OTTAWA -- An international study led by researchers at McGill University has found that those with poor dental hygiene tend to experience more severe COVID-19 symptoms.

Using the digital medical and dental records from 568 Qatari patients with COVID-19, the researchers found that those with periodontitis, better known as gum disease, were more likely to suffer from COVID-19 complications.

Specifically, the patients were 3.5 times more likely to be admitted to the intensive care unit, 4.5 times more likely to require a ventilator and 8.8 times more likely to die from COVID-19 compared to those without gum disease.

Of the 258 patients with gum disease, 33 experienced complications during the infection, while just seven of the 310 patients with healthy gums experienced a complication.

“Looking at the conclusions of our study we can highlight the importance of good oral health in the prevention and management of COVID-19 complications,” Belinda Nicolau, one of the study’s authors and professor at McGill’s school of dentistry, said in a news release.

“There is a very strong correlation between periodontitis and disease outcome.”

According to the Canadian Dental Association (CDA), gum disease occurs when plaque is not removed from the teeth and turns into tartar, which can lead to infection where the teeth meet the gums. If not treated, it can lead to painful infections, or loss of teeth.

The CDA adds that seven out of every 10 Canadians will develop gum disease at some point in their life, but it can be prevented with twice-daily brushing and daily flossing.

Dr. Meggan Schiffner, the lead dentist of Sierra Dental Calgary, said poor oral hygiene increases your risk factors for developing inflammation, your cardiac health, diabetes, premature births, and cancer.

The study -- published in the Journal of Clinical Periodontology back in February -- also found that patients with gum disease had elevated levels of D-dimer and C-reactive protein in the blood. Both are biomarkers that indicate when there is increased inflammation in the body.

The researchers believe high levels of these biomarkers may explain why patients are experiencing more severe reactions to COVID-19.

“Periodontitis causes inflammation of the gums and, if left untreated, that inflammation can spread throughout the body,” said Wenji Cai, co-author of the study and a PhD student from McGill’s dental school.

“In patients with severe cases of COVID-19, the virus causes an inflammatory response that can lead to complications such as being intubated or even death. Our research shows that periodontitis can exacerbate this.”

The researchers note that further study needs to be conducted in the area of COVID-19 and gum disease treatments to better understand the connection between the two. They are also calling for further research to understand what exactly might be causing this connection to better understand how to treat it.