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A Simple Formula for Whitening Your Teeth

Light-activated bleaching techniques such as BriteSmile and Zoom are marketed as "breakthroughs" in the science of teeth whitening. But are they any more effective than less expensive bleaching gels or over-the-counter white strips?

At the Center for Dental Health in Washington, D.C., patients won't find light-activated bleachings

"We've selected bleaching options," says dentist Eric Morrison, "that provide the most predictable results." He offers a system of preloaded whitening trays made by Ultradent Products. The tray adheres to the teeth and is worn for about 60 minutes per day until patients get the results they want.

Morrison and some researchers say the jury is still out on whether light is a more effective whitener; some studies suggest that the light does not enhance the results of bleaching.

Early Study Casts Doubt

Chemist Lee Hansen, a professor emeritus at Brigham Young University, explains there was an assumption that heat from the light served as a catalyst to decompose the bleaching gel.

"That's the theory behind it," says Hansen. But he found the lights don't generate enough heat or give off enough UV light to accelerate the chemical reaction.

As part of the study, a group of researchers at Clinical Research Associates, the Consumer Reports of dentistry, tried a combination of bleach and light on a small group of patients.

On one side of the patients' mouths, they applied bleaching gel alone. On the other side, they added the light. All the teeth became whiter, and there was no difference in the two sides.

Dentist Gerry Kugel of Tufts University says this one study was by no means the final word on light-activated bleaching.

He says a lot of patients do seem to like the procedure: When they leave the dentist's chair after an hour-long session, many can see the difference — and they may assume it's all from the light.

"You've got to remember that they're getting peroxide on their teeth," says Kugel. Zoom, for instance, is 25 percent hydrogen peroxide.

Within about seven days, however, when the teeth rehydrate, studies show there's a rebound in the color. That's why most patients are sent home with more bleaching gel that they can apply themselves.

A Time Advantage

But jump-starting the process with an in-office light bleaching does seem to offer a time advantage.

"My argument is that it's so minimal that I don't see it being worth what people are being charged for it," says Kugel. Costs vary regionally, but the average fee is about $500. However, a lot of dentists may disagree with Kugel.

About 20,000 dental practices offer Zoom, and several thousand others use BriteSmile.

Dentist Marilyn Ward, director of training for Discus Dental, maker of Zoom and BriteSmile, acknowledges that there has been controversy among dentists.

"But we have strong clinical studies, especially recently, showing that with an instrument study and with the shade guide, that you do have statistical significance in light versus no light," Ward says.

Those studies use a gadget that measures 16 points of color, similar to the machines that home-improvement stores use to match paint colors.

Building Demand

Zoom! started to take off as a brand several years ago, when company founder Bill Dorfman appeared on the hit TV show Extreme Makeover. As the program's aesthetic dentist, he repeatedly touted Zoom!

All of that consumer interest piqued the curiosity of researcher Joe Ontiveros, a dentist with the University of Texas. He recently presented his findings from a study, partially funded by Discus Dental, that analyzed the effects of bleaching gels alone compared with the combination of the Zoom light and gels.

"For some, people it was dramatic," says Ontiveros. "And for some people, you could barely tell the difference."

Ontiveros still recommends home bleaching trays to his patients first, "because it's got a long track record and it's very predictable."

He says he'll offer the light to those who don't want to wear the trays.

Bleach Is Bleach

"I've always said in my lectures, that bleach is bleach is bleach," says Harald Heymann, professor of operative dentistry at the University of North Carolina. His center has conducted clinical trials funded by Proctor & Gamble.

Whether a patient chooses chair-side bleaching by a dentist, take-home trays or over-the-counter whitening strips, the mechanism of action is the same, he says. The only difference is how long it takes to get the effect. The stronger the concentrations of hydrogen peroxide in the product, the faster the effect

So Heymann says there's a pretty simple formula. If you want quick results, go for a high concentration of peroxide. If you've got more time or you're more sensitive to the chemicals, tray-bleachings or Crest Whitestrips can work just as well.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Allison Aubrey is a correspondent for NPR News, where her stories can be heard on Morning Edition and All Things Considered. She's also a contributor to the PBS NewsHour and is one of the hosts of NPR's Life Kit.