Local exhaust ventilation may help control dental aerosols and droplets

Researchers at Newcastle University, England, conducted experiments on dental mannequins. Ten-minute crown preparations were performed with an air-turbine handpiece in a large open plan clinic, and full mouth ultrasonic scaling was performed for ten minutes in a single dental surgery. Fluorescein was added to instrument irrigation reservoirs as a tracer. In both settings, Optical Particle Counters (OPCs) were used to measure aerosol particles between 0.3 – 10.0 μm and liquid cyclone air samplers were used to capture aerosolised fluorescein tracer. An LEV device with High Efficiency Particulate Air (HEPA) filtration and a flow rate of 5,000 L/min was tested during the experiments.

The results show that using LEV reduced the dispersion of aerosols from the air turbine handpiece by 90% within 0.5 m, and this was 99% for the ultrasonic scaler. The settling of larger droplets was also measured for the air-turbine, and this was reduced by 95% within 0.5 m when LEV was used.

"This study shows that the effect of LEV was substantially greater than suction alone for the air-turbine and was similar to the effect of suction for the ultrasonic scaler," said IADR President Eric Reynolds, The University of Melbourne, Australia. "While no mitigation measure alone will completely eliminate risk, LEV appears to be a useful approach, which in addition to other measures, substantially reduces dispersion of aerosols, and therefore risk of exposure to pathogens."