Oral manifestations of COVID-19 and long COVID: taste dysfunction, mucosal lesions and periodontal links

Oral manifestations were among the first extrapulmonary signs attributed to COVID-19. This narrative review traces the chronological evolution of the evidence on taste dysfunction, oral mucosal lesions and the periodontal links of COVID-19 between 2020 and 2023 and characterizes the manifestations that persist in long COVID. Searches were conducted in OpenAlex, Crossref and PubMed with an upper publication limit of 2023, and the synthesis was organized into three evidence periods and three thematic axes. In the first half of 2020, taste and smell loss emerged as frequent sentinel symptoms, pooled gustatory dysfunction reached 38.2 percent, case series described heterogeneous oral lesions and ACE2 was identified in the oral epithelium. Between mid-2020 and 2021, living systematic reviews consolidated prevalence estimates, with taste disorders in 38 percent of 64,876 patients, and case-control studies associated periodontitis with severe outcomes, including a death odds ratio of 8.81. From 2022 to 2023, persistent taste dysfunction was estimated in 4.4 percent of patients, the Omicron wave reduced chemosensory involvement, the specificity of oral lesions was questioned and Mendelian randomization did not confirm a causal periodontal link. Taste dysfunction remained the most consistent oral manifestation across the trajectory, whereas mucosal lesions and the periodontal association remained partly unresolved.