One of the fundamentals in reducing cross contamination in the dental surgery is a dirty to clean workflow. This will reduce the risks of clean instruments coming into contact with dirty instruments.


Ideally, a dedicated decontamination area will have a dirty and clean room to reduce risks to a minimum.

Building structure and space often does not allow for this and decontamination rooms are usually a single room containing both dirty and clean areas. 

Decontamination of instruments that takes place in the dental surgery must have clearly defined clean and dirty areas.

Decontamination of instruments must be as far away from the dental chair as possible and only take place when the surgery is free of patients. Procedures such as manual cleaning or opening of decontamination equipment create the risk of exposure to possible contaminated aerosols or splashes. 

The dirty area would contain:

  • Setting down area for instruments
  • Hand wash sink
  • Washing and rinsing sinks or bowls
  • Ultrasonic bath
  • Washer disinfector
  • Inspection light

The clean area would contain:

  • Autoclave(s)
  • Inspection and bagging area 
  • Hand wash sink (now optional in a single room)

HTM 01-05 section 13 states that where there is limited space one hand wash sink in the decontamination area is acceptable. In small decontamination areas there is a tendency to use one hand wash sink more frequently and therefore the unused sink heightens the risk of legionella. 

Areas where dirty and clean areas do not have a physical barrier (such as a door, screen or wall), a robust routine cleaning schedule must be in place.

Through correct flow of the decontamination process, no instruments can be re-contaminated on a surface that has been previously used for decontamination.

Robust procedures for a structured flow from dirty to clean must be in place.

All areas are required to stay clutter free and wiped with disposable wipes after each process has taken place.

Where there are dirty and clean processes carried out in the same room, it is advisable to remove any clean instruments on work surfaces before undertaking processes on the dirty area to reduce the further risk of aerosol contamination. Pouches should be stored in drawers to prevent damage by water, steam or aerosols, as this would compromise the integrity of the pouch rendering it unsuitable to keep instruments in a sterilised state. 

HTM 01-05 2013 Edition states that unwrapped instruments can be stored in a non-clinical area or maximum storage one week. This includes the clean room of a two-room decontamination area.

Where dirty and clean decontamination areas are in the same room this would not be acceptable 

The unwrapped instruments should be kept dry and protected in specially designed storage racks within a cupboard or covered in drawers. Reprocessing is required for unused instruments after one week of storage.

Instruments can also be stored in the surgery in this state (unwrapped for one day). At the end of the day instruments must be sent for reprocessing.

Ventilation within a single decontamination area must flow from clean to dirty. Change clean air filters regularly and clean ventilation fittings according to cleaning schedules. Dirty air should not enter clean areas. Extractor fans placed over the manual cleaning areas are useful in reducing aerosol dispersion. 

Separate clean and dirty rooms are required to have separate ventilation systems.

Air conditioning units are useful in the reduction of steam and must be placed in the clean area but regular maintenance and filter changes are important to prevent legionella.