Disinfection of Dental Instruments

This article aims to refresh the reader’s knowledge of decontamination in dentistry.


By the end of this Article you should be able to:

- Discuss what is meant by instrument disinfection
- Describe the instrument disinfection process
- Discuss what requirements must be met by dental practices in respect to instrument disinfection
- List the types of sterilisers used in dentistry

Decontamination in Dentistry
Decontamination is the process by which reusable items are rendered safe for further use and for staff to handle. Decontamination is required to minimise the risk of cross-infection between patients and between patients and staff. (DOH, 2013)
What is decontamination of dental instruments?
Decontamination of instruments (also known as reprocessing) is a complex process that involves several stages, including cleaning, disinfection, inspection and a sterilization step. The diagram below summarises how the individual stages ideally link together to complete the process of instrument decontamination.


Compliance with HTM 01-05
The HTM 01-05 which stands for Health Technical Memoranda is one of several guidance documents in a series if Health Technical Memoranda which give comprehensive advice and guidance on the design, installation and operation of specialised building and engineering technology used in the delivery of healthcare. On 28th March 2013 the 2009 HTM 01-05 document was superseded by the new 2013 edition.

To help dental practices to improve their decontamination procedures the HTM 01-05 describes the specific benchmarks by which compliance with essential quality requirements and best practice can be achieved and demonstrated.

Essential Requirements Vs Best Practice
Essential quality requirements are a level of compliance expected as a result of HTM 01-05 implementation. Guidance contained within the HTM 01-05 document will assist dental practices in maintaining these requirements and developing towards higher levels of achievement in this area over time. In order to demonstrate compliance with essential quality requirements, practices will be expected to provide a statement on plans for future improvement.

Best practice refers to the full level of compliance that may be achieved immediately or via a documented improvement from essential quality requirements (DOH, 2013). Dental practices should carry out an assessment of the changes needed to move from compliance with essential quality requirements to compliance with best practice requirements.

Meeting the Essential Quality Requirements
In order to meet the HTM 01-05 (DOH, 2013) essential quality requirements instruments should be reprocessed using a validated decontamination process including a validated steam sterilizer, and at the end of the reprocessing cycle they should be sterilized.

Cross infection control policies
Practices should have in place a local infection control policy subject to update as required by the Code of Practice, or at two-yearly intervals, whichever is the shorter. This policy should contain detailed requirements/procedures for the decontamination of instruments.

The separation of instrument reprocessing procedures from other activities, including clinical work, should be maintained by physical or temporal means. Decontamination equipment including sterilizers should accordingly be located in a designated area. The layout within this area should reflect the progression from the receipt of dirty, used instruments towards clean instruments sterilized in a specific controlled clean area. In the first instance, where practices are meeting the essential quality requirements, the designated area for decontamination may be in, or adjacent to, a clinical room.

Staff involved in disinfection
The practice should have a nominated lead member of staff responsible for infection control and decontamination. Staff involved in decontamination should demonstrate current immunisation for hepatitis B and, subject to local policy, tetanus. Staff must be informed of the benefits (for example protection against serious illness, protection against spreading illness) and drawbacks (for example reactions to the vaccine) of vaccination. A documented training protocol should be in operation with individual training records for all staff engaged in decontamination. Separate wash-hand basins for use by staff conducting decontamination should be provided.

The Movement of Contaminated Instruments
The practice should have safe procedures for the transfer of contaminated items from the treatment to the decontamination area. The department of health (2013) recommend that sterilised instruments and single-use instruments should be clearly separated from those that have been used and are awaiting decontamination. A separate sterilised instrument tray should be used for each patient. These trays should be of a suitable size to enable them to be placed in the steriliser.

Alternatively, single-use instrument trays may be used, provided these have been stored in a clean and dry environment. Instruments for decontamination should be transferred as soon as possible after use to the decontamination area in order to avoid the risk of drying. Prompt decontamination is appropriate. Potable water immersion or the use of commercial gels/sprays may be considered if a delay in reprocessing is unavoidable.

Cleaning Instruments
According to the Department of Health (2013), effective cleaning of instruments is an essential prerequisite before sterilization and will reduce the risk of transmission of infectious agents. It is advised that wherever possible, cleaning should be undertaken using an automated and validated washer-disinfector in preference to manual cleaning, as a washer-disinfector includes a disinfection stage that renders instruments safe for handling and inspection. Research suggests that instruments cleaned as soon as possible after use are more easily cleaned than those left for a number of hours before reprocessing.

Manual Cleaning
The Department of Health (2013) state that “manual cleaning, governed by an appropriate protocol, is acceptable within the essential-quality-requirements framework. Within the best-practice framework, however, manual cleaning should be considered only where the manufacturer specifies that the device is not compatible with automated processes (including ultrasonic cleaning) or when the washer-disinfector is temporarily unavailable (for example for repair or validation)”. The reason that manual cleaning is not considered ass best practice is that it is difficult to validate and it can carry a greater risk of inoculation injury to decontamination staff compared with other methods. It is important that there are facilities and sufficient training in manual cleaning as this may be necessary when other cleaning methods are not appropriate or where other automated methods are temporary unavailable as previously mentioned. If the manual cleaning methods is used it is recommended that there should be systems in place to avoid recontamination of clean instruments, an agreed written procedure and a visual inspection for cleanliness, wear and damage should be carried out.

