Because the equipment and protection measures do not actually ensure 100% protection of aerosols in the dental office – researchers at the UNIVERSITY OF ILLINOIS (UIC DENTSTRY) have proposed a classification of dental procedures according to the particles they produce.
“Reopening dentistry after COVID-19: Complete suppression of aerosolization in dental procedures by viscoelastic Medusa Gorgo” was published online on Aug. 25, 2020, in Physics of Fluids.
”You can completely suppress the formation of sprays using a diluted aqueous polymer solution”
— Dr. Alexander L. Yarin, UIC

Type A procedures

They use high speed tools that disperse (or require) water or irrigation for cooling.

 These procedures produce ≤5µm particles and require:

– airborne transmission precautions depending on the type of cabinet ventilation (natural, mechanical, air-purifier)

– moderation and reduction of working time (eg to 5 min) with high speed parts (procedural mitigation)

– pragmatic organization of working time and breaks between patients to allow airborne particles to settle on surfaces – for disinfection (Fallow Time Calculator)

https://www.fgdp.org.uk/news/dental-fallow-time-calculator-launched

Register at https://myftc.co.uk/register.
Type B procedures

They use low speed tools .

 These procedures can produce ≤5µm aerosol particles to an extent that depends on how the instrument is used and requires:

– moderation and reduction of working time (procedural mitigation) through:

a. high volume suction

b. rubber dam insulation

– standard prevention and control measures currently used in Dentistry (PPE si IPS)
Type C procedures

These procedures do not require high speed tools.

 These procedures can produce splatter but are unlikely to produce ≤5µm aerosol particles and require:

– standard measures for the prevention and control of infection currently used in Dentistry (PPE si IPS).