There’s a lot of powerful chemistry inside each one of those whitening strips. When you zoom in to the individual ions flying around, it looks a lot like a sci-fi space attack. You pop on a goopy strip, and a short while later you’ve got teeth as white and gleaming as polished tile. But mixed properly, and applied in the privacy of your own bathroom, the stuff works its magic. The strips work without having to sit through your dentist’s annoying metal-on-tooth scraping.”]
Source: https://gizmodo.com/how-teeth-whitening-strips-attack-stains-like-tiny-spac-1470213143