If you're like most of us here at Greatist, braces and retainers still plague your middle school memories. The uncomfortable metal contraptions were the first step in a lifelong pursuit of the perfect smile, followed by making those pearly whites, well, white.

Not all oral-care options are created equal though. This video from Reactions explains how teeth-whitening actually works. Our teeth are naturally white, but over time they become stained with food remnants and other foreign particles. Most whitening products use hydrogen peroxide to remove color from these pigments, the same way we bleach stains out of clothes. Other products will give the teeth a blue tint, temporarily counteracting their usual yellow appearance. They’re all safe, but only some whitening products actually work.

Our takeaways: Mouthwash doesn’t work well, while whitening toothpaste is only a temporary fix. Your best bet for long-lasting white teeth is brushing and flossing regularly, as well as whitening strips or a trip to the dentist.

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