Patient care

Dental aerosol and a viral pandemic – what are the risks, and the means of protection, for dental professionals?

The current viral pandemic caused by the SARS-CoV-19 virus is already known to be a source of high health risk for many professions – with medical staff proven to be among the most endangered. Given that the virus is transmitted mostly via bodily fluids, there is a great risk for dental professionals in particular – including dentists, dental hygienists and other personnel assisting in dental care centres. The number one enemy here is infectious saliva droplets.

Saliva is a protective and beneficial fluid for humans’ health. The danger comes in the form of salivary viral loads of oral microbes; the new coronavirus being one of the most discussed, and dangerous, pathogens these days.

In general, coronaviruses are divided into the alpha, beta, gamma and delta group. They are known to be originally transmitted from animals to humans, and then spread via bodily fluids throughout the human population.

Statistics have shown that there are several dentistry-related occupations that are at very high risk of infection. According to the UK’s Dentistry magazine, the top 10 occupations with the highest potential exposure to COVID-19 are:

  1. Dental nurses
  2. Nurses
  3. Medical practitioners
  4. Houseparents and residential wardens
  5. Care escorts
  6. Dental practitioners
  7. Medical radiographers
  8. Medical and dental technicians
  9. Veterinarians
  10. Midwives

So, three out of ten of the most endangered occupations are directly connected to dentistry.

Similarly, according to the World Economic Forum the #1 most endangered occupation is the dental hygienist, with the dental assistant in third place and dentists (in general) in fourth place.
Why is that so? Taking the most common means of transmission of the virus into account, the answer is simple – these are the occupations that are most exposed to aerosols made of patients’ saliva during their job execution.

Which dental treatments are potentially the most dangerous?

Almost all routine dental procedures fully expose dental professionals to a patient’s saliva. WHO describes aerosol-generating procedures (AGPs) as being widely performed, worldwide, in dental practices. AGPs are defined as any medical, dental and patient-care procedure that results in the production of airborne particles (aerosols) <5 micrometres (μm) in size, which can remain suspended in the air or travel over a distance, and may cause infection if they are inhaled.

According to a study published by Sotiriou et al., there is a fair assumption that dental drilling produces aerosolized saliva that contains particles small enough to penetrate deep into the lungs of the dentist – usually while leaning very close to the patient’s mouth. These are also produced by ultrasonic scaling.

In dental aerosol we can find almost all of the pathogens that are to be found in the human body. So if a patient is infected with the coronavirus, there is a great risk of infection for the dental professional. Besides dental drilling, there are many other procedures that require the use of high-speed instruments, high-pressure air tools or air/water spray.

These kinds of dental procedures are the reason for frequent exposure of dental professionals to saliva, blood and other body fluids. The final dangerous pathogen-transmitting cocktail can be mixed from saliva microbes and blood – due to the invasive nature of the procedures.

What are dental aerosols and how are they transmitted?

Aerosols in general are liquid or solid particles, 5 μm or less in diameter, that are suspended in the air. They can remain in the air for a long time and be transported with spray-generating equipment at long distances. The source of dental aerosols is a patient’s saliva, nasal and throat secretion, dental plaque, gingival sulcus secretion, blood, tooth tissues and materials used for dental treatment.

Aerosol composition varies from patient to patient, and depends on the site and type of procedure in the oral cavity (i.e. tooth preparation, polishing, restoration and dental cleaning, surgical tooth extraction). The most intensive aerosol and splatter emissions occur during work that uses an ultrasonic scaler tip and from a bur on a high-speed handpiece.

During conservative treatment and professional oral hygiene procedures, the sites showing the highest microbiological contamination due to aerosol and splatter emission are: doctors’ and assistants’ masks, unit lamps, surfaces close to spittoons and mobile instrument material tables.

Infections occur in dentists more often than in the general population

Saliva contains protective components that are necessary for maintaining a healthy environment in the mouth – white blood cells, enzymes, antimicrobial agents (hydrogen peroxide, secretory IgA and others), electrolytes and many more. On the other hand, saliva is also the host and source of various pathogens – either bacterial or viral.

According to a study published by Cottone et al., type B viral liver infections occur in dentists at least three times more often than in the general population. Cytomegalovirus, human herpes viruses (including the “kissing disease” – mononucleosis), Epstein-Barr virus and many other viruses are quite easily spread via saliva aerosols during dental procedures. Unfortunately, the coronavirus is no exception to this. Therefore, it brings with it important questions – what kind of protection is appropriate? Is the medical face mask (that is generally worn by dentists) enough?

Which areas of a dentist’s face are the most endangered?

An interesting study has been conducted that shows a new perspective on whether the dentist is protected enough by wearing only a traditional medical face mask. The study published by Farahnaz Nejatidanesh et al., showed that the areas around the nose and the inner corners of the eyes are at significantly higher risk of contamination.

There was no significant difference between the right and left side of the face. In terms of contamination, the periodontists’ faces were significantly more contaminated than prosthodontists’ faces. The reason for this is probably to do with bleeding and soft-tissue irritation during ultrasonic scaling. The conclusion is that there is a requirement to protect mainly the eyes, nose and mouth area of dentists’ faces.

Whole face coverage is suggested to avoid pathogens from saliva

The potential transmission of various pathogens found in saliva (not only coronavirus, but also other types of viruses and bacteria) is present mainly during invasive dental procedures that can generate aerosols from saliva and blood. Due to the proximity of the dental specialist to the patient’s face, it has been proven that the most endangered areas of the dentist’s face are around the nose and eyes.

Therefore, it is very important to cover not only the mouth and nose with a medical face mask, but also to consider wearing special glasses or a transparent shield made of non-permeable material. Alongside this, it is recommended to use a disinfecting liquid – in the form of a mouthwash that the patient uses prior to the procedure, and if possible, also during the procedure. Besides this, there is the need to follow standard hygiene rules – for example, wearing medical gloves and cleaning and disinfection procedures between each patient.