COLUMBUS, Ohio New research shows that human teeth lost some enamel hardness after the application of several different products used in the home to whiten teeth. The study suggests that future generations of such products might be reformulated in an effort to reduce these side effects.
The researchers noted that teeth typically can restore their previous hardness after losing small amounts of enamel calcification. But this is the first study to show at a nanometer scale measuring in billionths of a meter how human teeth are affected by the popular home whiteners.
"There is some significant reduction in nano-hardness of enamel, but we are talking on a very minute scale. So even though it may not be visible to the human eye, it's important for research because that's how we improve products," said Shereen Azer, assistant professor of restorative and prosthetic dentistry at Ohio State University and lead author of the study.
Azer and colleagues applied the recommended treatments of five name-brand home whiteners to samples of human teeth and compared the effects to tooth samples that received no treatment. In all cases, the products reduced the hardness of the enamel as well as what is called the elastic modulus or stiffness, a measure of the ability of the tooth surface to bounce back in response to applied force.
Many studies have sought to determine how tooth whitening affects tooth enamel hardness, but results have been inconclusive. Azer said that previous studies measured the loss of enamel hardness in microns, or millionths of a meter, rather than on the nanometer scale used in his study.
"So this just gives us a better understanding of precisely how these products affect human teeth," he said.
The research is published in a recent issue of the Journal of Dentistry.
Tooth bleaching products contain solutions of various strengths of either hydrogen peroxide or carbamide peroxide, whi
|Contact: Shereen Azer|
Ohio State University