Biological Monitoring of Dental Office Sterilizers

The Centers for Disease Control and Prevention (CDC) recommends, and most states require, dental offices to monitor their sterilizers weekly using a spore test. Regular sterilizer monitoring using biologic indicators, i.e. spore tests, is considered the standard practice in dentistry, and when properly implemented, is a vital part of infection control verification. Biologic indicators consist of highly resistant, nonpathogenic bacterial spores. When spores are killed during a sterilization cycle, it is assumed that all microorganisms have been destroyed and sterilization is effective.

How should I conduct the spore testing?

The spore strips should be placed according to the sterilizer manufacturer’s instructions. If there are no instructions, place the spore test strip within a wrapped set of instruments in the most difficult area to be sterilized, which is normally the lower front area of the sterilizer. It is good practice to place the spore test strip in a different location of the sterilizer each week to help identify any “cold spots” within the sterilizer. Spore test results should be maintained for at least one year to track any deficiencies.

What if we receive a positive test?

Common factors for improper sterilization include chamber overload, excessive packaging material, inadequate exposure time, incorrect temperature/pressure settings, failure to preheat sterilizer, interruption of the cycle, and expired chemical solution (chemiclaves only). If a process indicator turns positive, then retest with the process indicator immediately. Ensure that the process indicator has not expired and that testing protocol has been met. Also check the sterilizer for any obvious inconsistencies.

Generally, a single positive spore test probably does not indicate sterilizer malfunction, especially if the process indicators demonstrate sterilizer effectiveness. However, if you receive a positive spore test, contact your biological monitoring service immediately for assistance.

OSHA Review, Inc. provides sterilizer monitoring services in all 50 states through the Spore Check System. The Spore Check System is endorsed by the Arizona, California, Ohio and Texas Dental Association.