The unexpected dangers of gum disease

Gum disease is common and unpleasant, but, according to a growing body of evidence, it could also play a role in a surprising range of seemingly unrelated health problems.

Cleaning your teeth may be even more important than you thought.

Plaque — a sticky substance that contains bacteria — builds up on teeth. If it is not brushed away, the bacteria can irritate the gums.

The gums may then become swollen, sore, or infected; this is referred to as gingivitis.

In general, gum disease can be treated or prevented by maintaining a good oral health regime.

However, if it is left to develop, it can result in periodontitis, which weakens the supporting structures of the teeth.

Gum disease, which is also called periodontal disease, is widespread. According to the Centers for Disease Control and Prevention (CDC), almost half of adults in the United States have some degree of gum disease.

The mechanisms behind periodontal disease are relatively well-understood, and newer research shows that this health problem may play a role in the development of a number of other conditions, including Alzheimer's disease, cancer, and respiratory disease.

In this Spotlight, we will cover some of the surprising links between gum disease and disparate health issues.

Gums and the brain

Although spatially the gums are near the brain, one wouldn't normally associate dental complaints with neurological conditions.

However, some studies have found a link between periodontal disease and tooth loss and cognitive function. One study looking at cognitive performance followed 597 men for up to 32 years. The authors conclude:

"Risk of cognitive decline in older men increases as more teeth are lost. Periodontal disease and caries, major reasons for tooth loss, are also related to cognitive decline."

Researchers have also linked periodontal disease with an increased buildup of beta-amyloid in the brain — the neurological hallmark of Alzheimer's.

Other experiments have produced evidence that one type of bacteria commonly found in cases of periodontitis — Porphyromonas gingivalis — can be found in the brains of individuals with Alzheimer's.

Following on from that discovery, in a more recent study, researchers showed that P. gingivalisinfection boosts the production of beta-amyloid in the brain.

In this study, the researchers paid particular attention to an enzyme produced by P. gingivaliscalled gingipain. They found that this protease was toxic to tau, another protein that plays a pivotal role in Alzheimer's.

It is worth noting that other researchers have concluded that beta-amyloid is produced in response to a pathogen. The way we view Alzheimer's is slowly changing.

In the future, scientists hope that targeting gingipain enzymes might help stop neurodegeneration in some people with Alzheimer's disease. They have already designed a gingipain inhibitor, which they are testing in humans.

The researchers hope that it will "slow or prevent further neurodegeneration and accumulation of pathology in [Alzheimer's disease] patients."

The heart of the matter

Although not everyone with heart disease has gum disease, and not everyone with gum disease has heart disease, there does appear to be a correlation.

Of course, individuals who smoke or drink large quantities of alcohol are more likely to have both oral and cardiovascular issues, but there appears to be more to the relationship than shared risk factors alone.

Whether gum disease is an independent risk factor for heart disease is still being discussed, but there are some theories as to how the two might be related.

What links the gums with the heart?

Some think that the link could involve inflammation.

Primarily, inflammation is a response to irritants or pathogens; it is a protective mechanism. However, if it continues for an extended period, it can damage tissues and organs.

It is possible that inflammation in the gums sets off a cascade that, ultimately, sparks inflammation in the cardiovascular system.

Alternatively, the link between heart and gum diseases may be due to bacteria.

Bacteria in the gums can enter the blood supply and be propelled to distant destinations, including the heart, where they can cause inflammation and damage.

As evidence that this is possible, researchers have shown that P. gingivalis is the most commonly found bacterial species in the coronary artery.

Cancer risk increase

Once again, gum disease and cancer do not, on the surface, appear to have much in common.

A study published in 2008 investigated tooth loss and cancer in 48,375 men. The authors concluded that there was, indeed, a link between gum disease and cancer. They write:

"Periodontal disease was associated with a small, but significant, increase in overall cancer risk."

Another, more recent, study involving more than 68,000 adults found a strong association between gum disease and overall cancer risk; the link was also significant between gum disease and pancreatic cancer.