CATEGORY 64 AUSTRALASIAN DENTIST hygienists traditionally provide care with the aid of a dental assistant, due to the bulkiness of the high-volume suction (HVE) and difficulties in maneuvering it. Dental hygienists working solo prefer using the LVE (saliva ejector) suction system, which is less bulky and easier to use than HVE suction.17,26 Moreover, LVE saliva ejectors provide an easy means of clearing the operating field and better patient comfort than HVE suction.18 Many clinical guidelines recommend 4-handed dentistry during the COVID-19 pandemic and that HVE be used during all dental treatment to minimize aerosol production.11,27–29 Other guidelines state that aerosol production by dental handpieces is complex and dependent on multiple factors such as handpiece speed, mix of air and water, coolant ports and types of bur used,27,28 which have been investigated in the current study. Our results show that both HVE and LVE significantly reduced the aerosol level for scaling. Whereas HVE was very efficient in reducing aerosol particles all sizes to a minimum level, LVE was more effective in the larger particle range. This finding is consistent with previous studies30–32; however, it disagrees with the LINICAL findings from Matys and Grzech-Lesinka.14 Interestingly, there was a statistically significant difference in aerosol particle levels between scaling with HVE and LVE. This contradicts the findings of Holloman et al,17 who found no difference in aerosol and spatter reduction during ultrasonic scaling with different suction types. This is likely due to a difference in sampling method (ie, Holloman et al17 examined bacterial counts), the distance between the operative area and sampling units, and the wider scatter that we observed. Moreover, Holloman et al17 measured real infection risk, whereas our study focused on measuring on aerosol generation alone. Yang et al3 also mentioned that simulated environments without a live patient is a limitation of many studies. However, regardless of saliva transmission and presence of patients, the efficacy of different suction should not change whether the experiment is done in the human mouth or mannequin because the procedure is the same. In fact, patients createmore variables because each patient’s oral hygiene and requirements of restorative work vary. Hence, the value of standardizing the experiment and eliminating potential variables outweighs the limitation of using mannequins. Previous studies that mainly measured aerosol and splatter during ultrasonic scaling with HVE and LVE also reported significant differences between the 2 variables, with reports of a ∼90%–93% aerosol reduction.5,25,33–35 In SARS-CoV-2 infections, when aerosol is emitted by a person breathing and/or speaking, particles of <5 μm in diameter carry more virus than larger particles.36 In the present study, we considered particle volume, summed over the size range measured. Some of these particles will consist solely of irrigation or cooling water and carry no pathogens. Others will carry a proportion of the patient’s saliva and present an infection hazard.The proportion may vary with particle size and where in the oral cavity they originate. Particle size determines where in the infectee’s airway the particles deposit, which can affect infection severity. This is an area that might benefit from future research. The effectiveness of HVEwas evident for drilling as well, regardless of the number of coolant ports used and the location of teeth. The most significant finding was that HVE was effective in removing all sizes of aerosol particles measured. This is noteworthy because previous reported methodologies Table 3. The Mean Level of Aerosol (Volume of Particles) Measured in Different Settings and Variables
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