National Elf Service

No bias. No misinformation. No spin. Just what you need!
The Dental Elf

Face masks: Extended use and re-use

Derek Richards

Dentists have been using face masks as part of their routine personal protective equipment (PPE) for many years. However, their close proximity to patients during treatment and the potential for the production of aerosols during dental treatment has focused much attention on the face mask and other items of PPE.  During the Covid-19 pandemic global shortages of PPE have forced consideration of protective equipment sharing measures such as extended use, re-use or reprocessing of single-use masks and respirators.

The aim of this rapid review was to summarise the guidance and systematic review evidence on extended use, re-use or reprocessing of any type of surgical mask or filtering facemask respirators

Methods

The Medline, Pubmed, Epistemonikos, Cochrane Database of Systematic Reviews and three preprint repositories (Litcovid, MedRxiv and Open Science Framework) were searched for systematic reviews exploring the extended use, re-use or reprocessing of any type of surgical mask or filtering facemask respirators (FFPR). The World Health Organization, European Centre for Disease Prevention and Control, the US Centers for Disease Control and Prevention, and Public Health England websites were searched for guidance documents.  Two reviewers searched for guidance documents which were screened for inclusions systematic review were also double screened for inclusion. Data extraction was carried out by two reviewers with the quality of the systematic reviews being assessed using the AMSTAR-2 checklist. The findings were integrated and narratively synthesised.

Results

Guidance documents

  •  6 documents were identified, 3 from the US Centers for Disease Control and Prevention, and one each from the European Centre for Disease Prevention and Control, Public Health England and the World Health Organisation.
  • The guidance documents were published or updated between March 17th 2020 and May 21st 2020 and written for the COVID-19 pandemic.
  • None of the guidance documents included a systematic review of the literature.
  • All the guidance documents depicted extended use, re-use or reprocessing as extraordinary, last resort measures favouring extended use over re-use because of reduced risk of contact transmission.

Systematic reviews

  • 4 relevant systematic reviews (3 from the same team) were included.
  • The reviews were considered to be predominantly of high-quality.
  • 3 were on different interventions for reprocessing of FFPR.
  • 1 related to surgical mask.
  • No reviews in our sample examined the impact of extended use or re-use of filtering facepiece respirators or surgical masks on the ability to meet technical standards or on healthcare worker acceptability outcomes such as comfort.

Main findings

  1. While extended use or re-use of single-use surgical masks or respirators (with or without reprocessing) is generally not recommended, guidance from various organisations supports such measures (preferably extended use rather than re-use) as a last-resort measure during critical shortage.
  2. Comparisons across guidance documents and systematic reviews highlight limited evidence, varying levels of detail, and areas of inconsistency, especially in relation to re-use of respirators (with or without reprocessing) during and after aerosol generating procedures.
  3. The reprocessing of surgical masks is not recommended.
  4. Reprocessing of respirators under controlled and standardised conditions is recommended, but there is inconsistency regarding how or when this should take place and further research is needed in this area.
  5. Where extended use or re-use is being practised, healthcare facilities and institutions should ensure that policies and systems are in place to enable these practices to be carried out in the safest way possible in line with available guidance.

Conclusions

The authors concluded: –

Extended use and re-use of single-use surgical masks and respirators (with or without reprocessing) should only be considered in situations of critical shortage. Where extended use or re-use is being practiced, healthcare organisations should ensure that policies and systems are in place to ensure these practices are carried out as safely as possible and in line with available guidance. Areas of guidance lacking clarity and consistency warrant further attention and investigation.

Comments

This rapid evidence review was conducted in line with Cochrane interim guidance for rapid reviews and a summary was published as part of the Oxford Covid-19 Evidence Review Service on the 5th June.  The reviewers examined six guidance documents none of which included systematic reviews of the evidence.  The reviewers search for reviews identified 4 relevant systematic review all of which are new having been conducted between March and April 2020. These reviews are all from Canada with 3 being from the same team, and all were either in peer review or pre-prints. There are considered to be mainly of high quality although only 2 studies in one of the included reviews looked at the effect of reprocessing on SARS-CoV-2.

Prior to the Covid-19 pandemic dental teams were used to changing masks after each patient. Guidance from a number of sources (C0DER Working Group 2020) has suggested longer periods of use up to 4 hours or on a sessional basis where there is no visual damage or obvious soiling. UK guidance documents suggests the risk assessment of sessional use while a small number of other international guidance documents have advised of the possible re-use of FFPR masks following re-processing.  This review would suggest that extended use or re-use should be a last resort measure.

