Sterilisation: the right cycle depends on the load, not on the type of instrument

Sterilisation is the most regulated procedure in the practice and the one on which the most unverified habits accumulate, because the result is not visible.

Autoclave classification rests on the loads they can process, and choosing wrongly means producing non-sterile instruments with an apparently successful cycle.

Class B autoclaves perform fractionated vacuums that remove air from lumens and porous materials. They are the only ones indicated for handpieces, hollow instruments and pouched material.

Class N units process only solid unwrapped instruments. Using one for a handpiece means the steam never reaches the internal lumen, and the instrument emerges hot but not sterile.

The reprocessing preceding the cycle determines the outcome more than the autoclave itself. Dried organic residue shields microorganisms from steam, and no cycle compensates for incomplete cleaning.

The ultrasonic bath or thermal disinfector is used before packaging, and instruments must be dried: residual moisture in pouches compromises maintained sterility.

Hinged instruments are processed open, because contacting surfaces receive no steam. It is the commonest error with pliers and scissors.

Pouches have an expiry that depends on storage conditions more than on absolute time. An intact pouch in a closed cabinet maintains sterility far longer than one left on a worktop.

A pouch that opens, gets wet or falls to the floor has lost sterility regardless of the printed date, and this must be understood by all staff.

Chemical indicators change colour when parameters are reached and are read at every cycle. They signal that conditions were achieved, not that microorganisms were inactivated.

The biological indicator, containing spores of resistant organisms, is the only one verifying actual efficacy, and it is run at the frequency the prevailing regulations require.

Traceability links the cycle to the patient, and it matters at the moment something goes wrong. Without a record one cannot know which instruments were used from a cycle later found non-compliant.

In summary: the autoclave class follows the load rather than habit, cleaning precedes and determines the cycle, hinged instruments are processed open, the biological indicator alone verifies efficacy, and traceability exists precisely for when something fails.