Bacterial contamination on the inner surface of the masks used by clinicians in a dental clinic

Abstract

Background.Wearing masks has become an essential safety measure during the coronavirus 2019 (COVID-19) pandemic. Especially clinicians in dental clinics should focus on infection control. However, there is currently no data regarding the frequency of replacement of the masks used in hospitals. Hence, it is necessary for dental clinic staff, who deal with many patients in an aerosol-producing environment, to have precise mask-wearing guidelines.Objectives. The aim of this study was to evaluate the contamination on the inner surface of the masks used by clinicians in dental clinics and provide basic data to describe hospital infection control guidelines in greater detail. Material and methods.For Study I,12 participants were recruited. The experiment was conducted indoors. After wearing the mask, the temperature and the humidity inside the mask were measured at the set time points (immediately after wearing the mask, and 10 min, 30 min, 1 h, 2 h, and 4 h after wearing the mask). During the experiment, talking was not allowed. For Study II, 23 clinicians from dental clinics were recruited. After wearing the mask, the temperature, the humidity and the number of colony-forming units (CFU) inside the mask were measured at the set time points. Finally, 15 samples were selected for the study based on a survey. Bacterial identification was conducted using the 16S rDNA sequencing.Results. The temperature and the humidity inside the mask increased significantly relative to room temperature and room humidity, respectively. Bacteria were found in all the masks worn for more than 10 min and the CFU values increased with the mask-wearing time. Bacteria belonging to the genera Staphylococcus, Bacillus and Roseomonas were detected in the used mask. Conclusions.A mask should not be worn for more than 2 h; however, the frequency of mask replacement can vary, depending on the number of patients encountered and the working environment.

Effects of chewing gum on mask contamination

“…In a previous study, the contamination rate inside the mask was also affected by wearing time and conversation, perhaps due to increased saliva outflow (Lee, 2022). In addition, previous studies showed that mastication could cause saliva outflow (Gavião et al, 2004).…”

“…The oral cavity contains many nutrients (Cha, 2021). It has been reported that wearing a mask maintains a warm temperature and high humidity inside the mask (Lee, 2022). Therefore, the inside of a mask presents ideal conditions for bacterial growth.…”

“…A previous study showed that used masks were contaminated by increased temperature and humidity, especially as the wearing time increased. In addition, the contamination rate increased with the conversation, suggesting that the outflow of saliva from the oral cavity due to conversation can increase the contamination rate of the mask (Lee, 2022).…”

Nanogallium-poly(L-lactide) Composites with Contact Antibacterial Action

“…Moreover, bacterial colonization on food packaging can decrease the food’s shelf-life or spread foodborne diseases [ 23 ]. Additionally, bacterial contamination also occurs on the inner and outer parts of face masks [ 24 , 25 ]. Since PLA is sensitive to all available sterilizing methods [ 26 ] and can become easily contaminated after sterilization, antibacterial components are frequently added to it.…”

Bacterial species and factors influencing the contamination of the inner and outer layers of face masks used in dentistry

“…3 Hence, in our previous study, we evaluated the temperature, humidity and contamination rates on the inner layer of masks according to the mask-wearing time. 4 Yet, it is important to assess the contamination rates on the outer layer of masks used in dentistry as well. No studies have referred to this issue so far.…”