A look at how disinfection and decontamination relates to dental handpieces.
Cleaning and disinfection of dental handpieces has never been more important. As the industry comes to terms with a new operating paradigm, staff and patients need to be sure that equipment is safe.
Although the most common routes of transmission for Covid-19 are via direct transmission, such as a cough or a sneeze and subsequent droplet inhalation, and contact transmission (particularly with the nose, mouth and eyes), evidence is emerging all the time of airborne aerosol transmission and transmission via saliva.
Some dental procedures can generate saliva droplets and aerosols which have the potential to contaminate anyone exposed to them or be inhaled. In addition, saliva contaminated droplets and aerosols have the potential to contaminate inanimate surfaces in a dental clinical setting.
This isn’t a fleeting problem; the virus can remain infectious in the air for hours and remain active on inanimate surfaces for several days.
Dental handpieces are the most frequently used devices in restorative dental surgery. Drills have been with us since 1875 and the first air turbine was demonstrated by former US Navy dental officer John Borden in 1956.
The widespread adoption of low and high-speed dental handpieces has revolutionised patient care. But the methods used to disinfect and sterilise such intricate devices remain subject to debate. As the dental industry comes to terms with a new way of working during a pandemic, especially during the winter months when Covid cases will inevitably increase, there has never been a greater need to ensure scrupulous disinfection procedures are in place.
Whether they use an air turbine or an electric motor to drive the head, today’s hand tools spin at phenomenal speeds (up to 400,000rpm in the case of a variable torque air-driven turbine). The high speeds are required for rapid removal of enamel and tissue, preparing cavities for repair and restoration, but modern tools with their myriad passageways and precision engineered turbines present a major decontamination challenge.
Laura Edgar, managing director of Aura Infection Control, explains, “Naturally, dental handpieces are required to be sterilised between patient use, but they are among the most difficult pieces of dental equipment to decontaminate.”
The biggest headache relates to micro-organisms from the patient’s mouth (which is filled with bacteria, fungi and viruses); the accumulation of particulate matter (mainly debris from restorative materials and hard tissues); even micro-organisms from the water and airlines. And let’s not forget the inevitable collection of blood and saliva within the handpiece chamber itself, including the turbine blades, gears, air and waterlines. Potentially, they are the perfect hiding place for the coronavirus. No wonder handpieces pose such a challenge for cleaning, decontamination, and sterilisation.
As Laura explains, “Dental handpieces are extremely difficult to clean, inspect and sterilise due to the small size and the length of lumens, as well as the myriad of other intricate working parts which require regular maintenance and lubrication to function efficiently.”
The cooling waterways can be contaminated by re-suction after a handpiece is stopped; blood and saliva are momentarily sucked back inside the tool. If it isn’t properly cleaned the next time the turbine is used it transfers that material to the next patient. And because handpieces have to be dismantled for oiling and inspection, fouled equipment poses a potential health risk to staff as well.
Handpieces should be sterilised between patients and sterilisation should be performed following cleaning. A handpiece cleaned with a disinfectant wipe can look spotless externally – but no one knows what hazards may be lurking inside. Both external and internal surfaces become contaminated during normal use.
The majority of dental surgeries now routinely autoclave handpieces between patients as a part of the infection control protocol – but during the coronavirus pandemic, it pays to be extra careful.
Laura says, “A handpiece can look spotless on the outside and operate perfectly – but hollow instruments with narrow internal lumens require meticulous decontamination as well as rigorous maintenance. How can you be sure that a handpiece is clean inside and out? It can be sterilised, but it still might not be clean. A poorly cleaned handpiece poses a cross-infection risk. That’s bad news at any time, but during the current pandemic it’s a major problem with very serious health implications.”
Aura recommends the Alpro WL series of products for cleaning and disinfection of single and contra-angle handpieces and turbines. The system consists of three products: WL Clean, WL Cid and WL dry. Used together these products can thoroughly clean and disinfect handpieces inside and out. All of them comply with the highest cleaning (EN ISO 15883) and disinfection requirements and have been thoroughly tested and approved by several manufacturers.
WL Clean solution is ready for use for the inner cleaning of medical and dental hollow part instruments such as turbines, handpieces, and all internally cooled instruments prior to disinfection/sterilisation. The product is both bacteriostatic and fungistatic.
WL Cid is used for the inner disinfection of handpieces and turbines. It contains a bactericide, yeasticide and a virucide capable of killing non-enveloped polio-, adeno- and noro-viruses as well as all enveloped blood-borne viruses, such as HBV, HCV, HIV, and influenza. WL Dry is a medically safe inert drying spray for the removal of residues of cleaning and disinfection agents and maintenance products and drying of spray channels and inner surfaces.
“Alpro products are recommended by handpiece manufacturers because of their quality and reliability,” says Laura. “What’s more, it isn’t a complex process and it can be easily added into an existing disinfection process with the minimum disruption. It’s the missing ingredient in the processing of dental handpieces.”
NHS England has issued guidance to dental practises operating during the coronavirus pandemic.
Risk mitigation measures include appropriate PPE, following IPC and decontamination guidance (including social distancing, hand and respiratory hygiene), as well as thorough cleaning and decontamination of the environment and equipment.
It adds, “Particular care should be taken to avoid surgical extractions at this time. Where it is necessary to remove bone, slow handpieces should be used with irrigation to reduce the risk.”
As for general decontamination advice, it says, “Decontamination of equipment and the environment following dental treatment should follow HTM 01-05.
“Decontamination of equipment and the care environment must be performed using either: a combined detergent/disinfectant solution at a dilution of 1,000 parts per million available chlorine (ppm available chlorine (av.cl.)) or a general-purpose neutral detergent in a solution of warm water followed by a disinfectant solution of 1,000ppm av.cl.
“If alternative cleaning agents/disinfectants are to be used, they should conform to EN standard 14476 for viricidal activity and only be used following the advice of the IPC team. Products must be prepared and used according to the manufacturers’ instructions and recommended product ‘contact times’ must be followed.
“Dedicated or disposable equipment must be used for environmental decontamination and disposed of as infectious clinical waste.”
Laura believes the dental industry is well placed to meet the challenges posed by a global pandemic because dentistry is built on careful contamination control. But she says, “The coronavirus threat has forced everyone to re-evaluate their processes and the issue of cleaning handpieces has posed many questions. These products are a solution to these problems. They are well-established, well-supported and we are able to demonstrate their efficacy. The questions dentists should be asking is not ‘can I afford to add this to my cross-contamination control process’ but ‘can I afford not to add them to my control processes’.