Chemical Indicators for Steam Sterlilization

Chemical Indicators for Steam Sterlilization

Sterilizer monitoring happens in various forms. Whether mechanical, chemical, or biological, monitoring should be done every time a sterilization process is performed.  

Mechanical monitoring consists of visually checking the sterilizer's gauges, computer displays, or printouts. While observing this information does not guarantee that sterilization has occurred, it is the first step in determining a problem with the process. Mechanical indicators should be recorded each time the sterilizer runs. Need a Sterilizer Monitoring Log? You can find our Sterilizer Monitoring Logbook here.

Chemical indicators use heat-sensitive chemicals that change colors when exposed to high temperatures or a specific time. The CDC states that internal chemical indicators should be placed inside each instrument pack. External indicators should be used when one cannot view the internal strip from the outside of the package. All too often dental professionals rely solely on external, rather than internal indicators, which is not in alignment with the CDC guidelines.

 All sterilizer loads with unwrapped instruments and loads with implantable devices should have an internal indicator placed on the same sterilizer tray.

 While chemical indicators do not guarantee sterilization, they provide visual confirmation the instruments were processed in the sterilizer.

 There are different types of chemical indicators:

  • Type 1: External – shows the item has been exposed to a sterilization process
  • Type 2: Specific test in certain sterilizers (e.g., Bowie-Dick test)
  • Type 3: Internal – responds to one critical parameter (time or temperature)
  • Type 4: Internal – responds to two or more critical parameters
  • Type 5: Internal – integrating; responds to all critical parameters (time, pressure, temperature). Equivalent or exceeds biological indicator requirements
  • Type 6: Internal – responds to all critical parameters for a specific sterilization cycle

Chemical indicators are either single- or multiparameter. A type III single-parameter internal chemical indicator will give feedback regarding a specific aspect of sterilization. It could indicate a measurement of time or temperature, but not both. A type IV (time and temperature) or type V (multiparameter internal chemical indicator can react to two or more of those set parameters. Type V indicators are the most common multiparameter indicators used in dentistry. Type V indicators confirm the sterilizer achieved the desired pressure and temperature, but also ensure the sterilizer achieved the desired temperature long enough to kill all life (sterilization).

Biological monitoring, or spore testing, is the only way to effectively confirm sterilization. Spore testing should be conducted weekly. Spore testing uses heat sensitive microorganisms such as Geobacillus stearothermophilus to verify the sterilization process is absolute (deadly to all life).

The CDC Guidelines recommend weekly biological monitoring of all sterilizers,  regardless of who owns the unit (consider this when using a loaner). Many state boards of dentistry enforce this as the law of the land. An argument could be made that weekly spore testing is the minimum standard of care for infection control.

In summary, always use chemical indicators and spore testing to ensure the effectiveness of sterilizers used in your dental office. If you have an indicator of failure, stop, do no proceed until the test is disconfirmed or the sterilizer is repaired. When putting a sterilizer in service always obtain a negative spore test first. New (even recently repaired) sterilizers can have problems that result in failed spore tests. Sterilization effectiveness is critical to patient safety.

Written by Deanna Otts-Whitfield, RDH, BSDH, MSHQS, CDIPC

Deanna Otts-Whitfield is a clinical consultant with Dental Compliance Specialists. She works with clients to help them successfully adhere to regulatory agencies. After high school, she served four years in the United States Marine Corps. She obtained her bachelor's degree in 2009 and executive master's in 2020. Just two years later, she decided to hang up her loupes. Her 14 years as a clinical dental hygienist have proved to be vital in the compliance sector. With experience in private and public health settings, her knowledge extends beyond the operatory. She has a passion for learning and helping people. You can contact her at

 Dental Compliance Specialists helps make dental offices safer for patients, dentists and their employees. We help our clients develop and maintain their compliance programs including OSHA/Infection Control, HIPAA, DEA regulations and prescribing practices, Radiation Safety, OIG/Medicaid Compliance, Record Auditing, and more by providing actionable systems, easy-to-use tools, robust training, and accountability. Most of our clients have never been in trouble and want to keep it that way. Sometimes, though, dentists call when they are in trouble. In either case, we are there to make a meaningful difference. If you need help call us at 817-755-0035.

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