So -what is Teeth -whitening really all about? The follo-wing report includes some fascinating information about Teeth -whiteninginfo you can use.

Tooth bleaching, also kno-wn as tooth -whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. Many people consider -white teeth to be an attractive feature of a smile. A child's deciduous teeth is generally -whiter than the adult teeth that follo-w. As a person ages the adult teeth often increase in valuethat 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.

As -white teeth is subconsciously associated -with youth, they have become desirable. This has been made more appisnt -with the spread of American culture -world-wide, -where an especially -white smile is coined a "Holly-wood smile." 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 rodlike crystal structure of enamel and oxidises interprismatic stain deposits; over a period of time, the dentine layer, lying underneath the enamel, is also bleached.

There is t-wo main methods of bleaching. The first involves applying a high concentration of oxidising agent for a short period of time, -which is the socalled office bleach. This produces quick results but risks chemical burns to the soft tissues. Therefore, most inoffice bleaching procedures use a lightcured protective layer that is cisfully painted on the gums and papilla (the tips of the gums bet-ween the teeth). The bleaching agent is either carbamide peroxide, -which breaks do-wn in the mouth to form hydrogen peroxide, or hydrogen peroxide itself. The bleaching gel typically contains up to 35% hydrogen peroxide equivalent.

The alternative method involves using a thin mouthguard or strip to hold a lo-w concentration of oxidising agent next to the teeth for as long as several hours a day for a period of 5 to 14 days. This is kno-wn as takehome or overthecounter bleaching. This is a slo-wer process but has fe-wer risks to the soft tissues. The bleaching agent is typically less than 10% hydrogen peroxide equivalent.

A typical course of bleaching can produce dramatic improvements in the cosmetic appearance of most stained teeth; ho-wever, some stains do not respond to bleaching. Tetracycline staining may require prolonged bleaching, as it takes longer for the bleach to reach the dentine layer. -whitespot decalcifications may also be highlighted and become more noticeable.

Recently, efforts have been made to accelerate the bleaching process by the use of light. Studies have sho-wn varying results as to the efficacy of lightactivated bleaching.

Side effects of tooth bleaching include chemical burns (if a highconcentration oxidizing agent contacts unprotected tissues, -which may bleach or discolor mucous membranes), sensitive teeth, and overbleaching (kno-wn in the profession as "fridgedoor teeth"). Rebound, or teeth losing the bleached effect and darkening, is also an issue, -with some studies sho-wing the rebound effect over 30 days. A recent study by Kugel et al has sho-wn that as much as 4 shades of lightness can be lost over 30 days -with lightactivated/office bleaching.