Your pre-workout smoothie, the berries topping your morning oatmeal, that second glass of red—all those, plus simple aging, make your smile dingier over time. Bad news for selfies; good news for the companies that make whitening pastes and strips. But which ones could work for you, and are there fine-print side effects to watch out for? For answers, read this guide and get your smile ready for a close-up.
First, Why Teeth Stain
The outermost surface of your teeth, called enamel, is mostly made up of a chemical called hydroxyapatite and is the hardest substance in your body, says William Graves, D.M.D., an associate professor in the department of surgery at Texas Tech Medical School. "But on a microscopic level it's also very porous, and over time, stain-causing substances can soak into those pores and discolor your teeth." The resulting stains, from foods and drinks, are extrinsic, occurring on the surface of the teeth, and sometimes can be removed by just brushing, says Peter Yaman, D.D.S., a clinical professor in the department of cariology, restorative sciences, and endodontics at the University of Michigan School of Dentistry. Others seep deeper into the enamel and need bleaching to make a difference. Instrinsic stains refer to the natural darkening of the deeper layers of your teeth over time, and whiteners can't do much to help, he says.
OK, So How Do Whiteners Work?
By the late 1960s, dentists started to notice a curious side effect in patients who had been prescribed hydrogen peroxide drops to treat gingivitis. Not only did their gum disease clear up, but their teeth looked whiter. Why? Hydrogen peroxide is primarily made of water and a free oxygen radical. When this free oxygen radical comes in contact with your teeth, it seeps into the enamel and oxidizes, breaking up stain molecules lurking inside. Enterprising dentists started experimenting, and before long, whitening products were born. Today there are three main types of bleaching: professional in-office procedures, dentist-provided custom trays for at-home use, and over-the-counter products such as whitening strips. "All of these work exactly the same way," says Kenneth Magid, D.D.S., an associate clinical professor of cariology at NYU College of Dentistry. "The only differences are how fast they work and how effective they are against stubborn stains."
While all bleaching treatments use hydrogen peroxide (or a form of it called carbamide peroxide), the concentration, which is what determines speed and effectiveness, varies wildly. In-office treatments pack as much as 35 percent to 40 percent hydrogen peroxide, which could be dangerous in the hands of a non-pro; at-home products usually max out at 10 percent to 16 percent . As a result, while many home products can achieve similar results, they take much longer. (We're talking weeks versus hours.) There is no shortage of over-the-counter options, but strips— clear, tapelike stickers that adhere tightly to your teeth— are the most common. They're good for nearly everyone, except those who have teeth that overlap. (In that case, the strips won't be able to lie completely flat in order to make contact with the full surface of the teeth.)
There are also OTC at-home trays, which you'll fill with a bleaching gel just before using. The possible downside? They're one size-fits-most, not all. A more customized option: dentist-provided trays. With these, you'll visit a dentist to have molds taken of your teeth, then leave with clear trays built to fit you precisely, as well as a bleaching solution that's usually stronger than what you can get over the counter. Custom trays are pricier than the prefab ones— around $250 to $400 versus $50 or less— but usually less expensive than a full in-office bleaching treatment, which can easily top $500. And the best part: They're reusable. "Keep the trays stashed away, and next time you can just buy the whitener from your dentist and reuse them," says Yaman.
What About Safety and Sensitivity?
Dentists are pretty much unanimous: Whitening is very, very safe. The at-home kits have too little hydrogen peroxide to do any damage, and while the concentrations used for in-office treatments are more potent, if you're seeing a reputable dentist, the risks to your gums are minimal. There is one unpleasant side effect of whitening that's pretty common: sensitivity. It occurs when the bleaching material penetrates an outer layer of the root called cementum, which covers the nerve chamber of your teeth. Your gums are supposed to protect you from this, but over time, gums can recede, exposing the vulnerable root surface. When bleaching solution seeps in, you'll know. "The surface of your enamel has no feeling, but the surface of the root does," says Magid. "And the longer you bleach, the greater your risk of sensitivity."
Surprisingly, this is why sensitivity can actually be worse with the gentler at-home products than with stronger pro treatments. "In-office bleaching takes a short period of time and the dentist controls where the material goes, so you might get sensitivity for 12 to 24 hours, but then it goes away," Magid says. To minimize contact with your gums and root surface, your dentist will carefully apply the solution to the teeth and will usually pack your mouth with gauze or cotton pads during the treatment to catch any drips. It's nearly impossible to be as careful at home. "With home bleaching, which can take weeks at a time, you may get bleach all over your gums and root surface, so sensitivity tends to build," he adds.
Sensitivity isn't dangerous, but as anyone who has ever experienced it will tell you, it hurts. You're much more susceptible to bleach-induced sensitivity if you already have sensitive teeth or if you've got chipped teeth, receding gums, or worn-down enamel from grinding. "These underlying factors expose more of the tooth and may set off inflammation and sensitivity," says Ronald D. Perry, D.M.D., a professor at Tufts University School of Dental Medicine.
When At-Home Bleaching Can't Help
If your teeth are more gray than yellow, they won't benefit from the power of peroxide. (This kind of discoloration is typically a result of the natural aging process but can also happen if you took certain medications while your teeth were still developing.) Ask your dentist about other cosmetic fixes, such as veneers, says Yaman.
Clearly, you've got options when it comes to whitening your teeth. One of them is deciding that you're fine as is, because no one needs a new reason to feel self-conscious. And whether or not your teeth are wedding-cake white, keep smiling. Research shows that a big grin makes you more memorable.
This story originally appeared in the April 2017 issue of Dr. Oz The Good Life.
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