Sterilisation

There are three types of small steam steriliser available. Each has specific operating conditions and load limitations.

Sterilisation

Sterilisation by means of steam (moist heat) is the recommended method for processing most dental instruments.

MAC Manual Part 3 Procedures: "Steam sterilisation is the method of choice for most dental instruments."

HTM 01-05 Section 4.2: "Saturated steam under pressure delivered at the highest temperature compatible with the product is the preferred method for the sterilisation of most instruments used in the clinical setting."

There are three types of small steam steriliser available. Each has specific operating conditions and load limitations.

Type N Steriliser: Non-Vacuum

Also known as Gravity, Downward Displacement, and Bowl & Instrument sterilisers.

Air removal is critical to enable steam to condense on instruments and effect sterilisation. In a Type N steriliser air removal is passive and for this reason no packaged instruments may be sterilised in these machines.

Devices with narrow lumens, including hand pieces, should not normally be sterilised in Type N sterilisers because the steam will not be forced into the lumen due to passive air removal.

With regards to lubrication, HTM 01-05 states "…that it is unlikely that sterility will be achieved – whatever steriliser is used – due to the presence of lubricating materials."

Currently HTM 01-05 permits the use of a Type N steriliser for processing lubricated hand pieces.

Type B Steriliser: Vacuum

Also known as Vacuum, Vacuum Assisted, and Porous Load sterilisers.

Air removal is critical to enable steam to condense on instruments and effect sterilisation. In a Type B steriliser air removal is active due to vacuum assistance, allowing appropriately wrapped items to be processed as well as lumen devices and hand pieces. The air is actively removed, and the steam forced into any lumens allowing for the sterilisation of hollow devices.

Type S Steriliser: Vacuum

This type of steriliser is designed to reprocess specific load types. The manufacturer of the steriliser must define exactly which load or instrument types are compatible.

Type S sterilisers should be used strictly in accordance with manufacturer instructions.

Critical Sterilisation Parameters

Regardless of the type of steriliser used, the critical parameters for sterilisation remain the same:

Temperature
The preferred temperature is 134°C to 137°C.

Time
A minimum of three (3) minutes holding time once the load has reached the temperature of 134°C.

Pressure
Approximately 2 Bar. The pressure is associated with the development of steam at 134°C and is typically recorded in addition to the temperature.

Most sterilisers are now fitted with automatic recording devices or at the very least printers, which record the cycle parameters. A data logger is considered to achieve Best Practice requirements.

In the absence of a printer or data logger, a manual record of each cycle is required.

For more information on testing and validating sterilisers please see the relevant sections of the Isopharm website.