The Articulate Dentist - A Blog by the Metro Denver Dental Society

Evidence-Based Considerations for RDH Using Aerosol-Generating Devices

 By: Ms. Karen Davis, RDH, BSDH

An unexpected benefit of the SARS-CoV-2 viral pandemic for dentistry is the emergence of data shedding light on the safety of utilizing aerosol-generating devices on patients during dental hygiene care. Many dental hygienists resumed practicing once the shut-down was lifted with uneasiness about clinician and patient safety while using aerosol-generating devices such as ultrasonics and air-polishing devices. Some states even passed rules and regulations prohibiting the usage of such equipment for many months, requiring dental hygienists to return to manual instrumentation. The Centers for Disease Control published recommendations to avoid aerosol-generating devices whenever possible during the pandemic until mid-2021 when additional language specified that the recommendation applied only when working on those with suspected or confirmed COVID-19. (1) Today there are clinicians that still struggle with concerns over personal and patient safety incorporating aerosol-generating devices, and have continued increased usage of manual instrumentation over power instrumentation.

Dental professionals accustomed to making evidence-based decisions noted early on the lack of scientific data related to dental environments and the transmissibility of the SARS-COV-2 virus. As a practicing dental hygienist, I for one was interested in what the science said about the risks of disease transmission during the pandemic in lieu of such unprecedented recommendations, rules and regulations on the profession.

Assumptions Do Not Equate to Science

On March 17, 2020 when the New England Journal of Medicine published data showing the SARS-CoV-2 virus could remain viable in aerosols for three hours and on inanimate objects for much longer (2), as a dental professional my knee-jerk reaction caused me to immediately question the safety of ever treating patients again. However, at a second glance, I examined how this study was conducted to determine how applicable it is to our dental environment. Suffice it to say, a dental environment already using universal precautions is a stark contrast to creating an aerosolized environment in a laboratory using a three-jet Collision nebulizer inside of a Goldberg drum. It is a leap to assume results of this laboratory study, where a large expression of viral aerosols was dispersed into a stainless-steel drum, equate to a dental treatment room not being a safe environment to incorporate power technology.

This virus appears to have stability and viability similar to but somewhat more significant than another virus (SARS-Cov-1) in experimental conditions (2). Therefore, increased infection control considerations, pre-rinse, increased use of High-Volume Evacuation (HVE), and increased use of Personal Protection Equipment (PPE) should be the new normal for dental professionals. HVE with an 8mm opening has been shown to reduce >95% of aerobic bacterial aerosols when used with ultrasonic and air polishing devices. (3) Likewise, recommendations to use low-speed polishing as opposed to air polishing with HVE are based upon assumptions one is safer than the other, yet not substantiated by current evidence. If you were skimping on previous OSHA and CDC guidelines regarding infection control in your dental practices, COVID-19 should have been a wake-up call to get your office in order. Thankfully, there are ample resources available from the OSHA, CDC, ADA and ADHA to guide clinicians on how to provide care once patients have been screened for COVID-19 exposures or symptoms.

Patient Preferences and Clinician Experiences Even in a pandemic as devastating and costly as this one, clinicians should still make evidence-based decisions. Evidence-based dentistry encompasses the best available science and two other important components: the patient’s preferences and values, and the clinician’s experiences and expertise. Charles Cobb, in his review of the literature presented at the 2000 World Workshop on the topic of mechanical therapy (4), concluded, “The best results are probably obtained by combining sonic/ultrasonic instrumentation with manual scaling.” This appears to be consistent with the current usage of power and manual instrumentation by most clinicians today. Completely eliminating power devices for dental hygiene care may have significant consequences. A study published in 2016 (5) evaluated ultrasonic versus hand instrumentation and established that hand and ultrasonic instrumentation can both achieve comparable outcomes, but ultrasonic instrumentation reduced the time by 36.6% in one referenced study and caused less soft-tissue trauma. (6) Other studies show time savings of 20-50% for thorough periodontal debridement. (7,8,9) Said another way, eliminating ultrasonic instrumentation could take as much as 50% longer in a COVID-19 environment. In the absence of incorporating power technology, are appointments lengthened to accommodate that reality? Will patients need to return to complete the necessary debridement? Will pathogenic biofilm be inadequately debrided? These are legitimate questions worthy of consideration.

