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Even before the COVID-19 pandemic, dentistry had robust infection control procedures in place. Unfortun-ately, not every dental office followed all the recommended standard procedures.1 However, the COVID-19 pandemic has served as an important "wake-up call" for many to tighten up their infection control practices. Similar to how the HIV/AIDS pandemic of the 1980s spawned a greater understanding of the spread of blood-borne pathogens, which led to the practice of routine wearing of gloves and masks by dental healthcare professionals,2 the COVID-19 health crisis has prompted the Centers for Disease Control and Prevention (CDC) to update its guidelines for protecting patients and healthcare personnel.3
With COVID-19 infection, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), some affected individuals may become severely ill, while others may be asymptomatic (albeit they may still transmit the virus).4 The upper airways and lungs are identified as the primary sites of SARS-CoV-2 infection. Nevertheless, the virus has also been found present in the saliva and oral flora, potentially through several identified routes. Frequent liquid droplet exchange may be possible owing to the anatomical proximity of the lower and upper respiratory tract and oral cavity.5 SARS-CoV-2 may enter the oral cavity via gingival crevicular fluid, which contains serum proteins and thus viral components. New research has shown that the virus may rapidly infect salivary gland epithelial cells, indicating that salivary gland cells may play a critical role in virus transmission.6
Excretion via the oral cavity and, therefore, airborne transmission amplification may occur via aerosols and aerosol-generating procedures, including respiratory droplets generated through talking, coughing, and sneezing of an infected patient. Transmission through fomites (materials or surfaces that are likely to transmit infection) can occur through interpersonal contact. Dental healthcare staff must have additional infection control measures in place to limit the risk of viral transmission.
ROLE OF THE INFECTION CONTROL COORDINATOR
With the discovery of new infectious diseases, transmission-based infection control protocols in oral healthcare need to be reexamined and adjusted accordingly.7 Transmission-based precautions are the second tier of basic infection control measures, which have been put in place to control or prevent the transfer of germs from one person to another in any healthcare setting to protect patients, their families, other visitors, and healthcare workers. They are used, alongside the usual standard precautions, when treating patients who may be infected or colonized with certain infectious agents, for which additional precautions are necessary to thoroughly prevent infection transmission. Owing to the highly infectious nature of SARS-CoV-2, individuals who are infected or suspected of being infected with this virus must undergo necessary transmission-based precautions to prevent disease transmission. These precautions must be revisited in light of the COVID-19 pandemic to tailor them specifically for the identified modes of transmission of SARS-CoV-2 in order to be effective in curtailing the spread of COVID-19. In addition, measures must be taken to ensure that dental practices understand the necessity of implementing these protocols for patient and staff safety.
While some transmission-based infection precautions have been updated for dental settings, the role of the infection control coordinator (ICC), crucial to mitigating infection risk in healthcare settings, has not been revised. With the onset of the COVID-19 pandemic, the ICC must also have a firm grasp on transmission-based measures. Despite the CDC's recommendations regarding the necessity of an ICC for almost 20 years now, incorporating a trained ICC is still not standard in many dental offices.8
The ICC is the key team member to turn to during any infectious disease outbreak, as ICCs have relevant and ongoing training in infection prevention. They are responsible for daily and long-term oversight of an office's infection control strategy, ensuring that all policies, procedures, and practices are relevant and successful. Dental offices whose staff includes a trained ICC will be up to date on all current infection control measures and will therefore be equipped to develop and implement necessary standard operating procedures (SOPs) for the rest of the team to follow.9The ICC will keep an updated log of safety-related records, guaranteeing compliance with current regulations such as ensuring that all dental staff receive vaccinations and up-to-date training.9
UPDATES OF STANDARD INFECTION CONTROL PRECAUTIONS AND PRACTICES IN DENTISTRY SINCE THE COVID-19 PANDEMIC
Aerosol and Air Quality Management
The pandemic has spotlighted the need for healthcare professionals to refocus on the current management of aerosols and air quality in dental settings. Dentistry has needed to take a hard look at the standard infection control procedures and protocols already in place, which have a proven track record of ensuring patient and staff safety when implemented correctly.
