Since the pandemic began, plenty of research has suggested a role for the mouth in how COVID happens – particularly that good oral health and hygiene may be protective to some degree, at least lessening the risk of severe illness.

Now, a new paper in the Journal of Oral Medicine and Dental Research lends additional weight to that idea in proposing a different route of infection than has been emphasized before.

Looking at x-rays of the lungs, the researchers note that the evidence doesn’t seem to support the notion that COVID is first and foremost a lung infection. Instead, it suggests the problem is vascular – involving the circulation – resulting in respiratory effects.

“Saliva is a reservoir of SARS-CoV-2,” they note,

thus any breach of the immune defenses of the mouth may facilitate entrance of the virus to the vasculature through the gingival sulcus or periodontal pocket. From the oral vasculature, the virus would pass through veins of the neck and chest, and reach the heart, being pumped into pulmonary arteries, and to the small vessels in the lung periphery.

In other words, the virus may enter the bloodstream through the gums, and from there, travel to the heart. From there, it’s a short path to the lungs.

“Poor oral hygiene and dental plaque accumulation may further intensify this pathway,” the authors add, lining up with earlier research suggesting that gum disease may in fact be a risk factor for worse COVID outcomes.

Although to an extent the passage of the virus across the mucous membranes of the nasal passage and mouth may occur in healthy individuals, the presence of poor oral health could act as a risk factor to identify individuals more likely to develop COVID-19 lung disease, or those who might progress to severe disease leading to intensive care admission, mechanical ventilation, or death. The co-morbid presence of periodontitis [severe gum disease] has been shown to represent an independent risk factor for other systemic inflammatory diseases that are characterized by hyper-inflammation and oxidative stress.

More research must be done to confirm or disprove this hypothesis, of course, and to that end, the authors suggest a few ways of testing it. We look forward to seeing if such research is indeed done.

In the meantime, the current paper may offer yet more motivation to stay vigilant about your home care and make choices that support good oral health. Considering all of the other health problems that gum disease has been linked to, there’s certainly nothing to lose while very much to gain.

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