Zinc in denture adhesives has been blamed in dozens of cases of nerve damage.

About 40 million Americans have dentures and use adhesives to secure them, and the products have long been considered benign. The American Dental Association said in its statement it knows of no confirmed cases of dental glues causing nerve damage.

The products, Poligrip brands from GlaxoSmithKline and Fixodent from Procter & Gamble, use zinc as a bonding agent. Scientists have only recently drawn a possible link between the zinc-containing denture creams and neurological problems. Glaxo says its product is safe if used properly.

Although zinc is an essential mineral for cell function, it can be harmful in high doses because it inhibits the absorption of other minerals. As a result, people who ingest too much zinc develop copper and iron deficiencies that can lead to severe numbness and weakness from nerve damage.

Most of those who have reported illness used excessive amounts of dental adhesive, often because their false teeth fit poorly and require more cream to form a bond.

“It’s a pretty rare problem,” said Dr. Michael Cartwright, an assistant professor of neurology at the Wake Forest University School of Medicine who has treated patients with the suspected link. “There are many, many people who use denture cream who don’t develop any kind of neurologic disease. We don’t know why it happens in some people – if they’re using large amounts (of denture cream), or if they have some other predisposition to copper deficiency.”

Glaxo officials, in a written statement, said the denture glue is not harmful if used normally. In addition, the company last fall began including a package insert for its Poligrip products: “Using excessive amounts of this product over a prolonged period of time has been reported to result in serious health effects from increased zinc intake.”

Ed Blizzard, a Houston lawyer who is representing dozens of patients in lawsuits over the products, said many of the people he represents have suffered permanent disabilities, and at least one person has died.

“Glaxo says, ‘Don’t use the product in excess,’ ” Blizzard said, “as if these people were alcoholics or something. They’re just trying to keep their teeth in their mouth.”