Time and time again, researchers keep finding a strange link between oral hygiene and the health of a person's heart.
It could simply be a coincidence, or it could indicate that gum disease and tooth loss are closely tied to our cardiovascular system. Right now, we don't have enough evidence to say for sure - but there's a new study shedding some light on the issue.
While many studies have shown a link between oral hygiene and heart issues, research from 2017 analysing data from nearly a million people found no relationship between tooth loss and cardiovascular disease.
Obviously, one study isn't enough to topple the entire idea, but further research is required before we can say anything for sure, especially given recent intriguing results. A large new study on 161,286 people in Korea has once again found that brushing your teeth is linked to a lower risk of atrial fibrillation (a type of arrhythmia) and heart failure.
During a 10.5 year follow-up, adults between the ages of 40 and 79 who brushed their teeth three or more times a day had a 10 percent lower risk of atrial fibrillation and a 12 percent lower risk of heart failure.
What's more, these findings were independent of age, sex, socioeconomic status, regular exercise, alcohol consumption, body mass index, and similar health issues such as hypertension.
To be clear, the researchers did not explore the exact mechanism underlying tooth brushing and cardiovascular issues, if such a mechanism even exists. But already there are several thoughts on what could be the cause.
While it might sound crazy, what goes on in your mouth can have a strong impact on your overall health, and it's something we're only just coming to realise. For example, recent studies have indicated that the cause of Alzheimer's disease could be linked to bacteria involved in gum disease.
When it comes to the plaque in our arteries, the plaque on our teeth also seems to matter. One theory is that bacteria living in between the teeth and the gums can enter the bloodstream and change the gut microbiome. This can then trigger systemic inflammation, which is known to facilitate valve injury, myocardial damage, and even heart failure.
But just as one study cannot topple these ideas, neither can one prove them. While the research from Korea follows a large group over a long period of time, these strengths are diminished by several limitations.
Subjects were asked to report their own brushing patterns; only individuals in the Asian population were considered; no actual electrocardiography or echocardiographic findings were used; and the presence of periodontal diseases was never confirmed.
Plus, while the study was done over a long period of time, it was retrospectively analysed, which means identifying a causal relationship was impossible.
Nevertheless, the conclusions match results from last year, which found that those who brushed their teeth less than twice a day had a 3-fold increase in the risk of having - or dying from - a heart attack.
At the time, cardiologist Ann Bolger warned that such results do not prove causation, and it's entirely possible that those who are attentive to their dental health are also careful about health in other parts of their body, including making lifestyle choices that benefit their cardiovascular fitness.
Even now, an editorial on this latest study from two independent experts warns that it's still too early to draw any more inferences.
"The causality of these associations is unclear, and it is certainly too early to recommend tooth brushing for the prevention of [atrial fibrillation] and [heart failure]," they write.
"While the role of inflammation in the occurrence of cardiovascular disease is becoming more and more evident, intervention studies are needed to define strategies of public health importance."
As of now, there's no proof that treating gum disease will prevent cardiovascular disease, but given these compelling results, experts say the potential link is just another reason to be vigilant about your oral health.
The study was published in European Journal of Preventive Cardiology.