For Whitening Teeth, Stronger Isn't Better
September 29, 2009

By Nancy Volkers
InteliHealth News Service

INTELIHEALTH - Stronger tooth-bleaching treatments don't leave teeth whiter in the long run, says a new study.

Brazilian researchers did the study. It involved 92 people. People had their teeth whitened using custom-fitted trays. They were randomly assigned to use either a 10% solution of carbamide peroxide or a 16% solution. The 16% solution is stronger.

Some studies have shown that stronger solutions of carbamide peroxide keep teeth whiter for longer periods of time. But no study has followed people for more than a few months after bleaching.

Each person received whitening treatment two hours a day for three weeks. Researchers looked at tooth whiteness before bleaching, one week after treatment, six months later and a year later.

At the one-week and six-month time periods, the 16% group had whiter teeth than the 10% group. But after a year, the 16% group had lost some whiteness. By then, both groups' teeth were about the same shade. Their teeth were still whiter than before bleaching, however.

The researchers also asked people questions about the foods and drinks they consumed. Some food and drink is more likely to stain teeth. People in both groups ate and drank about equal amounts of tooth-staining foods. Very few people used whitening toothpaste.

The study appears in the September issue of the Journal of the American Dental Association.