Along with standard precautions, a secondary tier of transmission-based precautions covering airborne transmissions may be necessary for some clinical situations, such as when a patient has a proven infection or is suspected of having a highly transmissible infection that routine procedures alone cannot entirely control.10 Aerosols carrying pathogens from the patient's saliva and oral fluids may be amplified into the air during the use of rotary dental and surgical equipment such as ultrasonic scalers.11Transmission-based precautions for aerosols can be employed to prevent the spread of infectious pathogens that remain contagious when suspended in the air over extended distances.12
In these cases, patients with infection or suspected of infection should be isolated in an Airborne Infection Isolation Room (AIIR) with regular air changes.10 Moreover, instead of relying on surgical masks, where much of the air and airborne organisms can enter at the sides, CDC recommendations advise using National Institute for Occupational Safety and Health (NIOSH)-approved, fit-tested N95 respirators and a complete respiratory protection program.10 The program should involve training and fit testing to verify that the respirator's edges and the wearer form an adequate seal so that no airborne pathogens may penetrate.
Because aerosols can remain suspended for up to 3 hours, it is crucial to perform a complete air change to filter out expired or contaminated air and facilitate the movement of "clean" air into the operatory, which can be achieved through ventilation with sufficient fallow time after aerosol-generating procedures (AGPs).12A common technique used to assess air circulation is to determine the Air Changes per Hour (ACH) to calculate the frequency with which the air in the room is completely exchanged in the clinical space following each operation to minimize the risk of airborne infection,13particularly if high-speed or ultrasonic devices were used.
Reducing aerosol dispersion is possible by modifying dental treatment practices, for example, through the use of rubber dams and engineering controls such as using portable high-efficiency particulate air (HEPA) filtration units immediately after AGPs as recommended by the CDC to capture pathogenic particles and reduce the risk of transmission.14Rubber dams have been demonstrated to significantly reduce airborne particles by 70% within 1 m of the operational range.15
It is also essential to be familiar with high-volume evacuation (HVE) tips and use them during AGPs. The use of HVE during AGPs has long been recommended, and the COVID-19 pandemic has merely highlighted that many dental professionals are not fully following protocols already in place. In order for a high-volume evacuator to be qualified as effective at minimizing bioaerosols, it must have an adequate bore size or opening diameter; bore size or opening diameter is thus a significant factor to consider. An opening of at least 8 mm or greater is recommended, as this can remove up to 100 cubic feet of air per minute.16 It should be noted that using a saliva ejector is insufficient, as it does not have the adequate opening size to be classified as a high-volume evacuator.16
Additionally, the suction tip should never be placed more than 15 cm away from the central incisor teeth.17It is vital to eliminate as much spatter, spray, and aerosol as possible at the point of use, regardless of whether there is a global pandemic. Aerosols must be eliminated as much as possible while they are being generated because they may remain suspended in the air for hours within the dental clinic, where dental care providers and patients may inhale them.12 A significant portion of these aerosols may also settle down on nearby surfaces, creating many contaminated areas and ultimately increasing the risk of infection.18
Hand Hygiene
Hand hygiene has been a significant part of infection control since the 1980s, having taken more than 100 years to become accepted as an essential practice.19Alcohol-based hand rubs (ABHR) are considered the most effective, simple, and cost-effective method of hand hygiene for preventing COVID-19 cross-transmission. However, even ordinary soap can make a difference, while an antibacterial soap can further enhance transmission prevention.20Furthermore, handwashing must be performed at the beginning and end of the day. The World Health Organization (WHO) recommends ABHR formulations containing 80% ethanol and 75% isopropanol, as these have significant virucidal activity against SARS-CoV.19
Healthcare providers should adhere to the WHO's recommendations called "My 5 Moments for Hand Hygiene," which advises disinfection (1) before touching a patient, (2) again before performing clean or aseptic operations, (3) after exposure to body fluids, (4) after touching a patient, and (5) after touching the patients' surroundings. A palmful of ABHR should be applied to all areas of the hands and rubbed until it dries completely to achieve proper hand hygiene.21
Personal Protective Equipment
Learnings from the HIV/AIDS epidemic resulted in an increase in the use of personal protective equipment (PPE) in healthcare settings, while the COVID-19 pandemic has brought the effectiveness of PPE under further scrutiny. Barriers are necessary to protect exposed areas such as the nose, mouth, eyes, and entrance to the upper respiratory tract from potentially infectious splatter and droplets generated during dental procedures. Because the respiratory tract is the primary entrance point for SARS-CoV, respiratory PPE such as medical, FFP-2, N95, and KN95 masks are recommended, especially during AGPs.3Every office should have a respiratory protection plan to ensure all staff members are safely wearing the appropriate masks.
