Infection control and instrument cycle
The clean and unclean flow — from dirty to clean zone
Sterilising a single instrument is easy. The hard part – and the trade you have to learn – is organising the entire workflow so that a clean instrument never crosses paths with a dirty one. This is called infection control and is built on a basic principle of one-way flow: instruments only move from dirty to clean, never back.
§The professional basis: NIR
In Denmark in the 1980s
§Clean and dirty zone
The sterilization room is divided into a dirty and a clean zone with a clear separation between them. Used instruments enter the dirty zone and move through cleaning and disinfection, over to the clean zone, where they are packaged and sterilized. You must not carry dirty items back into the clean zone, and you avoid splash and spray from cleaning hitting the clean area.
| Zone / level | What's happening | Why |
|---|---|---|
| Unclean zone—receiving. | Used instruments are collected, dirt loosened | Keeps contamination away from the rest |
| Cleaning | Visible dirt, blood and remnants removed (instrument washer / ultrasound) | Sterilization only works on clean |
| Disinfection | Microorganisms are reduced (often in the same machine, thermally) | Make handling safe |
| Clean zone – control/packing | Instruments are checked, lubricated, packed in bags/cassettes | Maintains sterility after the process |
| Sterilization | Autoclave with steam under pressure | Also kills bacterial spores |
| Storage | Sterile, packaged instruments are stored dry and clean | Maintains sterility for use |
§The Autoclave and DS/EN 13060
The dental clinic's small steam sterilizer (autoclave) must comply with the standard DS/EN 13060 for small steam sterilizers. Autoclaves are divided into types, and for hollow and packaged instruments, which are common in a dental clinic, the most advanced type (class B) is required, which with vacuum ensures that steam reaches deep into cavities and through packaging. Packages and cassettes must be suitable so steam can penetrate.
§Inspection and documentation
You don't trust the machine blindly – you check it. Each package gets a chemical indicator that changes and shows that it has been through the process. In addition, routine operational checks of the autoclave are run (e.g. a test that checks steam penetration and that no air remains), and the results are documented. As an assistant, you are often the one who runs the check and keeps a log – it's part of the clinic's self-inspection.
§Standard precautions apply to everyone
A key principle in infection control is standard precautions: you treat all patients as if they can carry infection because you cannot see it on the outside. So hand hygiene gloves masks and eye protection plus correct instrument handling are routine for every patient — not something you only do when you think there is a risk.
“Infection control is not what you do when someone is watching — it is the sequence you never deviate from even when you are busy.”