Page updated 9 October 2006
Cleaning of Instruments
- Pre-sterilisation cleaning
- sterilisation
- Storage
- Disposable apron/gown
- Visor or face mask
- Household gloves (surgical gloves should not be worn)
- Use a non-foaming detergent (Do not use washing-up liquid, which leaves a residue and the surface foam impedes visibility of sharp instruments)
- Use nylon brushes not green pads or wire brushes. Cleaning equipment (e.g. brushes) should be cleaned and sterilized (or alternatively use disposables) and stored dry between use. Brushes should not be stored in disinfectant solutions
- Cloths for cleaning and drying equipment should be non-shedding and disposable.
- Titanium and stainless steel instruments should not be processed together
- Fill basin with luke warm water. (water hotter than 35 0 C will coagulate proteins and inhibit their removal)
- Instruments should be fully immersed and cleaned below the waterline to reduce aerosol formation. Avoid scrubbing under running water.
- Disassemble multi-part instruments, pay attention to crevices and joints. (Multipart instruments can be kept together with elastic bands).
- Final rinse under hot water
- Always visually inspect instruments for residual debris or blood after cleaning and repeat if necessary . Any residual dirt or organic material will interfere with the disinfection or sterilisation process
- Dry instruments with lint free cloth e.g. disposable paper towel. Wet instruments should not be placed in the sterilizer as the water inhibits the sterilisation process
- Store in clean receptacle ready for sterilisation
- Rinse off blood or other gross contamination by immersing instruments under warm not hot water (do not rinse by running under a tap as this creates contaminated aerosols)
- Place instruments in a basket. Open or dismantle instruments if appropriate
- Always use in accordance with manufacturers instructions. A typical setting would be 20 to 40 o C for 3 minute, which minimizes the rate of coagulation of proteinaceous material or use default temperature setting.
- Use the detergent at the dosage as recommended by manufacturer (e.g. low-foaming enzymic, effective at low temperatures)
- Rinse thoroughly to remove detergent residues, by immersing in clean water (unless machine has an automatic rinse cycle)
- Drain and dry items
- Always inspect instruments for residual debris after cleaning and repeat if necessary Empty bath at least twice daily (every 4 hours or before solution becomes heavily contaminated)
- Only operate with the lid on.
- Empty, clean and dry bath at the end of the session/day
- Perform a weekly validation test to confirm ultrasonic action e.g. the aluminium foil test. A 5cm 2 foil strip is held using forceps in the centre of the bath for 3 minutes. Inspect the foil. The edges of the foil should be serrated with pitting and /or perforation of the centre of the strip. Alternatively use a commercial kit, which shows a colour change if the ultrasonic bath is producing sufficient cavitation (e.g.Sono-check; Medisafe). Record the results.
- A qualified test person should regularly maintain and test the ultrasonic bath
- Flush handpiece with water for 20 seconds before removing from the coupling
- Remove bur or rotary instrument
- Never clean or immerse in disinfectant, or place in ultrasonic bath. Do not use detergents containing chlorine as it will corrode the handpiece. Use detergents with a neutral pH (according to manufacturer's instructions).
- Carefully wipe outer surface of the handpiece using an alcohol wipe (isopropyl alcohol or 80% alcohol) for recommended contact time and allow to air dry
- Dry water channel with compressed air. Dry outer casing with a non-linting cloth
- Check that the service oil canister has the correct nozzle attachment for the handpiece and that the O-rings (if present) on the nozzle are intact. O-rings prevent back-flushing and spraying of oil onto the operator.
- Shake the oilcan vigorously so that it mixes the oil, cleaning solvent and propellant mixture. Place oilcan on a flat hard surface. Hold a soft absorbent paper towel around the head of the handpiece and insert the nozzle into the handpiece
- Spray service oil once (approximately 1 second) through the lumen onto the disposable soft paper towel
- Place handpiece with head downwards in a rack to drain off excess oil
- Clean off any excess oil with an absorbent cloth
- Steam sterilize at 134-137 0 C for 3 minutes
- If the handpiece manufacturer recommends post sterilisation lubrication of the handpiece, then use a separate canisters of oil for pre and post sterilisation lubrication
Three stages of decontaminating dental instruments
All instruments selected for use even if they were not actually used must be cleaned and sterilized. Steam sterilisation is the most practicable method for sterilizing reusable
dental devices because it has high lethality, is rapid and non-toxic. The need for cold sterilisation has almost disappeared in the dental surgery, as most items of equipment can now be steam sterilized or have been replaced with single use disposable items.
There are three stages in the decontamination of dental instruments and equipment:
Pre-sterilisation cleaning of dental instruments
If instruments are not clean they cannot be sterilized effectively. Cleaning lowers the bacterial load on a used instrument by log 10 3-4 i.e. by a thousand fold. Cleaning may be done either manually or by machine using an ultrasonic bath and/or a thermal washer disinfector. Best practice is to use an automated washing process. The BDA, Department of Health Estates & Facilities Directorate and the Medicines and Healthcare products Regulatory Agency (MHRA) all recommend automated cleaning whenever practical with a thermal washer/disinfector, as it is reproducible, and more easily controlled and validated than manual cleaning. Studies have demonstrated that washer/ disinfectors are more efficient at reducing the bacterial load during pre-sterilisation cleaning than either ultrasonic cleaning or hand cleaning of dental instruments. Staff safety is enhanced as handling of sharp contaminated instruments is significantly reduced, as instruments do not need to be scrubbed so there is less exposure to microorganisms and noxious chemicals. Furthermore, productivity is increased as more time becomes available for clinical activities. However, depending on the cycle time of the thermal washer disinfector the turn round time for instruments may be increased and additional instruments may therefore be required. The approximate down time for instruments cleaned in a thermal washer disinfector and sterilized in a vacuum sterilizer is 2 hours. If possible, when purchasing new items of equipment select devices that can be machine cleaned and thermally disinfected and sterilized .
