What are the healthy and safe tooth whitening methods?

There are essentially only two ways to whiten teeth, one is chemical bleaching, and the other is covering whitening. There are also methods of tooth washing, tooth washing and sandblasting to restore the original color of teeth. The main chemical component of tooth whitening medicine is urea peroxide, which reacts with teeth in different ways to discolor teeth. There are mainly cold light whitening, denture whitening, toothpaste whitening, mouthwash whitening, drug whitening, ultrasonic tooth cleaning and so on.