We have had hundreds of people from the dental profession enquire about our air purifier product with respect to the current situation around COVID-19.

Colleagues are confused about what to do and how to formulate their response in being able to open safely such that they can treat patients and reduce the risk of spreading COVID-19. This risk is higher to the dental team than it is to the patient when treatment is being undertaken partly due to the close proximity of team members and the inherent absence of the possibility of social distancing.

Many enquirers have asked about the evidence regarding this technology and several have been confused and/or misled by posts on social media.

We hope that the information below will make your decision easier.

AIR POLUTION IN DENTISTRY

All indoor environments can contain toxic chemicals, be it from furniture, flooring, cabinetry, or cleaning.

Dental clinics present a greater risk because of the materials used and the methods of treatment. Observers liken this bioburden to a (sometimes invisible) toxic cloud.

THE TOXIC DENTAL CLOUD

The toxic dental cloud spans from the floor to a height of six feet[1].

According to a Dutch meta-analysis[2] this cloud includes the following pathogens:

  • Staphylococcus aureus, Acinetobacter wolffii, Legionella,
  • Aspergillus, Mycobacterium tuberculosis, Streptococcus,
  • and Varicella-zoster virus,

A REAL RISK TO HEALTH

US analysts measured how your job impacts on health. They rated ‘jobs’ by using O*NET measures of exposure to contaminants, disease, infection, hazardous conditions, radiation and minor burns, cuts, bites, and stings.

Dental Professionals occupied 6 out of 7 of the most damaging jobs to health with Dentists, Hygienists and Dental Assistants in the top 4 most hazardous professions[3].

FROM WHERE?

  1. Materials

Exposure to Total Volatile Organic Compounds (TVOC) because of frequent routine dental cleaning and preparation of monomer rich chemicals were found to be contributors to a higher than normal biohazard.  The highest contributor to this is the routinely used MMA (methyl methacrylate), which ‘exceeds acceptable exposure levels’ ‘by a factor of 20’, ‘exacerbated by a lack of ventilation’.

Casting, grinding, and polishing acrylics, removing amalgam, creating crowns and perio disinfectants all releases toxins. Monomers such as methyl methacrylate used in dentures and cement are notorious for their acrid smell and volatile character.

Indeed, the Volatile Organic Compounds (VOC) in the dental office are reported to ‘far exceed ‘ recommended limits for indoor environments.

  1. Methods

Dentistry produces microscopic droplets that hover in the air for up to 6 hours over a substantial range.  Bacterial colony-forming units (CFUs) were found to increase at distances beyond five feet, from the site of the procedure more than three hours after procedures.

  1. Exposure to Infection.

Infectious airborne pathogens such as bacteria and viruses at the nano scale (<5 μm) can remain suspended and viable for long periods.

The pathogens present as biofilms in dental unit water lines (DUWL) are aerosolized during procedures.[4]

MRSA-positive surfaces were detected at 4 of the 7 clinics tested with 21% of Dental students carrying MRSA 10 times higher than that found in the general public.   Of 140 consecutive patients who were MRSA free, 8 became colonised or infected due to exposure from air-water syringes and reclining chairs.  The combined risk of volatile materials and airborne infections have been identified ‘over 1.5m from the patient’ is a risk ‘significantly underestimated by practitioners’[5]

PREVENTIVE OPTIONS

Preventive measures exist that minimize the risk of contamination. Few address the source of the risk, which is related to the materials used and the aerosolized viral and bacterial particles. Face masks do not work and even with stringent disinfection, “results clearly suggested that patients and dental staff remain exposed to infectious risk.” [6]

Options to prevent or reduce this risk include:

  • Reduced reliance on monomers and volatile toxic compounds or localise their preparation in quarantine areas.

Less well-known manufacturers provide composites and resins that retain the desired physical and esthetical performance without TEGDMA, Bis GMA and HEMA.[7]

  • Increase Ventilation

The risk of aerosol exposure applies to all people in the room.  Increased ventilation helps to disperse aerosols and can be achieved naturally (opening a window) or by mechanical means.

  • Increase time between patients.

If an AGP is performed on a patient with known or suspected COVID-19 in a room that is not mechanically ventilated the room should be vacated for 1 hour after completion of treatment before cleaning commences.[8]

  • Incorporate measure to purify the air

Removing the disease transmission is governed by two factors-: aerosol transport and aerosol infectivity.   Air Purification units can quickly improve Dental Air Quality through reducing odour, particulates, microorganisms, and dangerous substances.

AIR PURIFICATION TECHNOLOGY

The technology employed must process the air efficiently and remove the particulate challenge.

Various technologies are proposed that include:

  1. High Efficiency Filtration (HEPA)
  2. UVC Light
  3. TPA Bipolar Technology (Plasma)

High Efficiency Particulate Air Filtration (HEPA)

HEPA filters trap air contaminants in a web of fibres using either inertial Impaction, diffusion, interception, or sieving.  Capacity of HEPA filters decreases over time as the filter becomes saturated[9].  Warmer ambient temperature and humid environments encourage mould and bacteria to grow on the HEPA filter causing unpleasant odour and potentially hazardous waste.[10]  HEPA filtration require a maintenance program to ensure filters are changed regularly with time and cost burden.

Conventional filtration presents several drawbacks, including the low fluid permeability needed for high particle collection efficiency, which inherently increases the differential pressure across the filter and promotes infiltration of untreated air into indoor spaces at partial vacuum.[11]

Ultraviolet Light (UVC)

Disinfection occurs when a wavelength of 200 nm to 280 nm is delivered at sufficiently high dosage.  The UVC exposure damages nucleic acid preventing cell replication. UVC dosing is the amount of UV radiation a microbe is exposed to and depends on the intensity of UV radiation and exposure time.