Essential clinical PPE, including eye protection and surgical face masks, are sufficient for non-AGPs, along with performing approved disinfection measures immediately after each patient visit. The eyes are a potential entry point for the virus, owing to their exposed mucosal membranes. Therefore, team members and patients should wear a face shield or eye protection throughout procedures to avoid splashes.22 Basic clinical PPE is advised during AGPs, including eye protection in combination with fit-tested NIOSH-approved N95 respirators with full face shields and recommended execution of disinfection measures immediately after each procedure.10 The primary advantage of an N95 respirator is that it provides a tighter seal, minimizing the chances of air leakage.23
Although intact skin provides a barrier against the virus, it can still serve as a vector for transmission. Splash-proof long-sleeved aprons and gloves can offer protection. When oral healthcare staff treat patients with suspected or confirmed infections, transmission-based precautions call for the donning of PPE upon entering the operatory and proper doffing and disposal upon exiting.24 Immediately after removing all PPE, adequate handwashing or use of an alcohol-based hand sanitizer should follow to disinfect the hands properly.25
Respiratory Hygiene/Cough Etiquette
Coughing or sneezing presents a risk of infection transmission through the mucosal membranes. The oral cavity, respiratory tract, and eyes serve as entrance points for SARS-CoV-2, while salivary glands have been found to be a potential reservoir for the virus.26 Before the pandemic, many facilities already had measures in place to limit the dispersion of respiratory secretions. However, the need for such practices has become even more urgent since the pandemic.
Posters and signs should be hung or placed in strategic locations in the dental office that give helpful instructions on the importance of covering one's mouth or nose while coughing or sneezing, the use and proper disposal of tissues, and the performance of hand hygiene immediately upon contact with respiratory secretions.27
Sharps Safety
It has always been vital that dental healthcare professionals adhere to conventional workplace protocols when using or working around equipment such as needles, scalpels, and other sharp objects. Contaminated objects should be regarded as potentially infective and handled as such. Wearing gloves and discarding disposable sharps appropriately in puncture-resistant containers as close to the site of usage as possible is necessary at all times, according to the CDC, but has become even more critical during the pandemic to prevent further overloading of the healthcare system due to occupational accidents.28
We can take inspiration from sharps safety practices currently followed in China, where disposal of contaminated sharps is in government-designated COVID-19 patient medical waste disposal facilities.29This method helps manage ecological pollution caused by medical waste and further reduces transmission from contaminated waste, including sharps.29Before transporting the sharps, it is required that the outer surfaces of transport containers or bags be sprayed evenly with 1,000 mg/L of chlorine disinfection or an additional layer of medical waste bag be used on the outside. Disinfecting the transport tool with a 1,000 mg/L chlorine disinfectant solution should be done at the end of each transport.29
Instrument Processing
Applicable guidelines for processing contaminated dental instruments must be readily available and strictly followed. When dental offices were closed for prolonged periods during the pandemic, processing equipment had lain unused, and many did not realize that such equipment must be restarted properly. Therefore, it is vital to read the manufacturer's instructions on using equipment such as the autoclave for instrument sterilization or the ultrasonic bath for proper instrument cleaning to ensure proper everyday use, particularly if it has been lying dormant for an extended time.30
By appointing an ICC who oversees the processes and trains team members to carry out tasks related to processing contaminated instruments,31 including the proper cleaning, disinfection, and sterilization of equipment in a well-ventilated stericenter, it is possible to ensure the safe re-use of dental instruments for patient care. The role of all team members working in this area may also include:
• Keeping a sterilization log
• Performing regular maintenance of the processing equipment
• Conducting spore testing at least once weekly32
• Participating in ongoing training on up- dated guidelines from the in-office ICC, who is also responsible for overseeing the entire process
Operatory Disinfection
Elimination of infectious reservoirs through regular cleaning and disinfection of all surfaces should be part of any dental office's infection control protocols.33 Because of supply chain problems during the pandemic, many offices could not source their usual products. Although we are no longer experiencing supply chain issues, many offices have continued using other products instead of those they were previously accustomed to using. Therefore, team members must learn about the capabilities of and differences between various cleaning and disinfection products by reading product literature and should adhere to the manufacturer's guidelines for information on safe, effective use and contact times.34
The US Environmental Protection Agency (EPA) is actively reviewing effective disinfectants against the COVID-19 virus and generating a list of suggestions.35 Current recommendations from WHO include ethanol (70% to 90%), hydrogen peroxide (≥0.5%), and hypochlorite-based solutions in specific concentrations for a contact time of at least 1 minute, as these display a broad spectrum of effective antimicrobial activity.33Commercially available disinfection products may be used based on the recommendations from the manufacturers, and advised contact times should be followed.
