Instrument Processing Part 2: Packaging, Sterilization, and Storage

Why Packaging, Sterilization, and Storage Matter

Sterilizing instruments is not enough on its own. An instrument that leaves the autoclave sterile can become contaminated before it ever reaches a patient if it was packaged incorrectly, loaded improperly, or stored carelessly. Every step in this chain — packaging, sterilizing, documenting, and storing — is equally critical. Skipping or rushing any one step is a patient safety failure, not just a procedural shortcoming.

Packaging Instruments Before Sterilization

Packaging creates and maintains a sterile barrier around instruments from the moment the autoclave cycle ends until the package is opened chairside. Two common packaging methods are peel pouches and sterilization wrap.

Peel pouches are pre-formed, two-sided packages: one side is transparent plastic and the other is paper or a paper-film composite. Instruments are inserted, the open end is sealed (with a heat sealer or self-seal adhesive strip), and the package is labeled. Always choose a pouch size that fits the instrument without stretching or compressing the seal seam. A poor seal is a breach in the sterile barrier.

Sterilization wrap (envelope fold) is used for cassettes and larger tray setups. Place the cassette diagonally on a double layer of wrap. Fold the front point over the cassette, fold in the two side points, then fold the rear point over and tuck or tape it closed. This sequential fold allows aseptic opening at chairside — each layer unfolds away from the contents.

Internal chemical indicators must be placed inside every package before sealing. A Class 5 integrating indicator or a Class 6 emulating indicator changes color only when it has been exposed to the specific combination of time, temperature, and steam required for sterilization. The external color change visible on the outside of many pouches only tells you the package went through a cycle — it does not confirm sterilization conditions were met. The internal indicator is the evidence you need. If the internal indicator has not changed correctly when you open a package, do not use the instruments — reprocess the entire load.

Labeling Every Package

Before sealing, write directly on the paper side of the peel pouch or on the sterilization wrap using a permanent marker. Every package must display:

• Date of sterilization
• Load number (ties the package to the sterilization log entry for that cycle)
• Any additional information your facility requires (operator initials, expiration date if event-related storage policies apply)

Legible labeling allows you to trace any package back to its cycle record. If a biological indicator later shows a sterilizer failure, you can identify and recall every package from that load.

Loading and Operating the Steam Autoclave

The steam autoclave (gravity displacement or pre-vacuum/dynamic-air-removal type) kills microorganisms using saturated steam under pressure at elevated temperature. Follow the manufacturer's operation manual for your specific unit. General principles that apply across most units:

• Pouch orientation: Stand pouches on edge in a pouch rack or place them paper-side-to-plastic-side in alternating layers. This allows steam to circulate around all surfaces and allows condensate to drain away from the package.
• Load density: Do not overload the chamber. Packages must not touch the chamber walls or each other so tightly that steam cannot penetrate. Overloading is one of the most common causes of sterilization failure.
• Cycle selection: Choose the cycle that matches your load. Wrapped loads typically require a longer, slightly lower-temperature cycle than unwrapped loads. Hollow instruments (handpieces, tubing) require a cycle validated for hollow lumens — confirm with the manufacturer's manual.
• Starting the cycle: Verify that the water reservoir contains the correct level of distilled water, close and latch the door securely, select the cycle, and start. Never open the door mid-cycle.
• Monitoring cycle parameters: The autoclave's display or printout will show temperature, pressure, and time. Record these values in the sterilization log immediately after the cycle completes.

After the cycle ends, allow packages to dry completely inside the chamber before removing them. Wet packs — packages that are damp or have visible moisture after the cycle — are considered non-sterile because moisture can wick microorganisms through packaging material. Set wet packs aside, allow them to dry, inspect the seal, and if any doubt exists about integrity, reprocess.

Documenting the Cycle: The Sterilization Log

The sterilization log is a legal and quality-assurance record. A complete log entry includes the date, load number, cycle type, temperature reached, exposure time, pressure, operator initials, results of the internal chemical indicator, and results of any biological indicator test for that cycle. Biological indicator (spore test) results may be recorded when testing is performed, typically at least weekly or as required by your state regulations. Accurate, complete logs allow you to detect equipment drift, respond to equipment failure, and demonstrate compliance during inspections.

Storage: Event-Related vs. Time-Related Shelf Life

Current CDC guidelines support an event-related approach to storage: a package remains sterile until something happens to compromise it (torn seal, puncture, moisture, or being dropped). However, some facilities still use a time-related expiration date. Follow your facility's written policy and your state's requirements.

Regardless of policy, apply FIFO — First In, First Out stock rotation: place newly sterilized packages behind older ones so the oldest stock is used first. Store packages in a clean, dry, closed cabinet away from heat, moisture, and traffic. Inspect every package before use: if the seal is broken, the pouch is wet or torn, or the external indicator has not changed, treat the package as non-sterile and reprocess.

Safety Summary

• Never use instruments from a package with a failed or unchanged internal indicator.
• Never open an autoclave door during a cycle.
• Treat wet packs as non-sterile.
• Document every cycle — an undocumented cycle is an unverifiable cycle.
• Scope of practice: dental assistants may operate sterilization equipment; any deviation from established protocols must be reported to the supervising dentist immediately.