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Some of you who have been in practice for 25 years or more may remember that many instruments cleaned after patient treatment were placed into the heat sterilizer as unwrapped, loose items.
Since that time, we have seen a gradual evolution in reprocessing equipment and products used to package instruments. A variety of materials have become available since the days of wrapping items in thick muslin or paper towels. They include heat–sensitive bags, wraps, pouches, and perforated instrument cassettes. Cassettes are included in the category of instrument packaging because, among other features, they facilitate instrument processing and enhance instrument organization for specific procedures. When used, however, cassettes that contain cleaned instruments must also be wrapped prior to sterilization.
As per basic infection control principles, recommendations from the CDC and other organizations call for critical and semicritical items to be wrapped prior to sterilization and kept wrapped after processing. The obvious goal is to protect instruments from contamination after removal from the sterilizer and keep them sterile during storage. Not just any paper or plastic container will suffice. Specific factors should be considered when selecting a packaging material. They should:
- Be cleared by the FDA
- Ensure adequate penetration of the sterilizing agent
- Maintain sterility of items by providing an adequate barrier to outside microorganisms
- Be puncture–resistant and tear–resistant
- Be easily and completely sealed
- Have contents that can be easily removed while maintaining sterility
- Have material that is free of toxic elements and dyes
- Be low–linting if material is fabric
- Be cost–effective
It is also important for materials to be compatible with the type of heat sterilization used by the practice. For example, a number of the paper–plastic pouches normally used in autoclaves will char or burn when exposed to the elevated temperatures required for dry heat sterilization.
Inappropriate materials can also compromise the sterilization process by not allowing heat to penetrate sufficiently to reach and maintain required temperatures.
A significant innovation developed for instrument pouches was the addition of an external chemical indicator that changed color when sterilization conditions were reached in the unit chamber. Autoclave tape is the historical example of such an indicator. It was used to seal the instrument wrap or pouch and also serves as visible proof that items were exposed to a heat sterilization process.
Unfortunately, this temperature–sensitive tape is not reliable as a temperature indicator. To demonstrate this, I used to instruct students to take a piece of autoclave tape and place it on the inside of the rear window of their cars. After a few days of exposure to sunlight, the dark stripes of the tape were quite visible. In a similar manner, colored stripes would often begin to develop on the tape within a few minutes of exposure to steam in an autoclave — long before sterilization conditions are reached.
Because the heat and pressure conditions may be different on the inside of a loaded pouch from the outside of the container, guidelines have called for placing a chemical indicator on the inside of each package to verify penetration of sterilizing vapor.
If the internal indicator is not visible from the outside, use of an external chemical indicator is also recommended. Use of these separate temperature–sensitive impregnated strips has become a routine component of instrument processing and sterilization protocols in many dental practices. It should be emphasized, however, that these do not replace routine biological monitoring of the sterilizer, which demonstrates destruction of heat–resistant bacterial spores.
Recently, sterilization monitoring has become much easier for personnel charged with reprocessing instruments. Pouches are now available that contain built–in internal and external multiparameter steam indicators. These provide reliable, visible information concerning time, temperature, and exposure of items to steam in an autoclave.
When packages are removed after being run through a cycle, failure of either of these dual–quality control indicators to change color quickly alerts the person inspecting the processed packages that the sterilization cycle has failed, and the instruments should not be used. Thus, instrument processing and sterilization monitoring just became a bit more efficient.
Dr. John A. Molinari is Director of Infection Control for THE DENTAL ADVISOR. Previously, he was professor and chairman of the Department of Biomedical Sciences at the University of Detroit Mercy School of Dentistry. Contact him at [email protected].
