From Volume 47, Issue 6, June 2020 | Pages 480-484
Standard Operating Procedures (SOPs) and their implications will play a fundamental role in the phased re-introduction of clinical dentistry post COVID-19. These SOP documents will continually be updated as new scientific rationales emerge. Each individual SOP will have key themes dictating how dental appointments are managed, emanating from the initial work of Peng
Two versions of this article exist. The first was written after countless hours spent collating (and translating!) standard operating procedures (SOPs) from around the world. These were then presented against a backdrop of the virus to show how these SOPs vary internationally. Upon completing the article, in fact I was finishing the conclusion, when I became aware that The Cochrane Dental Services Evidence Review (CoDER) Working Group had put together very similar information, in a more formal and scientific manner.1 This is an incredibly important document, and one that gives real insight into what key elements are consistent throughout their SOPs. This article therefore is aimed at GDPs who may want to recognize the important key features of any SOP and why they are set out the way they are. The article follows on from the initial piece written on behalf of the BAPD.2
Any SOP will have a backbone of key principles designed to provide barriers to the transmission of SARS-CoV-2. Many of these protocols are based on work carried out after SARS-CoV-1, which displayed many transmission similarities to SARS-CoV-2. The main body of work to which I have referred to help structure this article is by Peng et al.3
What we, as GDPs, really need to know is why we are doing this? What key principles should we be adhering to and what impacts may this have on us professionally and personally?
As described by Zhang et al, SARS-CoV-2 is a newly identified, novel member of the human coronavirus originating in the Wuhan province of China.4 The disease caused by SARS-CoV-2 has been named COVID-19 by the World Health Organization. The clinical symptoms of the disease include fever, dry cough, fatigue, lymphopenia, anosmia and loss of taste, in infected patients. The main portal of entry into our bodies is via ACE-2 receptors, into which ‘spike proteins’ on the coronavirus surface bind.
Possible transmission routes (as described by Peng et al3) include direct and indirect transmission such as coughs, sneezes, and droplets (including aerosol) spread via oral, nasal and eye mucous membranes. Evidence cited by Wang et al also suggests that the SARS-CoV-2 virus can be transmitted through fomites (objects or materials which are likely to carry infection).5 There are several pre-print papers (at the time of writing) which suggest SARS-CoV-2 remains stable within faeces for several hours and urine for 3–4 days. In addition, Liu et al raise the possibility of the virus remaining stable on plastic, stainless steel, glass, ceramics, wood, latex gloves and surgical masks for seven days.6
The virus itself enters cells through the ACE2 cell receptors, which are found abundantly within the respiratory tract, and it is widely purported that dental practice personnel may be at an increased risk of infection. Tissue distribution of the ACE2 protein (as studied by Hamming et al7) highlighted the roles of both respiratory tract tissue and small intestinal tissue as portals of entry for the earlier SARS-CoV virus. A more recent study by Zhang et al reaffirms the similarities between these two viruses in terms of ACE-2 receptors as portals of transmission.8 The lungs play a key role in viral replication due to their increased surface area and high rate of cellular viral processing. As well as the lungs, ACE2 receptors are found in high quantities on the luminal surface of intestinal epithelial cells, suggesting that this could be a major transmission route for SARS-CoV-2. There are, as yet, insufficient studies to confirm transmission of SARS-CoV-2 faeco-orally according to the WHO,9 but this may well be an intense area of research in the coming months.
Airborne or aerosol transmission and its impediment is rapidly becoming the crux of how dentistry will look ‘post-COVID-19’. Direct droplet spread, short and long distance, is an accepted transmission pathway, but Santarpia et al also highlighted that viral shedding can be detected in normal passive breathing by those who may be asymptomatic or only mildly ill with COVID-19.10 In the dental environment, there is likely to be greater aerosol disturbance within corridors and surgeries as staff move around the building therefore, in effect, carrying it around the building through the air. From this, it can be deduced that breathing, coughing and sneezing are aerosol generating procedures, just of a differing type to that seen with a dental handpiece. Often, these more natural processes are less controlled than the production of a dental aerosol under rubber dam isolation, with the potential to be a more dominant vector for SARS-CoV-2 transmission. To date there have been no confirmed cases of COVID-19 related to the generation of dental aerosols.
Additional risk mitigation measures and PPE are going to dominate social media, dental literature and clinical practice for the foreseeable future. It is beyond the scope of this article to detail these, however, NHS England will release what they view as an appropriate SOP in due course.11 Looking abroad may provide some insight as to how best to implement various aspects of enhanced cross-infection protocols, and what can be expected over here in the UK.
Patient pre-visit triage is seen as a key component of many SOPs, as this allows for appropriate assessment of risk. This is usually carried out over the phone 24 hours in advance, by asking a series of questions to determine current COVID status. Ideally, a patient displaying symptoms of COVID-19 should be encouraged not to attend the practice, and instead advised to self-quarantine. If it is deemed essential that these patients are seen, then this may be on an emergency basis only, possibly at the end of a clinical session. This will help reduce viral shedding in the clinical environment. Another essential component of this stage is to look at ways to appoint specific patients according to relative risk. For instance, if a patient is elderly, or has more complex medical conditions, these patients may be exposed to lower levels of risk by being seen earlier in the day, when the practice is quieter and any aerosols have settled over night.
