5. Sterilisation, wrapping and storage

What sterilisation means

Sterilisation is a validated process that reduces viable microbes to a defined sterility assurance level. In dental practice this is almost always moist heat (steam under pressure). Disinfection is a lower bar — it is not a substitute for sterilisation of critical instruments that penetrate tissue or contact sterile sites.

Instrument categories

• Critical — penetrate soft tissue or bone. Require sterilisation after cleaning.
• Semi-critical — contact mucous membranes without penetration. High-level decontamination; sterilisation is preferred where the IFU allows.
• Non-critical — contact intact skin only. Clean and disinfect as per protocol.

Autoclave types

• Type N — unwrapped solid instruments for immediate use. Not suitable for wrapped loads or hollow items that need vacuum/steam penetration.
• Type B — vacuum cycles that can process wrapped loads and many hollow items if the IFU and load match the cycle.
• Type S — specified by the manufacturer for particular load types only.

Do not wrap instruments and run them in a Type N cycle “to keep them clean”.

Typical steam parameters

A common instrument cycle is in the region of 134 °C for a minimum holding time of 3 minutes (plus come-up time). Use the cycle the machine and IFU specify. Do not invent shorter cycles to save time.

Loading, drying and wrapping

Do not pack pouches so tightly that steam cannot circulate. Wet packs are not sterile storage. If a pouch is wet, stained or burst, treat the contents as unsterile and reprocess. Unwrapped items from a Type N autoclave are for immediate use — they are not stored as sterile stock. Each pack should allow traceability: date, autoclave identity, cycle/load number.

Storage

• Clean, dry, enclosed storage away from splash and the dirty zone
• Stock rotation — first in, first out
• Dropped packs are unsterile
• Open packs in the clean clinical zone immediately before use

External chemical indicators show the pack has been through a cycle; they do not prove sterility by themselves.