The colouring materials of various drinks (coffee, tea, coke) or smoking will be absorbed into the dental enamel. Some medicines or the decomposition by-products of dead teeth can change the colour of deeper layers in the teeth and cause so-called internal discolouration. Modern teeth whitening treatments used in case of real discolouration give excellent aesthetical results. Whitening of an individual tooth is carried out in the dental surgery in one sitting. The treatment can be started at any age of life. Its effect can last for approximately four years.