Brushing your teeth, flossing and visiting the dentist keep your teeth and gums healthy, but maintaining good oral hygiene is also important for your overall health, research suggests.
In some cases, oral problems can be a symptom of other diseases, such as diabetes. Research has also linked gum disease to heart disease, premature birth and even knee arthritis.
"The mouth is a portal into the rest of the body," said Dr. Donald Ratcliffe, chairman of the department of dental medicine at Staten Island University Hospital in New York. Growing research shows "there's a relationship between the bacteria — and the inflammation that bacteria cause in the mouth — [and] a lot of other diseases," he said. [5 Experts Answer: Is Flossing Really Necessary?]
Here are several ways that oral hygiene is related to the rest of your health.
Diabetes
One complication of diabetes is gum disease. Diabetes can change in blood vessels in ways that impair blood flow, which in turn, weakens gums and makes them more vulnerable to infection, according to Ohio State University Medical Center. Diabetes also increases blood sugar levels, and if these increases aren't properly managed, high glucose levels in the mouth can encourage bacterial growth.
A 2011 study found that dentists could identify people with diabetes 73 percent of the time based on only a count of their missing teeth and an examination of the abnormal openings between the tooth and gums. If the dentists took into account results from blood tests, the accuracy increased to 92 percent.
More than 7 million people with diabetes don't know they have it, and dentists could play a role in identifying those with the disease, the study concluded.
Heart disease
Several studies have linked periodontal disease, which is a chronic bacterial infection of the gums, with an increased risk of heart attack and stroke.
For example, a 2003 review of nine previous studies found that people with periodontal disease had a 19 percent increased risk of developing cardiovascular disease, compared with people without periodontal disease.
The reason for the link is not clear. Some researchers have suggested that periodontal disease increases inflammation in the body, which in turn, is a risk factor for heart disease. Others have suspected that bacteria from the mouth may find their way into the bloodstream, and contribute to plaque buildup in arteries. A 2005 study from researchers at the University of Florida even found oral bacteria inside artery plaque.
However, it's too soon to say the bad oral health actually causes heart disease. The two conditions share several risk factors, including smoking, old age and diabetes, which may explain why they occur together, according to the American Heart Association. Last year, the AHA said there is no conclusive evidence that gum disease actually causes heart disease, or that dental treatment prevents heart disease.
Still, for some heart conditions, the link between oral health and heart disease is more established. Endocarditis, a condition that involves inflammation of the lining of the heart valve, is most commonly caused by bacteria (including oral bacteria) that enter the bloodstream and travel to the heart. If you have poor oral hygiene, activities such as brushing your teeth may tear the oral tissue, and allow bacteria to enter the bloodstream, according to the Mayo Clinic. But the condition is rare in people with healthy hearts.
Oral health and pregnancy
Studies have linked periodontal disease in pregnant women with an increased risk of preterm birth. While these studies cannot prove that gum infections cause preterm birth, some researchers have speculated that the immune response to such infections might trigger preterm labor.
However, treating periodontal disease does not seem to reduce the risk of early delivery.
A 2011 study from Australia found that women with periodontal disease took longer to become pregnant than those without the condition.
Knee arthritis
A 2012 study suggested oral bacteria may contribute to some cases of knee osteoarthritis and rheumatoid arthritis. The researchers tested the synovial fluid, which is found in the joints, of 36 people with knee arthritis. Five of the patients had gum bacteria in their fluid. For two of the patients, the bacteria found in the joint fluid was a genetic match to bacteria found in the mouth.
Bacteria in the joints could exacerbate arthritis, the researchers said. However, because the study was small, more research is needed to prove that mouth bacteria can cause or worsen arthritis.
Respiratory illness
Bacteria in the mouth may also find their way to the lungs if a person breathes in tooth plaque, Ratcliffe said. This may cause pneumonia or other severe respiratory disease. The risk for this happening is highest in people with underlying conditions, such as conditions that compromise the immune system, he said.
Bacteria in the airways can also worsen chronic lung conditions, such as emphysema, according to the University of Maryland Medical Center.
Full medical history
Often, people might not think about the ways that their oral health affects the rest of their body. In fact, many people neglect to provide their full medical history to their dentist, such as medications they are taking, Ratcliffe said.
"People don't believe that we need to know some of that information, because they don't think it's related to dentistry," he told LiveScience.
For instance, people taking medications for breast cancer, prostate cancer, or osteoporosis may not realize that these drugs affect the ability of bone to heel. "If we do an extraction, the bone may not heel probably," which could result in an infection, Ratcliffe said.
Patients should be educated about the importance of disclosing their medication history to their dentist "so they don't get hurt," Ratcliffe said.
Follow Rachael Rettner @RachaelRettner. Follow LiveScience @livescience, Facebook & Google+. Original article on LiveScience.
