Zinc Poisoning Linked to Popular Denture Creams
Reports Suggest Overuse of Fixodent and Older Version of Poligrip May Cause Nerve Damage
Linking Zinc Poisoning to Denture Cream
Why did it take researchers so long to figure this out? In an explosive report, ABC news recently reported that publication of the Nations study in the journal Neurology was delayed by a reviewer, Kenneth Shay, DDS, with undisclosed financial ties to Procter & Gamble. Shay, it turned out, violated his confidentiality agreement by sharing the unpublished manuscript with P&G.
"The American Academy of Neurology considers any violation of these ethics policies to be egregious misconduct," the organization says in a statement provided to WebMD.
Shay says he was critical of the Nations report because he felt the researchers' method of measuring zinc in dental cream had "fundamental flaws." After the Nations team refused to accept his revisions, he says, he sent the manuscript to P&G.
"To fact-check my revisions, I shared it with a colleague at P&G," Shay tells WebMD. "I said, 'Don't share this around, but I'm interested in if the following facts are true or not. ... There was no sense of 'Squash this,' or anything. It was entirely my way of trying to make sure my review was accurate."
The ABC report implied that Shay managed to delay publication of the Nations report by about two years. In fact, it appeared some 15 months after it was submitted, "in line with standard time frames," according to the American Academy of Neurology.
And regardless of how the Nations team measured zinc, Shay -- a geriatric dentist at the Ann Arbor VA who has studied dental-cream use -- admits that many patients with poorly fitting dentures use wildly excessive amounts of denture cream to make them fit.
The irony, he says, is that the cost of using dental cream in this way quickly exceeds the cost of new, better-fitting dentures.
Is Fixodent Safe? Is Poligrip Safe?
Before May 2010, Poligrip contained a relatively small amount of zinc -- about 34 milligrams per gram in the original formulation and about 27.5 milligrams per gram in the Polyseal formulation, Nations and colleagues found. In February 2010, GlaxoSmithKline sent a "Dear Doctor" letter warning that excessive use of the product by patients could be dangerous.