In one person's mouth, the number of bacteria can easily exceed the number of people who live on Earth. This is according to Sigmund Socransky, a dental researcher at the Forsyth Dental center in Boston, who also asserts that in a plaque-free mouth, 1,000 to 100,000 bacteria live on each tooth surface, but when plaque is present, as many as 100 million to one billion bacteria may be growing on each tooth. It staggers the mind. But what does it do to the body?

Although many of these bacteria are beneficial, some can be quite harmful. In particular, the bacteria that flourish in your mouth when you have periodontal (gum) disease can permanently damage your gums, as well as the bone and connective tissue that support your teeth; this can result in tooth loss. But these bacteria impact more than just your mouth.

Researchers are finding that that they can worsen—or even cause—problems elsewhere in the body. Strokes, cardiac conditions, diabetes, stomach ulcers and pneumonia have all been shown to be more prevalent or to worsen in those suffering from gum disease. 

Heart attacks

University of Buffalo researcher Dr. Robert J. Genco found that, over a ten-year period, those with gum disease were three times more likely to suffer a heart attack. The precise reason for this causal relationship is still a mystery, but Genco suggests that the disease-causing bacteria may enter the bloodstream through tiny tears in the gums, then infect the liver and cause it to produce proteins that clog the arteries. Another possibility, Genco said, is that the bacteria may infect the arteries of the heart directly, producing blockages. He bases these theories on the fact that the oral bacteria porphyromonas gingivalis have been found in the arteries of those suffering from blockages and subsequent heart failure.

Infective endocarditis

Oral bacteria can also be life-threatening to those with a heart valve ailment. Because of this, those with afflictions such as mitral valve prolapse, rheumatic heart disease, a congenital heart defect, or a heart murmur may need to take antibiotics prior to receiving any dental treatment that might dislodge harmful bacteria into the bloodstream. The antibiotics are a precautionary measure to protect against infective endocarditis, a rare and sometimes fatal disease that can damage the valves and tissues of your heart. The bacteria from plaque—S. sanguis—is one of the most frequent causes of endocarditis, according to studies at the University of Minnesota in Minneapolis.

Strokes

University of Buffalo researchers studied the health histories of nearly ten thousand people between the ages of 25 and 75 and found that the 35 percent who had severe gum disease were also twice as likely to have suffered a severe stroke. Why? Dr. John Marler of the National Institute of Neurological Disorders and Stroke said that oral bacteria can cause fatty deposits in the carotid arteries in your neck. If these deposits break loose and travel through your bloodstream into your brain, they can lodge there, blocking blood flow to the brain and causing a stroke.

Diabetes

Periodontal disease probably doesn't directly cause diabetes, said Dr. Perry R. Klokkevold of the UCLA School of Dentistry, but it can make managing the disease much more difficult. The bacterial infection caused by periodontal disease diminishes the body's ability to manage its insulin levels, greatly upsetting a diabetic's blood sugar levels. This can result in complications such as blindness, heart problems, and kidney disease.

"We know that having gum disease will worsen diabetes," said Dr. Christopher Saudek, a diabetes specialist at Johns Hopkins University in Baltimore. "People with diabetes should be careful to keep their gums healthy."

Ulcers

Some stomach ulcers are believed to be caused by a bacterium called helicobacter pylori. Dr. Sherie Dowsett of the Indiana University School of Dentistry said that this bacteria is often found in dental plaque. From the teeth, the bacteria can migrate to the stomach, where they eat small holes in the stomach's lining, producing painful ulcers.

Pneumonia

Bacteria that reside in plaque are inhaled into your lungs each time you draw a breath. Among these are chlamydia pneumoniae and pseudomonas aeruginosa, two strains of bacteria notorious for causing respiratory disease. Normally, the body's immune system fights off these harmful invaders. But sometimes, such as after surgery or during an illness, the immune system's resistance to infection is low. It's then that these opportunistic bacteria attack the lungs and cause bacterial pneumonia, an infection that kills about 83,000 people each year.

The solution? Destroy their habitat

Daily brushing and flossing removes much of the plaque—the destructive bacteria's cozy habitat within your mouth. Gently brushing your tongue and the roof of your mouth removes even more. These simple acts of oral hygiene keep the bacteria count down to a more manageable level and minimize the chance that they'll move on to wreak havoc elsewhere in your body. And of course, there's the huge added benefit of cleaner, healthier teeth, fresher breath, and gums free from periodontal disease. You've got everything to gain, and nothing to lose, by simply devoting about ten minutes a day to ridding your mouth of plaque.

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Sources: The U.S. National Institute of Dental Research

The University of Buffalo, Buffalo, NY
The University of Minnesota, Minneapolis, MN
The UCLA School of Dentistry, Los Angeles, CA
Indiana University School of Dentistry, Indianapolis, IN
Johns Hopkins University, Baltimore, MD