An integrative review of oral manifestations in patients with COVID-19: signs directly related to SARS-CoV-2 infection or secondary findings?

We conducted an integrative review on oral manifestations in patients with COVID-19 based on the current available literature evidence. A bibliographic search was carried out on March 11, 2021, among published studies in the years 2019-2021 in the PubMed database and based on the search strategy ("COVID-19" AND "oral lesions" OR "oral mucositis" OR "oral manifestation"). After applying the inclusion and exclusion criteria, 29 articles were considered suitable for this review. A total of 110 cases of patients with COVID-19 who had oral manifestations were reported. The presence of ulcerated lesions was the most common finding, having a herpetiform and aphthous clinical pattern observed in most cases. Macules, petechiae, hemorrhagic blisters, pustular enanthem, mucositis, and halitosis were also among the most frequently described oral manifestations. The tongue was the most commonly affected site, followed by the palate and lip. Most of the reported cases were diagnosed only by the clinical aspect of the lesion associated with a positive SARS-CoV-2 test or the presence of other COVID-19 symptoms. Current scientific evidence still could not affirm that most of the oral lesions observed in patients with COVID-19 are related to the virus's direct or indirect action on the oral mucosa. To confirm this association, prospective and longitudinal studies are further needed, together with a larger number of patients, complemented by histopathological examination of these lesions. Additionally, molecular techniques, such as immunohistochemistry and in situ hybridization, may be necessary to perform the differential diagnosis with other oral lesions.