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The Reaction?
Terry Day, MD, director of head and neck oncologic surgery at Hollings Cancer Center at the Medical University of South Carolina and a spokesman for the American Academy of Otolaryngology-Head and Neck Surgery, says the study deserves notice because it points to why there's a growing trend in young people developing oral cancers -- especially affecting the tongue -- without a long-term history of those damaging vices.
"About 10% to 15% of oral and head and neck cancers do not seem to be related to tobacco and/or alcohol," he tells WebMD. "Other considerations still under investigation include genetic factors, the human papillomavirus (which causes genital warts), and nutrition factors. This study is interesting in that it points to the possibility of another factor being involved.
"But due to the small size, it's a serious limitation to whether or not you can say there's a relationship to teeth-whitening agents and oral cancer."
Until now, there has been little research on the long-term effects of tooth whiteners, and Davidson's study is believed to be the first to examine the link between cancer and tooth whiteners. Since they are considered "cosmetic" products, tooth whiteners don't fall under FDA regulation. While dentists have used these gels for some time, commercially available products have only been available for several years, so their long-term effects haven't been studied.
American Dental Association spokesman David Sarrett, DMD, a professor of dentistry at Virginia Commonwealth University, says there is no evidence that when used as directed, tooth whiteners increase cancer risk or cause other problems. But he does acknowledge they are abused by some people.
"Some patients are what we call 'tooth-whitening junkies' who are not satisfied until their teeth are snow white, and that's not achievable," he tells WebMD. "Even when using an over-the-counter whitener, I also advise people to first consult with their dentist, and always follow the product directions."
Leakage a Problem
When whiteners are applied by a dentist, which costs $200 or more, custom-fitted trays are used to hold the gel, reducing risk of hydrogen peroxide leakage; with over-the-counter products, the trays are usually not form-fitting.
But even under ideal conditions, reports Davidson, studies show that often less than 50% of the whitener is still in the trays one hour after application, indicating a lot of leakage.
Sarrett does caution against buying tooth whitening products over the Internet -- for another reason.
"They may have the right ingredients, but because they don't balance ingredients properly, they may not have the right pH, as with gels used by dentists or from reputable companies," he says. "It could be too acidic, which we know can damage tooth enamel."
SOURCES: The 6th International Conference on Head and Neck Cancer, Washington, D.C., Aug. 7-11, 2004. Bruce J. Davidson, MD, FACS, chairman, division of otolaryngology, Georgetown University Hospital, Washington, D.C. Terry Day, MD, director, division of head & neck oncologic surgery, Hollings Cancer Center; associate professor, Medical University of South Carolina, Charleston. David Sarrett, DMD, professor of dentistry and associate vice president of health sciences, Virginia Commonwealth University, Richmond; member, American Dental Association Council on Scientific Affairs.