Bleaching is a process of teeth whitening. Tooth color along with aesthetics of teeth is of great importance to patients. The color of teeth is influenced by both the intrinsic color and any extrinsic stains that may form on the surface of the tooth. Overall tooth color depends on the color of the dentine and also on the light scattering and adsorption properties of the dentine and enamel. Extrinsic stains are formed in such areas where the tooth brush does not reach and is often increased through smoking, intake of red wine, use of certain cationic agents and also metal salts like tin and iron.
Types of Bleaching:
There are three types of bleaching namely:
Dentist-supervised night guard bleaching- Here a relatively low-level of whitening agent is applied to a tooth through a custom fabricated mouth guard and is worn for night for at least two weeks.
In-office or power bleaching- Here generally high levels of whitening agents are used. For shorter time periods 25-35% of hydrogen peroxide containing products is used. Firstly the soft tissues are protected, then the whitening gel is applied to the teeth and then the soft tissues and the peroxide is further activated with heat or light. It results in significant whitening after the first visit but may require more visits for optimum whitening.
Mass market bleaching products-Here low levels of whitening agents are self applied to the teeth via gum shields, strips or paint on product formats. They require typically twice per day application up to two weeks.
The mechanism of tooth whitening by peroxide occurs by the diffusion of peroxide through enamel to cause oxidation and hence lightening of colored species. There are a number of approaches available for measuring changes in tooth color. They include both visual and instrumental measurements by dentists.
Bleaching in Dentistry