Is SARS-CoV-2 present in the periodontium? A post-mortem study.

Aims To investigate the presence of SARS-CoV-2, the virus responsible for COVID-19 infection, in the periodontal tissues of deceased individuals with a positive SARS-CoV-2 nasopharyngeal swab test.Sample selection Seven deceased individuals, who were admitted to the intensive care unit of the Hospital das Clínicas of the Medicine School of Sao Paulo University for invasive mechanical ventilation following a positive nasopharyngeal COVID-19 test result, underwent a post-mortem examination. Individuals with comorbidities were included. Exclusion criteria included a current smoking habit.Design A cross-sectional study involving a videoscope-guided autopsy to obtain a periodontal tissue sample. The plastic body wrapping was incised in the facial region, allowing the insertion of a video endoscope. A single sample of periodontal tissue (junctional epithelium, adjacent oral epithelium and underlying connective tissue) was obtained from the mesial interproximal papilla of the maxillary first molar (or if absent, the mesial tooth). The sample was cleaned using an enzymatic detergent (Riozyme) to mimic the effects of salivary flow and was collected using blunt dissection. The sample was divided into two samples for either histopathological analysis (haematoxylin and eosin stain) or molecular analysis. Real-time reverse transcriptase polymerase chain reaction (rRT-PCR) was used to test for the presence of the envelope (E) gene of SARS-CoV-2. Data on comorbidities, smoking status, period of hospitalisation and time from onset of symptoms to death were also collected.Data analysis Descriptive analysis was performed and results were presented as a cross tabulation. The presence of SARS-CoV-2 in samples was presented as the rRT-PCR cycle threshold value and the histopathological analysis results were Boolean (that is, presence/absence of vacuolisation or nuclear pleomorphism).Results A total of seven individuals were examined: four women and three men. The age range was 8-74 years and the range of periods between onset of symptoms and death was 10-31 days. SARS-CoV-2 was detected in five samples, with a mean cycle threshold of 31.38 (range 27.28-36.55). Nuclear pleomorphism and vacuolisation were found in two and three cases, respectively.Conclusions SARS-CoV-2 genetic material was present in most periodontal tissue samples of individuals with COVID-19. The sample size, however, was small and only included severely ill individuals with prolonged periods of hospitalisation. Consequently, the applicability of the findings to the general population is limited.