Whitening

The outer layer of a tooth is called the enamel. Every day, a thin coating forms on the enamel and picks up stains. Tooth enamel also contains pores that can hold stains. Whitening is not a one-time solution. It will need to be repeated from time to time if you want to maintain the brighter color.

The most common reasons for teeth to get yellow or stained are aging, tobacco, tea and coffee. All of these can stain the surface of the teeth.

It is also possible to have stains that are inside the tooth. These are called intrinsic stains. For example, intrinsic stains can be caused by exposure to too much fluoride as a child while teeth are developing. Other causes include tetracycline antibiotics. They can stain a child's teeth if taken by a mother during the second half of pregnancy or by a child who is 8 years old or younger. Teeth are still developing during these years.

Tooth whitening is most effective on surface stains caused by age, foods or drinks.

Cavities need to be treated before teeth are whitened. That's because the whitening solution can pass through decayed areas and reach inner parts of the tooth. If this happens, your teeth could become sensitive. Whitening also will not work on exposed tooth roots, which do not have an enamel layer. Receding gums can cause roots to become exposed. Whitening also does not work on crowns or veneers.

Whitening can be done in the dental office or at home. For in-office whitening, your dentist probably will photograph your teeth first. This step will help him or her to monitor the progress of the treatment. Your dentist also will examine your teeth and ask you questions to find out what type of staining you have and how severe it is.

Whitening in the office may involve two to six visits. Each one is likely to be about 45 minutes long.

When the examination is complete, the dentist or a dental hygienist will clean your teeth. Once this is done, the whitening procedure begins.

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.

There are two main types of whitening procedures. Non-vital whitening is done on a tooth that has had root-canal treatment and no longer has a live nerve. Vital whitening is performed on teeth that have live nerves.

Vital whitening may not improve the appearance of a tooth that has had root-canal treatment. If this is the case, your dentist will use a different procedure that whitens the tooth from the inside. He or she will place a whitening agent inside the tooth and put a temporary filling over it. The tooth will be left this way for several days. You may need this done only once, or it can be repeated until the tooth reaches the desired shade.

The most common type of vital tooth whitening uses a gel-like whitening solution. This product usually contains hydrogen peroxide. You will place the whitening gel in a tray that resembles a night guard or mouth guard. Then you place the tray over your teeth for a certain period of time — anywhere from an hour or two to overnight.

Tooth whitening can be done in the dentist's office or at home. In-office (chairside) whitening allows your dentist to supervise the process — and your progress — more closely.

In-office whitening usually takes 30 to 90 minutes. You will need at least two or three appointments with your dentist. The number of visits required will depend on the type of discoloration and how white you want your teeth to be.

Your dentist will start by asking about your medical history to learn how your teeth became discolored. Different types of stains will respond differently to the treatment.

Your dentist will apply a special protective gel, then the whitening agent. The most common substance used for in-office whitening is hydrogen peroxide.

Some whitening agents are activated by special lights or by heat. After the whitening agent is applied, the dentist will shine the light on your teeth for a short time. Some dentists have started to use lasers instead of a light or heat. Consumers like the high-tech aspects of laser treatments, but the technology is still too new — and too expensive — to justify its general use. The American Dental Association states that while the technique may be safe, there are no published data on the safety or effectiveness of using lasers for tooth whitening.

If your teeth are badly discolored, you may need more extensive whitening than can be done in the office. Or you may decide you would prefer to whiten your teeth at home.

For in-home whitening, your dentist will take impressions of your teeth and will make one or two custom mouthpieces to fit you. The number will depend on whether you are having both upper and lower teeth whitened. It is important that the mouthpiece fit well. A close fit helps the whitening agent to remain in contact with your teeth instead of irritating your gums. Over-the-counter mouthpieces are unlikely to fit correctly. They can cause gum irritation if the whitening agent seeps out.

At home, you will fill each mouthpiece with a whitening gel your dentist provides. You will wear the mouthpiece for several hours every day. Many people achieve the amount of whitening they want within a week or two. However, you may need to wear the mouthpiece for four weeks or longer.

Your dentist may want to see you a few days after in-office whitening to check your gums. If your gums were exposed to the whitening agent, they can become irritated. If you are whitening your teeth at home, your dentist will want to make sure the process is working properly, usually after a week.

Whitening is not a permanent solution. The stains will come back. If you smoke or consume a lot of staining foods or drinks, you may see the whiteness start to fade in as little as one month. If you avoid these sources of staining, you may not need another whitening treatment for six to 12 months.

Re-whitening can be done in the dentist's office or at home. If you have a custom-made mouthpiece and whitening agent at home, you can whiten your teeth as frequently as you want to. You should discuss your whitening schedule with your dentist. You can talk about what whitening products would work best for you.

Whitening is unlikely to cause serious side effects, although some people's teeth may become more sensitive for a short while. You may get mild gum irritation as well. Whitening procedures should not be done while a woman is pregnant. The effect of the whitening materials on the development of the fetus is not known. Since the procedure is cosmetic, it should be postponed until after delivery.