During dental procedures pathogens and bacteria become aerosolized. But just how mobile are these aerosols? As practitioners, knowing how diseases can contaminate your entire practice from a single patient’s oral cavity can help in learning how to address this dilemma.
Aerosol Particle Transmission
Particles are classified based on size: coarse particles are 2.5-10 microns, fine particles are less than 2.5 microns and ultrafine particles are less than 0.1 micron. The nose typically filters air particles above 10 microns. If a particle is less than 10 microns, it can enter the respiratory system. If it is less than 2.5 microns, it can enter the alveoli. An ultrafine particle, like the coronavirus, can enter the bloodstream and target organs such as the heart and brain.
Viruses are aerosolized by coughing, sneezing and a variety of dental procedures. As a result, particles can cross distances of up to 20 feet from an infected person, inciting secondary infections elsewhere in that environment. These aerosolized droplets can remain in the area, suspended in the air, even after the person who emitted them has left.
Below is a table showing how long COVID-19 can last in certain places/surfaces:
|Type of Surface||Longevity (in Hours)|
Dentists who treat patients using aerosolization are at an extremely dangerous risk of inoculation of themselves, their dental assistants, other office staff members and reinoculation of the patients. Most risk occurs from splatter and droplet transmission to the midface of the dentist and assistant, as well as the nasal area of the patient.
In addition, periodontal treatment has a much higher incidence of droplet transmission than prosthetic treatment. Ultrasonic and sonic transmission during nonsurgical procedures had the highest incidence of particle transmission, followed by air polishing, air/water syringe and high-speed handpiece aerosolization.
Because of these inherent dangers to dentists, team members, and patients, The Occupational Safety and Health Act (OSHA) recently released a report called “Guidance on Preparing Workplaces for COVID-19.” This document categorizes occupational risk as very high, high, medium and lower risk.
Recommendations for Dentists and Staff Coming in Direct Contact With Aerosols
The most effective ways to combat the spread of viruses over long distances include the following:
1. Installation of negative-pressure rooms or airborne infection isolation rooms
2. Frequent use of personal protective equipment (PPE) masks such as:
a. 1. R/P95, N/R/P99 or N/R/P100 filtering facepiece respirator
b. Air -purifying elastomeric respirator with cartridges
c. Powered air-purifying respirator (PAPR) with high-efficiency particulate air (HEPA) filter
d. Supplied air respirator
3. Use of eyeglasses with lateral protective shields
4. Wearing protective gloves
5. Utilization of a rubber dam to reduce contamination in the atmosphere
The fast and subtle way viruses infect people should make clinicians rethink their usage of traditional devices and focus their efforts on aerosol reduction. Clinicians should expect changes to take place; most notably in the architectural setup of the dental office. While waiting for these changes to take place, clinicians should research and evaluate the available solutions mitigate transmission risk.