Overuse of Denture Adhesive with Zinc Poses Health Risks
By Richard Bullock, DDS

When he began getting weak, 61-year-old Ronald Beaver figured he might just be feeling his age. Eventually his problem was traced to a serious blood disorder caused by low levels of copper.

“I didn’t know what to think,” Beaver said of his illness three years ago. “I had no idea.”

Beaver’s doctor mentioned that getting too much zinc can trigger loss of copper. The only source of that much zinc, they surmised, was the tubes of Poligrip denture cream he had been grossly overusing for a decade. “The dentures I had then didn’t fit that good. They would get loose and I would reapply,” he said.

Now Beaver and hundreds of other people claiming similar problems are suing consumer products giants Procter & Gamble Co., which makes Fixodent, and Glaxo SmithKline, maker of Poligrip. At least 25 lawsuits from 11 states have been consolidated for pre-trial hearings before a federal judge in Miami.

The companies say denture adhesive containing zinc is safe when used as directed. And the Food and Drug Administration, which regulates denture creams, has never issued any warnings about the products. Indeed, the amount of zinc found in the recommended application of denture adhesive is similar to the amount found in a 6-ounce hamburger, and the overwhelming majority of users have no problems. The zinc improves adhesive power.

The legal action followed a 2008 report in the medical journal “Neurology” about a possible link between denture cream zinc and nerve damage. Doctors at the University of Texas Southwestern Medical Center in Dallas described four patients who used excessive denture cream and had various nerve-related disorders.

The researchers said their report did not prove denture cream caused the problems, but concluded the issue warranted further study. The human body needs both zinc and copper in proper amounts, and zinc is commonly found in many foods, vitamin supplements and even cold lozenges. Too much zinc, though, can purge copper from the body. A copper deficiency can cause nerve damage, resulting in symptoms such as weakness and numbness in arms and legs, difficulty walking and loss of balance and even cognitive or memory impairment, according to the National Institutes of Health.

Dr. Jane Flinn, director of the undergraduate Neuroscience Program at George Mason University in Fairfax, VA, noted that all four patients in the report used excessive amounts of denture cream. In the four Texas cases, as well as that of Beaver and other plaintiffs, patients were using far more than the recommended amount of denture cream, perhaps two or three tubes per week. A tube is supposed to last three to 10 weeks, with directions calling for only small dabs of the adhesive to keep dentures in place.
           
Cincinnati-based Procter & Gamble and Britain’s Glaxo SmithKline said in statements to The Associated Press that their denture creams are safe when used properly. On their Internet sites, both have sections dealing with the issue of zinc in their denture creams. This summer, Glaxo SmithKline began including leaflets with Poligrip about the reports of possible problems from overuse and is adding similar wording to new packages.

When the adhesive product is used as directed, the amount of zinc that might be swallowed is small and very unlikely harmful. The lesson of this story is that excessive amounts of denture adhesives should not be used to compensate for ill-fitting dentures. See your dentist if a loose prosthesis necessitates the use of excessive adhesive. Dentures can be remade or relined to provide closer adaptation to the underlying tissue.

Dr. Bullock can be reached at University Park Dentistry in Palm Springs. Please call 760-……………