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Superinfections, COVID-19 severity, and oral health: Are there connections?

Oct. 1, 2020
Karen Davis, BSDH, RDH, says perhaps our message should be that visiting the dental hygienist may help prevent severe COVID-19 infections. Here’s why.

While strategies such as social distancing, hand hygiene, and wearing masks in public can help reduce the spread of this virus, perhaps our message should be that visiting a dental hygienist may help prevent severe COVID-19 superinfections. Here’s why.

Individuals with preexisting conditions, including periodontal disease, may be at increased risk of developing superinfections should they acquire the SARS-CoV-2 virus. Emerging evidence suggests that particular periodontal pathogens may contribute to an overabundance of pathogens circulating systemically in those with severe COVID-19 infections, contributing to a superinfection and subsequent serious outcome.1 While more scientific evidence is needed, it does remind us that optimal oral hygiene and maintaining routine preventive dental care have never been more important.

Do you think the average dental patient is aware of this potential oral connection to severe COVID-19 superinfections? Those of us in the dental profession need to speak up, inform our overdue recall patients, and help get the word out that maintaining good oral hygiene could save more than teeth. 

Dental professionals already know that poor oral hygiene and active periodontal infection are associated with adverse systemic conditions—such as heart attack, stroke, diabetes, and dementia—which can interrupt life spans substantially. Historically, these conditions collectively have taken far more lives than the SARS-CoV-2 virus, but today people listen differently to messages about infectious and potentially deadly viruses, don’t they?

Emerging evidence of superinfections

Risks leading to higher morbidity quickly emerged following the outbreak of the global COVID-19 pandemic. A recent retrospective study on COVID-19 provides insights: increased age (mean age of 69), male gender (70% of deaths), and underlying chronic health conditions (48% of cases) are correlated to more severe outcomes and mortality.2 The underlying chronic health conditions that have been identified include hypertension, diabetes, heart disease, and recently obesity.1,2 However, there appears to be a significant number of individuals who present with moderate to severe outcomes from SARS-CoV-2 with zero underlying health conditions.3 A high percentage (80%) of patients admitted into the ICU with COVID-19 present with extremely high bacterial loads.4 At least one study reveals that more than 50% of the deaths of patients suffering from severe COVID-19 also had bacterial superinfections requiring antibiotics.5 

Homeostasis is present both in the oral cavity and the lungs when there is a balance in the microbiota that thrives in the mucosal environments. Periodontal pathogens such as Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis have been identified as key pathogens contributing to periodontal progression and have been associated with several other chronic inflammatory conditions contributing to adverse outcomes. Similar to the imbalance that happens as oral biofilms become pathogenic and promote inflammation, microbial overgrowth in lung tissue can easily develop when a shift toward illness or systemic infection takes place.5 Periodontal pathogens can be aspirated into the lower tract of the respiratory system, initiating or worsening a respiratory condition such as pneumonia.6

A systematic review published in 2008 confirmed that good oral hygiene can help prevent respiratory infections, estimating that one in 10 pneumonia- related deaths could be prevented in the elderly by simply improving oral hygiene.7 It is also possible that improving oral hygiene might reduce risks for a severe outcome of another respiratory infection: COVID-19.

A recent publication from the British Dental Journal questions a potential link between oral hygiene and the severity of SARS-CoV-2 infections.5 The article references a robust amount of evidence confirming that reduction of periodontal disease can reduce the risk of pneumonia by reducing periodontal pathogens. Data such as these confirm the interrelationship between the oral cavity and respiratory infections, but it may be more than just a bacterial connection. Cytokines, such as IL-1, IL-6, and TNF, increase during periodontal disease.8 These enzymes produced during oral inflammation and circulating systemically can also modify lung mucosal tissue, increasing adhesion and colonization of respiratory pathogens and thereby increasing respiratory inflammation.1 Some patients with severe COVID-19 have higher levels of circulating inflammatory cytokines.9 It stands to reason that poor oral hygiene and active periodontal disease could promote pathogens leading to superinfections in COVID-19 patients. It is also possible that the overabundance of inflammatory enzymes might contribute to the cytokine storm documented in some patients with more severe COVID-19 outcomes. 

Messages to patients

As more evidence becomes available, we will have a better understanding of the oral connection related to the SARS-CoV-2 virus, but today we have a great opportunity to send social media messages, include banners with patient emails or newsletters, and verbally communicate that daily and professional dental hygiene care are critical to patients’ health. Now is the time to remind patients that they need to use their power toothbrush for a full two minutes during each use and change the brush head every three months. Patients must commit to daily interproximal cleaning, where most periodontal disease begins. If they are past due for their preventive or maintenance dental hygiene care, urge them not to delay any longer.

While strategies such as social distancing, hand hygiene, and wearing masks in public can help reduce the spread of COVID-19, perhaps we should add a message about how visiting your dental hygienist may help prevent severe superinfections occurring as a result of the virus.


  1. Sampson V, Kamona N, Sampson A. Could there be a link between oral hygiene and the severity of SARS-CoV-2 infections? Brit Dent J. 2020;228(12):971-975. doi:10.1038/s41415-020-1747-8
  2. Zhou F, Yu T, Du R, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020;395(10229):1054-1062. doi:10.1016/S0140-6736(20)30566-3
  3. Clinical management of severe acute respiratory infection when novel coronavirus (2019-nCoV) infection is suspected: interim guidance, 28 January 2020. World Health Organization. Accessed July 2020. https://apps.who.int/iris/handle/10665/33089
  4. Liu J, Liu Y, Xiang P, et al. Neutrophil-to-lymphocyte ratio predicts critical illness patients with 2019 coronavirus disease in the early stage. J Transl Med. 2020;18(1):206. doi:10.1186/s12967-020-02374-0
  5. Cox MJ, Loman N, Bogaert D, O’Grady J. Co-infections: potentially lethal and unexplored in COVID-19. Lancet Microbe. 2020;1(1):e11. doi:10.1016/S2666-5247(20)30009-4
  6. Scannapieco FA. Role of oral bacteria in respiratory infection. J Periodontol. 1999;70(7):793-802. doi:10.1902/jop.1999.70.7.793
  7. Sjögren P, Nilsson E, Forsell M, Johansson O, Hoogstraate J. A systematic review of the preventive effect of oral hygiene on pneumonia and respiratory tract infection in elderly people in hospitals and nursing homes: effect estimates and methodological quality of randomized controlled trials. J Am Geriatr Soc. 2008;56(11):2124-2130. doi:10.1111/j.1532-5415.2008.01926.x
  8. Tawfig N. Proinflammatory cytokines and periodontal disease. J Dent Probl Solut. 2016;3(1):12-17. doi:10.17352/2394-8418.000026
  9. Tay MZ, Poh CM, Rénia L, MacAry PA, Ng LFP. The trinity of COVID-19: immunity, inflammation and intervention. Nat Rev Immunol. 2020;20(6):363-374. doi:10.1038/s41577-020-0311-8

Karen Davis, BSDH, RDH, is the founder of Cutting Edge Concepts, an international continuing education company. She practices dental hygiene in Dallas, Texas. Davis is an independent consultant to the Philips Corporation, PerioSciences, and Hu-Friedy/EMS. She can be reached at [email protected].