Certainly, these approaches are being implemented in Australia, China, France, Italy and the provinces of Canada, where patients are being seen face to face. The Republic of Ireland has released its SOP document,12 with telephone pre-screening as key to their SOP.13 In Germany, there are no recommended qualifying questions but more basic questioning to establish if the patient is displaying COVID-19 symptoms in the previous two weeks.
One approach which is gathering traction is the increasing use of ‘teledentistry’. The BDA have produced guidance on appropriate considerations when using these platforms for their members. The Australian Dental Association have an open access document on how to get the best out teledentistry consultations.14 Both resources encourage the appropriate history-taking and onward referral pathways. Helpfully, the ADA have a direct, easy access link to the International Trauma Guide website. The BDA document contains information on patient safety and awareness for the clinician on the potential for these calls to be recorded by the patient.15
Rationale: Assessment of patients upon presentation at the clinical setting is essential to re-confirm the pre-visit screening. This will act as a second level of defence in preventing symptomatic patients from entering the treatment facility and posing a risk to others. As recommended by Peng et al, a key component of this is a temperature check using a contactless thermometer, assessing for temperatures of below 37.3 degrees.3 This will then be followed up by a series of questions determining current health status and risk of contracting/transmitting SARS-CoV-2.
There seems to be some variation seen on how this should be approached, with the Australian Dental Association recommending key questions, but no temperature check. The recommended questions are:
In the Republic of Ireland, a verbal checking for fever or respiratory symptoms is required but a temperature check is not mandatory. In Germany, assessment of risk should be confirmed again verbally but without any specific recommended questioning. Canada considers a temperature of over 38 degrees as an indicative sign of infection.
Attempts are being made by some countries to ascertain patient attitudes to risk as part of the patient evaluation. These are often consent forms and examples of these can be seen in Canada, the USA and also the UK, via an internet search engine enquiry. The layout and questions posed are often variations of a theme, with a signature required to verify absence of COVID-19 symptoms. Although the primary rationale behind these forms may be questionable, they do standardize the pre-evaluation questioning, allow recording and analysis of the results, as well as ensuring that patients do have a basic understanding of any potential elevation in risk.
Rationale: Transmission of infective droplets can occur directly and, as such, maintaining hand hygiene is vital. Faeco-oral transmission is now a suspected transmission route and is becoming a focal point of cross infection control procedures within a hospital setting. The risk of transmission through inadequate hand hygiene is from both the clinician and the patient. It would seem logical to ensure patients have optimum hand hygiene when entering the practice to reduce transmission spread through touching of fomite surfaces. Hand hygiene is therefore key for both the clinician and the patient.
Studies emerging from China, such as Meng et al16 and Peng et al,3 both reinforce the importance of hand hygiene, given that the virus can remain infective upon surfaces for several days. According to Peng et al, the infection control department of the West China Hospital of Stomatology in Sichuan have proposed a ‘two before and three after’ hand-washing protocol.3 Both these studies focus on dentist-patient transmission.
In Australia, the guidance is to ensure that an alcohol-based hand-rub is available to patients in the waiting room, but no specificity on its use. There is guidance on clinician hand hygiene following the WHO hand-washing guidelines.17 The ADA dental portal has access to ‘Cough Etiquette’ posters reinforcing the messages on how to control droplet transmission from a patient perspective.
In Canada, patient hand hygiene is promoted upon patient entry to the facility in both the SOPs of Alberta and Saskatchewan. Newfoundland suggests having hand sanitizer available but no jurisdiction on its use. This can be compared with Ontario, for instance, where hand hygiene is insisted upon when the patient enters the practice with 70–90% alcohol-based hand-rub.
The Republic of Ireland guidance recommends practices promote hand hygiene and cough etiquette, advising hand-washing upon entry to the practice for all people, as well as glove disposal (if they are wearing gloves). In France, the protocol is again to provide hand gel for patients in reception, as well as posters to reinforce techniques for clinicians.
Rationale: According to Peng et al, the main role of PPE is to act as a barrier to droplet and contact transmission, both direct and indirectly.3 As SOPs from around the world are developed and published, it seems that there are some variables noted on how barrier methods are applied.
Starting at the epicentre of the pandemic, China were early adopters of PPE staging, dependent upon risk.3,16 Triaging staff, such as receptionists, wore masks, disposable cap and work clothes. For staff working on patients not displaying signs of COVID-19, N95 masks, gloves, gowns, caps, shoe covers and face shields were worn. For patients displaying signs of COVID-19, these usual precautions plus full body protective clothing was adopted.
