Proposed Mechanisms for the Relationship between Periodontal Diseases and the Severity of Covid-19: Common Pathogens, Inflammatory Mediators, and Risk Factors.

Periodontal disease (PD) is a chronic inflammatory disease with some cytokine involvement, associated with several risk factors such as diabetes, obesity, etc., Corona Virus Disease 2019 (COVID-19), a new viral infection, also appears to be related to cytokine storm and similar risk factors. In this review, we intend to evaluate the possible relationship between PD and COVID-19. For data collection, English literature was searched in databases including PubMed and Google Scholar. The keywords searched were COVID-19, SARS-CoV-2, PD, respiratory Impact of Oral pathogens on respiratory diseases: Epidemiological studies indicated that oral pathogens are related to acute and chronic lung disease, and dental plaque is a likely reservoir for respiratory pathogens. Viral presence in the periodontal pocket: SARS-CoV-2 may be released from infected periodontal cells into periodontal pockets. Common inflammatory mediators: Several studies showed that the serum levels of interleukins (IL)-1, 6, 17, etc., increase in most patients with severe COVID-19. C-reactive protein (CRP) and endothelin 1(ET-1) may also be related to COVID-19 progression, and these mediators also increase in periodontitis. Common risk factors: Due to studies, diabetes mellitus (DM), obesity, aging, and male sex are the most important risk factors common between PDs and COVID-19 and may affect treatment outcomes and prognosis. PD seems to play a significant role in exacerbating COVID-19 and even affects the mortality rate of disease.