Teeth whitening is a cosmetic dental procedure that involves removing stains and discolorations from the teeth to improve their appearance. The most common method of teeth whitening involves applying a bleaching agent to the teeth, which breaks down the stains and brightens the enamel. Teeth whitening can be done in-office by a dental professional, or at home using custom-fitted trays and a bleaching gel. While teeth whitening is generally safe, it can cause sensitivity and should be done under the guidance of a dental professional.