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Corona and dental practice: Risk from aerosols at the dentist

COVID-19 Risk of aerosols when visiting the dentist

Many dental practices ask their patients to refrain from visiting the practice when typical corona symptoms occur, such as dry cough, fever, fatigue, chills, disturbance of the sense of smell and/or taste and breathing difficulties, or at least to contact the doctor by telephone beforehand. These are quite useful measures, but they completely miss the mark when it comes to two points.


Table of contents:

  • So-SARS-CoV-2-can-get-into-the-dental-office-unnoticed
  • The-main-problem-is-aerosols
  • How long can the corona virus survive in aerosols?
  • How can infection be prevented for patients?

  • How-can-SARS-CoV-2-get-into-the-dental-office-unnoticed


    • It is now considered certain that infected persons can be highly contagious even before the first symptoms appear. This means that even at this early stage, there can be high virus concentrations in the mouth and throat, which are quite sufficient for droplet infection or aerosol transmission.
    • To the same extent, point 1 applies to persons in whom the infection takes an asymptomatic course. That is, for people who develop no or only very weak symptoms and thus rightly believe they are completely healthy.

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    The main problem is aerosols

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    When we breathe, speak, sing or cough, we produce saliva droplets of various sizes and release them into our environment with the air we breathe. The large ones, 100 to 1000 micrometres in diameter, are produced when we cough. They fall quickly to the ground and that is why the distance of 2 metres from other people is so important.

    The situation is completely different with small droplets of 1 to 10 micrometres, which are already produced by normal breathing and talking - the so-called aerosols. Due to their low weight, these droplets can remain suspended in the air for much longer and their concentration increases with every breath an infected person takes.

    Special dental treatments, such as drilling or teeth cleaning, can probably increase the concentration of viruses in the room air considerably.



    How long can the Corona virus survive in aerosols?


    The survivability of Sars-Cov-2 viruses in such aerosol droplets, suggests a study reported in the journal Emerging Microbes & Infections on 22 June. At the British Ministry of Defence, specialists and virologists had created aerosol from artificial saliva with droplet sizes of one to three micrometres and loaded it with concentrated Sars-CoV-2 virus. Even after 90 minutes, "viable virus material" could be detected in a dark aerosol chamber at high and at low relative humidity.
    A similar study in the "New England Journal of Medicine" had already reported in April: that in aerosols of 5 micrometres SARS-COV 2 can survive for at least three hours.

    How can infection be prevented for patients?

    Preventing infection for patients is relatively easy in the summer months. Ventilation with the windows fully open is very effective, according to one study. In a well-ventilated room, the number of droplets dropped by about half after only a few minutes.

    In cold and cold-weather rooms, the number of droplets dropped by about half after only a few minutes.

    In the cold and damp winter months, this is associated with increased effort. In winter, "mobile room air filters" help, says Christian Kähler, head of the Institute for Fluid Mechanics and Aerodynamics at the University of the Federal Armed Forces in Munich.

    However, the devices must meet three requirements:

    1. The device should be able to filter at least six times the volume of the room for which it is purchased in one hour. Example: A treatment room has 30 square metres, which is 75 cubic metres. The air filter should be able to filter at least 450 cubic metres of air per hour.
    2. The filter system! Viruses can only be removed from the room air with a so-called HEPA filter (High Efficiency Particulate Air) of classes H13 or H14.
    3. The devices should be very quiet. Doctors, staff and patients sit in the same room with the devices all day. As a rule of thumb, larger devices have larger fans, require lower speeds and thus cause less noise.
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    To find out which practices have HEPA 13 or HEPA 14 room air filters, please contact us.

 

Bridge or implants was updated at 19.10.2021 14:17.