For UVC to be effective a sufficient dosage exposure must be maintained.[12]  The exposure is dependent on intensity of the light and air flow.   As air flow increases achieving a satisfactory exposure reduces.  Lower air flow requires increases in UVC intensity with a corresponding risk to human health.   Achieving a 3-log reduction (99.9 percent) of B. Subtillus (ATCC 6633) requires a 60 mJ/cm2 dose.[13]   UVC provides limited additional protection over the use of conventional HEPA filtration and as such is often combined to address particle filtration and infectivity.

UV lamps require checking with a meter to ensure the appropriate intensity is emitted as the amount of germicidal wavelength emitted reduces with age as does increased humidity and temperature.

High Energy Electron Discharge or Plasma

A new technology has emerged which employs low energy plasma discharge whereby air is drawn over an electron field destroying toxins.  Ultra-low energy plasma technology addresses both transport and infectivity of toxins and is shown to generate greater than 2.3 log reduction of infective virus loads with exponentially increasing inactivation of aerosolized MS2 phage’.

Units like the Woodpecker Q7 draw air across a high-voltage electrostatic discharge unit. The negative ions produced across this field contain an extra electron while the positive ions are missing an electron resulting in an unstable condition. To re-stabilise, the bipolar ions seek out atoms and molecules to trade electrons, effectively destroying particulate matter including bacteria and virus, odorous gases, aerosols, and VOCs.

Independent laboratory studies report Kill rate within 1 hour of 99.97% for H3N2 influenza virus and 99.99% for Staph Albicans.

The Ames Research Centre, (part of NASA) confirmed that plasma field technology destroys DNA within milliseconds.  Tests against MS2 Bacteriophage, a surrogate for SARS-CoV-2, the virus causing COVID-19 have recently been completed by an independent laboratory[14].

KEY MEASURES FOR AIR TECHNOLOGY PERFORMANCE

The UK Centre for Disease Control and Prevention (CDC) issued recommendations for hospital rooms occupied by persons under investigation.  In addition to Standard precautions the CDC recommends Airborne Precautions to include Isolation Rooms at negative pressure relative to surrounding areas with a minimum of 6 air changes per hour.  The CDC recommends removal of particles 0.3 micron in diameter with a minimum efficiency of 99.97%. [15]

UK CDC Air Quality Standards suggest the following standards:

  • Six Air changes per hour or more (See ACH)
    • ACH is Air Changes per Hour and indicates how many times per hour an air purifier device can exchange the air within a room.
  • Particles at 0.3 micron or smaller (See PM2.5 International Reference)
    • 5. is an internationally recognised measure of ultra-fine particulate matter (PM) with diameters of 2.5μm or less (PM2.5). Exposure to PM2.5 particulates contributed to 4.1 million deaths in 2016.
    • Exposure to air pollution and its disease burden. Health Effects Institute. 2018]
    • The World Air Quality Index reports PM2.5 air quality from in excess of 10,000 stations around the world.[16]
    • Woodpecker Q7 destroys particulates at the 14.6 nanometre scale – smaller than the smallest virus.
  • Minimum efficiency of 99.97% (CADR)
    • CADR (Clean Air Delivery Rate) is a numerical value describing the number of particulates a device will remove. CADR of 300 cfm will clean air faster than one rated 200.
    • Woodpecker Q7’s has one of the biggest CADR in the industry at 1000 cubic meters per hour

REDUCING THE FOG OF CONFUSION

We received hundreds of enquiries from the dental profession about air purification and current situation around COVID-19. Most expressed confusion about how to compare technologies, not helped by misleading posts on social media.

We focused on plasma technology because as a supplier, we did our due diligence and found, (despite its relative newness) that it offered the best match for UK Dental Practice.

The Woodpecker Q7 works quickly and efficiently with virtually no maintenance and is available at the lower end of the price range compared to established HEPA & UVC options.

 

[1] Dental Economics. 2017. Protecting Dental Staff from The Most Hazardous Job in America.

[2] Zemouri, C., de Soet, H., Crielaard, W. and Laheij, A., 2017. A scoping review on bio-aerosols in healthcare and the dental environment. PLOS ONE, 12(5), p.e0178007

[3] https://www.businessinsider.com/most-unhealthy-jobs-in-america-2017-4?r=US&IR=T

[4] Journal of Hospital Infection, 64(1):76-81.)

[5] Aerosols in dental practice – a potential hospital infection problem? Journal of Hospital Infection, [online] 64(1), pp.76-81}

[6] Aerosols in dental practice – a potential hospital infection problem? Journal of Hospital Infection, [online] 64(1), pp.76-81}

[7] http://www.elsodent.com/en/the-bio-plus-range/

[8] COVID-19: infection prevention and control guidance. Public Health England. Version 3. 19 May 2020

[9] https://monmouthscientific.co.uk/a-guide-to-clean-air-filters/

[10] https://www.intechopen.com/online-first/impact-of-air-conditioning-filters-on-microbial-growth-and-indoor-air-pollution

[11] J. Phys. D: Appl. Phys. 52 (2019) 25520.

[12] https://www.sciencedirect.com/science/article/pii/S0305417919300920

[13] UV Dose Required to Achieve Incremental Log Inactivation of Bacteria, Protozoa and Viruses. IUVA News / Vol. 8 No. 1

[14] https://www.implantsolutionsdirect.com/solutions/air-purification/

[15] https://www.cdc.gov/coronavirus/2019-nCoV/hcp/infection-control.html

[16] https://waqi.info/

0