Teeth whitening is a cosmetic procedure whose purpose is to cleanse tooth enamel from surface stains and pigmentations. Depending on the tasks, two types of teeth whitening can be distinguished - clinical and at-home. Clinical teeth whitening can be performed in a dentist's office or cosmetic surgeon's office, or through surgical and/or cosmetic whitening techniques that involve the injection of gels that chemically attack the layer of tooth structure. Home whitening includes hygiene products for removing yellowness and natural pigmentation of teeth.