Dental biofilm of symptomatic COVID-19 patients harbours SARS-CoV-2

Aims SARS-CoV-2 RNA has been recovered from different sites in the human body, including the mouth. The present study aimed to investigate the presence of SARS-CoV-2 RNA in the dental biofilm of symptomatic patients who tested positive in nasopharyngeal and oropharyngeal (NASO/ORO) samples. Materials & Methods An observational clinical study of individuals with flu-like symptoms was conducted between July and September 2020. Dental biofilm (BIO) samples were collected and analysed using real-time quantitative polymerase chain reaction (RT-qPCR) to determine the virus's presence. Results Seventy participants (40 +/- 9.8 years of age, 71.4% female) tested positive for SARS-CoV-2 RNA in NASO/ORO samples and were included in the study. Among them, 13 tested positive in BIO samples (18.6%; 95% CI: [9.5, 27.7]). The median and interquartile range of cycle quantification (Cq) for NASO/ORO and BIO samples were 15.9 [6.9] and 35.9 [4.0] (p = .001), respectively. BIO-positive participants showed a higher virus load in NASO/ORO samples (p = .012) than those testing negative (Cq = 20.4 [6.1]). Conclusions Dental biofilms from symptomatic COVID-19 patients harbour SARS-CoV-2 RNA and might be a potential reservoir with an essential role in COVID-19 transmission.