Mitigation of aerosol particles during composite attachment removal

Abstract

Introduction: The COVID-19 pandemic brought significant public and professional attention to the aerosol-generating nature of dentistry. In orthodontics, significant amounts of aerosolized particles may be produced and spread during aligner composite attachment removal with a handpiece. Methods have been proposed to mitigate aerosols during these procedures, such as using handpieces that minimize spraying or employing various types of suction. The purpose of this study was to determine which strategies most effectively reduce aerosolized particles when removing orthodontic composite attachments. Methods: A network of novel AeroSpec portable particle monitors was employed to record and store particulate data in real-time. 16 sensors were placed in a 3D grid system in and around a representative operatory at the UW Orthodontics Department. Composite attachments (Transbond LR) were removed from the anterior six teeth of maxillary and mandibular resin models placed in a manikin head. Particulate matter of optical diameter 2.5µm or less (PM2.5) was measured. Three different handpiece types were tested: conventional air-driven highspeed (StarDental), electric highspeed (BienAir), and air-free highspeed (Medidenta). Four different suction conditions were tested with each handpiece type: no suction, high-speed intraoral suction (IOS), extraoral suction (EOS), and both IOS and EOS together. Four repetitions of attachment removal with each handpiece and suction type were performed. Linear regression was used to compare average and maximum particle concentration by suction and handpiece. Results: During removal of the composite attachments, the highest concentration of particles was observed around the operator and decreased the further the sensor was located from the source of composite removal. Linear regression for the main effect of handpiece type indicated lower PM2.5 when electric or air-free handpieces were used compared to a conventional handpiece. Linear regression for the main effect of suction showed significant reductions when any type of suction was used compared to no suction. The simultaneous use of both IOS and EOS resulted in the greatest reduction in particulate concentrations. Conclusion: Air-free or electric handpieces should be considered over conventional handpieces to mitigate aerosol spread. Additionally, employing IOS, EOS, or the combination of both significantly reduced the spread of particles. Using an air-free or electric handpiece, along with simultaneous use of IOS and EOS, reduced the maximum particle concentrations that the doctor was exposed to by 92 to 94 percent, compared to a conventional handpiece and no suction.