Cross-infection risk assessment in dental clinic: Numerical investigation of emitted droplets during different atomization procedures

Cross-infection risk induced by the emitted droplets and bioaerosols during dental procedures has challenged service providers and patients alike. The present study aims to investigate the transmission mechanism of emitted droplets during the dental atomization procedures: vibration ultrasonic scaling (vUS) and rotation high-speed drilling (rHSD) and propose the risk assessment. Computational fluid dynamics (CFD) simulation was performed, and the experimentally recorded droplet velocity and diameter distribution during the atomization procedures were defined as initial boundary conditions. The droplet transmission in the dental clinic was analyzed from the final fate (deposition, suspension, and escape) and fallow time (FT) of emitted droplets. The results revealed that the diameter threshold for the droplet deposition and suspension was 60μm, and the fraction of deposited droplets would be stable at 79.5% for rHSD and 85% for vUS. The primary contamination distance was generally within 0.28 m and 0.4 m from the treatment position for the atomization procedures of rHSD and vUS, respectively. An increment of about 2% in the fraction of escaped droplets was noted when conducting the rHSD. The median of estimated FT for the atomization procedure of rHSD, 34 min, was longer than that of vUS, 30.6 min. In general, cross-infection risk during rHSD can be regarded as “higher” than vUS. The contribution of the present study can serve as guidance to decrease the cross-infection risk in dental clinics.