The dental profession will be different following the global response to COVID-19. The Occupational Safety and Health Administration and the Centers for Disease Control and Prevention have made specific recommendations to use a National Institute for Occupational Safety and Health-approved N-95 mask for treating dental patients.
A surgical N-95 mask covers the nose and mouth and works as a respirator that filters out airborne contaminants 0.3 microns or larger at the 95% level. The “N” indicates protection for non-oil aerosols. It is important to understand that gas, chemicals and odors can penetrate an N-95 mask.
A surgical N-95 mask is specifically tested for resistance to blood and body fluids — an important difference between masks made for health care, those available at the local hardware store, or even masks available on Amazon. An N-95 is intended to be discarded after use with one patient. OSHA requires a written respiratory protection plan to be in place at the office as a component of recommending N-95 for use by the team in the clinical environment.
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A key difference in the N-95 mask compared to the loose-fitting face mask typically used in the clinical operatory is the requirement for a fit test. A fit test first involves a medical assessment to check the pulmonary function, since the filtering capabilities of N-95 masks will require an increased respiratory effort. The goal is to provide a test for the seal where the mask touches the face.
Without the seal, air and associated particulates can be drawn in around the edges of a typical mask. The fit test is required to confirm the effectiveness of the N-95 respirator mask, since the extra protection is wasted without the seal. Facial hair, for example, will make it difficult to create the appropriate seal required of an N-95 mask.
What’s involved with a fit test?
A fit test is required prior to the first use of a tight-fitting N-95 respirator mask and must be retested every 12 months at minimum. Once the fit test is complete, the mask can be individually tested for its seal prior to use. The self test will assist in identifying if the fit test should be repeated more frequently. Changes to the face due to weight gain, dental work, facial surgery and/or facial scaring would indicate an additional fit test.
The fit test relies on sensory function to detect leaks in the seal of the mask. The first step in a qualitative pass-fail fit test identifies the person’s ability to taste and smell. The second step evaluates the seal of the mask on the face with the head and neck under a hood designed to hold the test substance (saccharin is one of the substances accepted by OSHA that smells/tastes sweet) in direct proximity to the mask.
The seal of the N-95 respirator is tested with head movements to the left and right, as well as moving the head down below the knees. A critical part of the fit test is to read a specific passage of text or count backwards from 500 to test the seal while speaking.
A quantitative fit test is required for those who are not able to detect odors and/or taste. The quantitative fit test is more precise in its measurements of the actual leakage of the seal.
What’s included in an OSHA-mandated respiratory protection plan?
The respiratory protection plan is intended for use as a reference, accessible to all members of the dental team. The plan addresses administrative duties, respirator selection and uses, medical evaluation and follow-up assessments, fit testing procedures, proper use maintenance and care of the respirator, and discarding of the respirator, as well as continued training regarding the use of respirators. The required documentation includes logs related to training and fit testing, and the medical assessment (retained for 30 years for each employee, active or inactive).
In our office, the respirators used include the 3M 1860 Surgical N-95 Respirator for use in the clinical operatory and the 3M 8233 N100 Respirator for use in the laboratory where we work with lithium disilicate (e.max), zirconia, acrylic resins, composite resins, dental stone, wax, abrasives and polishing compounds. We expect this to change as we learn more following the COVID-19 outbreak.
How does PPE fit with other protective measures according to CDC & OSHA?
Personal protective equipment is always at the bottom of the hierarchy of controls to exposure to occupational hazards and is considered to be the least effective method. The order begins with simply removing the hazard, substituting the hazard, isolating from the hazard, altering the manner in which people work when hazards are not well controlled and, finally, personal protective equipment for work in the presence of a hazard.
How do N-95 surgical masks fit with other available face masks?
Face masks include surgical masks and dental masks designed to stop the spread of large droplets by the person wearing the mask. The Food and Drug Administration approved face masks designed to serve as a barrier to keep sprays or splashes of blood and other body fluids from reaching the nose or mouth. Face masks are not designed to prevent the inhalation of small airborne contaminants, simply because they do not form a seal.
The area of concern regarding COVID-19 is that the virus remains aerosolized for three hours (where the virus is riding on the aerosolized droplets) and remains on surfaces for three days, according to the National Institutes of Health. The CDC found the coronavirus on a variety of surfaces on the cruise ship Diamond Princess 17 days after the cabins were vacated. It is possible that the protocols for tuberculosis will apply to dental treatment and a surgical N-95 respirator fulfills the airborne precautions required. A powered air purifying respirator is used for increased protection against toxic fumes, airborne particles or chemicals, and are made in disposable and re-usable options — and at this time is typically recommended for decontamination sites.
The American Society for Testing and Materials level 3 surgical mask filters out particulates 0.1 microns or larger at a 98% level. However, the design of this mask does not create a seal around the face. The design of the mask allows airborne particulate to be drawn behind the mask while breathing since there is no seal created and maintained against the skin.
A partial or full facepiece elastomeric respirator, which looks like a gas mask or what we think of visually as a respirator, is available as a reusable form of personal protective equipment. The filtration is provided by cartridges. This equipment requires continued inspection, maintenance, cleaning and employee training, as well as a dedicated storage area.
The recommendation for a surgical N-95 mask is not simply a matter of wearing the mask, it is important to use the mask correctly. It is intended to be a tight-fitting respirator in order to provide the protection.
Once the surgical N-95 mask becomes wet, it is no longer viable for use. It is also important to understand that placing the mask and taking the mask off (donning and doffing) is an equally important protective technique since touching the outside surface of the mask with an ungloved hand will transmit pathogens of any kind.
Douglas G. Benting, D.D.S., M.S., F.A.C.P. is a member of Spear Resident Faculty.