The American Dental Association (ADA) has issued a statement regarding the health risks of zinc-containing denture creams. The ADA statement was issued just after GlaxoSmithKline announced it would voluntarily stop the manufacture, distribution and advertising of Super PoliGrip denture creams that contain zinc.
The human body does need zinc â€“ but only in small amounts. Studies show that consuming at least 50 milligrams of zinc a day for a few months could lead to copper deficiency, which can cause anemia, bone loss, nerve damage and other problems. Ingesting 80 or 100 milligrams or more for months or even years can lead to irreversible damage.
Compelling evidence exists that long-term exposure to the zinc in denture cream can lead to nerve damage and disability. In August 2008, the peer reviewed journal â€œNeurologyâ€ reported on four patients suffering from neuropathy and other neurological symptoms typical of zinc poisoning and copper depletion. The article specifically linked excess zinc in denture cream to â€œprofound neurologic diseaseâ€ in the patients reviewed.
This past fall, researchers at Vanderbilt University and the University of Michigan published a study in NeuroToxicology that detailed 11 patients who had suffered from significant injuries and neurological disorders for a period of years. The study authors discovered that all 11 patients had used a zinc-containing denture cream, such as Fixodent or Super PoliGrip, to keep their dentures in place. Blood test confirmed that each suffered from zinc poisoning and copper deficiency. The study authors to concluded that: â€œInappropriate use of denture cream appears to be the sole source of excessive zinc in these patient.â€
In a letter to dentists dated February 18, GlaxoSmithKline acknowledged that in 2009 it received an increased number of adverse event reports describing the development of neurological symptoms, myeloneuropathy and blood dyscrasias. According to the letter, those reports, together with the published literature, suggest that excessive use of zinc-containing denture creams may lead to the development of excessive levels of zinc in the blood, associated with copper deficiency.
The letter said that as a precautionary measure, GlaxoSmithKline would stop manufacturing, marketing and advertising Super PoliGrip products made with zinc. Those products – Super PoliGrip â€˜Originalâ€™, â€˜Ultra Freshâ€™ and â€˜Extra Careâ€™ â€“ will be reformulated, with new zinc free varieties expected to be available this spring. In spite of this action, none of these products is being recalled and those currently in stores are still available for sale.
Procter & Gamble, the maker of Fixodent, the other zinc-containing denture cream on the market, has not indicated any plans to reformulate their product.
The ADA released its statement on zinc-containing denture creams on February 19. The ADA advised denture wearers to see their dentists if their dentures do not fit well, as studies indicate that the problems are linked particularly to patients who have ill-fitting dentures and use excessive amounts of denture cream with zinc. The statement pointed out that regular dental examinations and appropriate care can reduce the need for denture adhesive products. The ADA also said it will continue to monitor the issue of zinc in denture creams.
Dozens of people have filed lawsuits claiming excessive exposure to zinc in products like Super PoliGrip caused them to suffer from severe neurological injuries. Last year denture cream lawsuits pending in federal courts were consolidated in a multidistrict litigation in the United States District Court for the Southern District of Florida, Miami Division, before the Honorable Judge Cecilia Altonaga (MDL No. 2051).