Choose the Right Mask for the Task at Hand

The Occupational Safety and Health Administration (OSHA) mandates the use of personal protective equipment (PPE) to protect oral health professionals from disease transmission, specifically from bloodborne pathogens such as hepatitis B and human immunodeficiency virus.¹ The United States Centers for Disease Control and Prevention’s (CDC) Guidelines for Infection Control in Dental Health-Care Settings—2003 discuss the use of PPE to prevent splash and spatter to the skin and mucous membranes (eyes, nose, and mouth).² Splash, spatter, and aerosols that are potentially infectious from blood, saliva, and microorganisms are generated by handpieces, powered instrumentation, and rinsing. PPE includes surgical face masks, eyewear, gloves, and protective clothing such as lab coats. The US Food and Drug Administration (FDA) considers surgical face masks one-time-use disposable medical devices.³ There are many types of masks available, ranging from minimum performance to maximum filtration, depending on the purpose of the task at hand. Procedures that involve aerosols and potential for splash/spatter require masks with higher levels of filtration. Whereas, tasks without splash/spatter/aerosol potential, such as for brief examinations or when exposing radiographs, can be performed with masks that have little or no filtration.^4,5 With more than 12,000 standards, the American Society for Testing and Materials Standards (ASTM) is a global organization that develops voluntary guidance for a variety of industries and products to aid in quality control, product safety, and recommended usage and application.⁶ ASTM standard F2100-11 provides specifications for surgical face masks that includes bacterial filtration efficiency (BFE), sub-micron particulate filtration (PFE), delta P differential pressure, fluid resistance, and flammability.6 Molinari and Nelson state: “95% of dental aerosols are 5.0 microns or less in diameter and cannot be seen.”5 So masks with at least 95% BFE and PFE are preferable in the dental setting during procedures that generate aerosols, such as powered scaling and handpiece use. ASTM levels are classified into three levels of protection (low, moderate, high) to help clinicians decide which mask is appropriate for the task at hand. Level 1 masks (low protection at > 95% BFE and PFE) are suitable for brief examinations, exposing radiographs, and cleaning tasks. Level 2 masks (moderate protection at > 98% BFE and PFE) are preferable for procedures that involve a moderate level of aerosols such as hand instrumentation and sealants. Level 3 masks have a high level of protection (at > 98% BFE and PFE) and are used for procedures involving high levels of aerosols such as ultrasonic scaling, surgical procedures, and crown preparation. A level 2 mask would be sufficient for exposing radiographs and routine dental hygiene procedures such as hand scaling; however, a level 3 mask would be preferred if performing tasks such as ultrasonic instrumentation. Depending on the frequency of powered instrumentation use, it might be wise to continue to use level 3 masks. The 2003 CDC guidelines recommend masks be changed between patients, when they become wet from breath or splash, and during patient care with highly aerosolized procedures (every 20 minutes).² Wet masks can lead to microbial penetration, making the mask ineffective.2 Masks should create a seal covering the nose and mouth2 and be comfortable without any gaps, which may allow microorganisms to penetrate. Compliance with masks depends on comfort, temperature, and breathability. Delta P differential penetration represents the air flow measured in mmH20/cm2 so a mask with a higher delta P differential provides better filtration but less breathability.⁶ Masks are a required part of routine safe patient care and the selection depends on several factors including ASTM level for type of procedure being performed, comfort, and cost.

REFERENCES

1. Occupational Safety and Health Administration. Bloodborne Pathogens Standard Regulations (Standard 29 CFR. 1910.1030). Available at: osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=10051. Accessed May 8, 2018.
2. Kohn WG, Collins AS, Cleveland JL, et al. Guidelines for infection control in dental health-care settings—2003. MMWR Recomm Rep. 2003;52(RR-17):1–61.
3. Food and Drug Administration (FDA). Guidance for Industry and FDA Staff: Surgical Masks. Available at: fda.gov/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm072549.htm. Accessed May 8, 2018.
4. Molinari J, Nelson P. Face masks what to wear and when. The Dental Advisor. October 18, 2014.
5. Molinari J, Nelson P. Face mask performance: Are you protected? Available at: medicom.com/uploads/files/Medicom%20Face%20Mask%20Performance
6. %20Article_v3(1).pdf. Accessed May 8, 2018.
7. American Society for Testing and Materials Standards (ASTM). ASTM F2100–11. Standard Specification for Performance of Materials Used in Medical Face Masks. Available at: astm.org/Standards/F2100.htm. Accessed May 8, 2018.