Are all dental procedures equally high risk for aerosol generation? Evidence from a clinical experimental study

Aerosols and droplets generated during dental procedures represent a critical challenge for infection control and occupational safety. This study aimed to identify dental procedures and instruments associated with the highest aerosol and droplet production and to evaluate the effectiveness of Local Exhaust Ventilation (LEV) in reducing airborne contamination. This experimental study was conducted in 2025 at the Dental School Clinic of Hamadan University of Medical Sciences. Fifty-five participants each underwent one of three predefined dental procedures. The procedures were ultrasonic scaling using a piezoelectric ultrasonic scaler, restorative treatment using a high-speed air-turbine handpiece, and surgical extraction of impacted third molars using a straight surgical handpiece. Aerosol concentrations were measured at the dentist''s breathing zone, dental operating light, and workbench under LEV and non-LEV conditions using a GRIMM Model 1.108 aerosol spectrometer. Data were analyzed using repeated-measures ANOVA. A total of 330 participant-level aerosol outcomes were obtained (55 participants × six outcomes each, corresponding to three sampling locations under two LEV conditions) across the three procedures. All procedures significantly increased airborne particle concentrations across all size fractions (0.30–1.0 µm, 1.0–5.0 µm, and > 5.0 µm) compared with baseline ( p < 0.05). The highest concentrations were observed during surgical extraction performed with a straight surgical handpiece, particularly for 0.30–1.0 μm particles in the dentist’s breathing zone (164,445.10 particles/m 3 ). LEV significantly reduced particle concentrations across most particle sizes and sampling locations ( p < 0.05). Aerosol generation in dentistry is highly instrument-dependent, with submicron particles dominating exposure profiles. While LEV effectively reduces airborne contamination, its impact varies by particle size and spatial distribution. These findings support instrument-specific, multi-layered infection control strategies that integrate engineering controls with procedure-based risk assessment.