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Infection Control

Frequently Asked Questions - Sterilization — Packaging and Storage

What types of packaging materials are available for sterilizing instruments?

Packaging materials (e.g., wrapped or container systems) allow penetration of the sterilization agent and maintain sterility of the processed item after sterilization. Materials for maintaining sterility of instruments during transport and storage include wrapped perforated instrument cassettes, peel pouches of plastic or paper, and sterilization wraps (which can be either woven or unwoven). Packaging materials should be designed for the type of sterilization process being used. Packaging materials also should be appropriate for the items being sterilized. For example, nonpaper materials should be used to package sharp instruments which can easily puncture paper packaging. Avoid using metal closures (e.g., staples, paper clips) that can puncture packaging materials. A chemical indicator/integrator should be placed among the instruments, inside the package, as well as on the outside of each package (see FAQ Sterilization – Monitoring).

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Types and Use of Sterilization Packaging Materials

Sterilization Method Packaging Material Requirements Acceptable Materials
Steam autoclaveShould allow steam to penetrate.Paper
Paper peel packages
Wrapped perforated cassettes
Dry heatShould not insulate items from heat.

Should not be destroyed by temperature used.

Paper bags
Aluminum foil
Polyfilm plastic tubing
Wrapped perforated cassettes
Unsaturated chemical vaporVapors should be allowed to precipitate on contents.

Vapors should not react with packaging material.

Plastics should not contact sides of sterilizer.

Wrapped perforated cassettes
Paper peel pouches
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Can cassettes be used for sterilizing instruments?

The use of instrument cassettes facilitates instrument processing and can greatly enhance the organization of instruments. It also keeps all the instruments for a specific procedure together from the chairside procedure through cleaning, rinsing, drying, and sterilization. Following completion of dental treatment, instruments can be arranged in the cassette, transported to the instrument processing area, and placed in the ultrasonic cleaner as a unit. The cassette also can be rinsed and dried in this manner. In addition, a cassette system can reduce direct handling of potentially contaminated instruments before sterilization. Furthermore, instruments prearranged in the cassette will require less handling following sterilization.

Different types of cassettes are available. It is important to follow the manufacturer's recommendations for cleaning, wrapping, and sterilizing the cassettes. Perforated cassettes are preferable, since completely solid containers will not allow steam or chemical vapor to reach the contents and allow sterilization to occur. Cassettes can occupy more space than individual packages, so you should consider the size of the sterilizer and amount of storage space available before purchasing any cassette systems.

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How should items be stored following sterilization?

Sterile items and disposable (single-use) items should be stored in an enclosed storage area (e.g., cabinet or drawer). Dental supplies and instruments should not be stored under sinks or in other locations where they might become wet. Sterilized items should remain wrapped until they are needed for use.

Unwrapped items are susceptible to contamination. Avoid storing items loose in drawers or cabinets because unwrapped items cannot be kept sterile. Items stored in this manner are subject to contamination from dust, aerosols generated during treatment, and the hands of personnel who must handle them.

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What is the shelf-life of sterilized instruments?

Sterilized instruments should be stored in a manner that preserves the integrity of the packaging material. Storage practices can be either date- or event-related. Although some facilities continue to date every sterilized package and use shelf-life practices (first in, first out), other facilities have switched to event-related practices. This approach recognizes that the product should remain sterile until some event causes the item to become contaminated (e.g., a package becomes torn or wet). The quality of the packaging material, the conditions under which items are stored and transported, and the amount that they are handled all affect the chances that the package and its contents will remain sterile. All packages containing sterile items should be inspected before use to verify barrier integrity and dryness. Any package that is wet, torn, dropped on the floor, or damaged in any way should not be used. The instruments should be recleaned, packaged in new wrap, and sterilized again.

Even for event-related packaging, the date of sterilization should be placed on the package. If multiple sterilizers are used in the facility, the sterilizer used should also be indicated on the outside of the packaging material. This information can facilitate retrieval of processed items in the event of a sterilization failure.

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Selected References and Additional Resources

Association of Operating Room Nurses. Recommended practices for sterilization in perioperative practice settings. In: Fogg D, Parker N, Shevlin D, eds. Standards, Recommended Practices, and Guidelines, Denver: AORN, 2002;333–342.

Butt WE, Bradley DV Jr, Mayhew RB, Schwartz RS. Evaluation of the shelf life of sterile instrument packs. Oral Surgery, Oral Medicine, Oral Pathology 1991;72:650–654.

CDC. Guidelines for Infection Control in Dental Health-Care Settings, 2003. MMWR, December 19, 2003:52(RR–17).

Harte JA, Molinari JA. Instrument Processing and Recirculation. In: Molinari JA, Harte JA, eds. Practical Infection Control in Dentistry, 3rd ed. Baltimore: Lippincott Williams & Wilkins, 2010;221–231.

Klapes NA, Greene VW, Angholz AC, Hunstiger C. Effect of long-term storage on sterile status of devices in surgical packs. Infection Control 1987;8:289–293.

Mayworm D. Sterile shelf life and expiration dating. Journal of Hospital Supply, Processing, and Distribution 1984;2:32–35.

Miller CH, Palenik CJ. Instrument processing. In: Miller CH, Palenik CJ, eds. Infection Control and Management of Hazardous Materials for the Dental Team, 2nd ed. St. Louis: Mosby, 1998;135–174.

Miller CH, Palenik CJ. Sterilization, disinfection, and asepsis in dentistry. In: Block SS, ed. Disinfection, Sterilization, and Preservation, 5th ed. Philadelphia: Lippincott Williams and Wilkins, 2001;1049–1068.

Molinari JA, Rosen S, Runnells RR. Heat sterilization and monitoring. In: Cottone JA, Terexhalmy GT, Molinari JA, eds. Practical Infection Control in Dentistry, 2nd ed. Baltimore: Williams & Wilkins, 1996;149–160.

Schwartz RS, Butt WE, Bradley DV, Mayhew RB. Safe storage times for sterile dental packs. Military Medicine 1992;157:406–409.

Schwartz RS, Davis RD. Safe storage times for sterile dental packs. Oral Surgery 1990;70:297–300.

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