In the wake of news reports that the zinc found in many denture adhesives could lead to neurological problems, hundreds of denture wearers have been calling lawyers, hoping to join the growing number of suits filed against the makers of Super Poligrip and Fixodent.
One Houston firm representing 15 plaintiffs in denture adhesive suits has received about 150 inquiries, including several dozen from the Tampa Bay area, since separate stories about the lawsuits were published in the St. Petersburg Times and the Fort Worth Star-Telegram of Texas.
But instead of calling a lawyer, worried denture wearers should be calling their doctor first, neurologists say. That's because the symptoms many are reporting — numbness and tingling in the legs and arms — are more likely to be caused by problems such as diabetes, kidney or liver disorders or vitamin deficiencies than by excess zinc.
"It's very, very rare," said Dr. Lara Katzin, assistant professor of neurology at the University of South Florida, who added that zinc toxicity is "not even on the first 12 pages of possibilities to explain" peripheral neuropathy, or damage to the part of the nervous system that controls extremities.
Other possible causes: injury caused by a fall, hormonal imbalances, blood diseases, repetitive stress, infections.
Even Ed Blizzard, a Houston lawyer handling several cases, says a potential litigant's first visit should be to a doctor.
"We have told the people they should get tested for zinc and copper. They would need to establish first that they have neuropathy."
Excess zinc can deplete the body's copper, and it is copper deficiency that is linked to neurologic dysfunction, Katzin said.
A 2008 study by the University of Texas Southwestern Medical Center linked some neurological problems to heavy use of denture adhesives with zinc. Dr. Sharon Nations, lead author of the study, said anyone with neurological problems should see a doctor, who might refer them to a neurologist for testing. That could include blood or urine tests to check zinc or copper levels.
The U.S. Recommended Daily Allowance of zinc is 11 milligrams for men and 8 milligrams for women. One gram of denture adhesive can contain more than 30 milligrams, some of which inevitably is swallowed.
Patients in the study used about one to two 2.4-ounce tubes of adhesive a week; new Super Poligrip package inserts say a tube should last up to 10 weeks.
Hans Kimm of Tarpon Springs says he goes through two tubes of Fixodent a week. About four to five years ago, he started having strange pains in his legs. He said his doctors blamed his diabetes, then peripheral artery disease, and he had two stents put in.
But Kimm, 77, said when he read the report in the Times, he went to have his zinc and copper levels tested. His results showed elevated levels of zinc and low levels of copper, but still within allowable limits.
He has considered using a zinc-free product, but he says nothing else keeps his dentures in place.
Dr. Terry Kelly, a prosthodontist at Tampa's H. Lee Moffitt Cancer Center, says that denture adhesive is not a solution for ill-fitting dentures. He recommends no more than three dabs of adhesive per denture for most people. If you find you need more, you should see about having them refitted.
And soon, consumers like Kimm may not have to make a choice about using zinc adhesive. Three days after the Times' story, GlaxoSmithKline, which makes Super Poligrip, announced it would remove zinc from its adhesives. New products are expected in the coming months. The other target of lawsuits, Fixodent maker Procter & Gamble, has not announced a reformulation.
Joseph Clark, 53, of Clearwater says he's convinced the tingling he feels in his torso and legs is due to his longtime use of Fixodent. He said he called one law firm, which declined to take his case, but is planning to contact another.
Clark, who has worn dentures for six years, says he hasn't seen his doctor because he's unemployed and uninsured. But he has stopped using adhesives with zinc.
That may help his health, but it could hurt his legal prospects, attorney Blizzard said.
"A lot of people have stopped using the product. And if they get tested a week or month later, they're likely not to be positive'' for high zinc and low copper, he said. "Then you're left with neuropathy with the inability to prove" it was caused by zinc.
Richard Martin can be reached at [email protected] or (727) 893-8330.