How it works: All toothpastes, whitening or not, contain detergents and mild abrasives that prevent plaque buildup and subsequent yellowing. But whitening pastes have an extra ingredient: a polishing agent called silica, which removes surface stains from the enamel (the outermost layer of the teeth).
The whitening effect: One to two shades, when used twice daily for a month. Lasts only as long as it is used.
Good to know: Look for the American Dental Association (ADA) Seal of Acceptance on the tube. With long-term use, products not approved by the ADA could wear down enamel, revealing a dark, unflattering layer of dentin below.
Average cost: $3 to $10 a tube. (Shown: Colgate Total Advanced Whitening toothpaste, $3.80 at drugstores.)
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How they work: Each band is coated with a hydrogen peroxide gel solution (about a 10 percent concentration) that penetrates the enamel to bleach deep stains.
The whitening effect: Two to four shades, when used once daily for two weeks. Lasts 6 to 12 months.
Good to know: Available in only one size, the strips may not fully cover longer-than-average teeth or a wide smile. The gel also has a tendency to leak onto gums. “In people prone to sensitivity, that can lead to further irritation,” says Emanuel Layliev, a cosmetic dentist and the director of the New York Center for Cosmetic Dentistry, in New York City.
Average cost: $55 for 20 strips. (Shown: Crest 3D White Luxe Whitestrips Professional Effects, $50 for 20, 3dwhite.com.)
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How they work: The most precise and thorough over-the-counter option, each ampoule (tube) is filled with a 6.5 percent–concentration hydrogen peroxide gel solution. Squeeze the gel onto the attached brush, then paint it on your teeth.
The whitening effect: Up to five shades, when used twice daily for one to two weeks. Lasts 6 to 12 months.
Good to know: To keep the gel in place and to ensure that it reaches the enamel, not just the plaque on top, blot your teeth with a tissue before you apply.
Average cost: $45 to $144 a kit. (Shown: GLO Science GLO Solo Teeth Whitening, $45 for a two-week supply, sephora.com.)
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How they work: In a half-hour appointment, a dentist takes impressions of your top and bottom teeth, then creates soft plastic molds for you to wear at home. He’ll also prescribe a hydrogen peroxide gel (containing up to a 22.5 percent concentration) to squeeze into the trays before use.
The whitening effect: Five to eight shades, when used for 30 minutes twice a day for two weeks. Lasts 6 to 12 months.
Good to know: Prescription hydrogen peroxide can cause tooth sensitivity in some people. To minimize the chances, brush with a desensitizing paste. (Try Sensodyne toothpaste; $6 at drugstores.) And rinse with a nonalcoholic mouthwash that has a high fluoride content. (Try ACT Total Care Sensitive Formula mouthwash; $5 at drugstores.)
Average cost: $250 to $500 for a set of trays; $25 to $50 for the whitening solution.
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How they work: A dentist coats teeth with a hydrogen peroxide solution, then shines a blue light to speed whitening. “You can buy at-home versions of these lights, but they often cost as much as a professional treatment and won’t work as well,” says Bill Dorfman, a cosmetic dentist and the author of Billion Dollar Smile.
The whitening effect: Five to eight shades. Lasts 6 to 12 months.
Good to know: Take an anti-inflammatory (such as Advil) an hour before treatment to prevent discomfort. In the 48 hours following a treatment, the enamel is highly susceptible to staining. Temporarily avoid dark foods and drinks, like coffee, berries, and red wine.
Average cost: $200 to $800 a treatment. (Shown: Philips Zoom WhiteSpeed lamp, which takes less than an hour.)
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How they work: After removing a thin layer of enamel, the dentist glues on slim porcelain strips. (A week before, he’ll apply temporary veneers so you can see how real ones will look and feel.) Because of the price, these are suggested only for those with severe discoloration or money to burn.
The whitening effect: Whatever shade you desire; choose from about a dozen options. Lasts 20 to 25 years.
Good to know: If you can’t afford a full set of veneers, ask your dentist about a “mixed media” treatment, a combination of veneers and more traditional tooth whitening.