Evaluation of the spatter-reduction effectiveness and aerosol containment of eight dry-field isolation techniques

The novel coronavirus that was first identified in Wuhan, China, in December 2019, created a pandemic that has the potential to change the paradigm of health care delivery. Of interest to the dental community is the presence of SARS-CoV-2 in the saliva of the affected patients that can potentially cause transmission of COVID-19 via droplets. The highly infectious nature of the pathogen has created a sense of urgency and a need for extra caution to prevent the spread of the disease and the potential infection of patients and the entire dental team. Spatter consists of droplets up to 50 µm in size that are effectively stopped by barriers such as gloves, masks, and gowns. Aerosols are defined as droplet particles smaller than 5 µm that can remain airborne for extended periods and that have been reported to be significant in viral respiratory infections. In this study, aerosol represented by particulate matter with a size of 2.5 µm (PM2.5) was measured.

Eight dry-field isolation methods were tested in a setup that included a realistic dental manikin and a high-speed handpiece that generated air-water spray. Environmental noise generated by the suction devices, suction flow rate of each setup, and the amount of environmental spatter and aerosols, were measured.

The experimental setups showed significant variability in the suction flow rate, but this was not correlated to the level of sound generated. Some experimental setups caused a short-term level of noise that exceeded the NIOSH (National Institute for Occupational Safety and Health) guidelines and were close to the OSHA (Occupational Safety and Health Administration) recommended thresholds. It is also worth noting that the variability in the flow rate is not reflected in the efficacy of the experimental setups to mitigate spatter. All experimental setups, except the IsoVac system, provided statistically significantly better spatter mitigation compared to the control. All experimental setups also were efficient in mitigating aerosols compared with the positive control (P < .0001) and most systems yielded results similar to the negative control ambient PM (P > .05).

Results indicate that spatter reduction was significantly better amongst the setups in which an additional high-volume evacuator (HVE) line was used. All setups were efficient at mitigating PM2.5 aerosols in comparison to the control. The conclusions of this study should be interpreted with caution, and additional mitigation techniques consistent with the Centers for Disease Control and Prevention recommendations must be implemented in dental practices.