FDA regulates denture adhesives

The U.S. Food and Drug Administration (FDA) regulates denture adhesives, which are medical devices under the Food, Drug and Cosmetic Act.

A denture adhesive is a device intended to be applied to the base of a denture before the denture is inserted in a patient's mouth to improve denture retention and comfort.

FDA has classified this product as a low-risk device (class I). While manufacturers are not required to submit marketing applications to FDA for most class I devices, they still must register and list a class I device with the agency and comply with other applicable FDA requirements. These requirements include adverse event reporting, manufacturing controls, and labeling that is neither false nor misleading.

FDA monitors adverse events from medical devices through mandatory and voluntary reporting systems. Manufacturers and hospitals are required by law to report deaths and serious injuries. Manufacturers also must report malfunctions that could result in death or serious injury. FDA reviews reports submitted to the agency and has authority to take immediate action, when warranted, to protect public health. Consumers can report problems experienced with any product to FDA either by phone (800-FDA-1088), fax (800-FDA-0178), on-line (www.fda.gov) or mail (MedWatch, The FDA Safety Information and Adverse Event Reporting Program, FDA, 5600 Fishers Lane, Rockville, MD 20852).

New research suggest, loading up on denture cream can be hazardous to your health.

In the medical journal Neurology, Dr. Sharon P. Nations of the University of Texas Southwestern Medical Center in Dallas and her colleagues report on four denture-wearing patients who developed neurological problems.

All had abnormally high levels of zinc in their blood, accompanied by abnormally low levels of copper. Because denture cream contains zinc, and all of the patients habitually used "extremely large amounts," Nations and her team propose that excess denture cream use led to their neurological problems.

Balance between zinc and copper in the body is essential for neurological health. Taking in too much of one of these trace metals can cause depletion of the other.

Normal blood levels of copper range from 0.75 to 1.45 micrograms per milliliter (mL), but levels for the patients in the report ranged from less than 0.1 to 0.23 micrograms per mL.

The top normal number for zinc blood levels is 1.10 micrograms per mL, but patients had levels ranging from 1.36 to 4.28 micrograms per mL.

One patient's symptoms included weakness in the hands and poor balance, while another had weakness in her arms and legs that made her wheelchair dependent, along with cognitive decline and urinary incontinence.

These patients showed "mild neurologic improvement" after they quit using denture cream and began taking copper supplements.

Another patient took copper supplements but didn't stop using denture cream. His copper levels improved, but his zinc levels remained too high and he showed no improvement in his neurological symptoms. The fourth patient, who took copper supplements and stopped using denture cream, showed improvement in copper and zinc levels, but no improvement in neurological symptoms.

Testing revealed zinc concentrations between 17,000 and 34,000 micrograms per gram in the denture creams the patients used. This is the only "plausible explanation" for their high zinc levels and copper deficiency, the researchers say.

Used as recommended, a tube of denture cream should last from 3 to 10 weeks, the researchers note, but patients in the report were all using at least two tubes a week. Three had also lost their teeth at a relatively young age, meaning they had been used "extremely large amounts of denture adhesive daily for years."

Based on patients' denture cream use, the researchers estimate that they were exposed to at least 330 mg of zinc daily, far more than the recommended daily allowance of 8 mg for women and 11 mg for men. The National Academy of Sciences stated in 2001 that the largest daily tolerable zinc intake is 40 mg.