Hair gets whiter as you climb in years, but your teeth don't. With age, the outermost layer of tooth enamel thins and exposes the inner dentin, which has a yellowish hue, says Apa. This is unavoidable, but smoking and consuming food or drink that would stain your clothes will contribute to discolored teeth, especially if you don't brush immediately afterward, says Timothy Chase, D.M.D., a New York City cosmetic dentist.
Gray teeth are a different beast. "This is caused by the antibiotic tetracycline, which is used to treat bacterial and respiratory infections and acne. It increases calcium levels in your enamel, making it seem darker," says Apa. If you took this drug when your adult teeth were developing, they probably started to look gray when you were a teen and will continue to gray with age. (The antibiotic is no longer given to children under the age of 8 or to pregnant women, as it can affect the baby's teeth later in life.)
For mild yellowing, Chase recommends Crest 3D White Professional Effects Whitestrips ($50, at drugstores); it contains a higher percentage of hydrogen peroxide than other brands and can give you the sparkling results you'd get from a dentist. To prevent "zingers" (brief shooting pains), throbbing, and soreness afterward, pop two pain relievers a few minutes before applying the strips, says Glosman. Steer clear of strips that claim to whiten in 30 minutes or less (they contain more sensitizing peroxide) and don't whiten more than twice a year, as overdoing it can make teeth look weirdly translucent. Maintain results by brushing with a whitening fluoride toothpaste daily. Rembrandt Deeply White + Peroxide Fresh Mint Toothpaste ($7, at drugstores) is a dentist favorite.
If your stains are more brown than yellow, see your dentist for Zoom! laser whitening, which takes about an hour and costs roughly $500. But not even the most intense whitening treatment tackles grayness--this issue requires veneers, which are sheets of ceramic bonded to each tooth (cost: $1,000 to $3,000 per tooth).
The thickness of your gum tissue is genetic; gum disease (or gingivitis) is your own doing. Years of plaque buildup and aggressive brushing wear away at your sensitive gum line, giving it a peeled-back appearance, says Robert W. Gerlach, D.D.S., of P&G Global Oral Care Clinical. Plus, aging decreases the flow of saliva, which helps to wash away plaque-causing bacteria.
Not to sound like your mom, but brushing your teeth correctly is a must. Here's how: At least two times a day, use a soft-bristle toothbrush (it's gentler on gums than a firm one) to gently massage your teeth in small circular motions along the front, back, and sides. To ensure thorough brushing, imagine your mouth in quadrants--top left, top right, bottom left, bottom right--and brush each for 30 seconds, says Apa. And don't forget to floss! "It removes food, prevents plaque, and allows oxygen to flow through the teeth and gums," says Glosman. Try floss picks--they're easy to maneuver around your mouth--or opt for the Philips Sonicare AirFloss ($90, drugstore.com), which emits bursts of air to deep-clean between teeth.
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