Pre-brush mouth rinses
To whiten teeth, pre-brush rinses typically contain hydrogen peroxide. Twice a day, gargle the liquid for 60 seconds before brushing your teeth and the bleaching agent will make quick work of your intrinsic stains. The problem: Bleaching teeth takes time. "Hydrogen peroxide is so weak and unstable [for that] time of use that its effect is minimal," Dr. Plotino says. In 2006, a clinical trial showed that these special rinses are, essentially, no better than water at whitening your teeth. What's more, some users experienced increased gum sensitivity after using the rinses. "You get none of the benefit and all of the pain of hydrogen peroxide with the rinses," says Dr. Gerard Kugel, a dentist at the Boston Center for Oral Health in Massachusetts, who has conducted numerous studies on tooth whitening procedures, including the one above on pre-brush rinses. Yet, the placebo effect leads many people to believe these rinses actually work. "We saw no benefit, but about 30 percent of the participants said their teeth were getting whiter," says Kugel.