Toothpaste

"Your simplest and safest whitening option is to regularly brush with a non-abrasive whitening toothpaste," Smigel says. "Whitening toothpastes are perfect for those on a budget who want gradual and consistent whitening."

Many toothpastes claim to whiten teeth, but only select ingredients do so safely and effectively. "Most whitening toothpastes work on the principle of abrasion," Smigel says. But, he advises, it's best to stay away from toothpastes that list silica as an ingredient — especially if it's at the top of the list, since that means there's a high concentration of it. "Silica is an abrasive ingredient that scratches the stain from the tooth enamel," he explains. "It presents concerns in continued usage, especially on bonding, veneers, and other dental restorations." And, once your enamel is scratched, teeth are actually more susceptible to stains.

What else should you avoid? Sodium lauryl sulfate, a common detergent that can aggravate (and even cause!) oral problems such as canker sores and bad breath. "Instead, look for those that contain ingredients such as calcium peroxide, carbamide peroxide, and urea peroxide," Smigel says. "These ingredients are the safest, most effective whitening ingredients that will gradually whiten teeth without causing sensitivity."

Supersmile Professional Whitening System, $36, available at SkinStore.