Many patients prefer power technology when used with the lowest power and water settings possible and prefer achieving the end result in less time. While not all published data concurs, several studies confirm increased patient comfort with ultrasonic versus hand instrumentation (6,9,10) which should also impact evidence-based decision-making for clinicians. 

New Evidence Sheds Light on Dental Aerosols

An article titled, “Sources of SARS-CoV-2 and other microorganisms in dental aerosols” published by the Journal of Dental Research in 2021 (11) confirmed something we have long known in dentistry, that hopefully will increase the urgency for dental unit waterline safety in all dental practices. In this study, they analyzed the aerosolized DNA microbiota from 28 patients undergoing ultrasonic instrumentation, implant surgery, or restorative procedures and found a major source of DNA contaminant in aerosols came from the dental irrigants. In contrast, saliva did not significantly contribute to aerosolized contamination as pre-procedural rinses and HVE were utilized. Numerous other studies published since the outbreak of the pandemic have reached the same conclusion.


The risk of disease transmission in a dental environment never has been and never will be zero, but what is documented is minuscule. Universal precautions incorporated prior to COVID-19 have provided a high level of safety to patients and clinicians. The additional layering of infection-control practices must be incorporated in dental practices in a COVID-19 environment, but dental hygienists should feel confident that aerosol-generating devices can be incorporated safely. For more information and evidence on this topic, attend “Aerosol-Producing Devices for the RDH” on January 20, 2022, during the Rocky Mountain Dental Convention.

1) Guidance for Dental Settings. Interim Infection Prevention and Control Guidance for Dental Settings During the COVID-19 Response. Accessed Nov 1, 2021.
2) Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. New England Journal of Medicine, 2020: 382: 1564-1567. Doi:10.1056/NEJVc2004973.
3) Harrell SK, Molinari J. Aerosols and splatter in dentistry. A brief review of the literature and infection control implications. Journal of the American Dental Association, 2004: 135: 429-437.
4) Cobb CM, Non-surgical pocket therapy – Mechanical. Annals of Periodontology, 1996: 1: 443-490.
5) Krishna R, DeStefano JA. Ultrasonic vs. hand instrumentation in periodontal therapy: clinical outcomes. Periodontology 2000, 2016: 71: 113-127.
6) Tunkel J, Heinecke A, Flemmig TF. A systematic review of efficacy of machine-driven and manual subgingival debridement in the treatment of chronic periodontitis. Journal of Clinical Periodontology, 2002: 29: 72-81.
7) Checchi L, Pelliccioni GA. Hand versus ultrasonic instrumentation in the removal of endotoxins from root surfaces in vitro. Journal of Periodontology, 1988: 59: 398-402.
8) Cobb CM. Clinical significance of non-surgical periodontal therapy: an evidence-based perspective of scaling and root planing. Journal of Clinical Periodontology, 2002: 29: 6-16.
9) Drisko CL. Periodontal debridement: hand versus power-driven scalers. Dental Hygiene News, 1995: 8: 18-23.
10) Wennestrom JL, Tomasi C, Bertelle A, Dellasega E. Full-mouth ultrasonic debridement versus quadrant scaling and root planing as an initial approach in the treatment of chronic periodontitis. Journal of Clinical Periodontology, 2005: 32: 851-859.
11) Meethil AP, Saraswat S, Chaudhary PP, Dabdoub SM, and Kumar PS. Sources of SARS-CoV-2 and other microorganisms in dental aerosols. Journal of Dental Research 2021. Accessed October 31, 2021

Ms. Karen Davis is founder of her own continuing education company, Cutting Edge Concepts®, and currently practices dental hygiene in Dallas, TX. Dentistry Today has consecutively recognized her as a “Leader in Continuing Education” since 2006. Ms. Davis will be speaking on Thursday, January 20 at the 2022 RMDC.