Revisiting the importance of oral health management based on the lessons learned from the COVID-19 pandemic.

The oral cavity is the starting point and an integral part of the respiratory system. Oral bacteria are deeply involved in the onset and aggravation of lower respiratory tract diseases, including aspiration pneumonia, influenza, and chronic obstructive pulmonary disease. Oral health conditions, such as periodontal disease, influence the severity of coronavirus disease 2019 (COVID-19). Oral bacteria can be detected in the respiratory organs of patients with COVID-19, and the composition of oral bacterial flora may be altered. Aspiration pneumonia is common among patients with COVID-19 who are advanced in age or have underlying diseases due to poor oral hygiene management, fever, and other issues. While findings from further studies are awaited, maintaining a healthy oral cavity can prevent COVID-19 onset and aggravation. In addition to routine management of oral microflora at home and maintenance of periodontal health in dentistry, medical-dental collaboration is crucial for a prompt response to future pandemics, as humans have just experienced in COVID-19.