Ultrasonic Baths
Instruments may be cleaned using an ultrasonic bath, but this should be covered during use to restrict the release of aerosols.

Washing and Rinsing Instruments
Instruments cleaned in an ultrasonic cleaner (or in addition by hand) should be rinsed thoroughly in a dedicated sink or bowl (separate from the one used for the original wash) using satisfactory potable water, or freshly prepared RO water or distilled water in order to remove residual soil and detergents with minimum risk of salt deposition.

According to the HTM 01-05 washing and rinsing of instruments can be achieved by:

  • Two dedicated sinks with a separate or shared water supply.
  • One sink with a removable bowl, which can be contained within the sink that can accommodate the instruments for rinsing. This is the least preferred option as it requires lifting and moving bowls of contaminated water with associated spillage risks. The practice should have clear processes and protocols in place to ensure that the removable bowl is not used for the washing of instruments. Note: These sinks should not be used for hand-washing.

All instruments that have been through any cleaning procedure, including processing by a washer-disinfector, should be inspected to ensure they are clean, functional and in good condition. An illuminated magnifier is recommended because it makes it much easier to see residual contamination, debris or damage.

Instruments should be inspected for any visible soiling such as blood or dental materials. It is especially important to check joints, hinges or the serrated surfaces of jaws, which are difficult to clean. If there is any residual contamination, the instrument should be rejected and should undergo another cycle of the cleaning process.
Instruments may become damaged during use or suffer from general wear and tear over their lifespan. If devices are found to be faulty or damaged during inspection and function-testing, or if users identify that they are faulty, they should be taken out of use and either repaired or replaced. Instruments for repair should be decontaminated, labelled to identify they have been through the decontamination process, and then returned to either the manufacturer or a reputable repair company.

Handpiece Care
Handpieces should be lubricated according to the manufacturer’s instructions. Those that have been processed in a washer-disinfector might have had the lubricant removed and require lubrication again before going into the sterilizer. It is recommended in the Department of Health’s guidance (2013) that a separate canister of lubricant should be used for cleaned instruments. The canisters should be labelled so that it is clear which canister is used for unclean instruments and which is used for instruments that have been cleaned in a washer-disinfector. Another canister for use with handpieces after sterilization might be required if the manufacturer recommends it.

Following cleaning and disinfection instruments must then be sterilised. The HTM 01-05 states that “saturated steam under pressure delivered at the highest temperature compatible with the product is the preferred method for the sterilization of most instruments used in the clinical setting”. There are different types of sterilisers available in the healthcare setting, in each case, practice staff should consult with the manufacturer/supplier of the steriliser(s) to ascertain the status of the machine in respect of validation/verification and the recording of parameters achieved during sterilisation cycles.


Instrument storage and wrapping recommendations

  • The 2013 updated version of the HTM 01-05 has it’s main differences with the 2009 version in respect to instrument storage and wrapping. Previous guidance advised that instruments wrapped before or immediately after decontamination not be stored for longer 21-60 days dependant on type of steriliser. Having reviewed patient safety in respect to instrument storage new guidance has been set out by the Department of Health (2013). The advice set out in the HTM 01-05 can be summarised as follows:
  • Wrapped instruments may be stored up to 1 year
  • pre-sterilisation wrapped if type B or S;
  • post-sterilisation wrapped if type N.
  • Unwrapped instruments in the clinical area: maximum storage 1 day.
  • Instruments should be dry and protected from contamination, for example in mini-racks placed in cupboards or in covered drawer inserts. Instruments should not be stored on open work surfaces, particularly in clinical areas. It is important that practices have well developed protocols and procedures in place to prevent contamination of these instruments by ensuring that those required for a particular patient are removed from their protected environment before treatment commences. This eliminates the need to open cupboard doors or drawers during patient treatment.
  • If an instrument does need to be retrieved from a cupboard or drawer during treatment, the practice should have protocols in place to prevent contamination and to ensure that staff hands are clean and that new gloves are donned before handling unwrapped sterilised instruments.
  • Regard all instruments set out for each patient as contaminated after the treatment whether or not they have been used.
  • Instruments that are kept unwrapped should be reprocessed at the end of the working day, regardless of whether they have been used.
  • Alternatively, instruments can be reprocessed at the beginning of the next working day.
  • Unwrapped instruments in a non-clinical area: maximum storage 1 week.
  • Non-clinical area in this context is designated as a clinical area not in current use or in a clean area of a separate decontamination room.
  • Instruments should still be stored as follows: dry; and protected from contamination, for example in mini-racks placed in cupboards, or in covered drawer inserts. Instruments should not be placed on open work surfaces.
  • Develop a quality system approach so that the storage of wrapped instruments does not exceed one year.


Department of Health (2013) Decontamination: Health Technical Memorandum 01-05: Decontamination in primary care dental practices 2013 Edition. London, Department of Health 


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