Aerosols in the Dental Office: Best Practices for Patient and Practitioner Safety
Course Number: 619
Evidence of SARS-CoV-2 Transmission in the Dental Office
Evidence suggests that SARS-CoV-2 can be transmitted both directly from person-to-person by respiratory droplets with significantly less likelihood of indirect fomite-mediated transmission.4,5,82 A recent study found that up to two-thirds of patients with COVID-19 could transmit the virus 5 days after the onset of symptoms, and one-fourth of patients could transmit the virus after 7 days. They also found that infectiousness lasts a median of 5 days after symptoms began. 83 Live SARS-CoV-2 viruses have been isolated from saliva of infected individuals and the concentration of virus in saliva has been shown in some cases to be significantly higher than that on nasopharyngeal testing swabs.13,84,85 Not surprisingly, ACE2+ cells are abundant throughout the respiratory tract and salivary gland duct epithelium.25,74 Tissues in the oral cavity, including salivary gland ducts and epithelial cells have been identified as targets for infection and potential reservoirs for post-acute COVID-19 syndrome.86
In the initial stage of the pandemic, transmission of SARS-CoV-2 was thought to be increased in the dental setting due to the close interpersonal contact between individuals involved and by nature of the procedures performed during the delivery of dental care.87-89 Many precautions were put into place due to an assumption that both DHCPs and patients are at risk due to droplets containing microorganisms or direct contact with conjunctival, nasal, or oral mucosal tissues.17-20,32,87-90 It is established that, like many other viruses, the likelihood of such transmissions may be dependent upon the viral load of the infected individual and the susceptibility of the host individual.91 Potential pathways of SARS-CoV-2 transmission in the dental office are outlined in Figure 2.
As the pandemic progressed, newly unfolding discovery demonstrated that dental care delivery conveyed a relatively low risk of disease transmission in a care-delivery setting.26,27 Investigations demonstrate that in real-world settings, low amounts of microbial contamination were found in dental aerosols.45,92,93 In fact, it has been estimated that the risk of COVID-19 transmission during aerosol generating procedures is approximately equivalent to the risk conveyed during non-aerosol-generating procedures.94 It has become apparent that early in the pandemic all aerosols, including medical, dental, and respiratory aerosols, were considered to be potentially highly infectious. However, as the majority of material present in dental aerosols is derived from irrigation rather than salivary or respiratory sources, which means that extrapolation on risks conveyed by aerosol-generating dental procedures are likely not equivalent to risks demonstrated in medical procedures.95 It should be noted that the presence of COVID-19 viral particles in the saliva of both symptomatic and asymptomatic COVID-19 infected individuals and implementing strategic advanced risk-mitigation procedures is critical to promote safety for patients and dental healthcare workers in the dental office.96