Fundamental principles in designing reprocessing areas

It is recognized all too often that very little consideration is given to sterilization or reprocessing areas in either existing or newly designed dental practices. And yet reprocessing instruments between patients is crucial to meet today's hygiene rules in dental offices.

Not to mention the dental practitioner's moral and legal ‘duty of care’ calling for effective, well-defined and implemented infection control measures to prevent the transmission of infectious diseases to patients and staff.

It is particularly noticeable that since the emergence of SARS, the avian influenza outbreaks and the current Ebola pandemic, patients have become more sensitive to hygiene, not hesitating to question dental professionals about asepsis rules and standard precautions. This is also the case with tattoo, piercing and podiatry salons, corroborated by the numerous press articles dedicated to this topic.

Beyond the purely regulatory and safety aspects, many dentists have made the sterilization area a key asset for their activity. Located in a prime and visible location lets patients understand up front that their health and safety is important to them. The staff don’t hesitate to share this passion for hygiene with patients, happy to answer any questions they may have. Flattered by this attention, it makes the patient feel confident and secure.

To create new reprocessing areas or enhance existing ones is not an "insurmountable" challenge. It simply requires some basic principles this article will outline.

The amount of space of the reprocessing area

The amount of space dedicated to the reprocessing area is essential. In most of the cases it is undersized. The room must be functional, well lit and in correlation with the size of the dental practice and number of instruments to be reprocessed. The integration of cleaning and sterilization devices with their respective accessories and ensuring enough bench space for storage of instruments between the steps of the protocol i.e. before/after cleaning; before/after packaging and sterilization.

The first fundamental principal is to foresee two (virtual) areas in the room; a dirty and a clean zone. Rationally, instruments will travel in one direction from the dirty zone towards the clean zone. As a consequence of this one-way flow, processed (clean) instruments shall not enter the dirty zone; hence the reprocessing area should ideally be rectangular, a kind of pass-through corridor, featuring two doors (IN & OUT). Both areas require ventilation and the air flow must stream from the clean zone to the dirty zone to prevent potentially contaminated air from the dirty zone being circulated in the clean zone. This can be achieved by pressurizing the clean area or exhausting the dirty area.

At the entrance, there should be a hand washing basin equipped with an eye washing station, vital in case of accidental splashing of disinfectant or any harmful fluid. Soap and hydro-alcoholic gel dispensers should have an automated dispensation which avoids contaminating taps or bottles with soiled hands. It is recommended to pat dry hands with paper tissues.

Reprocessing area

The configuration of each workspace and device will follow the reprocessing steps i.e. pre-disinfection, rinsing, cleaning, rinsing, drying, packaging and sterilization. This room shall not be used for any other purpose. Floors and working surfaces shall be smooth, avoiding sharp corners and edges and be easy to clean and disinfect.

Waste

Waste should be disposed of into bags or containers through openings in the bench. Sharps and cutting items must be safely disposed of in specific plastic containers to protect staff, be collected and processed by specialized companies in treating contaminated waste. It is imperative to follow your local national guidelines as they may vary from country to country.

Pre-disinfection – Soaking

In order to prevent blood, saliva and debris from drying, all used and non-used instruments shall be soaked as soon as possible after the procedure, using one or more disinfecting containers depending on the number, type and size of the instruments i.e. a small one for burs and files, bigger one(s) for bulk of items, kits or cassettes, etc. Note the manufacturer’s guidelines NOT to immerse or soak transmission instruments in solutions! The manufacturer’s guideline on the concentration and contact time of the chemicals must be strictly observed.

The temperature of the solution shall not exceed 40-45°C, thus preventing coagulation of blood proteins which increase the challenge of cleaning. Another benefit of this crucial first step is the reduction of the microbial population, decreasing the risk of infection during handling and cleaning. A basin will permit rinsing of the instruments with tap water aiming to removal any residual chemicals particularly in hollow and hinged items. Chemical residues could lead to irreversible staining and damage to instruments should a thorough rinsing step be missed.

Cleaning

The cleaning step is of utmost importance. Mechanical cleaning by means of an ultrasonic cleaner offers a good level of performance.

Note: Manual cleaning is the least efficient method of cleaning particularly for complex or hollow instruments and rough surfaces. The degree of cleanliness relies on the operator's experience and appreciation and also raises the risk of staff injuries and infections.
In order to remove chemicals, all instruments must be rinsed with tap water in a second basin. This would ideally be followed by a second rinse with demineralized water to eliminate residues and salts present in tap water which could lead to whitish stains on sterilized instruments.

Washers or washer-disinfectors offer a preferred cleaning method thanks to the higher performance of the cleaning cycle validated by the manufacturer in compliance with stringent applicable standards (i.e. ISO-EN15833-1/-5). The cycle process includes pre-washing, rinsing, washing and drying which allows free space on the bench, sparing the soaking container/s and one basin. It is wise to keep the second basin.

Buffer bench space after cleaning

Next to the washing station, space is reserved to check the dryness and integrity of all instruments. Compressed air will assist drying hinged instruments (scissors, forceps, etc.) which may also require periodic lubrication. Transmission instruments will be maintained at the same place. Internal and external cleaning as well as lubrication should be mechanically assisted by means of an automated process validated by the manufacturer. It is virtually impossible to manually complete internal cleaning.

Packaging – Sterilization

An area should be considered for a pouch sealing device as well as an area for the temporary storage of packages prior to process in the bench top sterilizer. To ensure safe and efficient sterilization it is crucial to check the load and cycle–type for compatibility. Selecting a cycle which is not designed and validated for the type of load (instruments) will lead to non-sterile products. Additional space beside the sterilizer is intended for cooling and labeling of packages which have been released by the operator for storage and use. Special attention shall be paid to this last check making sure pouches are hermetically sealed and are completely dry. Non dried instruments/packages are not acceptable as sterile.


For extended storage time, pouched items should be stored outside the reprocessing area and surgery (operatory) in clean and dry drawers or cabinets. In doing so, single pouched items could be stored for 3 months which is the most common storage time. It can be different depending on local regulations.

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Conclusion

I would like all readers reflect on these two definitions:

Reprocessing:
„All activities required to ensure that a used medical device is safe for reuse" (ADA Guidelines for Infection Control - 2012)."

Sterilization:
„"validated process used to render a product free from viable microorganisms".
"…the presence of a viable microorganism on any individual item can be expressed in terms of probability. This probability may be reduced to a very low number; it can never be reduced to zero." (ISO/TS 11139:2006).

In other words; the better each step is accomplished, the closer to "zero".

Always bear in mind that each step of the reprocessing cycle is important. None shall be rushed or skipped which would compromise sterility and the safety of patients and staff.

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