Monitoring Sterilization of Dental Instuments

Dental Instrument Sterilization is clearly defined and outlined by the Centers for Disease Control Guidelines for Infection Control in Dental Health-Care Settings, issued in 2003. These guidelines are intended to educate dental personnel regarding infection control and to prevent the transmission of bloodborne pathogens.

This comprehensive document covers: hand hygiene, personal protective equipment, contact dermatitis/latex allergy, disinfection/sterilization, environmental infection control, waterlines/biofilms and special dental considerations such as hand pieces, radiographs and laboratory procedures.

The CDC's Guidelines for Infection Control in Dental Settings are evidenced based and well documented. The sterilization of dental instruments is one of the main areas of concern in dental offices. Along with the proper sterilization of instruments and materials, sterilizer monitoring is an essential part of the infection control program.

Many factors can cause sterilization to fail--from procedural errors that are easily remedied, like overloading, to mechanical problems that can take a sterilizer out of service until repairs can be made. Since this variety of factors can influence successful sterilization, the CDC and the American Dental Association encourage dentists to regularly assess the efficiency of their in-office sterilizers.

Sterilization should be monitored using both chemical and biological indicators. Chemical indicators, such as indicator tapes, are to be used with each instrument load. A color change of these indicators reveals exposure to the proper sterilization conditions.

Failure of the indicator to change color indicates that it was not exposed to the proper sterilization environment (e.g., proper pressure or temperature). In such cases, the instrument load should be re-sterilized. Indicator tapes are made specifically for certain types of sterilizers (i.e., tapes for steam sterilizers cannot be used to test chemical vapor sterilizers). Chemical indicators should not replace biological indicators, as only a biological indicator consisting of bacterial endospores can measure the microbial killing power of the sterilization process.

The CDC and ADA both recommend that sterilizers be monitored at least weekly with biological indicators. Each state dental board may actually have a requirement for biological monitoring.

Biological monitoring can be done in two ways. In-office incubator and spore monitoring strips can be purchased from dental supply houses. This method usually gives results in 24-48 hours. Mail-in spore monitoring programs are also available. This process usually takes a week. Although it takes longer to get results, mail-in monitoring programs may be more reliable and credible than in-house monitoring. A log of spore test results should be maintained in the dental office, usually in the sterilization area.

A positive test using chemical or biological indicators signifies that sterilization failed. If the chemical indicator does not change color or the spore test result is positive, the following steps are recommended. The sterilizer should be taken out of service. Instruments that were used after the last documented negative spore test should not be used. Sterilization procedures being followed in the office need to be reviewed to make sure operator error can be ruled out as the cause of failure.

Any identified procedural problems should be corrected, and the sterilizer retested using mechanical, chemical and biological indicators. If the repeat biological indicator test is negative and the other test results fall within normal limits, the sterilizer can be returned to service. If the biological indicator or the chemical tests indicate failure, sterilizers should be removed from use until the problem is identified and corrected. The dental repair company should be contacted for a service call and possible loan of an interim sterilizer.

Before the sterilizer can be returned to service, negative results should be returned for biological indicator tests conducted during three consecutive empty-chamber sterilization cycles to ensure that the problem has been corrected.