BRIGHTEN YOUR SMILE AND YOU’LL PROBABLY SMILE MORE OFTEN —which is good for your health. Studies show that smiling helps lower blood pressure, relieve stress, and boost your immune system. Plus, it feels good. What’s the best way to whiten your teeth? All of these treatments achieve their effect by saturating tooth enamel with a bleaching agent, either hydrogen peroxide or carbamide peroxide. What varies is the convenience, cost, and degree of whiteness. Check out these options and consult your dentist about the best one for you.

THE CREAM OF THE CROP. You’ll get the whitest white using mouth trays. Your dentist will create a custom mouthpiece from a thin vinyl, which holds the bleaching agent and must be worn at night or briefly during the day for 2 to 6 weeks.
Cost: $250 to $500
Pros: Because this takes time, bleaching agents can penetrate the teeth. Also, the chemicals are milder than those used for 1-hour in-office treatments. “Patients complain of less tooth sensitivity afterward,” says Pankaj Singh, DDS, a clinical instructor of advanced dentistry at New York University’s College of Dentistry. Cons: You have to wear the appliance for at least 2 weeks.
Cons: You have to wear the appliance for at least 2 weeks.
Not recommended: You can purchase over-the-counter trays, which Howard Strassler, DMD, director of operative dentistry at the University of Maryland Dental School, describes as “one size fits none.” Because the mouthpieces aren’t custom molded, the bleaching gel tends to ooze onto the gums and gets applied unevenly to the teeth.

THE FAST TRACK. If a mouthpiece seems too time-intensive and cumbersome, consider an in-office treatment. Your dentist will first apply a nail-polish-like barrier to prevent the bleaching gel from burning your gums. Soft plastic retractors will keep your cheeks, lips, and tongue away from the harsh chemicals. Then the whitening agent is applied—some for a full hour; others are wiped off after 15 minutes and then reapplied.
Cost: $500 to $1,000
Pros: Ideal for people who find mouth trays inconvenient or uncomfortable.
Cons: Dr. Strassler says in-office bleaching treatments are about 80% as effective as dentist-supervised tray systems. And, this method burns a bigger hole in your pocket.

THE STRIP. At your dentist’s office, you can purchase Ultradent’s Treswhite. Before using strips, get a dental exam. If the bleaching agent seeps through a cavity, says Dr. Singh, “that tooth is going to really hurt.” A dentist can assess if you’re a candidate for bleaching. If you have several fillings or receded gums, whitening may leave your teeth blotchy since fillings, crowns, and root surfaces don’t whiten. Dr. Singh doesn’t recommend over-the-counter glue-on strips, saying that to be effective, they must be used for months, in which case they become unhealthy.
Cost: About $50
Pros: A budget-friendly choice.
Cons: Less effective in whitening than mouthpiece or in-office treatments. Only whitens the six top and bottom front teeth, and doesn’t work well with crooked teeth.