key: cord-0847025-tclzmlmt authors: Akin, H; Karabay, O; Toptan, H; Furuncuoglu, H; Kaya, G; Akin, EG; Koroglu, M title: Investigation of the presence of SARS CoV-2 in aerosol after dental treatment date: 2021-05-16 journal: Int Dent J DOI: 10.1016/j.identj.2021.05.002 sha: 62731f231ae753665614dfc6b396d4c8dacdaf6b doc_id: 847025 cord_uid: tclzmlmt AIMS: The objective of the present study was to investigate the presence of SARS CoV-2 in aerosol and COVID-19 contamination distance during ultrasonic scaling and tooth preparation. METHODS: Twenty-four patients with COVID-19 were included in this study. Removal of supragingival plaque with ultrasonic instruments for 10 min and high-speed air-turbine using for the simulation of cutting the maxillary right canine tooth with a round diamond bur for 5 min were performed. Patients were randomly assigned to 2 groups: In Group A, medium-volume suction was used during treatment. In Group B, high-volume suction with an aerosol cannula was added to medium-volume suction. Prior to treatment, 5 glass petri dishes containing viral transport medium were placed in the operating room. After treatment, petri dishes were immediately delivered to a microbiology laboratory for real-time polymerase chain reaction (RT-PCR) analysis. RESULTS: RT-PCR test results were negative for all specimens in Group B. However, 5 positive test results for COVID-19 were detected in Group A specimens. CONCLUSION: Suction with an aerosol cannula is very important to prevent COVID-19 viral contamination via aerosol. In addition, a high-volume suction capacity (air volume) of 150 mmHg or 325 l/min is sufficient for elimination of viral contamination. Thus, high-volume suction should be used during dental treatments in COVID-19 patients. In December 2019, a novel coronavirus was identified among pneumonia patients in Wuhan city, Hubei Province, China. After rapid isolation of the virus, the discovery of a new coronavirus that had never been identified in humans before was declared, officially named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the World Health Organization on January 7, 2020. 1, 2 The respiratory disease deriving from SARS-CoV-2 infection was then named COVID-19. 1 has had an unprecedented impact on people across the world, and this outbreak quickly became a global public health crisis. 3, 4 Spread of infection is mainly through aerosols, droplets (coughing, gagging, sneezing) and direct contact, which poses a risk to the oral and nasal mucosae and conjunctivae. 2, 5 Self-collected saliva of most of 12 infected patients contained SARS-CoV-2 RNA. Therefore, COVID-19 transmission during dental procedures can happen through inhalation of aerosol/droplets from infected individuals or direct contact with mucous membranes, oral fluids, or contaminated instruments and surfaces. 5 During dental procedures, transmission should be of real concern in dental clinics. At present, there is only limited evidence of airborne transmission of viable virus via aerosol particles. Thus, the aim of the present study was to investigate the presence of SARS CoV-2 in aerosol and COVID-19 contamination distance during ultrasonic scaling and tooth preparation. The first hypothesis of the study was that SARS CoV-2 would be detected in aerosol during ultrasonic scaling and tooth preparation with medium-volume suction in the clinical environment. The second hypothesis of the study was that there is no difference in aerosol contamination between medium-and high-volume suctions. Five glass petri dishes with dimensions of 75 mm × 15 mm were sterilized for each patient and placed on the floor in a 12 m 2 operating room (2.9 m × 4.15 m). Each corner of the room received one petri dish, and the fifth dish was placed in the dental unit's cup holder (Stern Weber S200 Plus, Cefla Dental Group, Imola, Italy). The dental unit was set in the reclining position and the headrest had a ground clearance of 75 cm. This position was stored as Position A in the dental unit, which is able to store different positions. Thus, all patients were treated in the same position ( Figure 1 ). Three milliliters of viral transport medium, which comes in a screw-cap plastic tube, were poured into each of the glass petri dishes. Two clinicians (H.A and G.K) with over 10 years of clinical experience performed treatment protocol for all patients. In addition, operations were assisted by the other 2 experienced clinicians (E.G.A and H.F). The treatment protocol consisted of 2 sessions. Removal of supragingival plaque was the first session, performed with ultrasonic instruments (SC-A3, Cefla Dental Group, Imola, Italy). A 40.000 cycle per second (Hz) ultrasonic scaler was set at maximum power for all trials. The coolant volume of the ultrasonic scaler was adjusted to 50 ml/min, a volume reported as ideal for clinical use. Treatment time was standardized at 10 min. The second session consisted of high-speed air-turbine (Slent Power Evo 4LK, Cefla Dental Group, Imola, Italy) using. Immediately following scaling, a simulation of cutting of the maxillary right canine tooth with a round diamond bur was performed. It was ensured that the bur did not touch the teeth. Second sessions lasted 5 min. Water cooling was adjusted to 15 ml/min, and the aerator was set at maximum power for all trials. Patients were randomly assigned to 2 groups: In Group A, medium-volume suction was used during treatments. In Group B, high-volume suction with an aerosol cannula (1.5 cm diameter and 12 cm height) was used along with medium-volume suction. Dürr Vs1200 suction system (Dürr Dental SE, Bissingen, Germany; max unimpeded flow rate 2400 l/min, auxiliary air valve setting -170 mbar/hPa, max fluid rate of flow 24 l/min) was used. In addition, the suction machine was placed at a distance of 19 m from the dental unit. Furthermore, two flowmeter (Cattani 59168 and Cattani 040840, Cattani, Parma, Italy) was used to determine the suction capacity of the medium-and high-volume suctions. Mediumvolume suction had a suction capacity of 80 mmHg and 158 l/min (air volume), whereas highvolume suction had 150 mmHg and 325 l/min suction capacity (air volume). All clinicians wore masks (Type 7502, 3M, Minnesota, USA) and safety glasses at all times during treatments. Furthermore, sterile surgery uniforms and hair bonnets were used. When each operation was