UF researchers say consumers should know the facts before buying tooth-whitening products

For millions of Americans on a quest for that movie-star smile, the big question is not whether tooth-whitening products will work, but which one will work best.

Dental research conducted at the University of Florida may take some of the guesswork out of answering that question.

UF researchers compared several tooth-whitening products to measure whitening power and side effects, and they say consumers interested in whiter smiles should know all the facts before choosing one.

That’s no small task, given that store shelves are loaded with a dizzying selection of do-it-yourself tooth-whitening products in the form of toothpastes, paint-ons, strips and goo-filled trays. Even more powerful brightening brews are available by prescription from the dentist’s office. The use of tooth-whitening procedures in dental offices has increased more than 300 percent during the past five years, according to the American Academy of Cosmetic Dentistry. Ultimately, it’s not only the concentration of hydrogen peroxide that determines how much whitening occurs, it’s also about how well and for how long the product adheres to the tooth surface, and the length of time the product is used, said UF dental researchers, who presented their findings at last week’s annual meeting of the International Association of Dental Research.

Gum irritation and tooth sensitivity are two unpleasant but common side effects of using tooth-whitening products, and people should be aware of all the potential side effects, the researchers warned. Consumers, especially those who have many fillings, crowns or extremely dark stains, are advised by the American Dental Association to consult with a dental professional before beginning a tooth whitening plan.

“If you are considering whitening, there are some things you need to really look out for, and consumers should be able to make informed choices,” said Katherine A. Karpinia, D.M.D., an assistant professor of periodontology at UF’s College of Dentistry.

In two separate studies funded by Procter & Gamble, UF dental researchers compared a 14 percent hydrogen peroxide strip to a customized tray system using one of two concentrations of a carbamide peroxide gel — 16 percent and 20 percent. These levels of hydrogen peroxide and carbamide peroxide concentrations are available in tooth-whitening products available only through prescription from a dental professional.

Subjects wore the strips on their upper front teeth for 30 minutes twice a day for a period of three weeks, whereas the customized tray was used overnight for nine days to two weeks.

“We found the strip containing the 14 percent hydrogen peroxide got better results than the carbamide peroxide product in the tray in terms of bleaching, and also we had fewer side effects, such as gum irritation and tooth sensitivity, with the strip,” said study co-investigator Ingvar Magnusson, D.D.S., Ph.D., a professor of oral biology at UF’s College of Dentistry.

“Subjectively, in just looking at the strip users, there was clearly a physical difference in whitening,” Magnusson said. “But we used digital imaging in this study, which is much more objective.” Digital imaging is a computerized method of accurately measuring color change in teeth by comparing levels of red, yellow and white depicted in digital photographs taken before, during and after the treatment.

The digital imaging demonstrated those subjects who used the 14 percent hydrogen peroxide strip experienced a 91 percent improvement in reduction of yellowness compared to those who used the 16 percent carbamide peroxide product. Although gum and mouth irritation were similar between these concentrations, subjects who received the 20 percent carbamide peroxide tray product were about six times more likely to report adverse reactions to the product than the strip users.

Ultimately, both the strip and tray products were well-tolerated, produced good results and held their value — or whitening effect — over the long run, Karpinia said.

Consumers may feel these findings to be significant when looking for a cost effective way to whiten their teeth. Although tooth-whitening strips that are available over the counter have a lower concentration of hydrogen peroxide than the experimental strips studied at UF, they are available without a prescription and also work well, the researchers said.

”Quite often, the end results are pretty much the same,” Magnusson said. “What is important is that you get a product that has enough contact time with the tooth surface and that you follow the instructions on the package.”

Whether consumers choose to buy a tooth-whitening product over the counter at the supermarket or purchase a professional application from their dentist, Karpinia believes no one product is perfect for every individual and people need to make an informed choice.

“Remember, it’s all in the eyes of the beholder,” she said.