Prolonged mask wearing does not alter the oral microbiome, salivary flow rate or gingival health status – A pilot study

Abstract

The COVID-19 pandemic has resulted in the widespread use of N95 respirators and surgical masks, with anecdotal reports among healthcare providers and the public of xerostomia, halitosis, and gingivitis, a consortium of symptoms colloquially termed “mask mouth”. However, this has not been scientifically verified. The aim of this study was to assess changes in salivary flow rate, gingival health status and oral microbiome associated with prolonged mask use. A total of 25 dental students (mean age = 26.36 ± 1.58) were included in the study and evaluated at three time points: T1, at the end of at least 2 months of full-day mask wear (7.26 ± 1.56 hours/day); T2, at the end of a period of minimal mask use (1.13 ± 1.13 hours/day); and T3, at the end of 2-3 weeks of resuming full-day mask wear (6.93 ± 1.80 hours/day). Unstimulated whole saliva (UWS) flow rate, xerostomia (on a quantitative scale of 10), gingival index (GI) and plaque index (PI) were assessed at each time point. The salivary microbiome was characterized using 16S rRNA gene sequencing. Overall, UWS flow rates were normal (mean of 0.679 ml/min) and xerostomia, PI and GI scores were low (Mean of 3.11, 0.33 and 0.69, respectively) with no significant differences as a result of prolonged mask wearing. Similarly, there were no significant microbial changes at a false discovery rate (FDR) ≤ 0.05. However, some trends were identified using a nominal p-value cut-off of ≤ 0.01, namely Gemella sanguinis, Streptococcus sp. Oral taxon 066 and Oral taxon 058 were associated with prolonged mask wear. Trends were also seen by gender, race and age, for example an increase in P. gingivalis and P. intermedia with age. In conclusion, we found no evidence that prolonged mask wear adversely affects oral health. The findings support that the oral microbiome of healthy individuals is resilient.

Oral microbiome of the inner surface of face masks and whole saliva during the COVID-19 pandemic

“…Interestingly, the presence or absence of xerostomia had no impact on the profile of the oral microbiome on the inside of the mask. A recent study on the mask microbiome conducted on dental students reported that the severity of xerostomia was not significantly related to mask wearing time (16). Lin et al reported that P. gingivalis and F. nucleatum were clearly associated with xerostomia after radioiodine therapy (30).…”

“…To date, few significant studies on masks and the attendant microbiome have been published. A study conducted by Au et al in 2022 reported that continuously wearing a mask for 2 months did not significantly change the salivary oral microbiome compared to those with minimal mask use (16). However, only the saliva microbiome but not the oral microbiome inside the mask was directly investigated, and the participants were limited to young dental students with an average age of 26.36 ± 1.58 years (16).…”

“…A study conducted by Au et al in 2022 reported that continuously wearing a mask for 2 months did not significantly change the salivary oral microbiome compared to those with minimal mask use (16). However, only the saliva microbiome but not the oral microbiome inside the mask was directly investigated, and the participants were limited to young dental students with an average age of 26.36 ± 1.58 years (16). Park et al investigated bacteria and fungus obtained from masks by culturing samples on agar and counting the number and size of microbial colonies over time (17).…”

Oral microbiome as a co-mediator of halitosis and periodontitis: a narrative review

“…Oral-derived anaerobes can proliferate in chambers confined by face masks. Although the proliferation of microorganisms was observed on the inner surface of the mask, the amount of microbiome and VSC level did not significantly increase as the mask wearing time increased (33,36). Additional research is needed to scientifically investigate whether wearing a mask in turn increases microorganisms and VSC levels.…”

Treatments of COVID-19-Associated Taste and Saliva Secretory Disorders

“…Anecdotal reports have suggested that subjective sensation of mouth dryness is attributed to the prolonged mask wearing due to the COVID-19 pandemic. According to a recent assessment of changes in salivary secretion and oral conditions, however, there is no evidence that mask wearing affects the flow rate of unstimulated whole saliva [120]. In addition to head and neck radiotherapy for cancer patients and autoimmune disorders like Sjögren's syndrome, certain medications are related to reduction of salivary secretion.…”