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Dirty dentures? Dangerous MRSA may be lurking, dentists say

American College of Prosthodontists

Denture experts say a daily scrub with a stiff brush is vital to removing potentially dangerous biofilms from false teeth. New research also shows that microwaving or soaking in a germicide rinse can disinfect dentures for up to a week.

Here’s some bad news for the estimated 20 million people in the U.S. who wear full or partial dentures: There’s a good chance your choppers are covered with thin layers of icky, sticky bacteria known as biofilms.

Worse, some of the biofilm germs may be bad bugs such as MRSA, or drug-resistant staphylococcus aureus bacteria, which can lurk on the dentures until they’re breathed into the lungs, where experts fear they may cause nasty, hard-to-treat infections.

Fortunately, a team of scientists in Brazil has come up with two simple solutions that seem to work: Zap your dentures in the microwave for three minutes, or soak them in a solution of 2 percent chlorhexidine gluconate, a germicidal mouthwash, for 10 minutes.

Either method is enough to disinfect dentures coated with the toughest MRSA biofilms for up to a week, according to a recent study in the Journal of the American Dental Association. A third option, soaking the dentures in sodium hypochlorite, was effective only in the short term.

But the microwave approach, which zaps dentures with 650 watts, may be novel, suggest the authors, led by Karen Tereza Altieri, a dentist at the Araraquara Dental School at the Universidade Estadual Paulista in Sao Paulo.

“To our knowledge, we are the first investigators to report the effectiveness of this method in killing MRSA,” they write.

The study, which tested methods for eliminating MRSA on 36 dentures, is a small one. But some experts in the U.S. say they may recommend the methods to improve the oral hygiene of their patients.

“We do know there are links between the bacteria in the mouth and systemic effects throughout the body,” said Victoria A. Vickers, a San Antonio prosthodontist, a dentist who specializes in the repair and replacement of teeth.

Concern about biofilms on dentures is growing as researchers continue to identify links between oral bacteria and heart disease, chronic obstructive pulmonary disease or COPD, and respiratory diseases, including aspiration pneumonia.

The idea, experts say, is that bacteria form self-sustaining microbial communities bound together by a kind of polymer matrix that adheres tightly to surfaces. The biofilms are much more difficult to remove than single bugs. The dentures act as kind of a reservoir for the biofilms, allowing bacteria within them to multiply and thrive.

“Bacteria and yeast can embed themselves in the porous material,” of the acrylic dentures, said Vickers, who is also the public relations and communications director for the American College of Prosthodontists.  

When people get cuts or lesions in their mouths, the bacteria from the biofilms can migrate into those tiny wounds, leading to systemic illness.

About a quarter of people in the U.S. between the ages of 65 and 74 have no teeth, and many of those people wear full or partial dentures, according to the Centers for Disease Control and Prevention.

The trouble, Vickers said, is that many denture-wearers simply don’t clean their false teeth – or their mouths -- well enough.

“There are still a lot of patients who have gone 30 years wearing their old dentures,” she said. “They don’t clean them, they don’t scrub them well. They say, ‘I take them and I rinse them in the shower.'”

Instead, denture-wearers should wash their false teeth daily, with a stiff brush and soap and water, not toothpaste.

“The mechanical action works better,” she said. “You really need to scrub.”

Follow with a mouthwash rinse to make them taste better and swab of the inside of the mouth to remove bacteria there. Also, she said, be sure to brush your tongue.

Zapping dentures in the microwave or submerging them in the 2 percent chlorhexadine gluconate is a good disinfectant step, she said. But dentures that contain metal shouldn’t go in the microwave and the harsh chemical rinse might be too strong for daily use.

“I would microwave it or use the solution after being ill or after being hospitalized,” she said. “As dentists, we do recommend when someone has a cold or flu to replace their toothbrush.”

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