Our mouth is one of the most diverse habitats in our body: it is home to more than 700 species of bacteria, not to mention yeasts, viruses and a number of protozoa. This microbial community constitutes the oral microbiota which, like the intestinal microbiota, can influence our health.
The most common diseases caused by changes in the oral microbiota are tooth decay and gum disease. But over the years, scientists have discovered numerous clues suggesting that the oral microbiome is also linked to many other serious problems elsewhere in our bodies.
Respiratory diseases
The respiratory tract begins in the mouth and ends in the lungs. Therefore, it is not surprising that in the event of proliferation of the oral microbiota, some of the microbes that compose it can be inhaled and end up in the lungs.
This situation frequently leads to pneumonia. The risk of developing this infection, often fatal in the elderly, has been associated with poor oral hygiene, which leads to the proliferation of certain bacteria such as Streptococcus pneumoniae et Haemophilus influenzae.
Work has shown that improving oral hygiene in retirement homes, as well as the provision of dental care (carried out by professionals) could reduce the number of cases of pneumonia by a third. It is also important to ensure the cleanliness of dental appliances and other oral devices (mouthguards for athletes, for example).
Some research has also highlighted an association between poor oral health and chronic obstructive pulmonary disease (COPD), as well as with alterations in respiratory function, due to changes in the oral microbiota that result from such a situation.
Heart disease
Chronic periodontitis is one of the most common conditions caused by the oral microbiota. This disease results from the proliferation, due to inadequate oral hygiene, of bacteria present in the space between the gums and the teeth. It results in a destructive inflammatory response, which attacks the bones and tissues supporting the teeth, leading to their loosening and then their loss.
For years, researchers have noted that there is a significant statistical association between periodontitis and cardiovascular disease. This could be explained by common risk factors between these different conditions. So, periodontitis and heart disease are both more common among smokers.
Another hypothesis is that periodontitis bacteria may be able to travel to the heart and cause infection there. However, for now, scientists are still trying to elucidate the mechanisms that could be at work.
As mentioned previously, periodontitis triggers a strong inflammatory response. Remember that inflammation is one of the ways our body has to fight infections: it is accompanied by the production of cells and various chemical signals necessary for the proper functioning of the immune response. But too much inflammation can be damaging. According to some researchers, the inflammation caused by periodontitis could damage the cardiovascular system.
Periodontitis triggers significant inflammation.
Notably, one study found that treating periodontitis reduced levels of inflammation in the blood and significantly improved arterial function. Other work has also shown that treating periodontitis reduces overall levels of inflammation in the body.
This research demonstrates that oral disease can have significant effects on the function of tissues elsewhere in the body. Since many people live with untreated periodontitis, sometimes for decades, the deleterious effects on their health can potentially be significant in the long term.
Colon Cancer
Oral bacteria are able to travel through the stomach into the intestines. In general, the microbes that usually live in the mouth are not well adapted to these new environments, and they die quickly there. However, in 2014, two studies showed that bowel cancer tumors were heavily colonized by a species of bacteria called Fusobacteriumwhich is normally found in dental plaque.
This work also showed that Fusobacterium exhibits a high affinity for malignant cancer cells. This bacteria is in fact capable of binding closely to the surface of cancer cells, and of invading the tumor. Since then, multiple studies have confirmed that Fusobacterium can colonize tumors throughout the gastrointestinal tract.
Research has also shown that colon cancer patients heavily colonized with Fusobacterium respond less well to chemotherapy and have a shorter life expectancy compared to those who are not colonized. This could be because tumors infected with Fusobacterium are more aggressive and therefore more likely to spread than those that are not infected by bacteria.
Research continues to better understand this relationship, and to determine whether people at risk of bowel cancer could benefit from vaccination against this oral microbe.
Alzheimer’s disease
One of the most controversial links between oral health and pathology concerns Alzheimer’s disease.
In people with Alzheimer’s disease, suffering from chronic periodontitis is associated with greater cognitive decline. However, because periodontitis and Alzheimer’s disease are both associated with aging, it is difficult to determine whether there is indeed a cause and effect relationship.
However, in 2019, work revealed that the brains of people with Alzheimer’s disease were colonized by Porphyromonas gingivalis, one of the main bacteria responsible for periodontitis. The fact that the brain, an organ normally protected from microorganisms, can be infected by oral bacteria nevertheless remains very controversial, and additional research on this subject is necessary.
In addition, as in the context of heart disease, some specialists have also suggested that the inflammation caused by periodontitis suffered by patients with poor oral health could be an aggravating factor in Alzheimer’s disease.
The importance of good oral health
Poor oral hygiene can therefore have multiple harmful consequences for health. However, it is possible to control your oral microbiome, and thus prevent related diseases.
To do this, it is necessary to establish a daily oral hygiene routine. This involves brushing your teeth twice a day, as well as regular flossing, in order to control plaque and reduce the incidence of cavities and gum disease. As for the latter, quitting smoking can greatly reduce the risk of their occurrence. It is also advisable to visit a dentist at least once a year, in order to have a scaling carried out and to benefit from advice from a professional.
Following these recommendations will make your smile brighter, and could also extend your life expectancy by a few years…
