According to OSHA, dental health care providers have one of the highest risks of being exposed to Covid-19. This is mainly due to the fact that a large proportion of the procedures that dentists perform are aerosol generating. These droplets can easily transmit covid-19 from person to person, directly or indirectly – by interacting with contaminated surfaces. So the recommendation for respirators is unique in a dental setting. With new information emerging everyday (some scientific and some speculation), it is critical to know and develop a guideline for respirators specific to our dental practices.
How protective are surgical masks?
Much of the information regarding the protectiveness of different types of masks comes from research done on the influenza virus and SARS. N95 masks have a protective factor 30 times higher than regular surgical masks. This is due to N95’s formation of a seal around the nose and mouth. Since surgical masks don’t offer the same seal, airborne particles can easily leak in and around the mask. The ADA has recommended that any dental care professional who has performed aerosol-generating procedures with a surgical mask to be put in self-isolation for 14 days or perform a Covid-19 test.
The different types of masks
There are two main categories of respirators, filtering face-piece respirators (FFRs) and power air-purifying respirators (PAPRs). Dental care professional are recommended to use FFRs such as the N95 masks or higher grade filtering masks. The “95” indicates that the mask filters 95% of particles. There are higher-grade masks such as the N99 (filters 99% of particles).
Some FFR masks have an exhalation valve, which prevents moisture buildup and keeps lower temperatures in the mask during use. These masks should not be used in a sterile environment.
3M has recommended various masks that have the same performance as N95 masks:
- KN95
- FFP2
- P2 Particulate respirator
- Korea 1st class respirators
- DS respirators
Which masks is right for you
The most critical factor in choosing the right mask from the list above is the fit and seal of the masks. These masks are not one size fits all. You should test the masks periodically to determine any disruptions in the seal. A qualitative test is the Bitrex test, where when exposed, the subject does not detect any sweet or bitter taste of saccharin or bitrex (a solution of 95% water, 5% sodium chloride and 0.1% denatomium benzoate).
Discarding of PPE
Any respirator is meant for single use only, as it is now known that the Covid-19 virus can survive on surfaces for up to 72 hours. However, during time of crisis and extremely limited resources, re-use can be considered with personal judgment. Surgical masks can be worn as an additional layer on top of the recommended respirators to limit the chances of infected particles contacting the respirators. Ultraviolet irradiation, vaporous hydrogen peroxide and moist heat have been shown to be effective decontamination methods for respirators. However, over-decontamination can hinder the performance of the respirators, as they can deteriorate.