Volatile sulfide compounds and oral microorganisms on the inner surface of masks in individuals with halitosis during COVID-19 pandemic

Abstract

Abstract Mask-wearing is still recommended owing to the continuing impact of the COVID-19 pandemic. Within the closed chamber created by the mask, people are increasingly self-aware of their oral malodor. In this prospective and cross-sectional study, we aimed to measure volatile sulfide compound (VSC) levels in patients with halitosis and investigate the oral microbiome profile on the inner surface of their KF94 masks. We also investigated which oral microbiota increases VSC levels and whether the oral microbiomes of oral saliva and mask are correlated. A total of 50 subjects (41 women, average age 38.12 ± 12.58 years old) were included in the study, 25 healthy subjects and 25 patients with halitosis who wore masks for more than 3 h. The dominant bacterial species, bacterial profile, and Shannon diversity index of whole unstimulated saliva and the inner surface of the mask were investigated. The bacterial 16S ribosomal RNA genes of the major oral bacterial species were analyzed using real-time PCR. Gas chromatography was used to measure hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), which are representative VSCs. The total bacterial DNA copy number was significantly higher in the saliva sample than in the mask sample (p 0.8, p < 0.001). Oral bacteria, whose association with halitosis has been identified, increased VSC levels in mask-wearing subjects during the COVID-19 pandemic, particularly the number of Gram-negative anaerobes such as Pg and Td. Mask-wearing time was a major factor in increasing VSC levels. The study results suggest that people with halitosis could control these Gram-negative bacteria by improving oral hygiene and regularly changing masks.