Aerosol: Fact vs. Fiction!

What is the right way to deal with aerosol and bacteria?
That´s the key question when it comes to safety in the dental practice. But what is fact and what is fiction? Product Manager, Judith Berg, has put together some answers.

What is aerosol?

  • Aerosol is a mixture of air, water and solid particles.
  • Aerosol consists of small particles called droplet nuclei (1–5 μm) or droplets (5-50 μm) (1).
  • In an un-ventilated area, aerosols can remain in the atmosphere for up to 30 minutes after treatment and can be spread several meters during treatment (1)
  • Most of the contamination from aerosols can be found within a radius of 0.3 m to 1.5 m of the treatment site. (2).

How is aerosol created?

Physically, most aerosols in dental practice are created by atomization.

There are two sources of contaminated aerosol:

Rotating and oscillating handpieces / equipment (3,4)
They are created by supplying energy through rotating or oscillating handpieces to liquids (saliva, cooling spray, cooling water) which is atomized creating aerosols.
However, with appropriate equipment reprocessing, coolant supply, decontamination and water line decontamination - contamination of this aerosol can be minimised.

Patient (1,2)
Aerosol rebound occurs from the oral cavity after contact with the tooth or soft tissue. The aerosol is almost certain to contain germs, saliva and possibly blood (6) from the patient.
The bacterial and viral load from the patient's is dispersed and distributed via the spread of the aerosol.

What can I do to reduce the bacterial load of the patient?

Recently trials in China, due to the SARS CoV2 pandemic, have shown the effectiveness in dental practice of using pre-procedural mouth rinse: both 0.2% PVP-I solution as well as 1% H2O2 (= hydrogen peroxide) solutions reduce the number of germs – including the SARS CoV2. Numerous studies have proven the effectiveness of PVP-I (= povidone-iodine) in reducing germs. (7). In this study it was shown that CHX with the concentration of 0.2% was less effective.

Therefore, pre-procedural mouth rinse using e.g. PVP-I, H2O2 has been clinically proven as an effective way to reduce the bacterial load and viral contamination of aerosol (8) – it also reduces the negative impact of “aerosol being present during dental treatment”. It does not avoid or eliminate the need for recommended levels of PPE and relevant safety measures.

How can I protect my team and patients from aerosol?

You use a multi-layer strategy, following up to date recommendations of how to protect dental personnel and patients. However, professional handling of aerosol can reduce the risk from aerosol to the lowest possible level!

So what is key to effective infection control in dentistry:

  • effective disinfection of surfaces and reprocessing of dental equipment (9,10)
  • Use of appropriate PPE (personal protective equipment): masks, googles, gloves, scrubs, vaccination
  • effective use of mouth rinsing
  • rubber dam
  • anti-suck-back capabilities of equipment
  • high volume suction
  • dental unit water lines decontamination

(1) Veena, H. R., et al. (2015). "Dissemination of aerosol and splatter during ultrasonic scaling: a pilot study." J Infect Public Health 8(3): 260-265.
(2) Bennett, A. M., et al. (2000). "Microbial aerosols in general dental practice." Br Dent J 189(12): 664-667.
(3 )Graetz, C., et al. (2014). "Spatter contamination in dental practices--how can it be prevented?" Rev Med Chir Soc Med Nat Iasi 118(4): 1122-1134.
(4) Toroglu, M. S., et al. (2001). "Evaluation of aerosol contamination during debonding procedures." Angle Orthod 71(4): 299-306.
(5) Reitemeier B, Jatzwauk L, Jesinghaus S, Reitemeier C, Neumann K. Effektive Reduktion des Spraynebel-Rückpralls - Möglichkeiten und Grenzen. ZMK 2010:662-673.
(6) Shihama, K., et al. (2009). "Evidence of aerosolised floating blood mist during oral surgery." J Hosp Infect 71(4): 359-364
(7) Peng, X., et al. (2020). "Transmission routes of 2019-nCoV and controls in dental practice." Int J Oral Sci 12(1): 9.
(8) Eggers M, Koburger-Janssen T, Eickmann M, Zorn J. In Vitro Bactericidal and Virucidal Efficacy of Povidone-Iodine Gargle/Mouthwash Against Respiratory and Oral Tract Pathogens. Infect Dis Ther. 2018;7(2):249‐259.
(9) Bracher, L., et al. (2019). "Surface microbial contamination in a dental department. A 10-year retrospective analysis." Swiss Dent J 129(1): 14-21.
(10) Zemouri, C., et al. (2017). "A scoping review on bio-aerosols in healthcare and the dental environment." PLoS One 12(5): e0178007.