By: Dr. Abhishek Kumar Pandey, Asstt. Editor-ICN
LUCKNOW: The spread of coronavirus (COVID-19) has posed significant challenges for dentistry and medicine, and dental and medical schools, in all affected countries. The arrival of COVID-19 to Europe, an epicenter of the pandemic, was not unexpected having originated in Wuhan, China, in late 2019. The speeds of reaction and type of response to this disease around the world have been very variable according to differing healthcare systems, economies and political ideologies.
The available epidemiologic data suggest strongly that transmission of SARS-CoV-2 occurs primarily via respiratory droplets from coughs and sneezes within a range of about 1– 2 m and by direct contact. Indirect contact via contaminated surfaces is another likely cause of infection. Latest research also shows that airborne transmission is possible because the virus is stable for several hours to days in aerosols and on surfaces. Specifically, SARS-CoV-2 was detectable, albeit at progressively lower titers, in aerosols for up to 3 hr, up to 4 hr on copper, up to 24 hr on cardboard, and up to 2 to 3 days on stainless steel and plastic, respectively. The unique nature of dental interventions, which include aerosol generation, handling of sharps, and proximity of the provider to the patient’s oropharyngeal region, exposes dentists and oral health professionals to contagion.
Importantly, studies have shown the presence of SARS CoV- 2 in both saliva and feces of the affected patients. SARS-CoV-2 enters the cell in the same path as SARS coronavirus, that is, through spike S1 protein binding to the ACE2 cell receptor. ACE2+ epithelial cells of salivary gland ducts were demonstrated to be early targets of SARS-CoV infection, and SARS-CoV-2 is likely to have the same tropism for the salivary epithelium; this may be a possible explanation for the presence of SARS-CoV-2 in secretory saliva. Viral carriage in salivary fluids is a key, additional risk factor for aerosol-generating procedures that routinely take place in dental practice.
Dental teams should hold routine response plan briefings to ensure that workers and workplaces are prepared to minimize the risk of infection. Dentists, oral healthcare professionals, technicians, and cleaners should all be trained on the standard and transmission-based precautions in addition to following local government guidance such as frequent hand washing and self isolation for 2 weeks in case of mild cough or low-grade fever (37.3 °C or more). With some exceptions, there is overall a consistency in guidance that dental activity during pandemic should be limited to emergencies and urgent dental care. Most local governments and dental associations are not prescriptive as to what constitutes essential dental care and suggests that dentists use their professional judgment in determining a patient’s need for urgent or emergency care. According to the British Dental Association, “there should be a reduction in the amount of routine dental activity, particularly in respect of vulnerable groups and importantly that staff and patient exposure to potential infection should be reduced by avoiding all aerosol generating procedures wherever possible”. The American Dental Association has provided a list of dental procedures that are to be considered urgent—these mainly refer to potentially serious conditions and dental/oral pain.
Early recognition and prevention of transmission before dental treatment
Patient triage and consulting: – It is useful to use patient reminder calls to identify patients reporting illness or suspicious symptoms, in which case dental treatment should be deferred. Whenever possible, patient triage should be performed by telephone before confirming the appointment. Accompanying persons should not be allowed in the premises and patients should be provided with surgical masks; efforts need to be made to limit the number of patients in the waiting room to 1 person and for a limited time. Once patients enter the dental clinic, temperature measurement should be performed and, in addition to medical and dental history, patients contact history should be recorded, whereas travel history is perhaps less relevant at this stage due to the spread of the virus worldwide.
Patients not admitted for emergency treatment should be offered advice and instructions to temporarily manage their dental problems. For example, parents of children with orthodontic appliances may be asked to take pictures to document their clinical condition. Patients with mild symptoms from gingivitis should be given practical daily advice of oral hygiene, and pharmacologic management may be suggested if necessary. It is also important to prioritize the follow-up of these patients as soon as routine dental treatment resumes.
Set up of common spaces: – Visual alerts (e.g., posters) that promote respiratory hygiene and cough etiquette measures should be placed in waiting areas or at reception desks and are considered a component of standard precautions practiced routinely in dental settings. Key information to be provided to patients include covering the mouth and nose during coughing and sneezing, using tissues to contain respiratory secretions and promptly disposing of them, and performing hand hygiene after contact with respiratory secretions. Furthermore, waiting areas should be set up to ensure that physical distancing measures can be maintained (e.g., 1–2 m between patients). It is also useful to provide alcohol-based hand rub (ABHR) with 60–95%alcohol, tissues, and no-touch receptacles for disposal in waiting areas.
