Ask the Editors
What are some of the common errors that can lead to sterilization failure?
There are multiple factors that can adversely affect sterilization cycles in an autoclave, dry heat, or unsaturated chemical vapor sterilizer. Problems that apply to each of these heat sterilizers include:
1. Improper cleaning of instruments
Cleaning is the basic, critical step in instrument processing because it involves removal of contaminating debris and organic material from an instrument before sterilization. If blood, saliva, and other contamination remain, they can shield adherent microorganisms and potentially compromise the sterilization process.
2. Improper packaging
This factor includes using the wrong type of packaging material for method of sterilization, placing too many instruments in a package, and wrapping items in excessive amounts of packing wrap. If the material used to package instruments is not compatible or excessive wrap is used, the sterilizing agent (i.e., moist heat under pressure, dry heat, unsaturated chemical vapor under pressure) may not be able to appropriately contact instrument surfaces, thereby resulting in a sterilization failure. Also, if the packaging material cannot withstand the high temperatures required for dry heat sterilizers, it may melt and create additional problems with the unit.
3. Overloading the sterilizer
Overloading the chamber can result in prolonged warm up times needed to reach sterilization conditions, and may also prevent thorough contact of the sterilizing agent with all items in the unit. Not spacing wrapped instrument packages adequately is a common problem observed with sterilization failures. Most sterilizers sold in recent years are provided with racks or trays, which allow a maximal capacity of instrument packages and effective sterilization with prescribed cycles. A number of older units can also be fitted with available racks or trays.
4. Inappropriate sterilization time, temperature, and/or pressure
Issues to consider here include use of inadequate temperature or time during the sterilization cycle and interrupting the total cycle. Human error plays a role here if the sterilizer door is opened during the cycle or timers are incorrectly set, thereby resulting in incomplete sterilization.
5. Inadequate maintenance of sterilization equipment
Routine maintenance as recommended by the manufacturer is critical to the whole instrument processing protocol. Examples of problem areas here are defective control gauges, which may give erroneous readings of conditions inside the chamber and worn door gaskets and seals.
6. Use of improper equipment for sterilization
This potential problem is clearly addressed in the CDC Guidelines for Infection Control in Dental Health-Care settings – 2003, with the recommendation: “Use only FDA-cleared medical devices for sterilization and follow the manufacturer’s instructions for correct use.” Neither household ovens nor smaller toaster ovens meet the stringent criteria required testing and evaluation as heat sterilizers.