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FAQ - Instrument Processing - 2015
 FAQ  - Instrument Processing - 2015



I have a question regarding sterilization process indictor requirements. I know that an exterior and interior monitor should be used. Does the CDC recommend a Class 4 indicator for dental instruments?

First, it is recommended that the manufacturer’s instructions for use (IFU) be consulted and followed for any specific steam sterilization chemical indicator product.

The 2003 CDC guidelines for infection control in dentistry provides the following general information:

Sterilization Monitoring. Monitoring of sterilization procedures should include a combination of process parameters, including mechanical, chemical, and biological (247,248,277).These parameters evaluate both the sterilizing conditions and the procedure’s effectiveness.

Mechanical techniques for monitoring sterilization include assessing cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer and noting these parameters for each load (243,248). Some tabletop sterilizers have recording devices that print out these parameters. Correct readings do not ensure sterilization, but incorrect readings can be the first indication of a problem with the sterilization cycle.

Chemical indicators, internal and external, use sensitive chemicals to assess physical conditions (e.g., time and temperature) during the sterilization process. Although chemical indicators do not prove sterilization has been achieved, they allow detection of certain equipment malfunctions, and they can help identify procedural errors. External indicators applied to the outside of a package (e.g., chemical indicator tape or special markings) change color rapidly when a specific parameter is reached, and they verify that the package has been exposed to the sterilization process. Internal chemical indicators should be used inside each package to ensure the sterilizing agent has penetrated the packaging material and actually reached the instruments inside. A single-parameter internal chemical indicator provides information regarding only one sterilization parameter (e.g., time or temperature). Multiparameter internal chemical indicators are designed to react to >2 parameters (e.g., time and temperature; or time, temperature, and the presence of steam) and can provide a more reliable indication that sterilization conditions have been met (254). Multiparameter internal indicators are available only for steam sterilizers (i.e., autoclaves).

Because chemical indicator test results are received when the sterilization cycle is complete, they can provide an early indication of a problem and where in the process the problem might exist. If either mechanical indicators or internal or external chemical indicators indicate inadequate processing, items in the load should not be used until reprocessed (134).

Biological indicators (BIs) (i.e., spore tests) are the most accepted method for monitoring the sterilization process (278,279) because they assess it directly by killing known highly resistant microorganisms (e.g., Geobacillus or Bacillus species), rather than merely testing the physical and chemical conditions necessary for sterilization (243). Because spores used in BIs are more resistant and present in greater numbers than the common microbial contaminants found on patient-care equipment, an inactivated BI indicates other potential pathogens in the load have been killed (280).1

Infection Control and Management of Hazardous Materials for the Dental Team states:

Two types of chemical indicators exist. One indicator changes color after a certain temperature has been reached (e.g., autoclave tape and special markings on pouches and bags). This type of indicator is used commonly as an external indicator on the outside of every pack, pouch, or cassette to indicate that the item has at least been processed through a heat sterilizer. This identifies items that have been heat processed and items that have not, for otherwise they may look identical. This differentiation prevents the accidental clinical use of unprocessed items. These indicators do not indicate that sterilization has been achieved or even that a complete sterilization cycle has occurred. A sterilizer could heat up to the proper temperature, causing a change in the chemical indicator, and then immediately malfunction, preventing sterilization, but the indicator already would have changed color. Thus these indicators demonstrate only that an item has been exposed to a certain temperature for some unknown length of time.

The second type of chemical indicator is called an integrated indicator that changes color or form slowly, responding to a combination of time and temperature, or time temperature, and the presence of steam. These indicators are used commonly on the inside of every pack, pouch, or cassette to assess whether the instruments have been exposed to sterilizing conditions.2


The CDC recommends that a chemical indicator be placed inside every package that has been processed through a sterilizer…, and if that indicator can’t be seen from the outside of the package, another chemical indicator is to be placed inside the package.2

These indicators do not indicate that sterilization has been achieved. Only a biological spore test (live spore test) can provide the primary guarantee of sterilization.1

Regardless of the type of chemical indicator utilized, you must also perform a biological spore test according to your state laws regarding biological monitoring (e.g. most require weekly testing).

In summary, it is recommended that the manufacturer’s instructions for use be consulted and followed for any specific steam sterilization chemical indicator product. The primary guarantee of sterilization is made with a biological spore test. Integrated indicators are commonly used on the inside of every pack, pouch, or cassette. Any further questions on this matter should be directed to the product manufacturer.


1)     Kohn WG, Collins AS, Cleveland JL, Harte JA, Eklund KJ, Malvitz DM, Centers for Disease Control and Prevention (CDC). Guidelines for infection control in dental health-care settings—2003. MMWR Recomm Rep 2003;52(RR-17):1-61.    Accessed on July 9, 2015.

2)     Miller CH. Infection Control and Management of Hazardous Materials for the Dental Team, 5th edition. Elsevier/Mosby Publishers. Pages 138-141.





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