Teeth Whitening

How Teeth Whitening Works

Teeth whitening can help to counteract the discoloring effect of diet and age on the teeth and ensure that they are returned to their natural white color. Teeth whiteners rely on the use of bleaching agents, usually carbamide peroxide or hydrogen peroxide. These chemicals react with the stains in the teeth in order to remove them.

A tooth consists of an inner layer of dentin covered by a white, hard layer of tooth enamel. The enamel is the part of the tooth that can be seen in the mouth. When someone eat, drinks or smokes, particles of the food, drink or smoke can accumulate on the teeth. They gradually build up into a layer of what is known as a pellicle film. Brushing the teeth, using a whitening or abrasive toothpaste or having the teeth professionally cleaned by a dentist, can help to remove the pellicle film and revel the white enamel underneath. However, this is not how teeth whiteners work.

Removing the pellicle film cannot affect the underlying color of the tooth enamel. Tooth enamel is porous, which means that it can absorb some of the chemicals which make up the pellicle layer. As these chemicals make their way down into the tooth enamel, some of them can stain it. These types of stains, which lie deep within the tooth enamel, cannot be removed by brushing or professional cleaning.

Teeth whiteners can remove stains from inside the tooth enamel. Whiteners contain bleaching agents that can penetrate into the enamel. Once there, the carbamide peroxide or hydrogen peroxide can react with the stains. This is a type of chemical reaction known as an oxidation reaction.

Whitening products vary in terms of the concentration of bleaching agents which they contain. Dentists may offer stronger concentrations of bleaching agents than are available over the counter. Dentists can use concentrations of between 15 and 35 percent, while those which are available over the counter usually contain less than 10 percent carbamide peroxide.

Dentists will clean the teeth before they begin the surgery whitening process. They will then place a barrier over the gums to protect them from contact with the bleaching agents. A solution of hydrogen peroxide is then applied to the teeth and left on for a few minutes. The solution is rinsed off the teeth. The process will usually be repeated several times. A single treatment session can have a significant effect on the color of the teeth.

If the dentist is providing a kit for use at home, they will take an impression of the teeth and use it to make a custom mouth tray. The user will insert a bleaching solution into this tray and then fit it over their teeth for a certain amount of time, or overnight. The treatment may need to be repeated a number of times before the desired effect can be achieved.

Over the counter systems can be used in a similar way, with a mouth tray or strip applicators. The concentrations of bleaching agents in these home kits tend to be lower than those offered by dentists, so the effects can be smaller or take longer to achieve.

All teeth whitening products work in the same way, however, through a chemical reaction of bleaching agents in the teeth. In some cases, a dentist may speed up this reaction using a laser, but the basic reaction is still the same.