Covid-19: Study shows benefits of local exhaust ventilation in dental settings

One of the main ways in which Covid-19 is communicated is through airborne respiratory droplets—droplets that can be dispersed as a result of dental procedures. In a new study, researchers from Newcastle University examined the applicability of local exhaust ventilation (LEV) systems for controlling the dispersion of these droplets and aerosols and found that they could be quite valuable for this purpose.

According to James Allison, lead author of the study and a clinical research fellow at the university’s School of Dental Sciences, LEV is often referred to as extra-oral scavenging or suction when used in dental settings. While such systems are employed in other industries to reduce exposure to airborne contaminants, their use is not currently commonplace in dentistry. To investigate the potential benefits of LEV systems in dentistry, Allison and a research group conducted experiments on dental mannequins in both an open-plan dental clinic and a single surgical room.

Ten-minute crown preparations were conducted in the open-plan clinic using an air turbine handpiece, and full-mouth ultrasonic scaling was conducted over the same duration in the surgery. In both settings, fluorescein was added as a tracer to the instruments’ irrigation reservoirs and an LEV system with HEPA filters and a flow rate of 5,000L/minute was used.

Overall, it was found that using the LEV system reduced aerosol dispersion from the air turbine handpiece by 90% within 0.5m of the procedure—a figure that increased to 99% for the ultrasonic scaler within the same proximity. For the air turbine handpiece, the detection of larger droplets within 0.5m was also reduced by 95%.