Tooth bleaching

A common procedure in cosmetic dentistry. Many people consider white teeth to be an attractive feature of a smile. A child's deciduous teeth (milk teeth) are generally whiter that the adult teeth that follow. As a person ages the adult teeth often increase in value, that is to say they become darker. This darkening is due to changes in the mineral structure of the tooth, as the enamel becomes less porous. Teeth can also become stained by bacterial pigments, foodstuffs and tobacco.

Because white teeth are subconsciously associated with youth, they have become desirable. The procedure to bleach teeth uses oxidising agents such as hydrogen peroxide to lighten the shade of the tooth. The oxidising agent penetrates the porosities in the rod-like crystal structure of enamel and oxidises interprismatic stain deposits.

There are two main methods of bleaching. The first involves applying a high concentration of oxidising agent for a short period of time (the so called office bleach). This produces quick results but risks chemical burns to the soft tissues. The alternative method involves using a thin mouthguard to hold a low concentration of oxidising agent next to the teeth for several hours a day for a period of some weeks. This is known as the home or nightguard bleach. This is slower but has lower risks to the soft tissues.

A typical course of bleaching can produce dramatic improvements in the cosmetic appearance of most stained teeth, however some stains do not respond to bleaching. Tetracycline staining may require prolonged bleaching. White-spot decalcifications may also be highlighted and become more noticable.

Side effects of tooth bleaching are: Chemical burns if high concentration oxidising agent contacts unprotected tissues; sensitive teeth, and overbleaching to produce what are known in the profession as "Fridge-door teeth".