Protecting your team and patients

02 May 2012
Volume 28 · Issue 5

Malcolm Card provides advice to ensure effective decontamination.

It is important that dental team members follow a strict cross-infection regime in accordance with current infection control guidelines. This will protect themselves and patients from the risk of cross contamination and prolong the useful life of instrumentation.

The use of thermo washer disinfector dryers is currently a topic of much discussion. If you consider the fact that a member of your dental team is manually cleaning soiled and contaminated medical instruments with sharp protrusions, a task which is neither enticing nor effective, the question 'to have or not to have?' becomes clearer.

So why purchase an accredited thermo washer disinfector manufactured for purpose? The thermo-washer should be manufactured from high grade stainless steel, with the chamber of AISI 316 quality; this is to prevent corrosion by ensuring it can cope with the strong detergents used and the heavy amount of use within a busy dental practice.

Thermo washer disinfectors are sophisticated medical devices. Thorough cleaning is achieved by very high water flow rates, created by a powerful pump at high pressure. Process control is an essential feature that regulates and controls the various stages of the cycle. Temperature is regulated to ensure it is below 45°C during the initial stages to prevent possible coagulation of protein; it is then raised to above 60°C at which point the detergent or cleaning agent is introduced into the process. Detergents are formulated and validated for particular machines and developed to take into account the cleaning efficacy for the cycle profile and the necessity to minimise damage to instruments. Once the cleaning phase is complete the machine drains to waste to prevent any damage from residual detergent. The thermal stage starts by further elevating the temperature, typically to just over 90°C, possibly lower if the manufacturer has selected a longer 'hold' time. Drying is then applied to the instruments by several methods, but to keep cycle times to a minimum, the preferred method is by forcing hot air into the chamber in conjunction with a built in condenser which removes the majority of moisture with just a minimal ingress into the decontamination room.

Many users, when looking to purchase a thermo washer disinfector, are unaware of the medical standards and guidance demanded upon the manufacturer, not applicable to a domestic appliance. These are necessary as the machine has to reliably and reproducibly process contaminated items in a medical environment. The cycle must be monitored at all stages and a printed or data record stored for the required period.

Specialist machines have the facility to process a quantity of handpieces using specially designed rack that forces water through the narrow lumens. This should be supplied as standard with a range of appropriate racks and baskets. Whilst it may not be current advice in your area, it is prudent to purchase a machine that has such facilities to fully future-proof your practice or to check that it is available as a retro-fit option in the event that guidance changes.

As with any equipment purchase, your chosen manufacturer's representative will be able to advise you on product specifications and whether it is suitable for your requirements. Take the opportunity to ensure that the quality of the machine satisfies your needs and it is fit for purpose. Check if it has a service and validation protocol for daily and monthly testing by the user and an annual testing protocol performed by your test or service engineer. Look at the cost of consumables which should be readily available from the supplier or distributor and do not be tempted to use non-recommended detergent or accessories as they may not be validated to be effective in a dental environment or work in conjunction with the machine.

Unlike 'Best practice', 'Essential requirements' does not demand automated cleaning, but by integrating a high quality thermo washer disinfector into your decontamination process, you will reduce the risk of sharps injuries to your team, and will be introducing a reproducible, validatable, medically effective washing process, that will ensure you are doing the best you possibly can to reduce the risk of cross infection amongst your patients and your team; that has to be a good thing.

Within the dental practice, practitioners and their teams are all very aware of steam sterilisation of instruments and equipment that are used for invasive procedures. However several important factors are required in order to achieve a sterile state and a safe load:

  1. The sterilisation temperature band, normally 134°C -138°C.
  2. The quality of steam that produces moist heat and a saturated steam.
  3. The time this temperature is held for: a minimum of 3 minutes holding time.

These three critical criteria are where we get the term TST; Time, Steam and Temperature, which you may have seen describing chemical indicators, Helix test kits and Bowie Dick packs.

Very often air removal is a subject is overlooked but without this important phase none of the above criteria would be totally effective in sterilisation.

There is no debate about the fact that handpieces are hollow instruments. Therefore the instructions for use recommend the use of a vacuum machine. We are all taught at school that water boils at 100°C (or 212°F) yet our instruments need to be sterilized between 134°C and 138°C. This means that we have to raise the temperature of the steam by putting it under pressure – and the steam has to touch all surfaces of the instrument to achieve sterilisation. With a hollow instrument, this means that the steam has to contact all of the surfaces within the internal tubes – and this cannot be done within the three minute holding time if they still have air or fluids in them. A vacuum steriliser will evacuate the internal tubes, leaving the way clear for steam to penetrate. If the instrument was put into a downward displacement (N type) machine instead, air is not removed by drawing it out under vacuum, so is not as complete – which means that there could still be air and fluids remaining within the internal tubes, preventing steam from contacting all surfaces, and hence there is a risk that the instrument could have been through a 'sterilisation cycle' but not actually be sterile.

Pouched loads can remain in a sterile condition for a period of storage prior to use, currently a maximum 60 days according to HTM01-05 guidance.

Although there are many differing view of what the current guidelines require, this article clarifies what should be considered 'Best practice'. For more information regarding the issues of decontamination within your practice, you should contact a specialist decontamination supplier for advice.