A recent laboratory study indicates that do-it-yourself teeth bleaching
products may cause some weakening of teeth enamel, as well as the enamel’s
ability to recover from normal wear and tear. These home teeth bleach kits
have been written about in the March 2009 “Journal of Dentistry”.
According to Dr. Shereen S. Azer from the Ohio State University College of
Dentistry, “the public should not be alarmed of the bleaching process.”
“Human enamel has been shown to heal itself and ‘remineralize’ over time,”
meaning it has the ability to restore back the levels of surface calcium that
has been lost due to bleaching.”
A nanometer scale (one billionth of a meter) was employed by Azer and his
colleagues to measure the hardness and elasticity of tooth enamel both before
and after laboratory exposures to over-the-counter teeth bleaching solutions.
The researchers exposed 50 human tooth samples to 2 types of whitening strip
and 3 types of nightguard home bleaching systems,
Ten tooth samples each underwent bleaching regimens according to either the
3-week or 10-day manufacturer recommended treatment protocol. The 5 remaining
tooth samples served as unbleached “controls.”
Compared with before bleaching and versus unbleached controls, the bleached
enamel showed significant decreases in hardness on the nanometer scale, the
investigators report in the Journal of Dentistry.
The researchers also observed a significant decrease in enamel elasticity in
most bleached tooth samples compared with unbleached controls.
More study into the long term effects of bleaching agents and remineralization
of tooth enamel would be worthwhile, the researchers conclude.