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Poor Oral Health and COVID-19

Can poor oral health increase the risk of complications from COVID-19?

Can poor oral health increase the risk of complications from COVID-19? You’ve likely been wondering this—after all, the link between oral health (especially periodontal health) and systemic health has been examined for years now. In fact, the connection is quite strong with some conditions (diabetes, cardiovascular disease, respiratory infections, obesity, chronic kidney disease, and more).1 Based on decades of research and our own clinical experience, it seems plausible that the mouth/body connection might also play a role in severe complications from COVID-19.

A newly published article in The British Dental Journal examines how increased bacterial load may impact the severity of COVID-19.2 While COVID-19 is a viral infection, the authors of the article stipulate that high levels of bacteria (a “bacterial superinfection”) could compound the effects of the virus. Because oral bacteria can be aspirated into the lungs and produce cytokines, it’s possible that the cytokine storm seen in severe cases of COVID-19 is magnified by these pathogens. Here are some potential pathways the authors outlined:

  • The four primary risk factors for developing severe COVID-19 are diabetes, heart disease, hypertension, and obesity. Poor oral hygiene and periodontitis can exacerbate these conditions. Further, these health problems can disrupt the oral microbiome.
  • Certain members of the population develop moderate or severe complications from COVID-19 without having the primary risk factors noted above. Therefore, bacterial imbalance in the oral microbiome could play a role.
  • Respiratory viral infections, such as COVID-19 and H1N1, can predispose patients to bacterial superinfections, leading to more severe disease and increased mortality. In some instances, the bacterial superinfection is the cause of death and not the virus itself.3
  • Bacteria in the mouth can be aspirated into the lungs. In addition, the cytokines, such as IL-1 and TNF, found in periodontally diseased tissues can be present in saliva and then aspirated, causing inflammation or infection within the lungs, thus contributing to the “cytokine storm” found in patients with severe COVID-19.
  • Periodontal bacteria (most notably Prevotella, Staphylococcus, and Fusobacterium) are implicated in systemic inflammation, bacteremia, pneumonia, and even death. These pathogens have also been found in the metagenome of patients severely infected with SARS-CoV-2.

In the conclusion, the authors suggest the following: “Meanwhile, we recommend that oral hygiene be maintained, if not improved, during a SARS-CoV-2 infection in order to reduce the bacterial load in the mouth and the potential risk of a bacterial superinfection. We recommend that poor oral hygiene be considered a risk to post-viral complications, particularly in patients already predisposed to altered biofilms due to diabetes, hypertension, or cardiovascular disease.”2 Once again, the connection to oral health and overall health deserves attention.

Jill Rethman, RDH, BA
Editor in Chief


  1. Nazir M. Prevalence of periodontal disease, its association with systemic diseases and prevention. Int J Health Sci (Qassim). 2017;1172–1180.
  2. Sampson V, Kamona M, Sampson A. Could there be a link between oral hygiene and the severity of SARS-CoV-2 infections? Br Dent J. 2020;228:971–975.
  3. Cox MJ, Loman N, Bogaert D, O’Grady J. Co-infections: potentially lethal and unexplored in COVID-19. Lancet. 2020;1:e11.

From Dimensions of Dental Hygiene. July/August 2020;18(7):6.

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