GOOD ORAL HYGIENE PROTECTS AGAINST A LOT: Better oral health may help keep severe COVID-19 at bay, study says. “Previous research has found an association between poor oral hygiene and increased inflammation and heart disease, and COVID-19 severity has also been linked to an inflammatory response, the study authors noted.”

That said, this study is small, and I’d call it suggestive rather than proof. But you should be brushing and flossing anyway.