Cold sterile

May 31, 2013
My GPS is named Aimus. He does a pretty good job sending me where I need to go. A few weeks ago, Aimus went wild in the middle of the most turbulent freeway in Los Angeles.

by Noel Kelsch, RDHAP

My GPS is named Aimus. He does a pretty good job sending me where I need to go. A few weeks ago, Aimus went wild in the middle of the most turbulent freeway in Los Angeles. In rush hour traffic, he told me to make a U-turn. Nothing made sense, and he went blank, giving me no further directions.

Cold sterilization can do the same thing in the dental setting.

What is cold sterilization? Cold sterilization is a method of sterilization that requires the reusable semi-critical items to be immersed in EPA-approved liquid chemicals. These chemicals can include glutaraldehydes, peracetic acid, and hydrogen peroxide-based solutions. Single-use items can never be cold sterilized. They are not manufactured to be sterilized and may resist the process because of the materials with which they are made.

What do dental professionals need to know? The Centers for Disease Control and Prevention (CDC) has made strong statements in this area. They state that in all dental and other health-care settings indications for use of liquid chemical germicides to sterilize instruments ("cold sterilization") are limited. The first choice is always heat sterilization. The CDC refers to heat sterilization as "the method of choice when sterilizing instruments and devices. If an item is heat sensitive, it is preferable to use a heat-stable alternative or disposable item."

Time, Energy, and Process

For heat-sensitive instruments, this procedure may take up to 10 hours of immersion exposure. Items that are immersed must be timed. This may be difficult and you may have to go by the time at the end of day to the next day. There is no method of marking the time the item was immersed so you have to go by the last item immersed.

This method is bringing unnecessary exposure to one more chemical in the dental environment that is not required. Time-weight average (TWA is how long a single provider may be exposed to a given chemical) is very low on many of these chemicals. Direct ventilation may be required to the use chemical in your sterilization room. Extra specific personal protective equipment may also be required. It is vital to read all the directions on the label and MSDS sheet.

Once the item has been sterilized, the process does not end there. The item must be rinsed with sterile water to remove the entire chemical agent that could cause irritation or a chemical reaction with the patient. It must then be used immediately or packaged in a sterile package without touching the outside of the package that has been exposed to the environment. It is very difficult to maintain sterility with doing this process and packaging.


The biggest issue with this system is there no indications of sterilization. Heat sterilization offers three methods of monitoring the process, including time (timer on the sterilizer), chemical (internal and external indicator on the package, assures exposure to heat), and biological (weekly spore test of device). There is no way to monitor cold sterilization with these methods. Even the time has limitations. Sterility is not verified or assured with this process.

Studies have made it clear. Heat can penetrate barriers; it goes beyond biofilm, blood and tissue to kill organisms. Liquids just cannot get past those barriers to penetrate and kill. On top of that, some of the sterilants are so viscose they cannot even access the narrow tubing, lumens, and mated surfaces of some devices.

Aimus and I had to part ways because he could not give me the indicators that I need to stay safe. Cold sterilization may be the same situation for you and your patients. The bottom line is as the CDC states: "Therefore, due to the inherent limitations of using liquid chemical sterilants, their use should be restricted to reprocessing devices that are heat-sensitive and incompatible with other sterilization methods." All other items should be heat sterilized or disposable. No disposable device should ever be reprocessed.

One other reminder: At a recent course, I was asked if implants can be cold sterilized. The CDC has been so specific on implants. They must be sterile before implanting. They are to be quarantined until the results of the biological monitoring is known. They are to be heat sterilized before they are implanted. RDH

NOEL BRANDON KELSCH, RDHAP, is a syndicated columnist, writer, speaker, and cartoonist. She serves on the editorial review committee for the Organization for Safety, Asepsis and Prevention newsletter and has received many national awards. Kelsch owns her dental hygiene practice that focuses on access to care for all and helps facilitate the Simi Valley Free Dental Clinic. She has devoted much of her 35 years in dentistry to educating people about the devastating effects of methamphetamines and drug use. She is a past president of the California Dental Hygienists' Association.

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