I know what you're thinking. This sounds like your sanding down your teeth and how can that not cause sensitivity? Well the truth is, many toothpastes (especially whitening ones) have abrasive ingredients to polish away stains. But on an official ranking of "Relative Dentin Abrasion" (PDF), this one gets a score of 90—well below (or safer on tooth enamel) than Crest Pro Health Whitening's 162 and Colgate Total Whitening's 142. In fact, Opalescence rang in just under Aquafresh Sensitive. And unlike those big drugstore brands, this toothpaste isn't overly sweet and gloppy. It has a fresh mint flavor and leaves your mouth with a truly clean, tingly feeling. And as for whitening, you can expect to get your teeth up to two shades lighter in as little as four weeks. What's more, you don't even have to hit up your dentist to get it. It's readily available online.

$10.79 at Amazon (or $22.99 for a 3-pack from Opalescence)