Concerns among dental professionals regarding aerosol-generating procedures (AGPs) possibly putting dental professionals and their patients at risk of infection have been heightened by the COVID-19 pandemic. The World Health Organization (WHO) defines AGPs as any medical, dental, and patient care procedures that result in the production of airborne particles that pose an increased risk of transmitting infectious diseases.
In dental settings, the WHO defines all clinical procedures that use spray-generating equipment, including three-way air/water spray, ultrasonic scaling and polishing; periodontal treatment with ultrasonic scaler; any type of dental preparation with high or low speed handpiece such as AGPs.
Clinical procedures using aerosol-generating equipment cause aerosolization in the treatment area , resulting in rapid contamination of surfaces and the potential for spread of infection. In particular, the use of rotating water-cooled devices to perform interventions can aerosolize pathogens from the patient’s saliva and blood.
Case studies have revealed that SARS-CoV-2 can be viable in aerosols that remain airborne for several hours , while others have found significant amounts of SARS-CoV-2 RNA in patient saliva samples. The Centers for Disease Control and Prevention (CDC) defines aerosols as a suspension of small inhalable particles or droplets (≤ 5 µm) in the air that can sometimes cause adverse health effects in workers.
This is now recognized as an overemphasis in the public health literature on the size limits of particles capable of penetrating deeply into the lungs, and larger particles up to and beyond the 100 µm inhalable limit are known to transmit airborne infections . The CDC’s current view is that transmission of SARS-CoV-2 occurs through exposure of people to respiratory fluids containing infectious viruses.
Exposure can occur in three main ways (1) inhalation of air carrying small respiratory droplets and aerosol particles (2) deposition of aerosol particles on the nasal or oral mucosa of susceptible individuals (3) touching mucous membranes with hands dirty from exhaled respiratory fluid.
The WHO suggests that although the virus primarily spreads between people who are in close contact (1 m), the virus can also spread in poorly ventilated and/or crowded areas , as pathogenic aerosols remain suspended in the air and can travel further. of 1 m. Transmission via smaller aerosol particles is a likely mechanism for indoor super-spreading events where a single source transmits the virus to a large number of people. The highest virus load is present in respiratory particles less than 5 µm in diameter.
Infectious aerosols have several transmission routes during dental procedures. This includes direct and surface contact, and also through AGP. Significant respirable aerosol generation has been associated with the use of common dental handpieces such as ultrasonic scalers and air rotors. Due to the frequency with which these AGPs are performed in dental practices, they may serve as an important mode for the transmission of infections.
To limit exposure to aerosols , dental staff are recommended to wear personal protective equipment, with rubber dams and suction tubes to protect patients, although the use of rubber dams is limited to certain dental operations. Fallow time (FT) is observed between patients to allow ventilation to remove airborne particles.
The use of high-volume evacuators (HVEs) and newer extraoral high-volume evacuators/suction have also been used to remove aerosols near the aerosol generation area, while HEPA (high-efficiency particulate air) filtration devices They can be used to clean the air in the room. However, HEPA filter units are only effective once the infectious particles have traveled a certain distance in the air, making it potentially more beneficial to remove microorganisms from the air at the source.
Devices such as extraoral high-volume extractors/suction are known as local exhaust ventilation (LEV) devices. These are in principle control methods that capture particles near the point of generation, thus preventing the dispersion of particles to other areas. LEV devices have been evaluated for use in healthcare settings to prevent aerosol escape during AGP, such as sputum induction and medication nebulization, and encouraging findings have been reported for the use of LEV during dental procedures.
Aim
Our objective was to quantify the aerosol concentrations produced during different dental procedures under different mitigation processes.
Methods
Aerosol concentrations were measured by the optical particle sensor (OPS) and the broadband integrated bioaerosol sensor (WIBS) during time-recorded routine dental procedures on a manikin head in a divided enclosure. Four different standardized dental procedures were repeated in triplicate for three different mitigation measures.
Results
Both high-volume evacuation (HVE) and HVE plus local exhaust ventilation (LEV) eradicated all procedure-related aerosols , and the enclosure stopped the escape of procedure-related aerosols.
Aerosols recorded by OPS and WIBS were 84 and 16 times higher than background levels during FDI notation drilling of tooth 16 (UR6), and 11 and 24 times higher during FDI notation drilling of tooth 46 (LR6). ), respectively.
Ultrasonic scaling around the full lower arch (CL) or full upper arch (CU) did not generate detectable aerosols with the mitigation applied.
Without mitigation, the highest concentration of inhalable particles during the procedures observed by WIBS and OPS was during drilling LR6 (139/cm3) and UR6 (28/cm3), respectively.
Brief aerosol bursts were recorded during drilling procedures with HVE, these did not occur with LEV, suggesting that LEV provides protection against operator error.
Variation in required fallow times (49 to 280 minutes) was observed without mitigation, while no airborne particles remained when mitigation was used.
Conclusions This study has demonstrated the usefulness of HVE in the appropriate position during AGP dental treatments. LEV and room enclosures further reduce airborne particles. In the absence of HVE, airborne particles in the respiratory size range were identified. This is of vital importance in the context of the COVID-19 pandemic, as inhalation of such particles released when treating an infectious person could lead to transmission of the virus to dental staff and patients. Both detectors (OPS and WIBS) recorded much larger procedural particle count increases over baseline without suction for drilling compared to scaling. The WIBS recorded small increases in airborne particles during CU and CL scaling. Both HVE and LEV prevented significant increases in OPS or WIBS particle counts during AGPs. The data collected demonstrate that properly placed HVE and LEV were completely effective in preventing the airborne spread and persistence of inhalable particles originating from dental AGPs. Additionally, the use of an enclosure has an additive effect in restricting the spread of aerosols outside the area of operation. Particles recorded during procedures in the absence of suction are within the size range of airborne particles of probable respiratory origin that have been shown to contain SARS-CoV-2 RNA in clinical studies. Although this study was conducted with simulated teeth and not human subjects, this suggests that properly placed HVE and LEV would prevent the spread of respiratory viruses such as SARS-CoV-2 from aerosols generated by infected patients, and the enclosures may restrict the aerosol. from patient to patient. Clinical significance The use of properly placed HVE and LEV in clinics without mechanical ventilation can prevent the dispersion and persistence of inhalable particles in the air during dental AGPs. Additionally, the use of enclosures has the additional effect of restricting the spread of aerosols outside of an area of operation. |
