Aerosol Mitigation Strategies to Reduce Viral Spreading During Dental-Related Procedures

Objectives: To compare the effect of different aerosol-mitigation strategies in reducing viral spreading during aerosol generating procedures (AGPs) in a dental simulated model.
Methods: MS2 bacteriophage (1.8x10⁸ Plaque-Forming-Units [PFU]/mL) was added to the instrument-irrigation reservoir to be aerosolized during posterior-, anterior-teeth restorations or whole mouth scaler cleaning. Aerosol-mitigation condition groups were 1-Air purifier (AP); 2-High-volume aspiration (HVA); 3-AP +HVA, and 4-No-mitigation control. Dispersion of bioaerosols was assessed using agar-settle plates lawned with the Escherichia coli bacteriophage host, placed in a clockwise direction every 30cm up to 2m from the mannequin’s mouth (subject to available space). Viral air concentrations were measured using a six-stage Andersen cascade Impactor which samples based on aerodynamic diameter: above 7.0, 4.7-7.0, 3.3-4.6, 2.1-3.2, 1.1-2.0, and 0.65-1.0 micrometers. Differences between each mitigation vs. control were assessed using Mann–Whitney U tests. Kruskal-Wallis Test was applied for multiple comparisons.
Results: Compared with no-mitigation control, AP+HVA showed the highest viral spreading reduction for all three AGPs, both via settle plates and viral air concentrations (p<0.001) (Table). Results from the three AGPs in air samples showed that viral loads in the largest sized aerosols (>7.0 micrometers) were 93% lower in the AP+HVA group compared to control. Smallest aerosols (0.65–1.1 micrometers) reduced by 84% (p<0.05) vs. control (Table). The AP+HVA group reduced viral spreading more than AP or HVA alone compared to control (p<0.001). For AP alone, although a reduction was observed for all procedures in settle plates and air samples, this was statistically significant only for scaler cleaning (p<0.01). HVA alone reduced infectious virus ranging from 10.7-83.3% depending on sampling location in all three AGPs.
Conclusions: AP and HVA both reduce dispersion of infective virus during dental procedures, however the combination of both mitigations provide the greatest reduction in virus recovered on surfaces and in air samples.