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Tooth whitening

A tooth is comprised of an inner dentin layer and an outer hard enamel layer that is the protective layer of the tooth. The enamel layer of a tooth is naturally an opaque white or slightly off-white color. It is this enamel layer that can become stained or discolored. The enamel layer of a tooth is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. It is believed that this porous nature of the enamel layer is what allows staining agents and discoloring substances to permeate the enamel and discolor the tooth. Many substances that an individual comes in contact with on a daily basis can "stain" or reduce the "whiteness" of his or her teeth. Teeth become stained over time from contact with coffee, tea, juice, tobacco, and other foods. Currently, there are three basic methods to remove this layer of stain and whiten the teeth. White teeth have long been considered cosmetically desirable. More and more consumers are choosing to whiten their teeth. Teeth whiteners, also known as teeth bleaching agents, are in widespread use as a cosmetic means to enhance appearance and, generally, to contribute to better oral health and hygiene. Options for tooth whitening include toothpastes, mouthrinses, chewing gums, in-office bleaching, and most commonly tooth whitening solutions used with a tray obtained either over-the-counter or from a dentist. The tooth whitening solutions contain a which bleach the teeth. This solution is placed into a dental tray in which a patient wears to bleach his or her teeth. Many approaches are used to whiten teeth. Two of the most common approaches use abrasives or chemical whiteners, such as peroxides. Abrasives in combination with a polishing action are used to polish discolorations and stains off of the surface of the teeth. Thus, light reflected from the teeth represents the true intrinsic color of the teeth. Abrasives are a major element of most consumer toothpastes and prophyaxis pastes used by dentists. The second approach is the use of chemical whitening actives in a composition to intrinsically and extrinsically whiten teeth. Chemical whitening actives are applied to the teeth for period of time to allow the active to act upon the tooth and provide an improvement in the whiteness of the teeth. Whiteners are commonly applied to the teeth using toothpastes, rinses, gums, floss, tablets, strips and trays. A common chemical whitening active is peroxide. Among the early tooth whitening systems for do-it-yourself usage was a paste or gel containing a hydrogen peroxide or carbamide peroxide constituent. The gel or paste was applied to tooth surfaces by, for example, a toothbrush, a cotton swab, etc. A gel is a colloid produced by combining a dispersed phase with a continuous phase to produce a viscous, jelly-like, semisolid material. A "dental bleaching gel" is a gel that carries a bleaching agent that can be safely applied to teeth.

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