Real-time monitoring of bioaerosol generation during orthodontic procedures involving oral turbines and ultrasonic scalers

The common outcome of dental and orthodontic interventions is bioaerosol, which is a mixture of saliva, blood, and microorganisms in the air, and which can contain infection risks to both clinicians and patients. Although this has become a cause of concern since the COVID-19 pandemic, there is still limited information on the real-time data of aerosol behavior in orthodontic procedures. To measure and contrast real time bioaerosol generation, particle size distribution and microbial load among the orthodontic procedures using air turbines and ultrasonic scalers. This retrospective observational study analyzed 40 orthodontic sessions (20 air-turbine procedures and 20 ultrasonic-scaler procedures) performed in a tertiary dental teaching hospital. Real-time particle concentrations and size distributions were measured with an optical particle counter (AeroTrak 9310, TSI Inc., USA), and viable bioaerosols were collected with an SKC BioSampler at standardized distances of 0.5, 1.0, and 1.5 m from the patient. Between-group comparisons were performed using independent-samples t tests, procedural-phase comparisons using analysis of variance (ANOVA), and associations between aerosol measures, microbial load, and environmental factors using Pearson correlation; two-sided p < 0.05 was considered statistically significant. A total of 40 orthodontic procedures were analyzed, including 20 air-turbine procedures and 20 ultrasonic scaler procedures. Air-turbine procedures generated significantly higher aerosol concentrations than ultrasonic scaler procedures, with peak particle counts reaching 6.4 × 10⁴ particles/m³ and 3.5 × 10⁴ particles/m³, respectively. More than 80% of aerosols generated during air-turbine use were within the 0.3–2.5 μm size range. Mean viable microbial loads were significantly greater during air-turbine procedures (186 ± 32 CFU/m³) compared with ultrasonic scaler procedures (132 ± 26 CFU/m³). Predominant microorganisms isolated included Streptococcus mutans , Staphylococcus aureus , and Candida albicans . Aerosol concentrations decreased with increasing distance from the source and demonstrated exponential decay following instrumentation cessation. Enhanced ventilation and high-volume evacuation reduced aerosol persistence by more than 50%. A strong positive correlation was observed between total particle concentration and microbial load ( r = 0.82, p < 0.001), while aerosol persistence showed significant negative correlations with ventilation rate ( r = − 0.61, p = 0.008) and suction flow rate ( r = − 0.58, p = 0.011). Air turbine and ultrasonic scaler orthodontic treatments produce quantifiable bioaerosols with living microorganisms. There is high risk of aerosol and microbial exposures with the air turbines. Combining real-time monitoring with engineering controls as high-volume evacuation, HEPA-filtered ventilation and antiseptic pre-rinses can significantly reduce the risks of infection in orthodontic operating rooms.