First the dentist will put a rubber shield or a gel on your gums to protect the soft tissue. They will then apply the whitening product to your teeth, using a specially made tray which fits into your mouth like a gum-shield.

Teeth can become discoloured over a period of time. Discolouration can be caused by several factors including ageing, smoking, consumption of staining foods and beverages, staining caused by medication and hereditary factors. Professional teeth whitening refers to a technique where a whitener is applied to your teeth by your dentist in their dental office. In contrast, at-home teeth whitening is a process where the dental patient takes the bleaching materials home with them and performs their bleaching treatments on their own, unsupervised.

Research has shown that teeth whitening is perfectly safe for teeth and gums. This is because the teeth whitening procedures we use do not change the structure of the teeth; only the colour of teeth is affected. Side effects of tooth bleaching include: chemical burns, sensitive teeth, and overbleaching. Rebound, or teeth losing the bleached effect and darkening, is also an issue, with some studies showing the rebound effect over 30 days.

Using a laser with a whitening gel, this is an in-office bleaching system. The translucent bleaching gel is applied to the teeth and a laser light is used to activate the crystals to absorb the energy from the light and penetrate the teeth enamel to increase the lightening effect on the teeth. The length of time in the cosmetic dentist's chair depends on the degree of discoloration you have.

For whitening at home, your dentist can make trays to hold the whitening gel that fit your teeth precisely. Home whitening usually takes two to three weeks. Over-the-counter kits also are widely available for home use. Talk to your dentist if you want to use these home products. Be sure to use them according to directions to avoid overuse and possible damage to your teeth and mouth.

On average, teeth whitening may cost approximately $450-$500 with the results lasting for several months or more, depending on how well you do maintaining your whiter smile. On the low end, whitening strips start at about $25 in the drug store. In-office whitening procedures can cost anywhere from $400 to $900, depending on the product, the provider and the location where the procedure is performed.

Tooth whitening is the most common cosmetic service provided by dentists, and there are also a growing number of over-the-counter tooth whitening products to choose from.