October 13, 2020
by Marcel Donnet, Klaus-Dieter Bastendorf, Magda Mensi, Adrian Lussi
Dentists and scientists, supported by EMS, have measured bacterial contamination of room air during an AIRFLOW® treatment in two scenarios (without and with special protective measures). Although the results of this investigation cannot be transferred analogously to a possible viral load (e.g. SARS-CoV-2) in the aerosol, the data show an impres-sive reduction of the bacterial contamination of the room air if the AIRFLOW® treatment is carried out with appropriate protective measures.
Patients, dental staff and dentists are exposed to bacteria and viruses, which can lead to infectious diseases, especially of the oral cavity and the respiratory tract. Anyone who has chosen a profession in dentistry was aware that dental treatment always involves the risk of infection. In dentistry, the short distance to the patient’s oral cavity means a basic exposure to the patient’s saliva, blood, aero sols and sulcus fluid [Peng et al., 2020]. The main transmission pathway of bacteria and viruses is saliva droplets [Yang et al., 2020; Szymanska et al., 2005]. For these reasons, very strict hygiene rules have always been applied in dentistry. In recent decades, dentists have dominated the risk of influenza, tuberculosis, hepatitis and AIDS. Today, the risk of SARS-CoV-2 must also be successfully managed.
Nearly all dental instruments used in common dental treatments generate aerosols: low and/or highspeed handpieces, turbines, sonic and ultrasonic devices, air-water spraying and powder-water jet devices [Graetz et al., 2014]. Aerosols differ from droplets and spray mist. Due to their smaller particle size (< 50 µm), aerosols can be carried several meters away and can be detected for longer periods of time in the ambient air [Drisko et al., 2000].
In dentistry, aerosols can occur as solid particles, powder dust (non-contaminated), splashes that settle quickly (contaminated), device aerosol (non-contaminated) and treatment aerosol (contaminated). The risk of contamination depends on the type of treatment, the degree of patient infection and preventive hygiene measures to minimize the transmission of contaminated aerosols. To date, there is a lack of scientific evidence that shows the risk of aerosols and the danger they pose to clinicians and patients [RKI, 2020]. One reason for this is the difficulty in effectively measuring the level of contamination with bacteria and viruses transported in aerosols.
According to our research, there is no scientific literature on the viral and bacterial contamination of aerosols during professional tooth cleaning with AIRFLOW®. Therefore, we carried out an observational study in practice to better understand the risk of aerosol contamination by using the AIRFLOW® technology.
The aim of this observational study was to measure the bacterial load of the room air during an AIRFLOW® treatment in order to obtain information for the assessment of the risk of aerosol contamination for practitioners, practice team and patients during the use of the AIRFLOW® technology in different situations.
MATERIALS AND METHODS
The AIRFLOW® treatments were performed in the prophylaxis rooms of the company EMS (Nyon, Switzerland) by a dentist (Dr. Neha Dixit, EMS). The measuring procedure and the general conditions for the execution of the prophylaxis had previously been designed by the authors.
A total of 20 adult patients aged between 30 and 45 years were treated. The plaque index Quigley-Hein modified according to Turesky [Turesky et al., 1970] was 0.80. The prophylaxis sessions took place on four consecutive days with five patients each. Between treatments, the rooms were thoroughly ventilated to remove remaining aerosols and to restore a neutral situation for the next session.
The aerosol was measured for exactly ten minutes at each AIRFLOW® treatment. A cyclone system (PRELECT, Medentex GmbH, Bielefeld, Germany) pre-filled with filtered water and placed 20 cm from the patient’s mouth was used to collect the aerosols (Figure 1). With a Cattani high performance vacuum suction system 900 l/min (Cattani Micro Smart, Parma, Italy) 9 m3 of the air-aerosol mixture was suctioned during the ten-minute treatment. Immediately after the treat-ment, bacterial contamination of the aerosol was measured using an adeno-sine triphosphate (ATP) system. This method allows to determine the amount of all living bacteria [Watanabe et al., 2019].
Three measurement groups were defined for the study:
RESULTS AND DISCUSSION
With the presented method we were able to measure reproducibly the bac-terial contamination of aerosols generated during an AIRFLOW® treatment (Figure 2). The room air measurement during AIRFLOW® treatments with saliva ejector, mouth rinse and high vacuum extraction (group 3) showed the same level of bacterial contami-nation as was found for the control group (p > 0.05). With the use of mouthwash and high vacuum aspir-ation, the AIRFLOW® treatment did not lead to a higher level of bacterial aerosol contamination in the room air.
The contribution of the mouthwash or high vacuum suction to this result was not determined.
It was not the aim of the investigation to collect and measure larger droplets. These remain in the treatment environment and are not part of the aerosol. The risk of infection with these droplets is the smear and not the aerosol infection. The smear infection has been known for a long time and is controlled by the dental team through their protective measures [Watanabe et al., 2019].
It is imperative to strictly follow the RKI guidelines and recommendations for personal protective equipment, for surface disinfection as well as for the correct technology and proper use of the equipment.
The AIRFLOW® treatment with the use of Optragate, a suitable mouth rinse and high vacuum suction does not lead to an increased risk of bacterial contamination for the practice team and patients. In addition, it could be shown that aerosols can be effectively controlled with the “two-hand suction technique” using a high vacuum suction in the immediate vicinity of the treatment area
Donnet M, Mensi M, Bastendorf KD, Lussi A: Die bakterielle Kontamination der Raumluft während einer AIRFLOW®-Behandlung, zm 110, Nr. 12, 16.06.2020 (1194).
Note from the authors:
Furthermore unpublished investigations of the group of authors, which were carried out under the same protocol with the piezoceramic scaler PIEZON® PS, show that this technology does not pose an increased risk of bacterial contamination for dental personnel and patients when using protective me asures. Likewise rinsing with BacterX was carried out prior to treatment and use of the high vacuum suction and the two-hand technique. The final report will be published as soon as the tests are completed.
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About the Authors
Prof. Dr. Adrian Lussi University Hospital Freiburg, Department of Dental Conservation and Periodontology, Hugstetter Str. 55, 79106 Freiburg and dental clinics of the University of Bern Freiburgstr. 7, CH-3010 Bern.