Comparison of an Air-Fed Mask System with Hospital-Issued Personal Protection Equipments for Dental Aerosol Protection During the COVID-19 Pandemic

A pilot study was conducted with the aim of developing a system to protect the eyes, nose, and mouth from the aerosol generated from a high-speed dental handpiece during the COVID-19 pandemic.

The SARS-CoV-2 virus is known to be present in the saliva of an infected individual during the contagious viral shedding phase of the disease. The use of rotary dental instruments places oral health practitioners at risk of contracting COVID-19 from infected individuals. In particular, it is very difficult to protect the mucous membranes of the face against the extremely fine aerosol produced from a high-speed dental handpiece.

This study aimed to develop and test a novel PPE system for use during the COVID-19 pandemic. An air-fed spray-painting mask was used under a plastic hood to protect against the aerosol from a high-speed dental handpiece. This was found to be superior compared to hospital-issued N-95 masks and eye protection in our test model.

Subjects donned various forms of PPE whilst using a high-speed dental handpiece in a confined cubicle. The efficacy of each form of PPE was evaluated by adding fluorescein to the water coolant supply line of a high-speed dental handpiece before checking for facial contamination with an ophthalmology slit lamp.

Under our test conditions, the N-95 mask did not prevent nasal and mouth contaminations, but the combination of an air-fed mask with a sealed hood prevented these contaminations. Although goggles worn tightly did prevent contamination, the air-fed mask system was far more comfortable and did not fog up.

Under the rigorous test conditions of our model, we found hospital-issued PPE ineffective. We also found the single strategy of using positive airflow into a face mask ineffective, even with extremely high levels of airflow. Complete protection was only achieved reliably by the combination of physically sealing off the face from the surrounding airspace and using the air-fed system to provide an external source of air to breathe. We effectively made the clinical equivalent of a dive bell helmet. The air-fed mask is supplied by a standard dental air compressor and is simple to install for someone familiar with the technical aspects of compressors. The compressor does not rely on a filter and proves effective with cheap and easily accessible disposable items.

Under rigorous testing conditions, the developed air-fed mask system with a sealed hood on low flow performed better than hospital-issued PPE against high-speed dental aerosol protection. The developed system protects the operators from the air of the room contaminated with aerosol and brings in safe air from the outside for them to breathe.