Plaque not just a problem for your teeth

Dental plaque is the white stuff that collects on our teeth, most often in the spots that the toothbrush doesn't quite reach. It's a homegrown version of biofilm -- mobs of microorganisms that clump up and encase themselves in largish sugar molecules so they are fairly impenetrable. In biology, there's often strength in numbers.

As a biofilm, dental plaque, which can harden into tartar, may not be all bad. It can create a barrier to some potentially harmful bacteria. But much of the time, that benefit is canceled out by other bacteria in the plaque that may inflame gum tissue (gingivitis) and the underlying tissues that hold our teeth in place (periodontitis).

The trouble may not be limited to the mouth. A number of studies have linked gum disease to heart disease. Inflammatory factors, or even the bacteria themselves, may get into the bloodstream and make their way to the coronary arteries or the heart.

Dental plaque and gum disease have also been linked to pneumonia -- especially in people breathing with the help of a ventilator. Between 10 percent and 25 percent of patients on ventilators come down with pneumonia. When the ventilator pushes air into the patient's lung, the bacteria may get swept along with it. Once in the lungs, the bacteria grow and cause the inflammation that's characteristic of pneumonia.

Dental plaque isn't the only source, but several studies have found an abundance of the pneumonia-causing bacteria in the plaque of ventilated patients. Researchers have also found that the longer someone is in intensive care, the more abundant those bacteria become. Heavy use of antibiotics may be a factor: By altering the bacterial environment of the mouth, antibiotics may create an opportunity for bacteria that get into the lungs to colonize dental plaque, as well other areas of the mouth and the throat.

Cleaning patients' mouths with a mouthwash or certain kinds of gels looks like it might be a simple -- and inexpensive -- way to combat ventilator-associated pneumonia. Not every study has come out positive, but over all, the results are promising.

Most of the mouthwashes and gels that have been tested contained chlorhexidine, the active ingredient in prescription mouthwashes like Peridex and PerioGard.

The connection between dental plaque and pneumonia seems to be strongest among people on ventilators, but they may not be the only ones affected. For example, a number of studies have found that nursing home residents with poor oral hygiene are more likely to come down with pneumonia.

It's also possible that poor oral hygiene may cause some cases of pneumonia among those not living in nursing homes or hospitals, although so far, there's not much evidence of that. Still, even the prospect is added incentive to brush and floss.