Instrument Cassettes and Sieve Trays: Loading and Reprocessing
In many practices, hand instruments end up loose in a tray after treatment, are cleaned individually and then put back together into sets. This takes time, carries a risk of injury and means that instruments go missing or get damaged. Instrument cassettes and trays bring order: every instrument has a fixed place, from set-up through treatment to reprocessing. This guide explains the benefits, the difference between cassette, sieve tray and tray, typical set configurations and the most important rules for loading.
Key points at a glance
- Cassettes and sieve trays ensure complete sets, protect delicate working ends and make reprocessing more consistent.
- Instruments need to be handled individually less often after treatment. This reduces the risk of sharps injuries.
- Cassettes hold the instruments in place and can be reprocessed closed. Sieve trays hold instruments loose or in holders. Trays are mainly used for organised placement.
- When loading: hinged instruments open, do not overload, heavy instruments at the bottom, instruments must not cover each other.
- The instructions of the manufacturers of instruments, cassettes and equipment, as well as the practice's validated loading patterns, always take precedence.
Why cassettes and sieve trays?
Completeness
When every instrument has a fixed place, a gap is visible immediately. Checking for completeness becomes a visual check. The complete set is ready for treatment without having to look for individual parts.
Protection of the working ends
Loose instruments knock against each other in the tray, in the ultrasonic bath and in the machine. Fine tips of probes, scalers and curettes become dull or bent. In a cassette, the instruments lie separately and do not touch.
Occupational safety and process reliability
A considerable share of sharps injuries in the practice occurs while cleaning instruments. If the closed cassette goes straight into the reprocessing cycle after treatment, contaminated instruments need to be handled individually less often. At the same time, loading is standardised: every set is loaded the same way. This makes it easier to comply with validated loading patterns.
Cassette, sieve tray or tray?
The terms are not used consistently. As a guide:
| Feature | Instrument cassette | Instrument sieve / sieve tray | Tray |
|---|---|---|---|
| Design | Perforated box with lid and holders | Perforated tray, some with holders | Flat tray, open or with recesses |
| Instruments held in place | Yes, each instrument in its own holder | Partly, depending on version | Usually not |
| Reprocessing | Closed in the washer-disinfector, ultrasonic bath and steriliser (as specified by the manufacturer) | In the washer-disinfector and steriliser; instruments must not cover each other | Mainly for placement; suitability for reprocessing depends on the material |
| Protection of tips | High | Medium | Low |
| Typical use | Treatment sets for the dental chair | Surgical sets, larger instruments | Placement at the chair, storage |
In our shop you will find cassettes in various sizes, such as the cassette for 5 instruments, the cassette for 10 instruments and the cassette for 20 instruments, as well as mesh cassettes for 10 instruments. For placement there are the instrument sieve for up to 7 instruments, the tray for 5 instruments and scaler trays.
Typical sets
One cassette per type of treatment has proven its worth. Each practice decides which instruments belong in it. Examples:
- Basic set (examination): mouth mirror, explorer, tweezers, plus a periodontal probe. A starting point is the mouth mirror examination set.
- Periodontal set: periodontal probe, scaler and a selection of Gracey or universal curettes, for example from the Gracey curette set of 9.
- Surgical set: scalpel handle, periosteal elevator, retractors, forceps, needle holder and scissors. Ready-made kits include the periodontal surgery kit with 17 parts and the implant surgery set with cassette tray.
Colour markings on cassettes and instruments help to assign sets quickly and to train new staff.
Loading correctly: the most important rules
- Load hinged instruments open. Scissors, clamps and needle holders are loaded open or at most on the first ratchet step. This allows cleaning solution and steam to reach the joint, and the box lock is not under constant stress.
- Do not overload. Every instrument belongs in its holder. Extra instruments lying across create spray shadows and hinder drying and steam penetration.
- Do not stack instruments. In sieve trays, instruments should overlap as little as possible.
- Heavy instruments at the bottom. Heavy items are placed at the bottom or on lower levels so that they do not damage fine instruments.
- Secure small parts. Light parts that could shift in the water jet are fixed in suitable holders or inserts.
- Hollow items with the opening facing down. Bowls and cups are placed so that water can drain.
- Protect tips. For delicate tips, use only steam-permeable tip protectors suitable for sterilisation.
Common loading mistakes
- Using the cassette as a waste container: Disposables, swabs or filling residues do not belong in the cassette. They are disposed of directly at the chair.
- Letting gross soiling dry on: Cement and filling material are easier to remove while fresh. The time until reprocessing should be short.
- Continuing to use damaged instruments: Bent tips or corrosion are quickly noticed in the cassette. Such instruments are removed so that they do not affect others.
Reprocessing in the washer-disinfector and sterilisation
Cassettes with perforated walls are designed so that cleaning solution and steam reach all instruments. Many systems can be reprocessed closed in the washer-disinfector, in the ultrasonic bath and in the steam steriliser. Whether and how this applies to a specific product is determined by its manufacturer. For sterilisation, cassettes are packed depending on the risk classification of the instruments, for example in sterilisation wrap, pouches or containers. Instruments for critical procedures are sterilised packed.
It is essential that loading matches the validated loading pattern. If you introduce new cassettes or change the configuration, check whether the process is validated for it. In Germany, the principles of reprocessing are described in the KRINKO/BfArM recommendation and the brochures of the Instrument Reprocessing Working Group (AKI). Read more in our guide to instrument care and reprocessing. Advice on instruments with tungsten carbide inserts can be found in our guide Tungsten carbide instruments (TC).
You will find all cassettes, sieve trays and sets in the dental sets & storage category.
Frequently asked questions
What is the difference between an instrument cassette and an instrument sieve tray?
A cassette has a lid and holds each instrument in its own holder. A sieve tray is a perforated tray in which instruments usually lie loose or are only partly held in place.
Can instruments be reprocessed in the cassette in a washer-disinfector?
With many cassette systems, yes, provided the cassette is designed for it and the loading is validated. The instructions of the cassette and equipment manufacturers are decisive.
Why must hinged instruments be loaded open?
Only when open can cleaning solution and steam reach all surfaces in the joint. In addition, the box lock is then not under stress, which prevents stress cracks.
How many instruments fit in a cassette?
As many as the cassette has holders. Extra instruments should not be added, as they create spray shadows and put the tips at risk.
Do cassettes need to be packed for sterilisation?
That depends on the risk classification of the instruments. Instruments for critical applications are sterilised packed. The requirements of your hygiene plan and the manufacturers are decisive.