Tooth whitening is a non-invasive cosmetic procedure performed to render teeth whiter than what they appear. The procedure utilizes carbamide or hydrogen peroxide gel applied to the tooth in order to bleach the color on the tooth surface. t is highly recommended that you have your teeth cleaned by the hygienist prior to the procedure in order to get the best result. Tooth stain due to coffee, tea, smoking and red wine respond well to bleaching. Other types of stain such as drug-induced stain may respond to a much less extent. Also, bleaching does not work on fillings and crowns and a filling may have to be replaced with a lighter shade restoration to achieve the desired outcome. It is important that the dentist advise you of the type of stain on your teeth and plan the whitening procedure that will produce the most favorable results.