Introduction: A fast review of the definitions

The topic of aerosols and aerosol mitigation has come to the forefront for dentists trying to navigate the evolution of the COVID-19 pandemic, but it has always been an important part of safety protocols in dental practices. Dental aerosols are the air-borne particles created by dental procedures, and can be released from:

  • the oral cavity of the patient (ie bioaerosols like bacteria and viruses, released by the disturbance of saliva, skin, blood)
  • the equipment or materials used in procedures (ie microparticles released from dental burs or polishing procedures, water from delivery units, or the action of high-speed handpieces)

The US Centers for Disease Control (CDC) lists aerosol-generating procedures (AGPs) as those procedures that result in the release of airborne contamination of spatter or droplets, primarily those that utilize equipment like ultrasonic scalers, high-speed dental handpieces, air/water syringes, and the tools used in polishing and abrasion procedures involving compressed air and water . They even went so far as to recommend reducing the use of some equipment when other lower-aerosol-producing equipment, such as hand instruments, could do the job. But any dental procedure that creates aerosolized saliva can cause contamination from the plethora of bacteria and viruses found in the mouth (esp dental plaque), and the nose, throat and respiratory tract.

Size matters

Dental aerosols come in a range of sizes, mostly under 50 µm. Smaller, lighter particles (5 µm - 10 µm) carrying viruses and bacteria are potentially more dangerous, remaining airborne for longer and travelling further from their source . In particular, the SARS 2 (COVID-19) is not only a tiny virus but it remains airborne and stable for hours, posing a threat to both patients and staff.

Methods to reduce the risk of contamination by dental aerosols

First lines of defense, starting with PPE

Controlling particles and protecting both patients and staff requires multiple strategies for various types and sizes of microscopic droplets. The first line of defense is Personal Protective Equipment (PPE), which provides a physical barrier to the aerosols. The use of these measures has become ubiquitous since the pandemic. In response to COVID-19, the CDC released additional guidance for further minimizing droplet spatter and aerosols, enhancing it’s existing recommendations for layering of protective protocols, starting with plexi shields at reception stations, patient spacing, single-use gloves, gowns, masks that cover the nose and mouth, and face shields.

Many practices have implemented the use of a preprocedural antimicrobial rinse to further reduce the production of contaminated airborne pathogens. The ingredients in these rinses can either kill existing bacteria or prevent the reproduction or proliferation of bacteria, or, have been shown to have antiviral effects against some viruses. The anecdotally recognized gold standard for these rinses is chlorhexidine gluconate (CHX) but agents as varied as essential oils and hydrogen peroxide have been proven to reduce bacterial or viral loads. It should be noted however that these rinses are effective primarily in saliva and loose mucous membranes; they do not reduce pathogens locked in dental plaque, or other areas of potential release like the nasopharynx or blood from the operative site.

Use of Dental Suction Devices

Once dental aerosol is created, blocking the particulates with PPE is a good start but removing them entirely is significantly more effective. The use of a high-volume evacuator, or HVE, has been shown to reduce the contamination arising from the operative site by more than 90 percent , and is the preferred method for aerosol removal and reducing the risks of contamination (UV light being another alternative, but a cost-prohibitive one, for most practices) .

HVEs: Wet vs. Dry Vacuum

Traditionally, dental offices choose between wet or dry vacuums to protect their practices. Wet or dry refers to whether the vacuum pressure needed to suction or evacuate the contaminated air is created by water (wet) or air (dry). We’ll get into the differences between wet and dry vacuums in future articles, but for the purposes of today’s discussion, the advantage for aerosol mitigation falls to the dry vacuum pumps, which often have the capacity to pull larger volumes of air, and, as with the Aeras vacuum by Ramvac, can more easily facilitate the adding of additional HVEs, which has become a very desirable option. It is important to remember, when adding HVEs, to calculate the appropriate amount of added suction you can add to retain adequate flow. Every time you add a “user” (saliva ejector, nitrous scavenger) you diffuse the power of the vacuum over more users, and it’s important not to overburden the vacuum which would compromise it’s effectiveness. Information for each vacuum is defined by the manufacturer. For example, the DENTALEZ Aeras dry vacs allocate users as follows:
1 HVE= 1 user
1 saliva ejector = 1/5 user
1 Nitrous scavenger= ¼ user
And so on.

The size of the vacuum is the number of simultaneous users, so for example if a 10-operatory practice has 7 operatories working at the same time, and 1 HVE is used in each room then a 7-user vacuum is needed.

Chairside HVE

The CDC has also recommended additional HVE use at the source of the aerosol creation, to collect and remove saliva and blood immediately from the oral cavity. To answer this need, DENTALEZ designers created an easy-to-install hands-free HVE for at-the-source HVE suction during aerosol-generating procedures.

“I have worked with many hygienists throughout the pandemic who have struggled to find a comfortable and efficient method of utilizing HVE during scaling procedures, as well as one that is affordable to their practice. The Hands-Free-HVE checks all the boxes.” Mary Govoni, MBA, CDA, RDH

Conclusion

Reducing, removing and eliminating aerosols during dental procedures is critical to the ongoing health and safety of dentists, their staff and their patients. Taking stock of your current aerosol mitigation equipment and techniques at this moment should be part of any practice adjusting to the post-pandemic world. Increased PPE, incorporating the use of oral rinses and additional chairside HVE as well as enhanced vacuum power are all great options for improving your defenses against airborne pathogens.

The new Aeras Vacuum by Ramvac is an example of the kind of cloud-based diagnostic capability that can keep a practice up and running smoothly, protecting your staff from malfunction or down time, and protecting your equipment investments. All while providing the industry gold standard in quiet, efficient aerosol removal and 100% water-free operation. Embedded sensors in critical areas on our Aeras Vacuum monitor for indicators that typically herald trouble, including overheating or unwanted moisture.

Our easy-to-install hands-free HVE is another solution created specifically to solve the challenges in today’s dental practices. The HVE design is compatible with most patient chairs on the market today, and comes with a simple plug-and-play kit that comes with everything needed to assemble and use. The HVE is also easy to clean, designed with consideration for increased safety protocol, and using common dental practice disinfectants.

Want to learn more about aerosol mitigation in dental practices? View our on demand CE webinar with Mary Govoni and Viva Learning.

1. Harrel SK, Molinari J (April 2004). "Aerosols and splatter in dentistry: a brief review of the literature and infection control implications". Journal of the American Dental Association.
2. https://www.cdc.gov/coronavirus/2019-ncov/hcp/dental-settings.html#:~:text=Commonly%20used%20dental%20equipment%20known,%2C%20and%20air%20abrasion.
3. United States Centers for Disease Control and Prevention. Guidance for Dental Settings. Available at: cdc.gov/coronavirus/2019-ncov/hcp/dental-settings.html. Accessed October 21, 2020.
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7093851/
5. https://www.nature.com/articles/s41415-020-2274-3
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7093851/
7. Micik RE, Miller RL, Mazzarella MA, Ryge G. Studies on dental aerobiology, I: bacterial aerosols generated during dental procedures. J Dent Res. 1969;48(1):49–56. [PubMed] [Google Scholar]
8. Harrel SK. Contaminated dental aerosols. Dimensions of Dental Hygiene. 1(6);2003:16-20.