Saliva, a helpful diagnostic tool
Your doctor can collect and test saliva to detect for a variety of substances. For example, cortisol levels in saliva are used to test for stress responses in newborn children. And fragments of certain bone-specific proteins may be useful in monitoring bone loss in women and men prone to osteoporosis. Certain cancer markers are also detectable in saliva.
Routine saliva testing can also measure illegal drugs, environmental toxins, hormones and antibodies indicating hepatitis or HIV infection, among other things. In fact, the ability to detect HIV-specific antibodies has led to the production of commercial, easy-to-use saliva test kits. In the future, saliva testing may replace blood testing as a means of diagnosing and monitoring diseases such as diabetes, Parkinson's disease, cirrhosis of the liver and many infectious diseases.
How saliva disables bacteria and viruses
Saliva is also one of your body's main defenses against disease-causing organisms, such as bacteria and viruses. It contains antibodies that attack viral pathogens, such as the common cold and HIV. And it contains proteins called histatins, which inhibit the growth of a naturally occurring fungus called Candida albicans. When these proteins are weakened by HIV infection or other illness, candida can grow out of control, resulting in a fungal infection called oral thrush.
Saliva also protects you against disease-causing bacteria. It contains enzymes that destroy bacteria in different ways, by degrading bacterial membranes, inhibiting the growth and metabolism of certain bacteria, and disrupting vital bacterial enzyme systems.
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The problem with dental plaque
Though your saliva helps protect you against some invaders, it can't always do the job. More than 500 species of bacteria thrive in your mouth at any given time. These bacteria constantly form dental plaque ” a sticky, colorless film that can cling to your teeth and cause health problems.
If you don't brush and floss regularly to keep your teeth clean, plaque can build up along your gumline, creating an environment for additional bacteria to accumulate in the space between your gums and your teeth. This gum infection is known as gingivitis. Left unchecked, gingivitis can lead to a more serious gum infection called periodontitis. The most severe form of gum infection is called acute necrotizing ulcerative gingivitis, also known as trench mouth.
Bacteria from your mouth normally don't enter your bloodstream. However, invasive dental treatments ” sometimes even just routine brushing and flossing if you have gum disease ” can provide a port of entry for these microbes. Medications or treatments that reduce saliva flow and antibiotics that disrupt the normal balance of bacteria in your mouth can also compromise your mouth's normal defenses, allowing these bacteria to enter your bloodstream.
If you have a healthy immune system, the presence of oral bacteria in your bloodstream causes no problems. Your immune system quickly dispenses with them, preventing infection. However, if your immune system is weakened, for example because of a disease or cancer treatment, oral bacteria in your bloodstream (bacteremia) may cause you to develop an infection in another part of your body. Infective endocarditis, in which oral bacteria enter your bloodstream and stick to the lining of diseased heart valves, is an example of this phenomenon.
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Plaque as cause of common conditions?
Long-term gum infection can eventually result in the loss of your teeth. But the consequences may not end there. Recent research suggests that there may be an association between oral infections ” primarily gum infections ” and poorly controlled diabetes, cardiovascular disease and preterm birth. More research is needed to determine whether oral infections actually cause these conditions.
Poorly controlled diabetes: If you have diabetes, you're already at increased risk of developing gum disease. But chronic gum disease may, in fact, make diabetes more difficult to control, as well. Infection may cause insulin resistance, which disrupts blood sugar control.
Cardiovascular disease: Oral inflammation due to bacteria (gingivitis) may also play a role in clogged arteries and blood clots. It appears that bacteria in the mouth may cause inflammation throughout the body, including the arteries. This inflammation may serve as a base for development of atherosclerotic plaques in the arteries, possibly increasing your risk of a heart attack or stroke. Some research suggests that people with gum infections are also at increased risk of heart attack and stroke. The more severe the infection, the greater the risk appears to be. And gum disease and tooth loss may contribute to plaques in the carotid artery. In one study, 46 percent of participants who'd lost up to nine teeth had carotid artery plaque; among those who'd lost 10 or more teeth, 60 percent of them had such plaque.
