Gregory L. Paskerian, DMD, a private dentist and former assistant professor at Tufts University, says that the new whitening rage follows a continuum of products. “The strips and other over-the-counter whiteners do not damage teeth or burn gum tissue,” he says. “The trays (to hold the peroxide solution) you can buy may can contain an acidic, unbuffered solution, which could damage enamel.”

The best tray-type lightening, he says, is provided by the dentist, who can control the solution and timing.

“For the fastest and safest whitening,” Paskerian says, “you need to get the high-intensity light systems. This light changes the molecular structure of the enamel for a time, but it goes back to normal and at a lighter shade.”

He adds, though that whitening is not really a color change, but a brightness or value change.

Price says he wishes patients would concentrate more on keeping teeth healthy. “There are bleaching groupies,” he says, “People who can’t get enough. You can only get teeth so white.”

Price also says these solutions can sometimes cause gum sensitivity, although it is usually short-lived.