Teeth Whitening

What makes teeth turn yellow?

If coffee doesn't get to them, age will. Dark pigments in foods, beverages, and cigarette smoke can bind to your enamel, staining the surface of your teeth. If you're concerned, you might try using a straw when you drink dark-colored juice or cola to minimize its contact with your teeth. Tannic acid, the bitter compound in coffee, tea, and wine, can also cause yellow or brown stains when it combines with other particles on your teeth. Dairy products and saliva help neutralize this acid, so add a splash of milk to your coffee and stimulate saliva production by chewing sugarless gum.

No matter what you do, though, your teeth will likely yellow as you age. Deep grayish blue discoloration in the dentin (the material beneath the enamel) is usually hereditary, but teeth may also turn gray if they break or are knocked so hard that the roots die or if they were exposed frequently to the antibiotic tetracycline while they were still developing.

How can I make my teeth whiter?

Most teeth-whitening products and treatments rely on the bleaching agent hydrogen peroxide. This compound breaks down into highly active oxygen molecules called free radicals, which penetrate your enamel and dentin and unlock the pigments from both. (These molecules can make your cells more vulnerable to damage from carcinogens in certain foods or in cigarette smoke. In fact, you shouldn't use peroxide at all if you smoke.) Yellow and brown stains respond best; gray and blue teeth are more stubborn. Crowns and other dental work can't be bleached, so if you have capped teeth, think about whether you'd be willing to replace them to match your new pearly whites. Check out the following bleaching products and procedures, some of which are approved by the American Dental Association (ADA):

Whitening Toothpastes

Brushing with these toothpastes is only slightly more effective on superficial stains than using regular toothpaste or chewing sugarless gum. However, if you've already bleached your teeth, using a whitening toothpaste may keep them white longer. These products generally contain a very low concentration of peroxide (less than 1 percent); some have baking soda, too. The combination may leave your mouth feeling squeaky clean, but the bleach is too weak to lighten teeth much, especially since it is on them only for as long as it takes to brush. If you're going to try a whitening toothpaste, some dentists recommend alternating it with a regular one to cut down on your exposure to free radicals from the peroxide. Whitening toothpastes cost about the same as regular brands, around $2 or $3 per tube.

Bleaching Toothpastes

A few "bleaching" toothpastes contain up to 10 percent peroxide. These pastes are meant to be brushed in and then left on your teeth for five minutes, twice a day. But much of the bleach gets washed away by saliva, so they're probably not much more effective than less concentrated products. Check their labeling to see if they have the American Dental Association's Seal of Acceptance. They cost about $10 a tube. If your teeth start to feel sensitive after using a bleaching toothpaste, stop using it and see your dentist to make sure you haven't damaged your enamel.

Drugstore Bleaching Kits

These kits generally work for moderately stained teeth. You squirt a bit of 10 to 16 percent peroxide gel into a mouth tray (called a night guard) that you wear over your upper and lower teeth for a few hours a day. Most people see a difference after two weeks of treatment, and the effect can last as long as three years. But be warned that the ADA has only approved the Aura Glow pen or kit (which uses carbamide peroxide, the same ingredient used by many dentists), and the gel may erode your enamel and dental work or nauseate you if you swallow too much of it. Also, your teeth may be especially sensitive to temperature for a few weeks afterward. Using a home bleaching kit for more than three weeks can damage your teeth. They're not recommended for pregnant women. You can find the kits at drugstores for $10 to $15. A newer line of teeth whitening kits use a narrow peroxide tape that adheres to your teeth. Costs are $35 to $40 a kit.

Prescription Bleaching Kits

Your dentist can provide a safer version of what's in the drugstore. You'll get a more comfortable, custom-made mouth tray and a more viscous gel that you're less likely to swallow. It's also a good idea to get your kit through the dentist because he or she can check after a week or so to make sure the peroxide isn't damaging your dental work. You still may experience some sensitivity to heat and cold during the weeks you're using the trays, but your dentist can give you a fluoride gel to apply in between peroxide treatments. Expect to pay $400 to $500 for the initial visit, the kit, the fluoride, and any follow-up visits.

Power Bleaching

This treatment is a good option if your teeth are moderately to heavily stained. Your dentist applies a 35 percent peroxide gel to your teeth and then shines a strong light on them for up to two hours to accelerate the bleaching process. (Heat will do the same thing, but it tends to be quite uncomfortable, so most dentists don't use it.) The dentist will also position a rubber dam in your mouth to protect your gums and lips from the concentrated solution. Depending on how well you tolerate the treatment, you may choose to have it completed in one long session or a few shorter visits spaced out over weeks. The results should last about three years. Power bleaching can irritate the tissue at the centers of your teeth, though, and make them very sensitive, especially if your enamel or dentin has cracks, or if your gums have receded, exposing the roots. The treatment costs about $1,000.

Laser Whitening

This procedure is similar to power bleaching. The dentist uses the same peroxide solution, but the bleaching is accelerated with an argon laser rather than a simple light or heat source. The bleach is applied, exposed to the laser, and washed off several times over the course of the visit, which may last three hours. Argon laser bleaching is effective for dark stains as well as deep gray or blue discoloration, but it's even more likely to leave your teeth extremely sensitive than power bleaching or night guard kits. The cost is around $1,500. Avoid carbon dioxide laser treatments; the ADA cautions that they can damage your teeth.

What options do I have if bleaching doesn't work?

Bonding

If your teeth don't respond well to bleach or if your enamel is seriously damaged, you can try bonding. The dentist coats each tooth with a thin layer of resin that gets its natural-looking brightness from finely ground quartz. Sometimes the resin is removed, baked, and cemented back onto the tooth. Bonding can last eight years, but resin is prone to chipping and will stain just as normal teeth do. The procedure usually calls for only one office visit.

Veneers

Porcelain veneers are another option for badly stained or chipped teeth. Your dentist etches each tooth's surface and then glues on a thin piece of porcelain. You get to choose the exact shade of white you want.

Microabrasion

The dentist grinds a thin layer off the surface of your teeth. This method works best for enamel defects like white or brown spots from fluorosis (a harmless condition that results from swallowing too much fluoride while your teeth are still developing). The surface spots are removed, revealing a smooth layer of enamel.

References

ADA Council on Scientific Affairs: ADA Statement on the Safety of Hydrogen-Peroxide-Containing Dental Products Intended for Home Use. American Dental Association

American Dental Association. Tooth Whitening Treatments.