Tooth whitening or tooth bleaching is the process of
lightening the color of human teeth. Whitening is often desirable when teeth
become yellowed over time for a number of reasons and can be achieved by
changing the intrinsic or extrinsic color of the tooth enamel. The chemical
degradation of the chromogens within or on the tooth is termed as bleaching.
Hydrogen peroxide (H2O2) is the active ingredient most
commonly used in whitening products and is delivered as either hydrogen
peroxide or carbamide peroxide. Hydrogen peroxide is analogous to carbamide
peroxide as it is released when the stable complex is in contact with water.
When it diffuses into the tooth, hydrogen peroxide acts as an oxidising agent
that breaks down to produce unstable free radicals. In the spaces between the
inorganic salts in tooth enamel, these unstable free radicals attach to organic
pigment molecules resulting in small, less heavily pigmented components. Reflecting
less light, these smaller molecules create a "whitening effect".
There are different products available on the market to remove stains. For
whitening treatment to be successful, dental professionals (dental hygienist or
dentist) should correctly diagnose the type, intensity and location of the
tooth discolouration. Time exposure and the concentration of the bleaching
compound, determines the tooth whitening endpoint.