Manual cleaning
Staff should be provided with a written policy for manual cleaning and trained appropriately. Instruments should be cleaned as soon as possible after use. If saliva and blood are allowed to dry on instruments, the cleaning process becomes more difficult. Blood is corrosive to stainless steel instruments and will cause pitting and rusting if left for any length of time. Damaged and pitted instruments are more difficult to clean effectively and corrosion may reduce the life of the instrument. If it is not practical to clean the instruments immediately then pre-soak them in a non-ionic or enzymatic detergent solution, or pre-cleaning foam.
A dedicated deep sink (not a hand basin) should be used for decontamination of instruments preferably with a separate sink for rinsing. Manual cleaning should be undertaken in a safe and effective manner. Always take great care with sharp instruments. Before cleaning the instruments the member of staff should put on the following protective clothing:
Cleaning technique:
To clean instruments safely and effectively use the following method:
Mechanical cleaning with ultrasonic bath
Ultrasonic cleaning baths offer an effective method for cleaning intricate, jointed or serrated stainless steel and metal instruments and items that are heavily soiled e.g. with cement. Plastic instruments are not successfully cleaned by this method as they absorb the ultrasonic energy . Remember the ultrasonic bath only cleans, it will not disinfect instruments. The following are some key guidelines: -
Thermal Washer disinfectors
Small benchtop versions suitable for use in dental surgeries can be loaded with instruments in cassettes, trays or baskets and come supplied with connectors for a pressure flush of dental handpieces. The size, model and type chosen depend on the practice's workload, number of instruments, throughput volume and time requirements, as well as available space. Domestic dishwashers are not an acceptable alternative. They do not perform to the same specifications as washers/ disinfectors, may not adequately clean the inner surface of hollow or lumened instruments, and nor are they capable of validation in accordance with HTM 2030 (see www.dh.gov.uk for additional guidance on validation testing and protocols).
The washer disinfector cycle includes a cool -prewash (below 35 O C to prevent protein coagulation and remove debris) main wash, rinse, thermal disinfection and post- disinfection rinse. Thermal disinfection is achieved by the use of hot water (set between 80-90 O C) coming into in direct contact with the instruments and equipment for a specified period of time. This reduces the number of viable microorganisms contaminating the devices but may not necessarily inactivate some viruses and bacterial spores, so instruments are not sterile.
Validation of the cycle
Thermal washer disinfectors are required to operate to HTM2030 specifications and Model Engineering Specifications C31. Machines are designed with independent monitoring or "watchdog circuits" that are separate from the machine control system. Watchdog circuits monitor the detergent dosing verification, detergent cleaning cycle and thermal disinfection cycle and will alert the operator of any failures or malfunctions, either on the display screen and/or on the print out; and will abort the cycle if errors are detected. Models should be fitted with a printer (and some also have computer links) for maintaining a permanent record of the operation parameters and performance indicators of the disinfection cycle. The detergent formulation and concentration is critical and the washer disinfector must be capable of detecting any deviations and altering the operator to a failed cycle. The cycle must include a drying stage. Quarterly performance and function testing is performed by Competent Test person.
Cleaning of dental handpieces
Pre-sterilisation dental handpiece cleaning machines
Pre-sterilisation dental handpiece cleaning machines are recommended by the BDA. These devices vary in design and sophistication but all clean and lubricate the internal components of the handpiece. A typical machine cleans the air and water channels with the aid of a detergent spray solution, followed by cleaning and lubricating the bearings and gears with oil, and finally the excess oil is purged and the interior dried with compressed air. The process takes about 35-40 seconds. Manufacturer's advice on which type of detergent is compatible with their handpiece equipment should be sought prior to using the cleaning machine. Some models also include a handpiece vacuum sterilisation stage.
Thermal washer/disinfector safe handpieces
Many of the contralateral, straight and turbine handpieces currently available are thermal washer/disinfector safe. Only instruments designated by the manufacturer as being suitable for cleaning in a washer disinfector and carry the washer-disinfector symbol can be processed in a thermal washer disinfector. Remember to lubricate with service oil after the thermal washer disinfector stage.
Manual cleaning of dental handpieces
A suggested manual cleaning procedure is set out below. Manufacturers may offer different advice for their equipment, which should be followed, and will vary according to the age and design of the handpiece. Wear protective clothing e.g. heavy-duty gloves, goggles/visor, and a mask. Handpieces run by an electric motor do not require oil lubrication .
A method for manual cleaning of dental handpieces:
External cleaning of handpiece
Internal cleaning of handpiece
Instrument Inspection
Instruments should be function tested as part of the decontamination process. Instruments that are damaged should be repaired or taken out of service. Instruments that develop or sustain surface damage due to general wear, pitting or corrosion encourage dirt and bacteria to accumulate and are more difficult to clean and sterilize effectively. Furthermore they may be more prone to failing during function and could potentially harm patients or staff.
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