At least 0.1% (1,000 ppm) of hypochlorite solution serves as a safe concentration that is capable of inactivating the vast majority of pathogens.36 A higher concentration of 0.5% is recommended for disinfecting areas involving large blood or other bodily fluid spills. Before applying disinfectants, especially when using a hypochlorite solution, surfaces should be thoroughly cleaned with a mixture of detergent or soap and water using physical actions such as scrubbing to remove any organic material that could inactivate the solution regardless of the concentration used.36Rinsing with water to remove any residue may follow after the appropriate contact time.
Dental Unit Waterline Maintenance
Waterlines connecting dental units to handpieces such as air or water syringes and ultrasonic scalers are at risk for contamination due to the long narrow tubing and residual water and therefore require regular upkeep. If a dental office is closed for a period of months, or even as little as 2 weeks, the water lines will lie dormant, becoming a breeding ground for bacteria and requiring remedial work to return them to a safe standard.37 If water is not adequately treated, dental healthcare workers and patients may be at risk for adverse health complications, including disease transmission.38 Continuing to carry out routine testing and shock treatments with high-level disinfectants is one of the most effective methods for removing dental unit biofilms without causing damage to the equipment.39
Additionally, dental healthcare providers should adhere to current recommendations and tips from the US Food and Drug Administration and CDC on managing dental unit waterlines (DUWLs). These recommendations include having a written protocol in place for routine DUWL management and testing and regular monitoring of water quality.40 Waterlines should be routinely analyzed for any damage or visible contamination, including biofilm formation, which can be identified by a musty odor, clogged lines, or cloudiness and particulates in the water. Wherever necessary, the use of separate reservoirs, filtration systems, chemical treatment protocols, and delivery systems of sterile water should be correctly utilized. It is necessary to purge water through the lines at the beginning and end of each workday and for at least 20 to 30 seconds in between each patient to prevent contamination from back-flow, as well as to prevent stagnant water from settling.40 Check the manufacturer's handbook for dormant DUWLs to determine if they require shock prior to use.
According to EPA standards, water used in dental units should have the same standards as drinking water. Dental unit manufacturers can provide guidance on the best ways to maintain water quality and proper monitoring measures. Knowing when to use clean or sterile water is also critical. For nonsurgical operations, pure water that complies with regulatory drinking water standards may be utilized. Sterile solutions should be strictly used in surgical operations as a coolant or irrigant alongside sterile single-use devices.41 Appropriate delivery devices such as a bulb syringe, sterilized, single-use disposable supplies, or any sterile water delivery systems that bypass the dental unit must be used to supply sterile water during surgery. This is because the water-bearing pathway of conventional dental units cannot be reliably sterilized to deliver uncontaminated sterile water.42
CONCLUSION
While the infection control practices described in this article may seem daunting to implement, most are standard procedures that were already in place before the COVID-19 pandemic. An ICC who has ongoing training knows what infection control measures are required in the dental setting and will be up to date on any changes in guidelines and protocols. Currently, we know that proper sanitation measures, in conjunction with appropriate PPE use, regular air exchange, and routine maintenance of dental unit waterlines, can considerably lower the likelihood of SARS-CoV-2 transmission in dental settings. Now is the time to reexamine the processes already in place to ensure enhanced infection control.
Improved infection control protocols will likely be developed as researchers learn more about how infections and viruses spread. An ICC should be the designated team member to receive these updates and any relevant training and to implement any changes in infection control practices while ensuring that all staff members receive the training necessary to prevent infection transmission in the dental office.
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