Fallow time rationale and reducing it with risk assessments

(1153 words)

As you are all aware, Public Health England (PHE) have cascaded down to NHS practice via the office of the Chief Dental Officer (OCDO) that fallow time is one hour.  Fallow time begins when the aerosol generating procedure (AGP) has finished, not when the patient leaves.  OCDO also says to use chlorine bleach to wipe down after AGP. For Scotland, the CDO has just announced (14/10) that normal dentistry can resume on the 1st November.

Where did this one hour come from? 

It originates from data from a hospital environment and nothing to do with dentistry or the aerosols we produce. There are also no dental representatives on the government’s SAGE committee or NERVTAG. 

As you are aware, private practices, not being NHS, are not under the auspices of PHE or the OCDO, thus, we can use science and evidence to mitigate or bring down the time of fallow, whereas our NHS counterparts cannot.  

I will show here and share with you the science and evidence behind how we, at Dental Studio, are reducing the fallow time to a minimum of 20 minutes if ALL mitigations are followed.  You need to bear in mind that the evidence evolves continually. 

Page 37 of the FGDP guidance (1st June 2020) states: (https://www.fgdp.org.uk/sites/fgdp.org.uk/files/editors/Implications%20of%20COVID-19%20for%20the%20safe%20management%20of%20general%20dental%20practice%C2%A0-%20a%20practical%20guide.pdf)

Examples of justifiable mitigation would be: 

  • Type of procedure carried out – whether a high or low risk AGE
  • Use of rubber dam
  • Use of HVA
  • Duration of the aerosol generation
  • Dimensions of the room
  • Methods of ventilation

So why have a minimum time of 20 minutes?

The answer now lies in science.  The size of the virus is stated to be around 0.3 to 0.5 microns in diameter.  According to the Centre for Disease Control (CDC) in the USA the diameter size of an aerosol will determine how long it takes to settle.  The virus can many hours to settle if it alone but we know it is attached to the water from air rota or cavitron and so this takes up to 8 minutes to settle.  95% of aerosol is aspirated using an 8mm bore aspirator and of the 5% that is not, over 90% lands on the patient upper chest, on the bib. As you can see, just from those figures alone it leaves just a few % that will escape.

So, for that few % that has escaped, we now have to consider other factors:

  1. We screen patients and possibly take their temperature, so now, at worst, they are asymptomatic or pre-symptomatic carriers. The viral load in a pre-symptomatic carrier are reported to be low. So, we ask patients to wear face coverings and we in turn also wear our masks or visors when working and with our colleagues.
  2. We use rubber dam where possible, the aerosol is now not mixed with any saliva and the patient cannot emit secretions
  3. We use high volume suction
  4. We have ventilation that allows air changes in the room
  5. Have a look at the table on page 3 to see what our global counterparts are doing, which has done nothing to the infection rate as seen in the UK via test and trace.

To follow is a possible risk assessment for fallow time:

Fallow Time Risk Assessment

As a business, we need to be viable but be viable safely and for all concerned.  Otherwise, there will be no business.  The OCDO has allowed NHS practices to do 20% of their UDA contract, yet still, be paid the full amount of their contract value.  What help is there for private practices?  None, so we have to think for ourselves and use the science and evidence to facilitate treatments and consider the safe delivery for our staff, patients and our business – in that order.

At the time of writing this, there have been no dental transmissions of COVID that have been found by test and trace.  Our infection control measures in dentistry have always been the highest, quite frankly I would be more concerned with the other microorganisms we face over COVID. As I write this, according to worldometers.info in the UK there are 77 people in a serious condition and a reported 0.068% of the UK population have died, reportedly of covid. However, we know that this figure is likely to be far less than this due to an over-reporting of covid by doctors on death certificates; it is now likely to be around 29,000 deaths instead of 46,000.

In the middle of June, the UK reported the lowest number of daily deaths in the past 5 years. 

We are currently awaiting Scottish Dental Clinical Effectiveness Programme (SDCEP) to publish new guidance that will officially reduce the fallow to 30 minutes – this is due out any time now.  If this changes our RA significantly then we will review it.

About the Author:

Jo Russell, Oracle’s Managing Consultant, has over 30 years experience in the dental profession. Having successfully performed a number of roles within the practice, she has acquired a large amount of expertise in the dental field. She has a proven track record in Practice and Area Management, overseeing a large group of practices in London and the South. As a result of her experience, Jo saw the need for assisting clinicians in giving their businesses a fresh perspective on Practice Management, Compliance and Procedures.

She has a great deal of experience in teaching and training, having been involved for over 25 years in developing the dental team and writing various articles for several national Dental Magazines.

Jo has an ongoing commitment to dentistry with her experience as a CQC bank inspector and currently an expert witness for the GDC at Fitness to Practice cases, she has also gained further knowledge in:

  • Care Quality Commission compliance
  • Practice Management and Dental Practice Management
  • BTEC and ILM Professional Diploma in Dental Practice Management
  • Health and Safety at Work
  • Radiation Protection Supervisor
  • Clinical Governance
  • Practice Finance
  • Human Resources
  • Contracts
  • Marketing and Advertising
  • Reflective Practice
  • Customer Service
  • Certificate in Education
  • City and Guilds NVQ Assessor and Internal Verifier

Providing ILM Diploma in Dental Practice Management, Continuing Professional Development and teaching keeps Jo in touch with day to day, high-quality contemporary practice.


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