Dental procedures can pose a significant risk for viral transmission as commonly used devices emit aerosols, in which high numbers of SARS-CoV-2 viruses, copies of the virus can cause COVID-19.
The aerosols are generated when saliva mixes with water and air currents used in dental procedures. As a result, access to routine dentistry remains limited during COVID-19 pandemic.
Dentists, who are now back to work, had to introduce new room decontamination processes and personal protective equipment measures which significantly reduced the number of patients that could be treated in one go. day. In particular, dentists have to leave long periods between treatments, leaving empty rooms to allow aerosols to spread. This limits patient access and challenges financial viability for many dental establishments around the world.
Now, researchers at Imperial College London and King’s College London have measured and studied aerosol generation during dental procedures and proposed changes to prevent contamination in the first place to improve safety for both patients. and dental staff.
They recommend that dentists avoid using dental drills that use a mixture of air and water as the abrasive coolers, and select and control the drill rotation speed for the instruments. that uses only water as a refrigerator. Parameters have been identified that allow certain procedures such as dental fillings to be administered while simultaneously producing 60 times fewer aerosol droplets than conventional instruments.
Lead author Dr Antonis Sergis of the Imperial Department of Mechanical Engineering said: “Aerosol is a known transmission route for the virus behind COVID-19, so with our colleagues at King, we have tested it solutions that reduce the amount of aerosol produced in the first place. These may help reduce the risk of transmission during dental procedures. “
Co-author Professor Owen Addison from the Faculty of Dentistry, Oral & Craniofacial Sciences at King’s College London said: “This important work outlines the basic innovations that follow. to the aerosol features of dentistry that we currently consider to be high risk.This has allowed us to select drill parameters to keep our patients and dental team safe at this difficult time. we can provide all the procedures, because slowing down our drills is much less efficient, we now have a basis to do more than we have done in the last 6 months. “
The results are published today in Journal of dental examination and are already included as evidence in guidelines for dental establishments in the UK at the time of the pandemic. The collaborative research utilized the Imperial engineering and clinical experience of the Faculty of Dentistry, Oral & Craniofacial Sciences at King’s College London.
The researchers used dental clinical rooms at Guy’s Hospital in London to test how aerosols are generated at methods such as decay removal, insertion and polishing of fillings and alteration of prostheses. They measured aerosol generation using high-speed cameras and lasers. They used these conclusions to suggest changes.
They found that the use of air turbine drill types, the most common type of dental drill, creates dense clouds of aerosol droplets that propagate as fast as 12 meters per second and an entire treatment room could quickly become contaminated. In just one millimeter of saliva from infected patients there are up to 120 million copies of the virus, each of which has the potential to infect.
They tested a different type of drill, called a high torque electric micromotor, with and without the use of water and air currents. They found that using this type of drill at low speeds of less than 100,000 rpm without air currents produced 60 times less droplet than air turbine drill types.
In addition, they found that the concentration of aerosol and dispersion inside a room depended on the patient’s position, the presence of ventilation systems, and the size and geometry of the room. It is also influenced by the initial direction and speed of the aerosol itself, which can affect the type of cutting instrument (burr), and the amount and type of cooling water used.
The researchers say that by understanding how to reduce the amount of aerosol produced in the first place, their recommendations could help dentists get more help and help patients get the treatment they need. they need.
They also note that patients should still not attend dental appointments if they have COVID-19 symptoms.
Professor Owen Addison from King said: “As a result of the COVID-19 outbreak, dentistry has become a high-risk practice – but the need for treatments has not gone away. Our recommendations help reopen dentistry to patients. “
Their recommendations were incorporated into the evidence assessment in a dental document titled “Rapid Review of Aerosol Generation Methods in Dentistry,” published by the Scottish Dental Clinical Efficacy Program (SDCEP). The results of the study were considered by an expert action group convened by the Faculty of General Dental Practice (FGDP (UK)) and the College of General Dentistry and published in their guide titled “Implications of Covid-19 for the safe management of ‘general dentistry. “
Co-author Professor Yannis Hardalupas from the Imperial Department of Mechanical Engineering said: “The impact of the results is significant. For example, our work had a significant impact on risk classification for included dental procedures. in an FGDP (UK) document. “
The team’s investigation is ongoing. They are currently better assessing the risk of infection by measuring the amount of saliva mixed into the aerosols generated by dental instruments.