Tooth discoloration can occur under the influence of various factors. External discoloration are on tooth surface and they are caused by the accumulation of debris, poor oral hygiene and frequent intake of chromogenic food and drinks. Internal chromogens which are incorporated in enamel and/or dentine are the resul of development anomalies, usage of specific drugs or tooth trauma. External chromogens can penetrate enamel or dentine via developmental or traumatic defects developing internalized discoloration. Active compounds of whitening materials that are used today are hydrogen peroxide, sodium perobrate and carbamide peroxide as well as their combination. Main whitening mechanism is oxidation of large pigmented molecules in small molecules that are less pigmented. The most popular whitening technique is home bleaching because it is simple, effective and low-cost solution. Most often individually customized trays and whitening strips are used. Whitening in the office is done using bleach with a higher concentration of the active ingredient. Most common side effects of teeth whitening are sensitivity and gingival irritation, but are generally very mild and short-lived.