Dental Aerosol Management Interim Guidance from CDA’S COVID-19 Clinical Care Workgroup

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Dental Aerosol Management Interim Guidance from CDA’s COVID-19 Clinical Care Workgroup

Updated May 26, New: Resources for Upper-Room UV and portable HEPA room filtration, per CDC Guidance for Dental Settings, May 19

Introduction

As part of its overall charge to assist dental professionals during the COVID-19 pandemic, the California Dental Association COVID-19 Clinical Care Workgroup initiated an in-depth investigation into aerosol management in dentistry. This document reflects that work.

It is important to note that the environment is rapidly evolving and we are constantly learning more about the virus, its transmission and how to reduce risk during the provision of dental care. In particular, new products for dental aerosol management are being introduced almost daily and the evidence on the efficacy of these in the dental setting is just beginning to develop. We anticipate evidence on this will continue to emerge well after this resource is published.

Therefore, this document should be considered a living document that will be updated over time as information becomes available. What’s more, the California Dental Association is not a regulatory agency, therefore the guidance offered here is not intended to be construed as the “standard of care,” and should be considered along with guidance from local, state, and federal government agencies, local/regional hospital systems and/or other authorities.

Background

The delivery of dental services routinely involves exposure of dental health personnel and patients to the contents of saliva and blood through droplets, spatter and aerosols produced during patient care. The sources are numerous, including naturally occurring patient actions, such as coughing, and operator-generated through the use of dental equipment, including high-speed and slow-speed rotary, ultrasonic, air-water syringe, air-abrasion and polishing equipment.

Infection control and disease transmission prevention in the dental environment is guided by the federal Centers for Disease Control and Prevention1 and Occupational Safety and Health Administration 2 and is effectively managed through the layering of multiple tactics to identify and reduce the risks associated with treatment. These mitigation approaches are hierarchical and focus first on eliminating the risk when possible, then reducing it through administrative and engineering controls and the use of personal protective equipment. They build upon each other as depicted here:

1 Standard precautions, Transmission-based precautions 2 Dentistry Workers and Employers

In dentistry, these are:

• Screening for active disease prior to initiating treatment and implementing Aerosol Transmission Disease Standard Protocols to protect from treating patients known to be contagious for an ATD. (Elimination)

• Determining patient-specific dental treatment options to minimize disease transmission risk. (Administrative)

• Managing aerosols produced during treatment using equipment designed specific to that purpose. (Engineering)

• Adhering to rigorous protocols for equipment sterilization and surface disinfection. (Elimination)

• Utilizing PPE appropriate to transmission risk, including level of mask and gown protection and locations for donning and doffing. (PPE)

Air and aerosols in dental treatment and office spaces can be conceptualized into the following four zones:

ZONE 1 ZONE 2 Intraoral 3’ radius beyond the oral cavity

Operatory

ZONE 3 ZONE 4 Operatory General office

General office

Aerosol mitigation and containment strategies are specific to each zone and, most importantly, build upon the other controls and layer upon each other. The more effectively aerosols are managed in Zone 1, the fewer aerosols travel on to Zone 2 and so on through the four zones, collectively reducing the disease transmission risk to patients and dental staff.

While risk can never reach zero, dentistry employs a comprehensive approach to risk assessment, mitigation and infection control that demonstrates an excellent track record for the safe provision of care. Dental Aerosol Management | 3 of 6 cda.org/back-to-practice

Considerations for Aerosol Management by Zones

As noted above, dental health professionals routinely make decisions at each level of patient care based on assessed risk and in consideration of the oral health diagnosis. Generally, the risk associated with low-fluid procedures with primarily naturally generated aerosols is considered to be lower than that of high-fluid procedures with dental equipment-generated aerosols, though the pathogenic load and potential for infectivity for any type of dental aerosol is not known and cannot be accurately assessed.

During the COVID-19 pandemic and as dental practices that have been providing only emergency care for the last several weeks prepare to provide additional care, the CDC’s Transmission-Based Precautions and Interim Infection Prevention and Control Guidance for Dental Settings During the COVID-19 Response (dated April 27, 2020) are essential references for additional protections within the dental setting.

Present evidence strongly suggests SARS-CoV-2 is likely transmitted through aerosolized infectious material. The science on this continues to emerge as data is collected and analyzed. Early evidence suggests that presymptomatic and asymptomatic individuals may carry and transmit the virus. At this time with the current level of understanding, the most important strategy to diminish the risk of transmission is to screen for active COVID-19 and NOT treat an identified or suspected case. For all other patients one must consider risk mitigation strategies for all presymptomatic or asymptomatic patients who may have COVID-19 and require dental treatment.

The following are options to consider; they are not guidelines.

Zone 1: Options for intraoral aerosol management

• Choose treatment techniques that avoid, minimize, or otherwise manage aerosol production when feasible

• Maximize chairside HVE evacuation, including use of multiple evacuators if available (Note: Vacuum and line equipment maintenance optimize performance)

• In addition to HVE, if applicable: O Use additional continuous suction dental isolation systems O Use dental dams

• Anticipate, manage, attempt to reduce triggers for gagging and coughing (e.g. intraoral radiography; impressions) O Consider nitrous oxide to reduce gagging and promote nasal breathing into the scavenger

• Offer a preoperative viricidal rinse or mouth swab (e.g. hydrogen peroxide; povidone-iodine) Dental Aerosol Management | 4 of 6 cda.org/back-to-practice

Zone 2: Options for consideration to limit and manage aerosols within three ft of the oral cavity

• Decrease contamination of multi-use materials during aerosol-generating treatment by: O Setting out supplies and materials in the amount required for scheduled care O Avoiding opening drawers or cabinets to access materials or supplies O Utilizing non-treatment personnel to retrieve equipment, materials or supplies from outside treatment area and deliver to treatment personnel

• Reduce transfer of aerosol contamination outside treatment area by covering patient with large bib and hair covering or drape

• Remove or cover all exposed items that cannot be cleaned (e.g. glove boxes, computer keyboard)

• At this time, there is limited evidence on applicability and efficacy of the following for dental practice. Dentists may wish to evaluate emerging evidence on the value to your specific practice conditions of additional Zone 2 equipment, such as: O Free standing or chairside extraoral aerosol evacuation systems O Treatment hoods

Zone 3: Options for consideration to limit and manage aerosols in operatory

Efficient management in Zones 1 and 2 may significantly reduce additional management requirements in Zones 3 and 4.

