The effect of high-speed dental handpiece coolant delivery and design on aerosol and droplet production

• DOI: 10.31219/osf.io/twynh
• Publication Date: 2021-05-09T19:17:07Z
• Authors: James R Allison; David Edwards; Charlotte Bowes; Kimberley Pickering; Christopher Dowson; Simon Stone; Joanna Lumb; Justin Durham; Nicholas Stephen ...; Richard Holliday
• Keywords: Compressed air; Air contamination; Particle counter; Ram air turbine

Objectives: High-speed dental instruments produce aerosol and droplets. The objective of this study was to evaluate droplet production from a novel electric micromotor handpiece (without compressed air coolant) in real world clinical settings. Methods: 10-minute upper incisor crown preparations were performed triplicate an open-plan clinic with mechanical ventilation providing 3.45 changes per hour. A 1:5 ratio which allows water coolant without (Ti-Max Z95L, NSK) used at three speeds: 60,000 (60K), 120,000 (120K), 200,000 (200K) revolutions minute. Coolant solutions contained fluorescein sodium as tracer (2.65 mmol L−1). air-turbine positive control, negative control conditions conducted. Aerosol evaluated 3 locations (0.5 m, 1.5 m 1.7 m) using: (1) optical particle counter (OPC; 3016-IAQ, Lighthouse) detect all aerosol; (2) liquid cyclone sampler (BioSampler, SKC Ltd.) aerosolised fluorescein, quantified by spectrofluorometric analysis. Settled droplets detected analysis filter papers placed onto rig across the clinic.Results: Local (within treatment bay) settled contamination elevated above for conditions, no difference between conditions. not controls outside bay any condition. detection only increased At 0.5 levels highly air-turbine, minimally 200K 120K, 60K. Conclusions: Electric handpieces use water-jet alone air, localised but are unlikely beyond immediate area (1.5 m), allowing them be safely most