Best Practices for Sterilization Monitoring in Dental Settings

Why it matters

Sterilization monitoring is a critical step in ensuring that instruments and devices are safe to use on another patient.

Dental health care personnel should use a combination of mechanical, chemical, and biological monitoring to check whether a sterilizer reached the conditions necessary to achieve sterilization.

Recommendations

CDC provides recommendations for sterilization monitoring in the Guideline for Disinfection and Sterilization in Healthcare Facilities (2008) as well as on page 24–25 of the Guidelines for Infection Control in Dental Health-Care Settings (2003) and in the Summary of Infection Prevention in Dental Settings: Basic Expectations for Safe Care.

Mechanical monitoring

Mechanical monitoring involves checking the sterilizer gauges, computer displays, or printouts, and documenting in your sterilization records that pressure, temperature, and exposure time have reached the levels recommended by the sterilizer manufacturer. Since these parameters can be observed during the sterilization cycle, this might be the first indication of a problem. Mechanical monitoring should be conducted for every sterilizer load.

Do not use instrument packages if the mechanical monitoring indicates that the sterilizer did not reach the required temperature, time, or pressure to render the items sterile.

Chemical monitoring

Chemical monitoring uses sensitive chemicals that change color when exposed to high temperatures or combinations of time and temperature.

A chemical indicator should be used inside every package to verify that the sterilizing agent has penetrated the package and reached the instruments inside. If the internal chemical indicator is not visible from the outside of the package, an external indicator should also be used.

Inspect the chemical indicator immediately when removing packages from the sterilizer; if the appropriate color change did not occur, do not use the instruments.

Biological monitoring

Biological monitoring, also called a spore test, assesses the sterilization process directly by killing known highly resistant microorganisms. Because the spores used in biologic indicators are more resistant than the common microbial contaminants found on patient-care equipment, a negative spore test indicates that other potential microorganisms in the load have been killed.

A spore test should be used at least weekly to monitor sterilizers, and should use a matching control (i.e., biological indicator and control from same lot number). Follow the manufacturer’s directions for how to place the biological indicator in the sterilizer.

A spore test should also be used for every load with an implantable device. Ideally, implantable items should not be used until they test negative.

Sterilization records

Sterilization monitoring records are an important component of a dental infection prevention program. Maintaining accurate records ensures cycle parameters have been met and establishes accountability. In addition, if there is a problem with a sterilizer (e.g., unchanged chemical indicator, positive spore test), documentation helps to determine if an instrument recall is necessary.

Maintain your sterilization monitoring records (mechanical, chemical, and biological) long enough to comply with state and local regulations.

Sterilization failures

What causes a sterilization failure?

Mechanical, chemical, or biological monitoring failures can be caused by a number of issues, including but not limited to:

• Improper cleaning of instruments.
• Incorrect operation of the sterilizer.
• Improper loading or overloading of the sterilizer.
• Improper packaging.
• Improper packaging material selected for the method of sterilization.

What should I do if there's a positive spore test?

If the mechanical (e.g., time, temperature, pressure) and chemical (internal or external) indicators suggest that the sterilizer is functioning properly, a single positive spore test result probably does not indicate sterilizer malfunction.

• First, remove the sterilizer from service and review the sterilization operating procedures to determine potential reasons for the failed test.
• Recall and quarantine any implantable items and do not use them until they are shown to be sterile.
• Items other than implantable items do not necessarily need to be recalled.
• Repeat the spore test immediately using the same cycle that produced the positive spore test.
• If the result of the repeat spore test is negative and operating procedures were correct, then the sterilizer can be returned to service.

If the repeat spore test result is positive, remove the sterilizer from service and do not use until it has been inspected or repaired and re-challenged with spore tests in three consecutive fully loaded chamber sterilization cycles.

When possible, items from suspect loads dating back to the last negative spore test should be recalled, rewrapped, and re-sterilized.

See Table 12 of the Guideline for Disinfection and Sterilization in Healthcare Facilities (2008) for the suggested protocol to manage a positive biological indicator in a steam sterilizer.

Frequently asked questions

Do I have to perform a spore test if I don't use my sterilizer on a full time basis?

CDC does not provide a separate recommendation for sterilizers that are used on a part-time basis. CDC recommends that dental health care personnel monitor sterilizers at least weekly by using a biological indicator with a matching control (i.e., biological indicator and control from same lot number).