The sterilisation chain is the unidirectional workflow that takes instruments from contaminated to sterile — the forward flow principle. HTM 01-05 sets out the requirements for each step, and CQC inspectors verify both the process and its documentation. Here is the complete chain for dental practices in the UK.
The forward flow principle is the fundamental concept of sterilisation: instruments always progress from dirty to clean, then from clean to sterile, without ever going back. This unidirectional flow prevents the recontamination of instruments already processed. In a dental practice, this requires rigorous spatial organisation (separate zones) and temporal organisation (steps in the correct order). HTM 01-05 requires adherence to this principle, and CQC inspectors assess the decontamination workflow as part of the Regulation 12 assessment.
Immediately after use, instruments are immersed in a decontamination bath (enzymatic or detergent-disinfectant solution). This step reduces the initial microbial load and protects staff during subsequent handling. Soaking time varies depending on the product used (typically 15 to 30 minutes). Rotary instruments (turbines, contra-angles) follow manufacturer instructions — some require lubrication before cleaning.
Cleaning removes organic residue (blood, saliva, debris) that would prevent effective sterilisation. Two methods are used: manual cleaning (brushing under running water with a suitable detergent) and automated cleaning (ultrasonic bath or washer-disinfector). Ultrasonic cleaning is preferred — it reaches areas that manual cleaning cannot. HTM 01-05 recommends automated cleaning wherever possible.
After cleaning, instruments are rinsed thoroughly with clean water to remove all detergent residue, then dried completely. Residual moisture interferes with the sterilisation process — wet instruments in a pouch can compromise the cycle.
Each instrument is visually inspected under good lighting for residual debris, corrosion, or damage. Instruments that fail inspection are returned to cleaning. Approved instruments are placed in sterilisation pouches, sealed, and marked with a process indicator (autoclave tape). Each pouch is labelled with the date and cycle number.
The reference cycle for dental instruments is 134°C for 18 minutes (prion cycle), mandatory for instruments in contact with nervous or lymphoid tissue. The autoclave must be Class B (Type B vacuum steriliser, as recommended by HTM 01-05) to sterilise hollow instruments (turbines, contra-angles) and wrapped loads. The autoclave prints a report at the end of the cycle — this report is the proof that parameters were reached.
Before the first load of each working day, HTM 01-05 requires a steam penetration test (Helix or Bowie-Dick) for Type S and Type B vacuum sterilisers. A failed test means the autoclave must not be used until the problem is resolved.
Dental turbines, contra-angle handpieces, and ultrasonic scaler tips are hollow instruments — steam must penetrate internal channels to ensure sterilisation. HTM 01-05 recommends a Type B vacuum steriliser with a pre-vacuum cycle for hollow and wrapped instruments: Type N autoclaves do not reliably sterilise hollow loads.
Turbines require particular attention: lubrication per manufacturer's instructions before cleaning, use of the Helix test (not Bowie-Dick) to validate steam penetration into channels, and individual packaging in appropriately sized pouches. A failed Helix test means hollow instruments in the load are not sterilised — even if the autoclave report shows "cycle passed." For details on autoclave testing, see the biological controls guide.
Sterilised pouches are stored in a clean, dry, enclosed space away from dust and moisture. The first-in, first-out (FIFO) principle applies. HTM 01-05 specifies that unwrapped instruments must be used on the day of sterilisation — storage of unwrapped instruments is not permitted. Wrapped instruments that are date-stamped may be stored for up to 1 year.
Each cycle is recorded in the sterilisation register with: date, time, cycle number, parameters, result, and operator identity. The autoclave report is retained. HTM 01-05 requires every machine to have its own dedicated logbook, and records must be kept for a minimum of 2 years. A digital register links each instrument to its cycle automatically, completing the traceability chain.
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