INTRO: The aim of this study was to evaluate the incidence, severity, duration of oral manifestations in individuals with Coronavirus Disease 2019 (COVID-19) and the association of these manifestations with the severity of COVID-19 and the patient's oral hygiene. METHODS: This study included 820 patients with confirmed COVID-19. A questionnaire form including oral hygiene habits, the severity of Covid-19, the presence, severity and durations of oral manifestations was prepared, and a web-based survey was performed using Google-forms. Obtained data was analysed with Pearson chi-square and Fisher's exact tests with statistical significance set at P < 0.05. RESULTS: The most commonly reported manifestations were taste dysfunction (63.4%), xerostomia (59.9%), halitosis (31.1%), dysphagia (27.8%), hypersensitive teeth (27.2%) and gingival bleeding (14.3%). The incidence of the oral manifestations was found significantly associated with severity of COVID-19 (P = 0.000 V = 0.151), presence of systemic diseases (P = 0.034, V = 0.074) and age (P = 0.023, V = 0.099). Tooth brushing decreased the incidence of aphthous like lesions of tongue during Covid-19 (p < 0.05). CONCLUSION: Maintenance of oral hygiene was associated with a reduced incidence of aphthous-like lesions, underscoring the protective role of routine oral care. These findings highlight the need to integrate oral health assessment and hygiene education into COVID-19 management protocols, which may also be important for potential future pandemics.