What You Should Know About Teeth Whitening
Heather Colman
So what is teeth whitening really all about? The following
report includes some fascinating information about teeth
whitening -- info you can use, not just the old stuff they used
to tell you.
Tooth bleaching, also known as teeth 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 are
generally whiter than 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.
As white teeth are subconsciously associated with youth, they
have become desirable. This has been made more apparent with
the spread of American culture worldwide, where an especially
white smile is coined a "Hollywood smile." The procedure to
bleach teeth uses oxidizing agents such as hydrogen peroxide to
lighten the shade of the tooth. The oxidizing agent penetrates
the porosities in the rod-like crystal structure of enamel and
oxidizes interprismatic stain deposits; over a period of time,
the dentine layer, lying underneath the enamel, is also
bleached.
There are two main methods of bleaching. The first involves
applying a high concentration of oxidizing agent for a short
period of time, which is the so-called office bleach. This
produces quick results but risks chemical burns to the soft
tissues. Therefore, most in-office bleaching procedures use a
light-cured protective layer that is carefully painted on the
gums and papilla (the tips of the gums between the teeth). The
bleaching agent is either carbamide peroxide, which breaks down
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 mouth guard or
strip to hold a low concentration of oxidizing agent next to
the teeth for as long as several hours a day for a period of 5
to 14 days. This is known as take-home or over-the-counter
bleaching. This is a slower process but has fewer 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; however, 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. White-spot 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 shown varying results
as to the efficacy of light-activated bleaching.
Side effects of tooth bleaching include chemical burns (if a
high-concentration oxidizing agent contacts unprotected
tissues, which may bleach or discolor mucous membranes),
sensitive teeth, and overbleaching (known in the profession as
"fridge-door teeth"). Rebound, or teeth losing the bleached
effect and darkening, is also an issue, with some studies
showing the rebound effect over 30 days. A recent study by
Kugel et al has shown that as much as 4 shades of lightness can
be lost over 30 days with light-activated/office bleaching.
About The Author: This article is Copyright © 2006, Heather
Colman. Find more teeth whitening resources at:
http://www.teeth-whitening-support.info
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