Coronavirus infectious disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a pandemic in March 2020 by the World Health Organization. Periodontitis, one of the most prevalent diseases worldwide, leads to alveolar bone destruction and subsequent tooth loss, and develops due to pro-inflammatory cytokine production induced by periodontopathic bacteria. Periodontopathic bacteria are involved in respiratory diseases, including aspiration pneumonia and chronic obstructive pulmonary disease (COPD), and other systemic diseases, such as diabetes and cardiovascular disease. Patients with these diseases have an increased COVID-19 aggravation rate and mortality. Because aspiration of periodontopathic bacteria induces the expression of angiotensin-converting enzyme 2, a receptor for SARS-CoV-2, and production of inflammatory cytokines in the lower respiratory tract, poor oral hygiene can lead to COVID-19 aggravation. Conversely, oral care, including periodontal treatment, prevents the onset of pneumonia and influenza and the exacerbation of COPD. The reduced chance of receiving professional oral care owing to long-term hospitalization of patients with COVID-19 may increase the aggravation risk of infection in the lower respiratory tract. It can be hypothesized that periodontopathic bacteria are involved in the COVID-19 aggravation and therefore, the management of good oral hygiene potentially contributes to its prevention.

由严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）引起的冠状病毒感染性疾病2019（COVID-19）在2020年3月被世界卫生组织宣布为大流行病。牙周炎是世界上最流行的疾病之一，导致牙槽骨破坏和随后的牙齿脱落，并由于牙周病菌诱导的促炎性细胞因子产生而发展。牙周病细菌参与呼吸系统疾病，包括吸入性肺炎和慢性阻塞性肺疾病（COPD），以及其他全身性疾病，例如糖尿病和心血管疾病。患有这些疾病的患者的COVID-19恶化率和死亡率增加。由于牙周病菌的吸入会诱导血管紧张素转化酶2（SARS-CoV-2的受体）的表达，以及下呼吸道中炎性细胞因子的产生，不良的口腔卫生可导致COVID-19恶化。相反，包括牙周治疗在内的口腔护理可预防肺炎和流感的发作以及COPD的恶化。由于COVID-19患者长期住院治疗而导致接受专业口腔护理的机会减少，可能会增加下呼吸道感染的加重风险。可以假设牙周病细菌参与了COVID-19的恶化，因此，良好的口腔卫生管理可能有助于其预防。可以预防肺炎和流感的发作以及COPD的恶化。由于COVID-19患者长期住院治疗而导致接受专业口腔护理的机会减少，可能会增加下呼吸道感染的加重风险。可以假设牙周病细菌参与了COVID-19的恶化，因此，良好的口腔卫生管理可能有助于其预防。可以预防肺炎和流感的发作以及COPD的恶化。由于COVID-19患者长期住院治疗而导致接受专业口腔护理的机会减少，可能会增加下呼吸道感染的加重风险。可以假设牙周病细菌参与了COVID-19的恶化，因此，良好的口腔卫生管理可能有助于其预防。