Introduction: Theories or hypotheses regarding the connection between COVID-19 and periodontal disease are increasing during the COVID-19 pandemic. COVID-19 has been reported to have adverse outcomes related to the establishment of a cytokine storm, which is similar to the cytokine expression profile and cells involved in periodontitis. Nevertheless, the exact etiology why cytokine storm is vulnerable in COVID-19 as well as periodontitis still not clearly understood. The hypothesis: Recently, the phenomenon of angry macrophages can be explained by M1/M2 macrophage polarization. Periodontitis patients that harbored Porphyromonas gingivalis have a greater M1/M2 ratio than healthy patients, thus have more active M1 macrophages that produce pro-inflammatory cytokines. We hypothesize that periodontal disease could be a burden in defense mechanism toward infectious diseases, particularly the COVID-19. Evaluation of the Hypothesis: Endotoxin tolerance caused by P. gingivalis lipopolysaccharides shifts immune response from T helper (Th)-1 toward Th2, which leads to a less effective antivirus system. This mechanism may explain the connection between COVID-19 and periodontal disease through their cytokine profiles, microbial balance, and M1/M2 homeostasis. Recommendation for maintenance of oral hygiene and periodontal treatment is mandatory in the COVID era.

Original languageEnglish
Pages (from-to)28-35
Number of pages8
JournalDental Hypotheses
Issue number1
Publication statusPublished - 1 Jan 2021


  • COVID-19
  • Macrophage polarization
  • Periodontitis
  • Porphyromonas gingivalis
  • Th1/Th2


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