BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is the cause of the ongoing coronavirus disease 2019 (COVID-19) pandemic. It has been hypothesized oral health may be related to the severity and complications of COVID-19. The aim of this study was to analyze the prevalence of apical periodontitis and the frequency of root canal treatment in a sample of patients with SARS-CoV-2 infection (COVID-19), correlating them with the severity of the disease.Material and MethodsThis retrospective study was conducted following the Strengthening Reporting Observational Studies in Epidemiology (STROBE) guidelines. The study examined 280 patients with positive real time PCR COVID-19 test whose treatment was performed in our hospital. Fifty-two patients aged 52.3 ± 17.3 years, including 30 males and 22 females, who had an orthopantomography in their clinical record, performed in the last 2 years, were included. Patients with SARS-CoV-2 infection were grouped as mild or moderate (MM) and severe or critical (SC) illness groups, according to the NIH COVID-19 Treatment Guidelines (Wu & McGoogan 2020). Radiographic records were analyzed and apical periodontitis (AP) was diagnosed as radiolucent periapical lesions (RPLs), using the periapical index score (PAI). Student’s t test, χ2 test and multivariate logistic regression were used in the statistical analysis.ResultsThe number of carious teeth was significantly higher in the SC group (3.4 ± 4.1), which showed more than twice as many teeth with carious lesions than the MM group (1.4 ± 1.8) (p= 0.02). Multivariate regression analysis showed association between the number of carious teeth and the severity of SARS-CoV-2 disease (OR = 1.5; 95% CI = 1.1–2.1;p= 0.017). Endodontic status (OR = 7.12; 95% CI = 1.2-40.9;p= 0.027) also correlated with the disease severity.ConclusionsThe results suggest that the oral health status of COVID-19 patients correlated with the severity of the SARS-CoV-2 virus infection. Significant association has been found between the severity of COVID-19 disease and the presence of a greater number of teeth with caries lesions, as well as with endodontic status.Key words:Apical periodontitis, caries, COVID-19, root canal treatment, SARS-CoV-2