Date of Award

Summer 2021

Document Type


Degree Name

Master of Science (MS)



First Advisor

Liu, Dawei

Second Advisor

Nimeri, Ghada

Third Advisor

Dentino, Andrew


Objective: The COVID-19 pandemic has placed a new emphasis on defining aerosol generating procedures and evaluating ways to reduce those aerosols. Both biocontaminants and particulate matter can potentially be transmitted with dental aerosols with negative health effects associated with each, especially aerosols with particulate matter of 2.5 micrometers or less (PM2.5). This study aims to evaluate the PM2.5 aerosol production from orthodontic debonding with a high-speed, air-driven handpiece without water coolant and assess the effectiveness of traditional four-handed high-volume evacuation (HVE) and two commercially available hands-free high-volume evacuation (HFHVE) systems. Methods: Orthodontic debonding was simulated using a dental manikin and acrylic dental model with composite-based adhesive attachments bonded to 28 teeth, with a 4 mm x 2 mm x 1 mm rectangular aligner template. A high-speed, air-driven handpiece without water coolant was used to debond the composite attachments. PM2.5 aerosol concentration was measured with an air quality monitor suspended 6 cm above the maxillary central incisors. Seven trials were completed for all evacuation systems and controls. The mean PM2.5 aerosol concentrations for each evacuation system were compared with an analysis of variance and post-hoc test of multiple comparisons using the Bonferroni test. P value less than 0.05 was considered statistically significant. Results: Orthodontic debonding with no evacuation system produced a significantly elevated level of PM2.5 aerosol concentration compared to all three evacuation systems tested. There was no statistically significant difference between four-handed HVE and the two other HFHVE systems, however the trend of the data suggest four-handed HVE reduces aerosols more effectively. Conclusion: Orthodontic debonding with a high-speed, air-driven handpiece should be classified as an aerosol generating procedure, and some type of evacuation system should be used to reduce aerosol levels. Four-handed HVE is likely the most effective system for aerosol reduction, but the two other HFHVE systems evaluated in this study may be effective alternatives for a solo practitioner without an available assistant. All groups produced aerosol levels higher than baseline, so appropriate personal protective equipment (PPE) should be utilized.

Included in

Dentistry Commons