Dental Mitigation Strategies to Reduce Aerosolization of SARS-CoV-2

Abstract

Limiting infection transmission is central to the safety of all in dentistry, particularly during the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Aerosol-generating procedures (AGPs) are crucial to the practice of dentistry; it is imperative to understand the inherent risks of viral dispersion associated with AGPs and the efficacy of available mitigation strategies. In a dental surgery setting, crown preparation and root canal access procedures were performed with an air turbine or high-speed contra-angle handpiece (HSCAH), with mitigation via rubber dam or high-volume aspiration and a no-mitigation control. A phantom head was used with a 1.5-mL min−1 flow of artificial saliva infected with Φ6-bacteriophage (a surrogate virus for SARS-CoV-2) at ~108 plaque-forming units mL−1, reflecting the upper limits of reported salivary SARS-CoV-2 levels. Bioaerosol dispersal was measured using agar settle plates lawned with the Φ6-bacteriophage host, Pseudomonas syringae. Viral air concentrations were assessed using MicroBio MB2 air sampling and particle quantities using Kanomax 3889 GEOα counters. Compared to an air turbine, the HSCAH reduced settled bioaerosols by 99.72%, 100.00%, and 100.00% for no mitigation, aspiration, and rubber dam, respectively. Bacteriophage concentrations in the air were reduced by 99.98%, 100.00%, and 100.00% with the same mitigations. Use of the HSCAH with high-volume aspiration resulted in no detectable bacteriophage, both on nonsplatter settle plates and in air samples taken 6 to 10 min postprocedure. To our knowledge, this study is the first to report the aerosolization in a dental clinic of active virus as a marker for risk determination. While this model represents a worst-case scenario for possible SARS-CoV-2 dispersal, these data showed that the use of HSCAHs can vastly reduce the risk of viral aerosolization and therefore remove the need for clinic fallow time. Furthermore, our findings indicate that the use of particle analysis alone cannot provide sufficient insight to understand bioaerosol infection risk.

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

“…Several methods of reducing risks from aerosol dispersion in dentistry have been proposed, for example, reducing aerosol production using alternative dental handpiece designs ( Allison, Edwards, et al 2021 ; Vernon et al 2021 ), reducing pathogenic load with mouthrinses or antimicrobial irrigants, and reducing escape from the mouth using dental dams ( SDCEP 2021a ). Where potentially contaminated aerosols do escape, ventilation is important in reducing exposure ( Zemouri, Awad, et al 2020 ), but this is often dictated by building configuration and may be difficult or costly to change.…”

Influence of flow rate and different size of suction cannulas on splatter contamination in dentistry: results of an exploratory study with a high-volume evacuation system

“…Hence, it is not surprising that during the SARS-CoV-2 pandemic, dentistry was officially classified as one of the very high-risk occupations for transmission of the disease [ 2 ]. But is that assessment correct or too random in comparison to other medical specialties, especially as a paucity of robust data supporting some of these restrictions [ 3 ]? Yet, in dental practice, various fluid-cooled instruments were identified as aerosol-generating procedures (AGPs) and pose a potential risk to the patients and dental personnel; however, the exact infection dose required in virus copies to trigger an infection, e.g., with SARS-CoV-2, is currently unknown.…”

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

“…Several methods of reducing risks from aerosol dispersion in dentistry have been proposed, for example reducing aerosol production using alternative dental handpiece designs (Allison et al 2021b; Vernon et al 2021), reducing pathogenic load with mouthrinses or antimicrobial irrigants, and reducing escape from the mouth using dental dam (SDCEP 2020). Where potentially contaminated aerosols do escape, ventilation is important in reducing exposure (Zemouri et al 2020a), however this is often dictated by building configuration and may be difficult or costly to change.…”