11 At-Home Teeth-Whitening Products We Swear By

With so many at-home teeth whitening. options on the shelves, it's hard to know where to start — so we went straight to the pros for guidance. "A whitening treatment's effectiveness depends on two factors: The concentration of hydrogen peroxide and how well and long the bleaching product remains isolated on your teeth," explains Brian Kantor, DDS, a NYC-based cosmetic dentist at Lowenberg, Lituchy & Kantor. "The length of time your teeth will stay whiter varies and is influenced by how often you drink coffee, tea, dark soda, red wine, or smoke. People whose teeth have more of a yellow or brown tone usually bleach better than people with gray tones in their enamel."

Think of the delivery method this way: According to Dr. Kantor, things like strips will work better if you need serious whitening, versus a pen, which is great for touchups but won't deliver dramatic results since the product isn't on the teeth long enough to penetrate.

From the tried-and-true Crest Whitestrips to a dentist-developed system that rivals in-office treatments, here are the best whitening kits that have the pros' stamp of approval.