A dentist that I used to work with in the East Coast, took me aside one day to discuss a concern about a patient. He mentioned that a patient whom I saw a couple of days prior for an adult prophylaxis, has called the office to let us know that she was not feeling good and was having cold like symptoms. She mentioned that she felt the same way 6 months ago after a dental cleaning. 

She also asked if next time we could not use the prophy jet polisher or the ultrasonic scaler.  I was greatly surprised to hear this news since I have not had such complaint before. She was a healthy patient with slight onset of early gingivitis. I was perplexed then, but my research delivered the answers I was looking for.  

Disease Transmission & Personal Protective Barriers

As healthcare professionals, it is embedded in our minds about the importance of implementing proper infection control protocols (disinfection, sterilization, the use of universal precautions, and personal protective equipment) to reduce disease transmission and its potential effects on the health of the patient and clinician.  It makes clear sense to protect ourselves and our patients from the splatter that occurs during appointments which contain microorganisms and blood. 

However, have you ever wondered what is truly in the air during and after procedures that is typically not visible to the naked eye? How our PPEs protect us from it? What measures are we taking to protect our patients? I honestly didn’t give it a second thought until the complaint from one patient and now the Covid-19 pandemic. 

A Microscopic Look: Splatter vs Aerosol  

Let’s take a microscopic look into what we are actually protecting ourselves and our patients from. 

An oral cavity is perfectly suitable for growth of broad range of microorganisms, harboring over 700 species of bacteria, viruses, and fungi.8 These microorganisms can spread rapidly through splatter and aerosols when using high-powered devices such as air polisher, high-speed handpieces, air/water syringes and ultrasonic scalers.6

Splatter is considered large particles of water, saliva, blood and other debris that travels a short distance and settles down quickly. It usually lands on the floor, nearby operatory surfaces, the patient, or the clinician. You would recognize splatter on the face shield, protective eyewear, or other surfaces. Although after a short period of time, it might be hard to detect when it dries up clear.11

On the other hand, aerosols are tiny airborne particles or droplets that range in size from .5-10 microns in diameter.3 To make it more relevant, an average cross-section of a human hair is 50 microns. The human eye can’t see anything smaller than 40 microns in size. These aerosol particles remain in the air for a considerable amount of time after completion of a dental procedure. They represent an infectious hazard because of gross contamination with microorganisms found in saliva, nasopharyngeal secretions, biofilm, and blood.1

Can’t See It; What’s the Problem? 

You might ask why is this important to keep in mind? Due to inhalation of aerosol particles that linger in the air for considerable amount of time, dental health professionals have a higher risk for respiratory infections such as common cold, pneumonia, tuberculosis, influenza, sinusitis and different types of coronaviruses (SARS, MERS, COVID19). The viral particles can survive within small droplets in the air for several hours.

Studies have also shown that Legionella antibodies in dental personnel are higher in comparison to the general population. This is the gram-negative bacteria that contributes to Legionnaires’ disease (pneumonia type illness) and Pontiac fever (mild flu-like illness). Furthermore, Staphylococcal, viral and skin infections, and conjunctivitis (pink eye) can transpire.6  

Let’s remember that dental aerosols do differ in its composition, depending on the health status of the patient and the type of procedure being performed. With over 700 species of bacteria, fungi, and viruses present in a human mouth, aerosols contain millions of bacteria per cubic foot of air.13 Experiments have revealed that bacteria could be recovered six inches to up to 6.5 feet from the mouth of a patient.1,13 The clinician’s mask is the highest level of contamination, followed by the arms of the operator, head, chest and inner surface of the face shield of the clinician and assistant.

Aerosol Producers? 

So, the big question is, what produces the most airborne contaminants in dentistry? I was in disbelief when I read the research. Out of all possible high-energy equipment used in a dental office, the one that produces significantly higher aerosol and splatter is the ultrasonic scaler. Yes, you have heard it right! Following that is a high-speed handpiece, air polisher and air/water syringe.13

Studies are showing that the level of airborne contaminants in the dental treatment rooms after only four hours of dental procedures is 3.3 times higher than before treatment. 47% of microbial aerosol peak concentrations was due to scaling procedures and only 11% to cavity preparation.5

Now take a moment to consider the population that you serve in your practice. 

According to the recent report from the Center of Disease Control and Prevention (CDC), 47.2% of adults aged 30 years and older have some form of periodontal disease. Prevalence of periodontal disease increases with age, therefore, 70% of adults 65 years and older have it.7

Periodontal disease begins as acute inflammation of the gingival tissue and can progress to tooth loss if left untreated. It’s a complex, multifactorial infection, therefore, using an ultrasonic scaler subgingivally on periodontally involved teeth produces hazardous aerosols containing blood.8,10

Enhancing Safety

What precautions are you taking to reduce aerosol and splatter in your practice to protect yourself, your patients, and your dental environment? It is important to remember that we should NOT rely on a single precautionary strategy. 

A study done by Maghloutha and associates concluded that microbial aerosol concentration decreased by 50-70% at the end of a workday once proper methods to reduce aerosol contamination were put in place.6 What are these methods? Let’s take a look at the first four main layers of defense in reducing hazardous aerosol. 

1. Personal Protective Barriers

Occupational Safety and Health Administration (OSHA) and Center for Disease Control and Prevention (CDC) strongly recommend following standard precautions as the first layer of defense against hazardous aerosols. This includes donning of PPE: masks, gloves, safety glasses for both patient and clinician, and gown/lab jacket. 

