Just like skin and hair colour, tooth colour varies from person to person. Teeth can change colour for many reasons. Tooth whitening can also lighten the natural shade of your teeth. Only natural teeth will be whitened, not caps, crowns, veneers, fillings, or dentures. Results are not permanent, but last about six months.

Causes of tooth discolouration

Both external and internal causes can affect the colour of teeth. External stains can appear on the outside of the tooth after drinking tea, coffee, red wine and other richly coloured food or drink. Smoking is another major cause.

Internal stains develop on the inside of teeth. The antibiotic tetracycline, often used for young children, can cause problems. So can too much fluoride during childhood. If these are used while adult teeth are still forming, they can cause permanent internal stains. (For more information, see fluoride.)

As we age, our teeth may naturally darken. Cavities, fillings and tartar build-up also contribute to discolouration.

How are teeth whitened?

The bleaching process is simple, using a form of peroxide to bleach the teeth. As the peroxide breaks down, oxygen enters the enamel and bleaches coloured substances. This lightens the natural colour of the teeth without removing any of the tooth surface.

Formulations differ depending on the way the product is applied. It can be painted on, applied as a strip, or put in a tray that fits around the teeth. Some products are worn for 30 minutes twice a day, while others are worn all night. No freezing or numbing of the teeth is required.

A number of different products are available to bleach teeth. Some can be bought over the counter and applied at home. Others require a visit to the dentist.

Whitening toothpastes – These toothpastes use mildly abrasive chemicals to remove surface stains. Some have polishing agents that make teeth cleaner, and so, whiter. They do not contain bleach. Toothpastes may help, but cannot whiten your teeth as much as other methods.

Whitening strips – Whitening strips were developed to replace trays and bleaching solution. They are more comfortable than a tray. Strips are like a sticky tape that you apply to your teeth. Typically, they are worn twice a day for half an hour each time, but this varies depending on each product. They are inexpensive, convenient, and easy to use.

Home whitening gel kits – These kits can be purchased over the counter at a local store or pharmacy. Squeeze the concentrated peroxide gel into mouth trays, place them on your teeth, and leave them for the time specified.

Look for a kit with a tray that will form to your teeth. Use care, since a tray that doesn’t fit well may allow solution to touch and irritate the gums. It is also awkward and frustrating to bite into a tray that doesn’t fit well. Follow product instructions carefully and pay attention to any cautions. Do not use these products for more than 14 days without supervision by your dentist or hygienist.

If you have sensitive teeth, dental problems, or had dental work done recently, talk to your dentist or hygienist before starting a whitening system. Those who are pregnant or have gum disease should not use tooth whiteners.

Tooth sensitivity is a common side effect. If sensitivity develops, try one of the following measures:

Use the whitening system for only half the recommended time. For Instance, wear the tray for 15 rather than 30 minutes.
Stop using the whitening system for two or three days, then begin again.
Stop using it altogether and call your dentist or hygienist.

If you have any kind of reaction, stop using the product.

Professional tooth whitening – Your dentist or hygienist has several options available to whiten your teeth. The most common method is similar to mouth tray gel kits you can buy. Two main differences exist. First, your dentist makes the rubber mouth trays so that they fit your teeth perfectly. As well, since the bleaching gel your dentist uses is much stronger, it tends to be more effective.

Your dentist or hygienist will give you tubes of bleaching gel along with instructions on how to use it. The length of time you need to wear the trays varies depending on the product. It may take a few weeks to achieve the colour that you want. Your hygienist or dentist will supervise you through this transition.

Your dentist can use another method of professional tooth whitening, known as ‘laser’ or ‘power’ bleaching. Your dentist will put a rubber seal or ‘dam’ around your teeth to protect your gums. The gel is painted onto your teeth, then a special bright light pointed at them. The light speeds up the whitening process, which on average takes an hour or two.

How long will the effects last?

The results of different bleaching methods can last anywhere from a few months to years. This varies from person to person and depends on many factors. What you eat and drink, whether you smoke, and your brushing habits can all affect how long whitening lasts.

Bear in mind that bleaching does not always result in the whiteness you expected. Again, results vary and depend on the health and shade of your teeth. It is important to discuss all of your options with your hygienist or dentist before making any decisions.

Will whitening damage my teeth? Are there side effects?

No evidence suggests that whitening is harmful to gums. However, we don’t yet know whether it has long-term effects on nerve and blood vessels inside the teeth.

Potential side effects include tooth sensitivity to hot and cold, a sore throat, and tender gums. These side effects are more likely immediately after laser bleaching. Most sensitivity disappears after a few days. Contact your dental hygienist or dentist if symptoms persist.

For additional information
on this topic:

Canadian DentalAssociation
www.cda-adc.ca/en/oral_health/index.asp

American DentalAssociation
www.ada.org/public/topics/whitening.asp

Health Canada
www.hc-sc.gc.ca

Who should avoid whitening?

In certain cases, your hygienist or dentist may recommend against whitening.

Cavities or gum disease should be treated before whitening is done.
If your teeth are sensitive to hot and cold, whitening could make the condition worse.
Some stains do not respond to whitening as well as others. Whitening may take longer on various internal stains, like tetracycline staining.
Whitening will not work on false teeth, crowns, veneers or fillings (both amalgam and composite). Your dentist can replace many of these to match the colour of your own tooth enamel after you are done whitening.
Whitening is not recommended for children whose teeth are still developing or for pregnant or breastfeeding women.

Your smile affects how you feel about yourself. If you would like to improve the colour of your teeth, whitening may be a great option.

A Bright White Smile Bleaching may be the answer

Tooth whitening or bleaching offers a painless, simple way to make teeth look whiter and brighter. If you are unhappy with the colour of your teeth, you might consider bleaching.