Infection prevention is the largest single area of the Knowledge Test, and the one where a dental nurse's day-to-day responsibility is most direct. Questions tend to be procedural: what happens in what order, which item goes in which waste stream, and what to do when something in the cycle goes wrong.
What cross infection covers in the Knowledge Test
- The decontamination cycle from dirty intake through to sterile storage
- Manual cleaning, ultrasonic baths and washer-disinfectors
- Autoclave types, cycle parameters and what a failed cycle means
- One-way workflow and the separation of clean and dirty zones
- PPE selection, sequence and when it must be changed
- Waste segregation: clinical, offensive, sharps, amalgam and domestic
- HTM 01-05 principles and local policy
Where candidates lose marks
Confusing disinfection with sterilisation — they are not interchangeable, and questions test the distinction directly.
Assuming a sterilised pack stays sterile regardless of storage. Packaging integrity and storage conditions both matter.
Forgetting that a compromised cycle means reprocessing, not 'use it first'.
The decontamination cycle, in order
Almost every question in this area is really asking whether you know the order. Each stage exists to make the next one possible, which is why skipping or reversing a step is always the wrong answer.
- 01Transport dirty instruments to the decontamination area in a closed container
- 02Clean — manually, in an ultrasonic bath, or in a washer-disinfector
- 03Rinse
- 04Inspect under illumination and magnification for residual debris
- 05Sterilise in a validated autoclave
- 06Dry, package where required, and store clean and dry
Disinfection is not sterilisation
Disinfection reduces microorganisms to a level unlikely to cause harm. Sterilisation removes or destroys all microorganisms, including spores. They are not interchangeable, and a question offering both will be testing exactly that.
| Waste | Examples |
|---|---|
| Sharps | Needles, blades, burs, matrix bands |
| Clinical (infectious) | Items contaminated with blood or saliva |
| Amalgam | Amalgam capsules, extracted teeth with amalgam |
| Offensive | Non-infectious but unpleasant waste |
| Domestic | Packaging and general waste |
One-way flow
The decontamination area runs dirty to clean in one direction, and nothing travels back. Returning a tray through the clean side, storing sterile packs near a sink splash zone, or mixing benches for convenience all break the principle — and all appear as distractors.
Worked examples
Real questions from our bank, with the reasoning. No sign-in needed.
A sterilised pouch is found stored beneath a leaking pipe. What is the correct action?
- ADry it and return it to stock
- BUse it first today
- CReprocess the itemCorrect
- DMove the shelf and keep the pack
Why: Moisture breaches the packaging barrier, so sterility can no longer be assured regardless of how the pack looks.
Both free mocks draw from this topic in the same proportion as the real paper — 65 questions in 90 minutes, with an explanation for every answer and a per-topic breakdown at the end.
Start a free mock examCross infection questions, answered
What is the difference between disinfection and sterilisation?
Disinfection reduces microorganisms to a level unlikely to cause harm but does not reliably destroy spores. Sterilisation destroys all microorganisms including spores. Instruments that penetrate tissue must be sterilised, not merely disinfected.
What is HTM 01-05?
The Department of Health guidance on decontamination in primary care dental practices in England. It sets out essential and best-practice requirements for the decontamination cycle, the layout of decontamination areas, and record keeping.
In what order should the decontamination cycle run?
Transport, clean, rinse, inspect, sterilise, dry and store. Inspection sits deliberately before sterilisation: sterilising an instrument that still has debris on it does not make it safe.
What should happen if a sterilised pack gets wet in storage?
It should be reprocessed. Moisture compromises the packaging barrier, so the sterility of the contents can no longer be assured — drying it and using it anyway is not acceptable.
Which waste stream do extracted teeth with amalgam go in?
Amalgam waste, not clinical or domestic. Amalgam is a mercury-containing hazardous waste and is segregated separately.
The other nine topics
Independent study material, not affiliated with or endorsed by NEBDN. Always check the official NEBDN website for the current syllabus. NEBDN does not publish a pass mark for the Knowledge Test.