Figure 2.

Location of ACE2 on oral cavity and its interaction with the SARS-CoV-2. Binding between the SARS-CoV-2 S protein and the ACE2 protein allows entry of the coronavirus, which subsequently allows its replication and the immediate activation of a possible innate immune response against the virus, including the infiltration of a myriad of immune cells and the subsequent production of many proinflammatory cytokines. This triggers the manifestation of symptoms and signs in the oral cavity of patients with COVID-19 (a). Various spaces and surfaces in the oral cavity where the virus and its receptors are detected, such as the oral mucosa, periodontal tissues, salivary glands, and tongue (b).