ASTM level 3 masks are highly recommended to protection against occupational respiratory infections. Moreover, it is advisable to change masks between patients and definitely once it becomes wet during patient treatment. During airborne infection isolation precautions, such as Covid-19 pandemic, N95 masks are suitable.4

2. Pre-procedural Mouth Rinses

The second layer of defense is using pre-procedural antimicrobial mouth rinses. Rinsing before performing any dental procedures not only reduces bacterial count in the mouth and saliva, hence less hazardous aerosol production, but also decreases number of microorganisms introduced into patient’s bloodstream during invasive dental procedures. 

It is imperative to understand that not all mouth rinses perform equally in reducing aerosolized bacteria. Studies have concluded that rinsing 60 seconds with 0.12% Chlorhexidine (in comparison to Listerine, water, and combination of essential oils in an alcohol base) demonstrated the most effectiveness in reducing salivary bacterial count by up to 94.1%.1,2

3. High-Volume Evacuation (HVE)

Using high-volume evacuators during aerosol producing dental procedures reduced hazardous aerosol particles by 89.7% compared to intraorally positioned standard saliva ejectors.3 An effective method of aerosol reduction is to place the HVE near an ultrasonic scaler or high-speed handpiece. 

4. Patient Position

Patients should be treated in a supine position to allow clinicians to work away from the breathing pathway of a patient.6

Additional methods to minimize hazardous aerosol particles produced during dental procedures are:

  • High-efficiency particulate air room filters (HEPA) and ultraviolet treatment of ventilation system.6 Although expensive, but highly effective. 
  • CDC further recommends flushing waterlines to eliminate microbial accumulation in the beginning of a day and between patients. 
  • Use of rubber dam when appropriate and autoclave dental handpieces after every use.
  • Use protective barriers on surfaces that are hard to disinfect to reduce surface contamination.4

There is much to consider in order to minimize hazardous airborne particles during dental procedures. Our patients and team members rely on us for safe practices to keep everyone healthy. There is no single 100% effective preventative measure, therefore, use precautionary strategies presented above to keep yourself, your team and your patients safe! 

So why was Mrs. Jones feeling sick after her appointments? To answer this question, as a team we had to re-evaluate office systems and protocols for infection and aerosol control. We implemented and strictly adhered to the four layers of defense for reducing hazardous aerosol production that is mentioned above. As a result, Mrs. Jones became our practice ambassador and happily returned for her hygiene and restorative needs.  


1. Sawhney, A., et al. (2015). Aerosols: How Dangerous They Are in Clinical Practice. Journal of Clinical and Diagnostic Research : JCDR9(4), ZC52–ZC57. Retrieved from

2. Narayana, T., Mohanty, L., Sreenath, G., & Vidhyadhari, P. (2016). Role of Preprocedural Rinse and High Volume Evacuator in Reducing Bacterial Contamination in Bioaerosols. Journal of Oral and Maxillofacial Pathology: JOMFP20(1), 59–65. Retrieved from

3. Jacks, M.E. (2002) A Laboratory Comparison of Evacuation Devices on Aerosol Reduction. Journal of Dental Hygiene: 76(3):202-6. Retrieved from

4. Kohn, W.G., Collins, A.S., Clevelant, J.L., Harte, J.A., Eklunt, K.J., Malvitz, D.M. Center for Disease Control and Prevention. Guidelines for infection Control in Dental Health-Care Settings-2003. MMWR 2003; 52 (Report No. 17). Retrieved from

5. Barlean, L., et al. (2010). Airborne Microbial Contamination in Dental Practices in Iasi, Romania. OHDMBSC: 4(1), 16-20. Retrieved from

6.  Raghunath et al. (2016) Aerosols in Dental Practice- A Neglected Infectious Vector; BMRJ, 14(2): 1-8, 2016; Article no.BMRJ.24101. Retrieved from

7. Periodontal Disease

8. How, Kah Yan et al. “Porphyromonas gingivalis: An Overview of Periodontopathic Pathogen below the Gum Line.” Frontiers in microbiology vol. 7 53. 9 Feb. 2016, doi:10.3389/fmicb.2016.00053. Retrieved from   

9. Paramashivaiah, R., & Prabhuji, M. L. V. (2013). Mechanized Scaling with Ultrasonics: Perils and Proactive Measures. Journal of Indian Society of Periodontology17(4), 423–428. Retrieved from

10. Barnes, James B., Harrel, Steven K., Rivera-Hidalgo, Francisco., Blood Contamination of the Aerosols Produced by In Vivo Used of Ultrasonic Sealers Journal of Periodontology  1998;69:434–438. Retrieved from

11. Bloodborne Pathogens & Aerosols

12. Marcelle M. Nascimento, in Microbiome and Metabolome in Diagnosis, Therapy, and other Strategic Applications, 2019. Retrieved from

13. Singh, A., et al. (2016). Aerosol, A Health Hazard During Ultrasonic Scaling: A Clinico-Microbiological Study. Indian Journal of Dental Research: 27(2), 160-162. Retrieved from;year=2016;volume=27;issue=2;spage=160;epage=162;aulast=Singh

14. H.R.VeenaS.MahanteshaPreethiA.JosephSudhirR.PatilSuvarnaH.Patil (2015) Dissemination of aerosol and splatter during ultrasonic scaling: A pilot study. Journal of Infection and Public Health; 8(3), 260-265. Retrieved from

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