Western blots also showed the expression of ACE2 and TMPRSS2 in cultured gingival epithelial cells.25When comparing different sites of the oral cavity, the expression values of ACE2 were 14.6% for gingiva, 2.0% for palate, and 18.2% for tongue.26Ohnishi et al immunohistochemically stained human gingival tissues with or without periodontitis using an anti-TMPRSS2 antibody.27Gingiva with periodontitis was found to express TMPRSS2 more significantly than healthy gingiva. Here, ACE2 is linked to periodontitis.