Want a Whiter Smile? What You Need to Know

According to the Academy of General Dentistry, tooth whitening is a $600 million industry that is growing by 15 to 20 percent each year and showing no signs of slowing down. In addition to the whitening procedures performed under the supervision of a dentist, drugstore and supermarket aisles overflow with whitening remedies.

Whitening products fall into two main categories: those that contain peroxide, which actually changes the natural color of the tooth, and others, such as whitening toothpastes, that remove surface stains using polishing or chemical agents and mild abrasives. Because whitening toothpastes don’t change the color of teeth, their effects are more subtle than bleaches. This article focuses on products containing peroxide.

Bleaching, or whitening of the teeth using peroxides, is available both through your dentist and in several types of over-the-counter products. The American Dental Association recommends you consult with your dentist before using a bleaching product, even an over-the-counter one. That’s because bleaching can be uncomfortable for people with sensitive teeth or an exposed root. Also, because most products only bleach natural teeth, if you have tooth-colored fillings, crowns, veneers, or dentures, bleaching may leave some areas whiter than others. In addition, for example, your natural teeth may appear whiter than areas where work has been done. Your dentist can also evaluate whether bleaching is right for your teeth, since different kinds of discoloration respond differently to whitening.

Most bleaching is not permanent, so keeping your teeth pearly white means repeating the bleaching process regularly. How long a bleaching treatment lasts depends upon which method you choose and on how well you take care of your teeth, whether you smoke, and what you eat and drink.

Dentist-Supervised Bleaching

Your dentist can perform a bleaching process in the office or prescribe a procedure for you to do at home.

Chair-side bleaching. Your dentist begins a whitening treatment by applying a protective gel or rubber shield to your gums to protect them from the bleaching agent. Your dentist etches your teeth with an acid solution and then applies an oxidizing agent to the enamel. Your teeth are exposed to a bright light or a laser to hasten the lightening.

It usually takes three to four sessions, each lasting about 30–60 minutes, to achieve the color you want. Chair-side bleaching can offer more uniform results than at-home bleaching methods. A newer technique, called power bleaching, uses a highly concentrated form of hydrogen peroxide as the lightening agent. It can deliver results in just one session. Your teeth will darken again within one to three years, and you may need to repeat the procedure. Costs vary, with some dentists charging between $100 and $250 a session and others charging a single fee of $250 to $400 per arch (upper or lower teeth).

Bleaching pulp-damaged teeth. When the pulp is dead or injured, a tooth will darken. To correct this problem, your dentist can rinse the pulp chamber with a bleaching agent while performing root canal therapy. If the stain persists or the tooth darkens after the root canal procedure is completed, your dentist can reopen the pulp chamber and fill it with bleach for several minutes under a heat light. This process may have to be repeated several times. Alternately, the dentist can fill the pulp chamber with bleaching solution and cover it with a temporary filling. In this case, you’ll need to return after a few days to have the bleach removed and the tooth permanently sealed. Costs vary; some practices charge between $300 and $600 per tooth.

Home bleaching (dentist-prescribed). To enable you to do the bleaching at home, your dentist makes a custom-fitted mouthpiece to hold the bleaching chemicals (carbamide peroxide or hydrogen peroxide). Then you spread the chemicals into the mouthpiece and put it on for the recommended period (between 30 minutes and several hours) each day for a week or two. Some users report tooth sensitivity during the treatment, but it usually subsides once the treatment is complete. This procedure generally costs between $250 and $400 per arch (upper or lower).

Over-the-Counter Bleaching Kits

All of the following products contain some kind of peroxide as their active ingredient and, therefore, actually change the natural color of the teeth. The bleaching agents in these products usually aren’t as strong as the chemicals found in the products administered by a dentist. However, the cost is substantially lower.

Whitening strips. Whitening strips are thin, flexible pieces of plastic applied directly onto the teeth. After the specified amount of time, usually 30 minutes either once or twice a day, the strips are peeled off the teeth. This process is repeated for between five and 14 days. In general, the strips designed for use over a shorter number of days contain a higher concentration of the peroxide ingredient than those intended to be worn over a longer number of days.

Gels. The main difference among the gels is how they are applied to the teeth. Some are applied with a small paintbrush, while others come in a pen-like applicator. Generally, the gel is applied before you go to bed and left on, and is used for about two weeks.

Combination gel and light. One whitening system, called Luster 1 Hour White, involves using a mouth rinse and applying a whitening gel to the teeth you want to whiten. Then you hold a special light up to your teeth for two minutes to boost the whitening effects of the rinse and gel.

Whitening rinses. A whitening rinse from Listerine promises whiter teeth in 12 weeks. Simply rinse with the product for 60 seconds twice a day before brushing.

Which Method Is Right for You?

Unfortunately, there is no simple answer. It isn’t clear which bleaching method is the most effective. An analysis of studies that compared at-home whitening products (dentist-dispensed and over-the-counter) with placebos and with each other found that whitening products are effective. The analysis, conducted by the independent Cochrane Collaborations, found differences among the products, primarily because of varying levels of the active ingredients. But the researchers didn’t recommend one product over another, because they found that most of the existing studies on whiteners were sponsored or conducted by the makers of whitening products and thus were not very reliable. The researchers concluded that more independent studies are needed. They also suggested that consumers be made more aware of side effects such as tooth sensitivity and gum irritation.

One advantage of over-the-counter bleaching methods is that they cost far less than techniques offered by dentists. On the other hand, as of May 2009, none of the over-the-counter bleaching products carries the ADA Seal of Acceptance, while several bleaches used or dispensed by dentists do carry the seal.

Some Internet companies sell materials to make a bleaching tray for use at home. However, according to the Academy of General Dentistry, trays can cause gagging, gum irritation, or damage to existing dental work if not properly fitted and supervised by a dentist.

There is not yet enough information to determine the long-term safety of whitening products. Therefore, they are not recommended for children younger than age 16, women who are pregnant or breast-feeding, people with sensitive teeth or an allergy to peroxide, or those with gum disease or worn tooth enamel.

Source: Dental Health for Adults: A Guide to Protecting Your Teeth and Gums. Copyright © by Harvard University. All rights reserved.