CATEGORY AUSTRALASIAN DENTIST 65 LINICAL failed to measure small aerosol particles (0.5–10 μm). Small particles deposit in human pulmonary bronchioles and alveoli. Our study demonstrates that using either HVE or LVE significantly reduces aerosols of this particle size during drilling and scaling (Fig. 3b).4,14,37 Although we observed similar trends to those reported by Matys and Grzech-Lesniak,14 they reported a significantly lower concentration of aerosol particles, which could be explained by differences in room size, the distance at which the particle sensor was placed, and/ or different settings on their air-purifier system. One novelty of our study was the evaluation of the ‘no chip air’ aerosolreducing function found on newer HSHs. Conventionally, aerosol exposure is managed using HVE, by decreasing handpiece speed, or by using handpieces with fewer coolant ports. Although the new ‘no chip air’ function is innovative, whether the absence of air spray could affect the pulpal temperature of the drilled tooth remains unknown. More recently, Lempel and Szalma38 found that effective ‘no chip air’–mediated reduction of aerosol is possible while maintaining a thermally safe environment for the tooth. We investigated the effect of suction systems and air spray settings for dental HSHs and ultrasonic scalers on aerosol generation. Following the air sampling protocol described here, future research could involve other aerosol-related variables (eg, aerosol settling time). Although it has been reported that droplets take 30–0 minutes to settle,12 the time and distance variables of droplets remain unknown.The present studywas conducted in an enclosed clinical room and should be repeated in an open clinical environment with single- or multiple-chair units to determine whether the safer combination of suction systems, and handpiece and scaler spray functions still apply. In conclusion, within the current study limitations, we report several findings. The most intensive dental aerosol was generated by high-speed handpieces and ultrasonic scaling. Caution should be exercised during these procedures to minimize cross infection. For scaling, the HVE suction system was more effective in reducing aerosol generation than LVE suction or no suction at all. We recommend the new aerosolreducing ‘no chip air’ function (if available) for cavity preparation as the function is highly effective in reducing the aerosol generated, regardless of the number of coolant ports and the location or type of tooth being prepared. Acknowledgments. The authors acknowledge the University of Otago Research Grant. The authors thank Phil Fitzgibbon, Neralee Montague, and Gina Narbey from NSK Oceania for their support for research equipment, Ana Grymak for her assistance with MATLAB plots, Tom (Shiyao) Chen for graphic figures, and Dr Nick Heng for his critical reading of this manuscript. Financial support. M.J. and J.C. would like to thank the New Zealand Ministry of Business, Innovation and Employment (MBIE) for financial support under the COVID-19 Innovation Accelerator scheme. University of Otago authors would like to acknowledge the University of Otago ResearchGrant (UORG) for project funding. Conflicts of interest. All authors report no conflicts of interest relevant to this article. u For a list of references email: gapmagazines@gmail.com Fig. 3. The total volume of aerosol (μm3/m3) created by (a) different activities; (b) during scaling and drilling with different types of suction; and (c) during scaling and drilling with different types of suction [the volume mean diameters for each size range are 0.42 μm (channel 1), 0.83 μm (channel 2), 2.4 μm (channel 3), 4.2 μm (channel 4), 8.3 μm (channel 5), and 20 μm (channel 6)]; and (d) during drilling in different locations; 1 incisor and 1 posterior tooth per maxillary and mandibular arch, with and without HVE.
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