Links

Primary Paper

Extended use or re-use of single-use surgical masks and filtering facepiece respirators: A rapid evidence review.  Elaine Toomey, Yvonne Conway, Christopher Burton, Simon Smith, Michael Smalle, Xin-Hui Chan, Anil Adisesh, Sarah Tanveer, Lawrence Ross, Iain Thomson, Declan Devane, Trish Greenhalgh.

Oxford CEMB- Covid -19 Evidence Blog

Review protocol and associated materials

Other references

Recommendations for the re-opening of dental services: a rapid review of international sources, Version 1.3 16th May. The (CoDER) Working Group. (accessed 11th June 2020)

 Dental Elf – 30th  Apr 2020

How much extra protection does an FFP3 mask offer in the dental surgery?

 Dental Elf – 25th  Mar 2020

Surgical masks versus N95 respirators

 

Photo Credits

Photo by Mika Baumeister on Unsplash

 

Tools for measuring oral health and orofacial pain in dependent adults
Refugee dental care – factors associated with access
Pre-treatment mouthwash to reduce patient to dentist infections
Written by

Derek Richards is a specialist in dental public health, Director of the Centre for Evidence-Based Dentistry and Specialist Advisor to the Scottish Dental Clinical Effectiveness Programme (SDCEP) Development Team. A former editor of the Evidence-Based Dentistry Journal and chief blogger for the Dental Elf website until December 2023. Derek has been involved with a wide range of evidence-based initiatives both nationally and internationally since 1994. Derek retired from the NHS in 2019 remaining as a part-time senior lecturer at Dundee Dental School until the end of 2023.

Add a comment
  • COVID-19 Dental Elf Blogs -3 - National Elf Service

    COVID-19 Dental Elf Blogs -3 - National Elf Service

    6 years ago
    […] Face masks: Extended use and re-use […]
  • Michael Logies

    Michael Logies

    6 years ago
    PS: Streaming steam at 100 °C (for 5 minutes) is a method missing in the review which would be cheap and suitable for disinfecting FFP2-masks, but they would have to dry afterwards outside the cheapest device with this method, a baby bottle steam sterilizer. The method was invented by Robert Koch himself (https://en.wikipedia.org/wiki/Robert_Koch) for his microbio lab, because autoclaves exploded too often in his time. I did a german presentation on it (http://www.logies.de/dampftopf.zip), because I disinfect my dental handpieces this way for about 15 years now (now after putting them through a Assistina 3*3 for validated internal cleaning). Some literature: Towle D, Callan DA, Lamprea C, Murray TS. Baby bottle steam sterilizers for disinfecting home nebulizers inoculated with non-tuberculous mycobacteria. J. Hosp. Infect. 2016;92(3):222–5. Towle D, Callan DA, Farrel PA, Egan ME, Murray TS. Baby bottle steam sterilizers disinfect home nebulizers inoculated with bacterial respiratory pathogens. J. Cyst. Fibros. 2013;12(5):512–6. Gräf W, Kunz B, Loisl B. Zur hygienischen Aufbereitung dentaler Übertragungsinstrumente (Hand- und Winkelstücke, Turbinen) in der zahnärztlichen Praxis. Zentralbl Hyg Umweltmed 1995;198(1):72–83. Available at: http://www.ncbi.nlm.nih.gov/pubmed/9409896. Accessed September 10, 2010. (This german publication started this topic for me.)
  • Michael Logies

    Michael Logies

    6 years ago
    Recently a german, technical university tested autoclaving FFP2-masks. They tested 10 times autoclaving them (121 °C, 20 min), and no relevant changes could be measured for filtration, particle sizes or on inspection with electron microscopy. Deepl.com should translate: https://www.tu-darmstadt.de/universitaet/aktuelles_meldungen/einzelansicht_259072.de.jsp That`s why I autoclave FFP2 and chirurgical masks in my dental office.
    • 1 reply
    • Derek Richards
      Derek Richards 6 years ago
      Hi Thank you for your comment. The example you higlight is a single small study while the review included infromation from 4 systematic reviews. Overall though the reviews authors do note that:- 'Reprocessing of respirators under controlled and standardised conditions is recommended, but there is inconsistency regarding how or when this should take place and further research is needed in this area. Where extended use or re-use is being practised, healthcare facilities and institutions should ensure that policies and systems are in place to enable these practices to be carried out in the safest way possible in line with available guidance.'
      • Michael Logies
        Michael Logies 6 years ago
        Derek, you wrote: "No reviews in our sample examined the impact of extended use or re-use of filtering facepiece respirators or surgical masks on the ability to meet technical standards or on healthcare worker acceptability outcomes such as comfort." The "Technische Universität Darmstadt" did these technical tests. That`s why their study is more relevant for me than the four reviews. ("Comfort" I can evaluate myself, I don`t need a study/review for that). It`s simply the best available evidence, IMHO. I would like to look into the primary studies of the 4 reviews, though.