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.)