In December 2019, fatal pneumonia cases occurred in the city of Wuhan, China. After genetic analysis, the cause of this agent was determined as an unknown coronavirus.The disease was named coronavirus disease of 2019 (COVID-19). The virus was initially called 2019-nCoV, and later renamed SARS coronavirus-2 (SARS-CoV-2). Since then, health authorities and the healthcare profession have been implementing biosecurity mechanisms to avoid contagion. In this article, we will present some preventive practices for dental work.
Route of transmission
Before starting, it is important to know the routes of transmission and infection. COVID-19 is transmitted directly and interpersonally, mainly by inhalation of respiratory droplets (Flügge droplets). It can also be transmitted indirectly by contact with contaminated surfaces (fomites).It is suspected that transmission of COVID-19 is not only limited to the respiratory tract and that ocular exposure may be a route of entry of the virus. Thus, droplets can be located on the nasal, oral, and conjunctival mucosa.Direct or indirect interpersonal transmission through saliva may also be a route of transmission, and the presence of viral particles in the saliva of infected individuals has been reported. Although not confirmed, it is suggested that the airborne route through aerosols, produced during medical procedures (which would include those generated in dental care) may be another route of transmission.
Airborne transmission
The CDC mentions that transmission by this route is currently uncertain. However, person-to-person transmission over long distances is unlikely. For this reason, in the case of dental care where the distance is minimal, attention to this route takes on special relevance.On the other hand, special care must be taken because many dental procedures generate aerosols and droplets containing infectious agents. These can affect healthcare professionals, but can also spread to surfaces and the clinic environment.At this point, it is worth mentioning that the use of barriers, as well as disinfection aspects, should be reviewed to evaluate possible changes or adjustments.
Possible impacts on biosafety aspects in the dental practice
One of the basic principles of biosafety is that the exposed worker should follow universal precautions for any individual regardless of whether we know his or her serology or other elements (such as social stratum, etc.) since he or she can potentially carry and transmit pathogenic microorganisms.In general terms, biosafety procedures and techniques are still in force. In this sense, this review is performed at the time dental care begins. Biosafety practices must seek to avoid and minimize this and other infectious diseases. That is not only limited to the act of dental care itself but transcends it and includes measures such as, for example, spacing the schedule of care to minimize contact times between patients in the waiting room.
How to keep the environment sterile?
Heat sterilization
Most viruses are inactivated at temperatures between 56 and 65 °C maintained for 1 hour, as it denatures the capsid and envelope proteins. Therefore, sterilization by dry heat at standard parameters ensures the death of all viruses.
Masks
Surgical masks cannot be used in case the intervention involves the generation of aerosols, in which case respiratory or self-filtering masks (FFP2 or N95) should be used.Respiratory masks (such as N95) are used during the care of patients with respiratory infections transmitted by airborne particles. In other words, the use of respiratory masks is recommended for any respiratory infection and is, therefore, no exception for COVID-19 as it is a disease of this type.With respiratory masks, the facial seal should be checked every time they are used to minimizing air leakage. As this may differ from mask to mask, the manufacturer’s recommendations should be reviewed. The test consists of a positive seal test which means that when exhaling no air should be felt and a negative seal test when inhaling no air should be felt and the mask should be brought close to the face.Both surgical masks and respirators are discarded with each patient. Contamination of the respirator surface can be avoided by placing a surgical mask over it or by placing a face shield over it.The use of biosafety elements similar to the surgical ward should be mandatory to reduce the risk of contagion, face shield, and mask due to the risk of our profession in the category of exposure/transmission.Procedures that generate aerosols and therefore expose personnel to respiratory pathogens imply the mandatory use of protective equipment (respiratory mask and eye protection or face shields) regardless of whether there are symptoms of respiratory infection.Current protocols recommend the use of an FFP2 or N95 mask, cap, gloves, eye protection or face shield, disposable impermeable gown, and shoe covers.
Air Control with Extraoral Suction Systems
Many offices have added innovative equipment, such as extraoral suction systems. These devices suck aerosols from the mouth and prevent them from entering the airflow.High-speed drilling dental surgery and dental hygiene ultrasound cleaning visits can then be performed safely with Extraoral Suction Systems. These systems can remove 99.9% of saliva, blood, and other liquid atomized droplets, which may be expelled from the patient’s mouth during routine dental treatment.These units are a bit expensive, there are several thousand, but the investment is worthwhile. When patients learn about the existence and upcoming use of the device during the visit, they will not hesitate to schedule an appointment immediately.
Other methods of air control
The effect of the use of ultraviolet radiation for the inactivation of microorganisms on surfaces and environments, particularly in operating rooms, is well known. With the irruption of this virus, several reports have appeared promoting lamps for use in clinics.Its use through portable lamps is complex since it depends on the correct installation of the space. Care should be taken to avoid exposure due to its effects.As for ozone purifiers, although some purifiers have an EPA number, the EPA does not certify air purifying devices. It is not effective when used at concentrations that do not exceed health standards.In places without the possibility of ventilation and their ventilation systems are closed circuits, the use of HEPA (High-efficiency particulate area) filters is still recommended.