The Standards for Dental Clinics (March 2024) sets out the sterilisation chain as: clean → disinfect → dry → pack → sterilise → check load → store. Standard 1.1f/g requires pre-sterilisation items to be kept in a dedicated area. Each step is unidirectional — no backtracking, no shortcuts. Validation of the sterilisation process (Standard 5.1), cycle parameter checks (Standard 5.4), and completed load verification (Standard 6) are documented at each cycle. This guide details the chain in full for Maltese dental practices preparing for HCSD inspection.
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). The Standards for Dental Clinics (March 2024) sets out the chain as: clean → disinfect → dry → pack → sterilise → check load → store, with pre-sterilisation items kept in a dedicated area (Standard 1.1f/g).
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. Washer-disinfectors should comply with EN ISO 15883; automated cleaning is preferred 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 (per the Standards for Dental Clinics — or evidence-based equivalent) to sterilise hollow instruments (turbines, contra-angles) and wrapped loads, validated per EN ISO 17665-1. 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, the Standards for Dental Clinics expects a Bowie-Dick or Helix test to validate proper autoclave function. Cycle parameter checks once each load is completed (Standard 5.4) and completed load verification (Standard 6) are documented for every cycle. 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. The Standards for Dental Clinics (March 2024) specifies Class B steam sterilisation (or evidence-based equivalent) for hollow and wrapped instruments: Class 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. The Standards for Dental Clinics requires pre-sterilisation items to be kept in a dedicated area (Standard 1.1f/g) — the dedicated-area discipline mirrors the post-sterilisation storage discipline. Unwrapped instruments processed alongside wrapped loads should be used promptly rather than stored.
Each cycle is recorded in the sterilisation register with: date, time, cycle number, parameters, result, and operator identity. The autoclave report is retained. Sterilisation records must be maintained and accessible for inspection. A digital register links each instrument to its cycle automatically, completing the traceability chain.
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