Entering Phase 3 of the Ontario Government’s economic reopening plan means creating a work environment that follows CDC (Centers for Disease Control and Infection) recommendations.  Within this document contains specific infection control strategies that when used together, decrease the likelihood that COVID-19 and other pathogens be transmitted from patient-to-staff and vice versa.  The biggest concern for business owners, regardless of business type, is how to incorporate these safety measures while still being conscious about cost.  Although we are still learning more about COVID-19, what WE do know is that it is an RNA-Virus transmitted via droplet secretions.  However, transmission is not limited to droplet but can also be contact and air-borne when aerosolized.  The dental office is a unique setting for managing infection control since so many procedures create splatter and aerosols.  Below is a list of common dental procedures and their likelihood for generating medical aerosols (Ferrazzanno, Ingenito, 2020).

Harrel and Mollinari recommend 3 levels of defense in the reduction of aerosols:

1. Personal Protective Barriers

2. Routine Pre-procedural Rinse

3. Use of High Volume Evacuators

Personal Protective barriers, like n95 masks in combination with face shields, are considered the gold standard for protecting staff directly involved in AGMPs.  Unfortunately, the COVID-19 pandemic has highlighted insufficiencies that we have regarding the supply of these protective devices.  The high demand for n95 masks and face shields has led to ridiculously unreasonable price gouging, forcing organizations to implement strategies for conserving such barriers and minimizing expenses.  The CDC has published recommendations for extended use and limited reuse of n95 masks in the health care setting.  

• Extended use is favoured over re-use because it is expected to involve less touching of the respirator and therefore less risk of contact transmission (CDC, 2020)  

Experience in settings that follow extended use demonstrate that respirators can function within their designed specifications for 8HRS of continuous or intermittent use (CDC, 2020). 

Although wearing an n95 mask for extended periods is uncomfortable for staff involved with patient care, it can be an effective strategy reducing costs and preserving inventory for those dental cases that are emergent and necessary.   

The oral environment, with its combination of elevated moisture and warmer temperature, makes for a suitable medium for bacterial growth (Checci et al., 1991).  Microorganisms can leave this environment and become aerosolized during routine dental procedures such as scaling,  cross-contaminating the dental operatory and risking the safety of staff and patients.

Pre-procedural rinses in adults using .12% Chlorhexidine have demonstrated a decrease in the number of colony-forming units in both aerobic and anaerobic bacterial counts (Vessler et al., 1991).  The SAME holds true for children. Thomas(2011) demonstrated a reduction in aerobic and anaerobic bacterial counts in children between 10-15yrs of age when using a preprocedural rinse of either .12% Chlohexidine (Periogard), .05% Cetylpyridnium (Reach), or normal saline (Thomas, 2011).  The greatest reduction in bacterial colony forming units was when Periogard was used (Thomas, 2011).  

• Periogard is a preprocedural rinse that can be purchased over the counter with a prescription for 14.00CAD/473ml’s.  A relatively inexpensive option for killing oral microorganisms and preventing them from being aerosolized into the dental environment.  

Figure 2: Periogard preprocedural rinse

Removing infectious aerosols from the dental field BEFORE they can enter the external environment is a successful and cost effective approach for protecting dental staff and patients from COVID-19 and other organisms.  The alternatives are negative pressure rooms and HEPA-filter systems which require higher costs and in some cases, complete restructuring of the dental practice.  

A High Volume Evacuator (HVE), with or without preprocedural rinse, has been shown to reduce the number of colony forming units during in-vivo dental procedures defined as aerosol-generating.  Narayana (2016) showed a decrease in colony forming units when either an HVE or preprocedural rinse was used versus no therapy in adults undergoing ultrasonic scaling (Narayana, 2016).  The reduction was even more pronounced when these two techniques were used in combination (Narayana, 2016)

• HVEs have shown to reduce infectious contamination from the operative site by more than 90%   

HVEs are easy to use and cost effective.  Below is an example of an HVE system on the market and an associated adjunct:

Figure 3: ADU 22 Dental Cart System 

Cost: 2598 CAD+tax

Figure 4: Covidian Evacuator tips

Cost: 100/pkg 100 CAD+tax  

The most interesting CDC recommendation, and restated by Ferrazzano (2020) is that:

• Dentists should avoid AGMPs whenever possible.  This means avoiding the use of dental hand-pieces and the air/water syringe.  Use of electronic scalers is not recommended.  Prioritize minimally invasive/atraumatic restorative techniques.

The accuracy of this statement is hard to challenge however, certain professions can not take place without the use of AGMPs and rely on infection control strategies similar to those listed in this article for protecting the health of medical professionals and patients.  Respiratory therapists perform AGMPs like intubation and suctioning on a daily basis.  These procedures are considered essential for treating respiratory distress and failure.  During the COVID-19 pandemic, these procedures could only be performed in patients that:

1.  screened negative for COVID-19 and with the appropriate personal protective equipment (PPE) or 

2. in patients that screened positive for COVID-19 in negative pressure rooms with the appropriate PPE or

3. in patients that screened positive for COVID-19 in a single patient room with the door closed and the room has to be allowed to settle for a period of up to 45 minutes or

4.  in patients that were considered persons under investigation (PUI)/unknown COVID status a single patient room with the door closed and the room has to be allowed to settle for a period of up to 45 minutes

The appropriate PPE was essential and we used techniques such as paralyzing patients prior to intubation, which totally eliminated the cough reflex and the possibility for aerosolized microorganisms, to protect staff and patients.  Tertiary and peripheral hospitals in Ontario were able to fight COVID-19 by altering the ways they delivered medical treatment.  Oral health is a critical component of human physiological well-being and sustained via dentistry.  Recommendations that allow for dentistry to be practiced safely can be carried out cost-effectively.  There is a lot of research in AGMPs and COVID-19.  By using this research, health care professionals operating dental clinics can continue to safely maintain the oral health of their patients while at the same time, working within an operating budget.  

References:

1. Interim infection prevention and control recommendations for healthcare personnel during the Corona Virus Disease 2019 Pandemic https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html

2. Checchi, L., Matarasso, S., Pirro, P., D’Chille, C. (1991). Topographical Analysis of the facial areas most most susceptible to infection with transmissible diseases in dentists. International Journal of Periodontics Restorative Dentistry, 11:165-172

3. Harrel, S.K., Molinari, J. (2004). Aerosols and splatter in dentistry. Journal of American Dental Association, 135(4): 429-437.

4. Ferrazzanno, G., Ingenito, A., Cantile, T. (2020) COVID 19 Disease in chi9ldren: what dentists should know and do to prevent viral spread.  The italian point of view.  International Journal of Environmental research and public health, 17(101):3642.

5. Narayana, T.V., Leeky, M., Sreenath, G., Vidhyadhri, P. (2016). Role of Preprocedural rinse and HVE in reducing bacterial contamination in bioaerosols study. Journal of oral and Maxillofacial pathology, 20(1): 59-65.

6. Thomas, E. (2011). Efficacy of two commonly available mouth rinses used as preprocedural mouth rinses in children. Journal of Indian Society of Pedodontics and Preventive Dentistry, (29)2:113-116. 

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