finished, the clinicians and patient left the operating room to allow the deposition of droplets and aerosols. After 30 min, viral transport medium was transferred from the petri dishes to screw-cap plastic tubes using a sterile syringe. For each patient, 5 specimens were obtained. Specimens were immediately delivered to the microbiology laboratory and stored at 2 to 8 ºC. Specimens were taken to a negative-pressure room in a Class 2-a biosafety cabinet. They were then vortexed at least 5 sec. Afterward, Relative Risk (RR) tests were used to analyze the data with a 95% confidence interval. Table 1 . PCR test results are presented in Table 2 . According to the relative risk analysis, medium-volume has negative effect on the PCR test results (0.917). PCR test results were negative for all specimens in Group B. However, positive test results (8.3% according to relative risk analysis) were detected in the patients (5 patients) of Group A. These were specimen Numbers 1, 2 (twice), 3, and 5 (twice), whereas the specimens of Number 4 exhibited no positive PCR test results for any patients ( Table 2) . SARS-CoV-2 RNA was detected in samples of the Group A. Thus, first hypothesis that SARS CoV-2 would be detected in aerosol during ultrasonic scaling and tooth preparation with medium-volume suction in the clinical environment was accepted. Whereas, no SARS-CoV-2 RNA was detected in Group B using PCR testing. Therefore, the second hypothesis of the study was there is no difference in aerosol contamination between medium-and highvolume suctions was rejected. In dental literature, limited studies have been performed about COVID-19 contamination during dental treatment. Ultrasonic scaling and cutting procedures with highspeed air-turbine were performed under water cooling. The present study is the first study in the dental literature to investigate possible SARS CoV-2 contamination via aerosol. On the other hand, Bennett et al. 6 demonstrated that aerosol peaks tended to decrease to background levels within 10 to 30 min, caused by rapid deposition of particles after aerosol generation at patient head height. Consistent with this study, Veena et al. 7 found that the aerosol cloud could remain in the air up to 30 min after scaling. Thus, in the present study, 30 min was waited before obtaining specimens from petri dishes to allow deposition of droplets and aerosols. In addition, some of the samples of the Group C demonstrated positive results in petri dishes 1, 2 and 3. These ones were far away from the source. Therefore, these results can be explained that their contamination can only be from aerosols. Furthermore, according to BS EN ISO 10637 8 , high-volume system has an air intake of more than 250 l/min at each cannula connector of the largest bore operating hose. In addition, Holliday et al. 9 used two different flow rates, 40 l/min low-volume suction and 159 l/min medium-volume suction. In the present study, 325 l/min high-volume suction and 158 l/min medium-volume suction was used. Gloves, mask, and glasses are the main personal protective equipment during dental treatments. However, there is a resistance to the use of protective equipment in dental care. In 1990, the American Dental Association appealed to the courts against the mandatory use of protective equipment, claiming that no professional had contracted the disease. 5 In last 2 decades, knowledge about AIDS and now COVID-19 push dentist to review safety standards. The American Dental Association and the US Centers for Disease Control and Prevention have recommended using high-volume suction during dental treatment to minimize dissemination of droplets, spatter, and aerosols. [10] [11] [12] Nevertheless, dentists have resisted to this recommendation. The present study shows the importance of the high-volume suction for infection control during dental treatments. In addition, based on the results of the present study, high-volume suction with aerosol cannula is very important to prevent SARS CoV-2 virus contamination via aerosol from patient to patient or from patients to clinicians. Moreover, clinicians could mitigate the potential risk of the virus using UV air disinfection devices or hepa-filter air cleaner devices in the operating rooms. The limitation of the present study is that a few samples (5 dishes in a room) were evaluated in the present study. The samples could be placed around the dental unit. In addition, clinicians' masks and safety glasses were not evaluated. On the other hand, bur was not touched to the teeth when simulating the cutting teeth. Thus, high energy particles were not produced. Moreover, during dental treatment, only one dental unit was used, as well. However, 9 additional dental units were attached to the same suction system. It was not evaluated that whether sufficient pressure can be supplied when all dental units are used simultaneously. In future studies, suction system capacity should be evaluated when all dental units are used at the same time. Within the limitations of the study, high-volume suction with an aerosol cannula is very important to prevent COVID-19 viral contamination via aerosol. High-volume suction of 150 mmHg or 325 l/min is sufficient values to prevent COVID-19 contamination. Thus, highvolume suction should be used during dental treatments. COVID-19 Transmission in Dental Practice: Brief Review of Preventive Measures in Italy A detailed report on the measures taken in the Department of Conservative Dentistry and Periodontology in Munich at the beginning of the COVID-19 outbreak Guidance for dental treatment of patients with disabilities during COVID-19 pandemic Coronavirus disease 2019 (COVID-19): challenges and management of aerosol-generating procedures in dentistry COVID-19: a new turning point for dental practice Microbial aerosols in general dental practice Dissemination of aerosol and splatter during ultrasonic scaling: a pilot study Dental compressed air and vacuum systems Evaluating contaminated dental aerosol and splatter in an open plan clinic environment: Implications for the COVID-19 pandemic Guidelines for infection control in dental healthcare settings-2003 A laboratory comparison of evacuation devices on aerosol reduction American Dental Association Current Policies: Adopted 1954-2013 Informed consent: For this type of study, informed consent was not required.