Many factors can affect the heat sterilization process. If the process is not routinely monitored, a problem that can jeopardize patient protection can go undetected.  Physical monitoring alone, such as observing dials, gauges and printouts, is not sufficient.  Sterilizing failures involving overloading, improper packaging, or air pockets will not show up on the dials.   Chemical and biological monitoring must be used in addition to physical monitoring to adequately verify the process.  Sterilization monitoring falls into three major categories:

1. Mechanical and Electronic Indicators, which are the dials, gauges and printouts on your sterilizer.  These do not indicate sterility, only gross equipment malfunction.
   
2. Chemical Indicators usually in the form of color-changing ink, and are used to show that one or more conditions of sterilization were met, but cannot be used to show that the conditions necessary for sterilization were achieved.
   
3. Biological Indicators (BIs) which are a standardized, viable population of bacterial spores known to be resistant to the mode of sterilization being monitored and are inoculated into a liquid or onto a paper carrier.  Biological indicators are intended to demonstrate whether the conditions were adequate to achieve sterilization through actual organism kill.

CDC - "Proper functioning of sterilization cycles should be verified by the periodic use (at least weekly) of biologic indicators (i.e., spore tests)."

ADA - "Biological monitors should be used routinely to verify the adequacy of sterilization cycles.  Weekly verification should be adequate for most dental practices."

OSHA - "Autoclave efficiency can be verified by means of biological ...indicators. ...documentation kept for the sterilizer...should include results of routine spore testing."

Is weekly spore testing adequate?  Additional testing may be necessary when:

1. A new type of packaging or tray material is used.
2. Following training or retraining of personnel.
3. A new sterilizer is used initially or after repair.
4. Implantable devices are in the load.
5. Following any changes in sterilization procedures.