Related Experiment Video
Updated: Oct 22, 2025
Employing the Forced Oscillation Technique for the Assessment of Respiratory Mechanics in Adults
Published on: February 9, 2022
Fallow time determination in dentistry using aerosol measurement in mechanically and non-mechanically ventilated
Shakeel Shahdad1, Annika Hindocha2, Tulsi Patel2
1Honorary Clinical Professor in Oral Rehabilitation & Implantology and Consultant in Restorative Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Barts Health NHS Trust, The Royal London Dental Hospital, London, UK. shakeel.shahdad@nhs.net.
Abstract:
Aim To calculate fallow time (FT) required following dental aerosol generating procedures (AGPs) in both a dental hospital (mechanically ventilated) and primary care (non-mechanically ventilated). Secondary outcomes were to identify spread and persistence of aerosol in open clinics compared to closed surgeries (mechanically ventilated environment), and identify if extraoral scavenging (EOS) reduces FT and production of aerosol.Methods In vitro simulation of fast handpiece cavity preparations using a manikin was conducted in a mechanically and non-mechanically ventilated environment using Optical Particle Sizer and NanoScan at baseline, during the procedure and fallow period.Results AGPs carried out in the non-mechanically, non-ventilated environment failed to achieve baseline particle levels after one hour. In contrast, when windows were opened after AGPs, there was an immediate reduction in all particle sizes. In mechanically ventilated environments, the baseline levels of particles were very low and particle count returned to baseline within ten minutes following the AGP. There was no detectable difference between particles in mechanically ventilated open bays and closed surgeries. The effect of the EOS on reducing the particle count was greater in the non-mechanically ventilated environment; additionally, it also reduced the spikes in particle counts in mechanically ventilated environments.Conclusion High-efficiency particulate, air-filtered mechanical ventilation, along with mitigation (high-volume suction), resulted in reduction of fallow time (ten minutes). Non-ventilated rooms failed to reach baseline level even after one hour of fallow time. There was no difference in particle counts in open bays or closed surgeries in mechanically ventilated settings with an extraoral suction device reducing particulate spikes. This study confirms that AGPs are not recommended in dental surgeries where no ventilation is possible.
