Preventative measures for prion diseases

Prions are infectious agents with unconventional characteristics: they’re smaller than viruses and are incredibly resistant to standard procedures applied in dental clinics to remove or inactivate viruses, bacteria, fungi or other known micro-organisms.

In this article, we will explain the risks associated with prion diseases and how to deal with potentially infected tools correctly, to ensure that your dental clinic is as safe as possible.

The term ‘prion’ (Proteinaceus Infective Only Particle) was coined to emphasise the hypothesis that the infectious agents comprise of proteins alone, with no nucleic acids present.

Their ultra-microscopic structure is different to that of viruses and, as such, they cannot be considered or treated as viruses, fungi, bacteria or parasites.

3 things to know about prions:

• Prions are 10,000,000 times smaller than bacteria cells.
• It’s very difficult for traditional detergents, disinfectants and water molecules to penetrate the nucleus
• Many treatment systems are ineffective in rendering them non-infectious.

The way in which prions infect people is caused by a certain alpha and beta protein that has been misfolded, which causes other proteins to assume the same abnormal structure. These proteins are then able to infect adjacent proteins.

In short, prions are proteins that exist in two different forms; one is normal and the other is mutated. Once the mutated form takes hold, the prions can induce other normal prions to convert into the mutated form. As a result, a small number of abnormal prions can infect a whole population of normal prions and convert them, one by one, into mutated proteins.

This can have very serious consequences as levels of mutated prion proteins gradually increase in the body. For example, when the PrP misfolds, it leads to the fatal degeneration of the nervous system in both humans and other mammals.

Prions are responsible for transmissible spongiform encephalopathies (TSEs), which are fatal neurodegenerative diseases in humans. These include:

• Creutzfeldt-Jakob disease (CJD)
• Gerstmann–Sträussler–Scheinker syndrome
• Fatal familial insomnia or sporadic fatal insomnia

In dentistry, the transmission of prion diseases is essentially linked to contact being made with potentially infected tissue—as the diseases are not transmitted through the air or by external contact—and the fact that prions are particularly resistant to standard decontamination procedures.

Prions have demonstrated that they are particularly resistant to standard inactivation procedures, both physical (heat and UV rays) and chemical (such as treatment with phenol, chloroform, formaldehyde and alcohols).

This resistance, together with the severity of the diseases, means that special procedures must be strictly adhered to when treating equipment (surgical instruments and accessories) used for at-risk procedures.

To effectively prevent the spread of disease, dental clinics must, where possible, use disposable equipment. When this is not possible, stricter-than-normal decontamination and sterilisation procedures must be applied.

This can be achieved with prolonged sterilisation in a Class B autoclave.All instruments used for invasive procedures should be sterilised using the prion cycle (134°C for 18 min) or chemical procedures capable of hydrolysing proteins (highly concentrated sodium hypochlorite or hydroxide).

Here is a summary of our recommended steps for treating prion-contaminated equipment (follow them in order):

1. Immediately after use, place the instruments in a 1 M sodium hydroxide solution for 1 hour at room temperature, kept separate from your other instruments stored in a disposable container;
2. Wash your instruments thoroughly, preferably using an automatic washer (ultrasonic tank); dry, without using compressed air, and pack (we recommend using a Thermodisinfector);
3. Run a “special” 18-minute cycle at 134°C in a class B autoclave (with steam sterilisation and fractionated vacuum for porous loads) without adding any other instruments to the same cycle, or 6 consecutive cycles at 134°C for 3.5 minutes each;
4. Treating them as “dirty instruments”, sterilise your tools completely by washing them, packing them and sterilising them again as you normally would when carrying out your routine procedure.

The Pro System line accounts for all steps in the sterilisation process, creating a system of machines and devices that are well connected and highly innovative. Thermodisinfection, ultrasonic washing and autoclave treatment: learn how to sterilise your equipment thoroughly in a way that is safe and efficient, which will also help prevent prion diseases from spreading.

Ultrasonic tanks and Thermodisinfectors

Our new Pro System ultrasonic tanks improve, automate and speed up the cleaning of dental tools, reaching every area and removing even the most stubborn residue.

Thermodisinfectors are very important when sterilising your tools, especially during the cleaning stage: in one cycle alone, they will pre-wash, wash, disinfect and dry your equipment, eliminating the need to clean your tools by hand and the risks associated with it.

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Class B autoclaves

All class B autoclaves from the Pro System line are designed and created to fully reflect Euronda’s philosophy: constant innovation to protect dentists, assistants and patients throughout the world.

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Euronda also offers Monoart® and Alle: two lines of disposable products and disposable surgical equipment with a wide range of accessories, solutions and tools to protect dentists, assistants and patients.