Can Denture Cream Cause Neurological Disorders?
Abstract & Commentary
By Joseph E. Safdieh, MD, Assistant Professor of Neurology, Weill Medical College, Cornell University. Dr. Safdieh reported that he received grant/research support from the American Academy of Neurology.
Synopsis: Excessive use of denture cream, which contains high concentrations of zinc, may cause copper deficiency nervous system syndromes.
Source: Nations SP, Boyer PJ, Love LA, et al. Denture cream: An unusual source of excess zinc, leading to hypocupremia and neurological disease. Neurology 2008;71:639-643.
Over the past few years, copper deficiency has been reported as a cause of various neurological syndromes, most commonly a myelopathy with or without neuropathy, similar to subacute combined degeneration. Other syndromes reported with copper deficiency include optic neuritis and motor neuron disease-like syndromes. The most commonly reported causes of copper deficiency include dietary deficiency, gastrointestinal surgery and malabsorption syndromes.
Excessive ingestion of zinc has also been reported to cause copper deficiency. An elevated level of intestinal zinc induces upregulation of metallothionen, a copper binding protein. Copper is then sequestered in the intestine, not absorbed, and is excreted in the stool. As clinicians, we take advantage of this process by treating Wilson disease with zinc sulfate to treat copper overload.
The authors of this study report four patients with various neurological syndromes who all used excessive amounts of denture cream. The syndromes demonstrated by the patients included myeloneuropathy with poor cognition, motor neuron disease-like illness, and dorsal column myelopathy with and without neuropathy. All of these patients demonstrated significantly decreased serum copper and ceruloplasmin levels as well as elevated serum levels of zinc. All patients had normal serum B12 levels and no intramedullary spinal cord abnormalities on MRI. All patients used two or more tubes of dental cream per week, which is much higher than should be used if following the product labeling. All patients were treated with copper supplementation. The three patients who demonstrated some degree of improvement also stopped using denture cream. One patient continued to use denture cream and did not improve.
The authors also performed metallurgic analysis of major brands of denture cream to determine the concentration of zinc, and determined that there were indeed very high levels of zinc in the creams. They calculated that the affected patients were exposed to approximately 330 mg of zinc per day, much higher than the recommended allowance of 8–11mg per day. They hypothesize that the high zinc exposure caused the copper deficiency syndromes. They noted that a direct toxic effect of zinc could not be excluded, but was unlikely.
Commentary
This paper should interest the general neurologist encountering patients with myelopathy or myeloneuropathy when no identifiable cause, such as B12 deficiency or a demyelinating disorder, is found. Patients presenting with these syndromes should be asked about their use of denture creams. The authors note that a standard tube of denture cream should last 3–10 weeks with recommended use. If patients are using significantly more than that amount, they should be screened with serum copper, zinc, and ceruloplasmin levels. It is not known if excess zinc ingestion may also cause cognitive impairment in the elderly, since this group uses denture cream very commonly. This condition is likely rare, but it is quite important for neurologists to be familiar with as it is treatable and potentially reversible with cessation of denture cream use and copper supplementation.
Excessive use of denture cream, which contains high concentrations of zinc, may cause copper deficiency nervous system syndromes.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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