Environmental cleaning and disinfection :- Dentists or dental managers should ensure that the dental clinic is a safe environment for patients and workers at all times. SARS-CoV-2 can survive on surfaces for up to 3 days; hence, door handles, light switches, and other potentially contaminated surfaces can be the vehicle of indirect contact between patients and dental professionals and should be cleaned frequently. Guidelines have been published and constantly updated by the WHO, as well as by local institutions across the world. In general, routine cleaning and disinfection procedures are appropriate for SARS-CoV-2 in healthcare settings, including those patient care areas in which aerosol-generating procedures are performed. The CDC proposes the use of standard cleaners and water to pre-clean surfaces prior to applying an EPA-registered, hospital-grade disinfectant to frequently touched surfaces or objects. EPA registered disinfectants that have qualified under EPA’s emerging viral pathogens program for use against SARS CoV- 2 have been published and include hydrogen peroxide, quaternary ammonium, sodium hypochlorite, and ethanol at various formulation types and contact times.
Infection control :- Since the fecal-oral route is considered one of the 2019-nCoV transmission routes, attention to hand hygiene before, during, and after dental practice is important. Dentists should exercise extreme caution to avoid contact with their own facial mucosal surfaces including their eyes, mouth, and nose. Since transmission of airborne droplet is considered one of the main routes of infection spread, application of personal protective equipment such as masks, protective goggles, gowns, helmet, gloves, caps, face shields, and shoe covers is strongly recommended for all health care personnel. Covid-19 patients should not be treated in a regular dental care setting without special considerations. Unexpected circumstances may occur when the dentist cannot delay treatment or refer the patient to the appropriate medical institution. Under such circumstances, special protective clothing such as hazardous materials (hazmat) suits is required. If hazmat suits are not available, white coats, gowns, head caps, protective eyewear, face shields, masks, latex gloves, and virus-proof shoe covers should be used.
Mouth rinses:-The effect of chlorhexidine, which is commonly used for pre procedural mouth washing in dental practice, has not yet been demonstrated to be capable of eliminating 2019-nCoV. However, oxidative agents containing mouth rinses with 1% hydrogen peroxide or 0.2% povidone- iodine are recommended. Pre-procedural use of mouthwash, especially in cases of inability to use a rubber dam, can significantly reduce the microbial load of oral cavity fluids.
Appropriate disinfectants :- Since there is still little information available regarding 2019-nCoV, relatively similar genetic features between 2019-nCoV and SARS-CoV indicate that the novel coronavirus can be vulnerable to disinfectants such as sodium hypochlorite (1000 ppm or 0.1% for surfaces and 10,000 ppm or 1% for blood spills), 0.5% hydrogen peroxide, 62–71% ethanol, and phenolic and quaternary ammonium compounds if utilized in accordance with the manufacturer’s instructions. Studies show that other biocidal agents such as 0.05–0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate probably have lower efficiency. In addition to the type of disinfectant, paying attention to other factors such as the duration of use, dilution rate, and especially the expiration time following the preparation of the solution according to the manufacturer’s instructions is also crucial.
Management of medical waste: – Prior to any inappropriate accumulation, dental office waste should be routinely transported to the institution’s temporary storage facility. Reusable tools and equipment must be properly pre-treated, cleaned, sterilized, and properly stored until the next use. Dental waste resulting from the treatment of suspected or confirmed 2019- nCoV patients is considered medically infectious waste that must be strictly disposed of in accordance with the official instructions using double-layer yellow medical waste package bags and “gooseneck” ligation.
Pre- and peri-operative procedures:-
There are standard and specific procedures that can be implemented to reduce the likelihood of viral spread and of generating droplets and aerosols during dental treatment. These practices have not been tested or validated for SARS-CoV-2 and are mainly based on results obtained with oral bacteria or recommendations related to common viruses such as influenza.
When assigning a treatment room, at risk patients (elderly, people with underlying diseases and those with positive contact history but without symptoms) should be separated from others whenever possible and a treatment room with a closed door should be used.
A pre-operational antimicrobial mouth rinse is believed to reduce the number of microorganisms that populate the oral cavity and disseminated by means of the aerosol generated via dental procedures. Pre-procedural mouth rinse containing oxidative agents such as 1% hydrogen peroxide or 0.2% Povidone is recommended for the purpose of reducing the salivary load of oral microbes, including potential SARS CoV- 2 carriage, whereas the most commonly used chlorhexidine mouth rinse may not be effective.
The use of rubber dam is thought to significantly minimize the production of saliva- and blood-contaminated aerosol or spatter; however, there is no direct evidence of a reduction of viral loads. Early studies show that application of rubber dams during restorative procedures could significantly reduce airborne particles in ~ 3 feet diameter of the operational field by 70%. The reduction of bacterial contamination of the atmosphere, peri-operatively, is greatest at 1 m from the headrest; therefore, the use of rubber dam would minimize significantly the inhalation of infective aerosols by dental personnel. Conversely, more recent evidence suggests that use of rubber dam results in significantly higher aerosol levels on various areas of the dentist’s head. Although in this latter case the aerosol generated is likely to contain less viral particles, overall these data strongly suggest that dentists are required to cover their heads with suitable protective wear.