In Australia, PPE is worn in accordance with risk status of the dental patient. Low risk clinical and epidemiological risk patients are treated using standard PPE. Higher risk patients are treated using FFP2 masks and gowns. In France, there is a recommendation that non-clinical staff wear masks and visors (only if a splatter screen not present). Protective glasses or face shields are recommended, as well as FFP2 masks (but only during AGPs), as are surgical gowns. The Republic of Ireland has suggested that standard precautions plus goggles or a visor is satisfactory for AGPs on asymptomatic patients. The additional use of gowns and respirator masks, if patients are displaying COVID-19 positive signs, is recommended. Head covering and shoe covers have not been recommended.
Rationale: The rationale for additional in-surgery protocols is simply to further reduce droplet and contact transmission of SARS-CoV-2.
Looking again at the Peng and Meng studies emanating from China,3,16 pre-procedural mouthrinses with 1% Hydrogen Peroxide or 0.2% Povidone are recommended. Peng et al suggest rubber dam is effective at removing 70% of airborne particles within the operative field and should be used alongside high volume suction and a four-handed dentistry technique.3
The Australian Dental Association support the use of pre-operative mouthwash, as well as rubber dam, where possible. The Canadian provinces also support these measures. The Republic of Ireland, however, found the evidence for mouthwashes is insufficient to support their use. In France, mouthwash is recommended – again Hydrogen Peroxide or Povidone Iodine alongside rubber dam usage, however, this guidance stipulates rinsing the isolated field with Sodium Hypochlorite first.18
In terms of handpiece use, France has recommended speed increasing handpiece usage, whilst Spain has recommended restorations only that do not require a high speed, especially during initial re-opening phase. The Cochrane (CoDER) document should be consulted for a more detailed overview of how many countries are managing AGPs and handpiece usage.1 Again, the variance is substantial.
This document is far from exhaustive, and it would require a vast quantity of work to compare every detail of each individual standard operating procedure (SOPs). However, what hopefully has been demonstrated is the wide variance in approaches taken internationally. The same five themes form the backbone of patient management throughout any of the SOPs considered. Thorough consideration and application of these five themes will hopefully minimize patient risk.
It seems clear that there is no real consensus on how best to categorize or profile risk. In some instances, risk is solely based upon the patients presenting symptoms, for example in France, if the patient is asymptomatic, then both urgent and non-urgent treatment can be carried out. Other countries have adopted SOPs which also risk profile the procedure. This is where most variance is seen. The Republic of Ireland states that, if community transmission is low, then there is insufficient evidence to restrict AGP use. Sweden and Germany have adopted similar standpoints. Other countries, such as Canada, quantify risk in terms of procedure and risk of aerosol transmission.
The most difficult element of comparison, of course, has been the wide variety of clinical approaches taken and looking for comparisons. This can be very difficult as, in countries such as Canada, the guidance changes between provinces, meaning that, within one country, there may be several different SOPs. It is important, however, not to overlook the fact that there is a sound evidence base to support the fact that transmission of SARS viruses can be prevented in controlled environments. Then there are, of course, some excellent studies which support the use of barrier mechanisms that the many dentists around the world would consider standard. Seto et al studied transmission of SARS within a hospital setting and found that, when all four of the following; surgical (or N95) masks, gowns, gloves and hand-washing, were used, then these staff members did not contract SARS-CoV-1.19 These precautions would provide adequate protection in non-aerosol generating conditions. The authors concluded that prevention of droplet and contact spread was key to preventing transmission of this virus.
One dentally relevant difference between SARS-CoV-1 and SARS-CoV-2 is that the main viral shedding period for SARS-CoV-1 is when the patient is displaying signs of febrile illness. SARS-CoV-2 patients show significant viral shedding whilst asymptomatic. Young et al and Cheng et al demonstrated that hand hygiene and mask wearing by patients, alongside N95 mask, hand hygiene, gowns, gloves, goggles and face shield, was adequate to prevent transmission of SARS-CoV-2 during AGPs.20,21
The requirement for sufficient evidence base is now at the forefront of our professional minds. Once again we are turning our heads to the science and find that it is lacking in quantity and/or quality to substantiate significant clinical changes. It must not be forgotten that the end users of these decisions are dentists, their staff, and their patients. Time will tell what the upsurge in demand will have on supply chains and pricing. One doesn't have to search too hard on social media forums to see how inflated costs of PPE are concerning for practice owners. Moreover, the reported practical difficulties of respirator mask usage may see compliance issues developing in the future.
Financially, the cost of the additional PPE will need to be covered from either the top or middle of the balance sheet, and different practices will have varying approaches to this. Coupled with reduced patient flow through, possible economic recession and air settling periods, dental practices may find the coming months or years financially challenging.
SARS-CoV-2 has identical routes of transmission, irrespective of geographical location. The variance seen internationally in preventing transmission of this virus reflects both the paucity of scientific evidence, but also the multifactorial nature of spread and susceptibility. What is most important, is that those working within the dental profession recognize the key transmission routes of the SARS-CoV-2 virus, and the most effective ways to impede this. It must not be overlooked that modern clinical dentistry has cross infection at its core. There is substantial evidence to suggest that these measures alone are sufficient to prevent excessive transmission of SARS viruses through droplet or contact spread.
