COVID-19 and the dental profession: Establishing a safe dental practice for the coronavirus era

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus causing the disease referred to as COVID-19 by the World Health Organization.^[1] SARS-CoV-2 is the seventh member of a family of coronaviruses known to infect humans.^[2] This group of the coronavirus family, also referred to as Coronaviridae, is further divided into four subcategories: Alpha, beta, gamma, and sigma; alpha and beta are major concerns to humans.^[3] Typically, these viruses cause mild clinical symptoms; however, in the past 18 years, there have been three noteworthy strains that belong to the beta-coronavirus subtype and have led to epidemics in their outbreak communities. These are SARS in 2002, Middle-East respiratory syndrome (MERS) in 2012, and now the SARS-CoV-2 which has emerged to cause the current pandemic with significant morbidity and mortality.^[4-6]

Using genome sequencing, it was found that the natural host for COVID-19 began in a specific species of bat, Rhinolophus affinis, also known as the horseshoe bat, and used an intermediate host before becoming infectious to humans.^[7] A study done in South China reported that 70% of pangolins tested positive for beta-CoV, one of which showed 99% match to the novel coronavirus.^[8] For this reason, it is suspected that pangolins may be the intermediate host for this virus, but this has not been firmly established. It is known, however, that SARS in a process called spillover, emerged from civet cats and MERS from camels.^[9] Although the animal source of COVID-19 cannot be conclusively identified at this time, zoonotic transfer of COVID-19 virus to humans has been well documented.^[10]

TRANSMISSION MODE AND IMPACT ON DENTISTRY

SARS-CoV-2 enters cells through the angiotensin-converting enzyme 2 (ACE2) receptors found in most cells of the respiratory system as well as salivary gland cells.^[11] Salivary gland cells are believed to be the first sites where SARS can be detected, and it is theorized that COVID-19 follows the same path.^[12] Similar to other viruses, SARS-CoV-2 is not a living organism and depends on host cells to replicate. It contains protein molecules covered by a protective layer of lipid, which binds to the receptors and fuses with the membrane of the host cell to begin viral entry.^[13] Therefore, it is prudent to note that it cannot be killed and will only disintegrate under certain conditions.^[14] The danger that SARS-CoV-2 poses, however, is related to its long incubation period and highly infectious nature.^[15] This single-stranded RNA virus can be directly transmitted through respiratory droplets produced by the breathing, talking, sneezing, or coughing of an infected person who comes in contact of others.^[16] It is also possible for indirect fomites transmission through the touching of contaminated nonliving materials or aerosolization transmission in a confined space.^[17,18]However, at the time of writing of this paper, airborne transmission, while widely speculated, has not been reported.^[19] Studies have demonstrated that large respiratory droplets of more than 10 μm in diameter can be dislodged from an infected person and travel up to 6 feet, with coughs traveling at a velocity of 10 m/s and sneezes traveling at 50 m/s.^[20,21] Furthermore, aerosols including droplet nuclei can remain suspended in the air for an extended period of time and smaller particles of 0.5–10 μm have potential to enter and trap in the respiratory tract down to alveolar space.^[21-25] Aerosolized particles have been reported to remain in the air up to 30 min post- dental procedures, but a recent study published by the New England Journal of Medicine demonstrated that the SARS- CoV-2 virus remained stable in aerosols for the duration of the experiment, lasting 3 h.^[26,27] The WHO relents that this experiment was performed under conditions that do not accurately mimic coughing or a clinical setting.^[28] These discrepancies indicate that further research is needed to accurately gauge the viability of SARS-CoV-2 in aerosols intra- and post-dental procedures. SARS-CoV-2 has a mean size of 0.125 microns and a median incubation period of 5–6 days from exposure to onset of symptoms, ranging from 2 to 14 days, making asymptomatic carriers the biggest threat to containment.^[29,30] Posterior oropharyngeal saliva samples from patients with COVID-19 indicate that viral loads of RNA are highest on presentation and shortly after symptom onset, suggesting that the virus could be transmitted easily even when infected individual is asymptomatic.^[31] Contact transmission of the virus can also be attributed to the abundance of ACE2 receptors found in the oral and nasal mucosa, as well as the nasopharynx.^[32] This puts health care workers, especially dentists, dental hygienists, dental staff, oral, and maxillofacial surgeons, otorhinolaryngologists, and anesthesiologist at higher risk. In March 2020, Occupational Safety and Health Administration (OSHA) classified dentists/dental providers in the very high-risk group for COVID-19.^[33] In addition, many dental procedures produce significant amount of droplets and aerosols; therefore, it is imperative for clinicians to know the transmission pathway and to be able to contain the spread of infection in dental office.^[34]