Anti-retraction handpiece can significantly reduce the backflow of oral bacteria and HBV into the tubes of the handpiece and dental unit as compared with the handpiece without anti-retraction function. Therefore, the use of dental hand pieces without anti-retraction function is not indicated during COVID-19 epidemic and/or pandemic.
The use of saliva ejectors with low or high volume can reduce the production of droplets and aerosols, and the use of a complete four-hand operation is also desirable. Procedures that are likely to induce coughing should be avoided (if possible) or performed cautiously.
Infection control precautions and practices for oral healthcare workers
Standard precautions :- Dentists follow a uniform infection control protocol to treat all patients, irrespective of their medical histories. Infection control precautions were introduced largely because of the human immunodeficiency virus (HIV) epidemic and were designed and updated to prevent transmission of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), and other blood borne diseases. These standard precautions are designed to protect healthcare personnel and patients from pathogens that can be spread by blood or any other body fluid, excretion or secretion.
Elements of standard precautions include –
(1) Hand hygiene
(2) Use of personal protective equipment (PPE, e.g., gloves, masks, eyewear)
(3) Respiratory hygiene/cough etiquette
(4) Sharps safety (engineering and work practice controls)
(5) Safe injection practices (i.e., aseptic technique for parenteral medications)
(6) Sterile instruments and devices
(7) Clean and disinfected environmental surfaces.
According to the US Occupational Safety and Health Administration (OHSA), standard precautions during patient care are determined by the task being performed and the type of exposure that is anticipated, not by the patient. For example, only gloves may be needed when obtaining dental radiographs, whereas protective eyewear and clothing, gloves, and masks are necessary when placing restorations.
Standard precautions that apply to most dental procedures, including oral examination, are the use of PPE such as surgical mask, goggles/eye protection or face shield, gown or protective clothing, gloves, and head cap. Oral healthcare professionals should perform hand hygiene before putting on and after removing PPE, including gloves. Any reusable PPE and equipment must be properly cleaned, decontaminated or sterilized, and maintained after and between uses. Standard precautions are routine infection control practices and should be in place in dental clinics at all times.
Transmission-based precautions:- Unfortunately, due to the unique characteristics of dental procedures where a large number of droplets and aerosols could be generated, the standard protective measures in daily clinical work are not effective enough to protect from COVID-19—or from any other diseases that can spread through contact, droplet or airborne routes—especially when patients are in the incubation period, are unaware they are infected, or choose to conceal their infection. Hence, a second level of precautions, referred to as transmission-based precautions, need to be implemented and is always used in addition to standard precautions. There are three categories of transmission-based precautions: airborne, droplet, and contact, and these also apply to other respiratory viruses.
Notable additions to standard precautions include the utilization of particulate respirators by dentists and chair side assistants (e.g., N-95 masks authenticated by the National Institute for Occupational Safety and Health or FFP2/3-standard masks set by the European Union) and use of high-volume evacuation (HVE) or systems that improve the general ventilation and effectively control the airflow patterns and filtration of the circulating air. In dental offices in which these airborne precautions cannot be implemented, having the patient wear a mask at any time when outside the operative room, placing the patient in a private room distant from other patients, ensuring a level of room ventilation (e.g., frequent natural ventilation via windows, for example, 5-min air change between each patient), and avoiding the presence of unnecessary individuals in the room will reduce the likelihood of transmission.
COVID-19 has been causing tens of thousands of deaths globally, and many of these fatalities are doctors and healthcare workers. Despite the tight restrictions imposed by local governments across the world, dentists are healthcare professionals who continue to have a duty of care, especially to patients in pain, and are at high risk of SARS-CoV-2 transmission during this pandemic. It is therefore of outmost importance that infection control and other recommended procedures are adhered to and implemented in the dental setting.
Following the announcement of the disease outbreak by international or local authorities, dentists can play a significant role in disrupting the transmission chain, thereby reducing the incidence of disease by simply postponing all non-emergency dental care for all patients. Dental professionals must be fully aware of 2019-nCoV spreading modalities, how to identify patients with this infection, and, most importantly, self-protection considerations. Every patient should be considered as potentially infected by this virus, and all dental practices need to review their infection control policies, engineering controls, and supplies. Health care providers must keep themselves up-to-date about this evolving disease and provide adequate training to their staff to promote many levels of screening and preventive measures, allowing dental care to be provided while mitigating the spread of this novel infection. In conclusion, health care professionals have the duty to protect the public and maintain high standards of care and infection control. This new emerging SARS-CoV-2 threat could become a less pathogenic and more common infection in the worldwide population. Thus, it is important to make informed clinical decisions and educate the public to prevent panic while promoting the health and well-being of our patients during these challenging times.