BACKGROUND: Coronavirus disease (COVID-19) and periodontitis share common characteristics, such as an exaggerated inflammatory response. As periodontal diseases were shown to be associated with respiratory diseases, such as pneumonia, it is quite possible that a relationship may exist between periodontitis and COVID-19. Hence, the aim of the present study was to determine whether periodontitis and poor oral hygiene are associated with COVID-19. METHODS: A case control study was conducted. Patients who had positive real-time reverse transcription polymerase chain reaction results for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were included in the case group (n = 79), and patients with negative results were included in the control group (n = 71). The periodontal examination involved recording the plaque scores, calculus scores, tooth mobility, gingival bleeding, probing depth, recession, and clinical attachment level (CAL). RESULTS: Logistic regression analysis showed significant associations of mean plaque scores >/= 1 (odds ratio (OR), 7.01; 95% confidence interval (CI), 1.83-26.94), gingivitis (OR, 17.65; 95% CI, 5.95-52.37), mean CAL >/= 2 mm (OR, 8.46; 95% CI, 3.47-20.63), and severe periodontitis (OR, 11.75; 95% CI, 3.89-35.49) with COVID-19; these findings were more prevalent in the case group. CONCLUSION: Based on the abovementioned observations, it can be concluded that there is an association between periodontitis severity and COVID-19. Gingival bleeding and dental plaque accumulation are also more frequent among COVID-19 patients. Hence, it is essential to maintain periodontal health and good oral hygiene as an important measure for COVID-19 prevention and management. This article is protected by copyright. All rights reserved.