• Zone 3 aerosol management is primarily accomplished through environmental controls and will differ based on dental office or clinic layout and air flow. Depending on your conditions, you may wish to evaluate the following options: O Keep treatment room doors closed during aerosol-generating procedures O Create barriers between adjacent operatories and/or between treatment areas and common areas, using materials such as plastic, acrylic or plexiglass for the purpose of reducing lateral spread and providing a surface upon which aerosols collect and can be disinfected

• Evaluate air flow within treatment space and consider options that improve flow if deemed useful and feasible, such as the addition of a room air filtration device or other means to increase the fresh air turnover rate in the operatory. Consider the use of a portable HEPA air filtration unit while the patient is actively undergoing, and immediately following, an aerosol-generating procedure (CDC Guidance for Dental Settings, May 19). O The use of these units will reduce particle count (including droplets) in the room and will reduce the amount of turnover time, rather than just relying on the building HVAC system capacity. O Place HEPA unit within vicinity of patient’s chair, but not behind DHCP. Ensure DHCP are not positioned between the unit and the patient’s mouth. Position the unit to ensure that it does not pull air into or past the breathing zone of the DHCP.

• At this time, there is limited evidence on applicability and efficacy of the following for dental practice. Dentists may wish to evaluate emerging evidence on the value to your specific practice conditions of additional Zone 3 equipment, such as: O Ultraviolet-C Irradiation, hypochlorous acid (HOCl) or other viricidal foggers for air or surface decontamination Dental Aerosol Management | 5 of 6 cda.org/back-to-practice

Zone 4: Options for consideration to limit and manage aerosols in common areas

Efficient management in Zones 1, 2 and 3 may significantly reduce additional management requirements in Zones 4. Evaluation of Zone 4 options is best accomplished by evaluating the air flow patterns in your office or clinic space.

• Increase fresh air from outside for dilution of aerosols by opening window or increasing fresh air input at HVAC

• Consider using fans to direct air flow away from common and administrative areas

• Remove unnecessary items from waiting room, such as magazines and children’s toys

• Regularly disinfect frequently touched materials and surfaces (e.g. telephone receivers, door handles, tables / other flat surfaces, pens, etc.)

• Place posters on cough/sneeze hygiene in waiting areas; give masks to unmasked patients as they arrive

• Consider placing cough shields at front desk

• Evaluate existing HVAC system, consider enhanced filtration if deemed useful and feasible. Dental Aerosol Management | 6 of 6 cda.org/back-to-practice

ADDITIONAL RESOURCES

General Aerosol Management Resources • Aerosols and splatter in dentistry, A brief review of the literature and infection control implications. JADA, Vol. 135, April 2004 • Transmission routes of 2019-nCoV and controls in dental practice. International Journal of Oral Science (2020) 12:9 • Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals. Nature. April 2020 • Being a front-line dentist during the Covid19 pandemic: a literature review, Maxillofacial Plastic and Reconstructive Surgery (2020) 42:12 • Comparative dynamic aerosol efficiencies of three emergent coronaviruses and the unusual persistence of SARS-CoV-2 in aerosol suspensions MedRxiv This version posted April 18, 2020. All rights reserved. No reuse allowed without permission.

Government Regulation for Dentistry • CDC Interim Infection Prevention and Control Guidance for Dental Settings During the COVID-19 Response • Infection Prevention Practices in Dental Settings • The California Workplace Guide to Aerosol Transmissible Diseases (CalHOSA 2020) • OSHA COVID-19 Dentistry Workers and Employers

Disinfection • CDC/NIOSH, Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Healthcare Setting (CDC Guidance for Dental Settings, May 19) • Ultraviolet Air and Surface Treatment • Hypochlorous Acid: Harnessing an Innate Response • Evaluation of Liquid- and Fog-Based Application of Sterilox Hypochlorous Acid Solution for Surface Inactivation of Human Norovirus • Chemical Disinfectant: CDC Guideline for Disinfection and Sterilization in Healthcare Facilities (2008)

Stand-Alone Evacuation Systems • Pilot Study: British Dental Journal • Personalized Ventilation Systems

HVAC • ASHRAE Position Document on Infectious Aerosols, April 2020 • ASHRAE position document on airborne infectious diseases, February 2020

A variety of regulatory agencies oversee the health of the nation and the supplies and equipment used in health care. If you are considering purchasing new equipment or using new types of materials or supplies, you may want to confirm their authenticity with the appropriate agency or authority.

• National Institute for Occupational Safety and Health (NIOSH) is the division of CDC responsible for worker safety and approves protective equipment. • U.S. Food and Drug Administration (FDA) along with CDC, OSHA and NIOSH regulate N95 masks. • ASHRAE advances the arts and sciences of heating, ventilation, air conditioning, refrigeration and their allied fields. • Environmental Protection Agency (EPA) is responsible to ensure access to clean air, land and water.