom made home bleaching trays.

impressions are taken of the upper and lower teeth.

custom trays are then made allowing for placement of gel within.

carbide peroxide gel is placed in the trays and inserted into the mouth and worn overnight.

the gel is most active for the first 2 hours. the efficiency then decreases by around 50%.

a shade difference is usually seen after 3 nights of wearing the trays.

fantastic because it is 

controllable (keep going until you’re happy with the result), 

reusable (keep the trays safe and reuse them in a year or two) 

and generally cheaper.

in surgery – laser/power whitening.

bleaching procedures generally use a light-cured protective layer that is carefully painted on the gums and papilla (the tips of the gums between the teeth) to reduce the risk of chemical burns to the soft tissues. 

the bleaching agent is either carbamide peroxide, which breaks down in the mouth to form hydrogen peroxide, or hydrogen peroxide itself. 

the gel typically contains between 10% and 44% carbamide peroxide, which is roughly equivalent to a 3% to 16% hydrogen peroxide concentration. 

power or light-accelerated bleaching uses light energy which is intended to accelerate the process of bleaching. 

different types of energy can be used in this procedure, with the most common being halogen, led, or plasma arc. 

internal bleaching

often sought after in teeth which have been endodontically treated as tooth discolouration becomes a problem due to the lack of nerve supply.

a way around this is by sealing off the bleaching agent inside the tooth itself and replacing it every few weeks until the desired shade has been achieved.

it is common to have this done on a front tooth for aesthetic reasons.

over the counter

there are many ‘home’ whitening tools on the market. from toothpaste, rinses and strips to entire kits. 

it is big business. 

however, to be deemed safe for home use, the quantity of active ingredient is small, therefore the effect will usually be very, very gradual sometimes taking years.

it is worth noting:

the legal percentage of hydrogen peroxide allowed to be given is 0.1–6%. 

bleaching agents are only allowed to be given by dental practitioners, dental therapists, and dental hygienists.

bleaching is most effective with yellow discoloured teeth. 

it is least effective when the original tooth colour is greyish. 

if heavy staining or tetracycline damage is present on a patient’s teeth, and whitening is ineffective (tetracycline staining may require prolonged bleaching, as it takes longer for the bleach to reach the dentine layer), there are other methods of masking the stain. 

eg. bonding/veneers