The Dispersion, Persistence, and Control of Viral Bioaerosols in Dentistry

Abstract

Bioaerosols containing viruses and other microorganisms are dispersed from the mouth during dental procedures, posing infection risk to patients and professionals. Uncertainty over viral bioaerosols caused unprecedented worldwide disruption during the COVID-19 pandemic, and millions couldn’t access dental care, impacting oral health. This project aims to determine: the extent of virus dispersion in dental bioaerosols; if dispersion can be controlled using bioaerosol control measures; and the effect of environmental parameters such as ventilation. A model of viral dental bioaerosols was developed using two bacteriophages (MS2, phi6) infused into a mannequin’s mouth during dental procedures with an air turbine handpiece. Physical aerosol was measured using optical particle counters, and bacteriophage captured in surface and air samples. Infective bacteriophage was measured using plaque assay and bacteriophage RNA quantified by reverse transcription quantitative polymerase chain reaction. Distance of virus dispersion, persistence of virus over time, and the effect of control measures (ventilation, rubber dam, waterline disinfectants, suction, local exhaust ventilation [LEV], electric micromotor handpiece) were explored. Without control measures, dental procedures led to dispersion of infectious virus over significant distances from the procedure (6.9 m in air, 2.8 m on surfaces), and at low ventilation rates, remained airborne for a prolonged time (46 min). Increasing ventilation rate to recommended levels reduced persistence to only a few minutes. Viral RNA recovery was greater than infectious virus, suggesting not all dispersed virus remains infectious. Control measures produced substantial reductions in physical aerosol and infective virus, particularly LEV, which often eliminated virus recovery completely. In conclusion, viral bioaerosols in dentistry can be dispersed over substantial distances and remain airborne for considerable time. However, improved ventilation and control measures commonly used in dentistry reduce this. Infection control guidance should include when and how to employ these measures to reduce risk in everyday care and during infectious disease outbreaks.