RECOMMENDATIONS

While there are many organizations making reporting guidelines about patient care during the COVID-19 pandemic, our group focused on evidence-based recommendations to provide clear information, practices, and materials that general dentists, hygienist, specialists, and auxiliary teams could implement. This is to minimize the risk of COVID-19 exposure to themselves and their patients and continue to be used in post-pandemic. Furthermore, our knowledge of the SARS-CoV-2 is evolving rapidly and recommendations may change just as quickly. Therefore, current guidelines made by federal/state governments and governing organizations should be reviewed frequently.

DISCUSSION

It is important to realize that, even pre-COVID-19, it was part of routine practice for all OHCP to update medical history and record vital signs including temperature for every patient in every visit. Most providers agree that regardless of COVID-19, patients with symptoms of flu, respiratory, infectious, or other systemic diseases that put patients and providers at risk should seek medical care and elective dental procedures should be delayed. It is a known fact that oral health-care providers are at the forefront of infection control with an in-depth knowledge of cross-contamination and have always adhered to the state regulatory protocols in treating patients with infectious diseases, even before COVID-19. In contrast, with the exception of the OR, medical health- care providers and staff do not use adequate PPE during patient interaction and do not quite follow infection control guidelines as closely.^[77] Therefore, it is not surprising to see numerous policy and procedures related to PPE emerged during the COVID-19 for medical staff in hospitals and medical facility alike.

There is a paucity of information about the length of time that aerosolized or droplet nuclei of SARS-CoV-2 can remain in the air after a dental procedure before settling on a surface or in a person’s respiratory tract. With adequate ventilation, 30 min between patients following thorough disinfection is reasonable time for safety measure.^[26] It should also be noted that children appear to have less serious symptoms to COVID-19 than adults but could be asymptomatic carriers. This may play an important role in decision making to treat pediatric populations for routine dental care.^[78] With negative pressure ventilation rooms, air purifiers, and proper/ adequate PPE, it is possible to begin providing routine dental care to many patients who are suffering at this time. Patient education and assurance are also important. As the interruption of care continues, manageable and restorable conditions can quickly change into emergencies with loss of teeth and supporting structures. Dental students and residents are also missing the opportunity to complete their educational requirements. This is a global dilemma, and in the United States, all dental schools in coordination with the Commission on Dental Accreditation are working hard to plan alternative solutions. Perhaps when FDA-approved testing becomes widely available, COVID-19-positive patients can be identified and should receive only emergency treatment until they have been shown to have resolved the disease. Those who test negative will be able to receive routine dental care with transmitted-based precaution. However, at this point, there are many variables and it may not be practically possible in a large scale. With information provided in this article, thoughtful considerations should be given to return to practice safely. As we are heavily affected by this seemingly ever-lasting pandemic, it is pertinent for all OHCP to remain up to date with new information due to the rapidly evolving nature of this virus. We are in the midst of the pandemic, we continue to learn about the disease and how to best manage and treat it. More scientific evidence and studies are required to understand the specific behavior and infectious nature of the novel SARS-CoV-2 virus that could lead to developing vaccine or medications to control the disease. Until then, the aforementioned precautionary measures are highly recommended, and the use of fit-tested respirators will be needed to enhance protection for the foreseeable future.