# Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures
## 4 Discussion  
The present study provides a useful simple model for assessing the microscale distribution of liquid particles generated by four common dental devices. The high-speed handpiece generated the most and the largest splatter particles (>600 \(\upmu\)m) at 1.2 m away from the source. Furthermore, aerosols (<5 \(\upmu\)m) and droplets (<30 \(\upmu\)m) were detected at 1.2 m away from the source, with the triplex syringe producing the greatest number of the smallest diameter aerosol particles. The airborne spreading of splattered fluid, droplets and aerosols is a major concern in dental practice because of the risk of transmitting potentially pathogenic bacteria (such as _Legionella pneumophila_ or _Pseudomonas aeruginosa_) and both oral and respiratory  
Figure 7: Average diameter of splatter (**a**) and aerosols/droplets (**b**) particles by four aerosol-generating procedures (AGPs) at location 10. (**a**) Different dental AGPs generated different splatter particles at a distance 120 cm away from the source. ns: no significant difference. ***: \(p\) < 0.0002 vs. ultrasonic scaler; ***: \(p\) < 0.0002 vs. ultrasonic scaler. ***: \(p\) < 0.0002 vs. high-speed handpiece. (**b**) Aerosol particles difference between different AGPs. ***: \(p\) < 0.0002 vs. triplex syringe. ***: \(p\) < 0.0002 vs. low-speed handpiece. viruses [2; 3; 26; 27], including human influenza viruses and SARS-CoV-2. Visualising and mapping the distribution of these liquid particles is important to develop preventive strategies. There is limited data available on the microscale distribution of contamination induced by aerosol-generating devices. Previous studies used fluorescein tracers [13; 25] or bacterial tracers [23] to detect \"bio-aerosol\" contamination at up to 2 m. However, different studies have used different definitions for aerosol and splatter particles: [PERSON] et al. defined aerosol particles as \(\leq\) 10 \(\upmu\)m and splatter as \(>\) 10 \(\upmu\)m in diameter [25], while [PERSON] et al. used a cutoff value for droplets and aerosols of 5 \(\upmu\)m (\(>\)5 \(\upmu\)m--droplets; \(\leq\)5 \(\upmu\)m--aerosols) [28], in the same manner as the present investigation. The current study used a fluorescence gel imager and a microscope to capture images of splatter (\(\geq\)100 \(\upmu\)m), droplets (5-100 \(\upmu\)m) and aerosol (\(\leq\)5 \(\upmu\)m). Such particles were found to be generated by the ultrasonic scaler, triplex syringe, high-speed handpiece, and low-speed handpiece. All four AGPs generated considerable contamination of the patient's chest area (locations 4, 5, and 6), which is consistent with past studies with macroscale contamination pattern [23; 25]. This patient chest contamination can be effectively dealt with using a disposable waterproof (plastic-backed) bib or apron for the patient. The present data demonstrate that the high-speed handpiece generates the most splatter of large particles (\(>\)600 \(\upmu\)m in diameter) and that this contamination extends a considerable distance, at least 1.2 m away from the mouth. This pattern is also consistent with past work with macroscale contamination [13; 25; 29; 23]. Smaller aerosols particles (\(\leq\)5 \(\upmu\)m) are produced by several dental procedures, and these may pose an increased risk of transmitting respiratory infections, such as COVID-19 [6; 30; 31]. According to the World Health Organisation (WHO) definition, airborne aerosol particles that are \(<\) 5 \(\upmu\)m in size and are generated by AGPs can remain in the air, and then travel over some distance to then cause infection if they are inhaled [12]. Our study utilised a fluorescent microscope to image the aerosol and droplet particles retained on the filter paper fibres in collection sites at 1.2 m away from the source.