Dental sterilizer monitoring · United States
Requalifying a sterilizer after a failure, repair, move or install
Requalifying a sterilizer means running a fresh test series before it goes back to work: three consecutive spore tests (biological indicators) for each cycle type you use, plus three Bowie-Dick tests on a pre-vacuum steam sterilizer (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
The series is due after installation, a relocation, a redesign, a major repair or a sterilization failure (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices). Where CDC's own texts disagree — empty chamber or fully loaded — follow the instructions from the maker of your sterilizer and record which state each cycle ran in.
When a sterilizer must be requalified
“All steam, ETO, and other low-temperature sterilizers are tested with biological and chemical indicators upon installation, when the sterilizer is relocated, redesigned, after major repair and after a sterilization failure has occurred”
Source: CDC/HICPAC, guideline for disinfection and sterilization in healthcare facilities (2008), sterilizing practices.In plain words: steam, ethylene oxide (ETO) and other low-temperature sterilizers all get biological and chemical indicator tests at five moments — installation, relocation, a redesign, a major repair, and after a sterilization failure (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
Two limits travel with that sentence:
- It covers steam, ETO and other low-temperature sterilizers, so the five triggers belong to those kinds of units (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
- It names “major repair” without defining it. This page's sources hold no definition, so the instructions from the maker of your sterilizer are the place to look.
What the test series looks like
“Three consecutive empty steam cycles are run with a biological and chemical indicator in an appropriate test package or tray. Each type of steam cycle used for sterilization (e.g., vacuum-assisted, gravity) is tested separately. In a prevacuum steam sterilizer three consecutive empty cycles are also run with a Bowie-Dick test.”
Source: CDC/HICPAC, guideline for disinfection and sterilization in healthcare facilities (2008), sterilizing practices.In plain words: three cycles in a row, each one carrying a biological and a chemical indicator in an appropriate test package or tray (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices). Each type of steam cycle you use is tested on its own — e.g., vacuum-assisted and gravity get their own series (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices). And on a pre-vacuum steam sterilizer, three empty cycles with a Bowie-Dick test are added to the series (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
The Bowie-Dick cycles belong to a prevacuum steam sterilizer, so a gravity unit does not run them as part of requalification (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices). If you are new to the test itself, the guide to which dental sterilizers need the Bowie-Dick test, and how often covers it.
Empty chamber or fully loaded: CDC's texts disagree
The three requalification cycles are not worded the same way in every CDC text. Here they are side by side, in CDC's own words.
| CDC text | What it says |
|---|---|
| 2003 dental guidelines | “rechallenge the sterilizer with biological indicator tests in three consecutive empty chamber sterilization cycles after the cause of the sterilizer failure has been determined and corrected”Source: CDC, 2003 dental infection-control guidelines, recommendation VI.F.9.cChamber: empty |
| 2024 dental page | “If the repeat spore test result is positive, remove the sterilizer from service and do not use until it has been inspected or repaired and re-challenged with spore tests in three consecutive fully loaded chamber sterilization cycles.”Source: CDC, 2024 best practices for sterilization monitoring in dental settingsChamber: fully loaded |
So the texts disagree: one runs the three cycles in an empty chamber (CDC, 2003 dental infection-control guidelines, recommendation VI.F.9.c), and the 2024 page runs them fully loaded (CDC, 2024 best practices for sterilization monitoring in dental settings). This page does not pick a side.
What to do about it: follow the instructions from the maker of your sterilizer, and record which chamber state each requalification cycle ran in. That is advice, not a quoted rule — this page's sources do not settle the disagreement. Dental Logbook records the chamber state on every requalification cycle and never chooses one for you.
When the sterilizer goes back in service
After a failed spore test, two paths lead back. The short one turns on the repeat test:
“If the repeat spore test is negative, and mechanical and chemical indicators are within normal limits, put the sterilizer back in service”
Source: CDC, 2003 dental infection-control guidelines, recommendation VI.F.8.c.In plain words: a negative repeat spore test, with the mechanical and chemical indicators within normal limits, puts the sterilizer back in service (CDC, 2003 dental infection-control guidelines, recommendation VI.F.8.c).
“Do not use the sterilizer until it has been inspected or repaired or the exact reason for the positive test has been determined”
Source: CDC, 2003 dental infection-control guidelines, recommendation VI.F.9.a.In plain words: after a positive repeat test, the sterilizer stays out of use until it has been inspected or repaired, or until the exact reason for the positive test has been determined (CDC, 2003 dental infection-control guidelines, recommendation VI.F.9.a). The three-cycle rechallenge then comes after the cause of the failure has been determined and corrected (CDC, 2003 dental infection-control guidelines, recommendation VI.F.9.c).
Back in service after requalification means the whole series is recorded as passed: three consecutive negative spore tests per cycle type, and on a pre-vacuum unit the three Bowie-Dick tests. A good log marks the sterilizer back in service only then, with the date and the name of the person who released it.
The whole failure path — the repeat test, the loads to recall, and the questions to ask — is in what to do when a dental sterilizer fails a spore test.
What to record
A good requalification record holds these. They are product defaults, not quoted rules.
- The trigger and its date: installation, relocation, redesign, major repair, or failure.
- One line per cycle: date and time, sterilizer, cycle type, and the chamber state — empty or fully loaded.
- What each cycle carried: the test package or tray with its biological and chemical indicators, and the result of each.
- On a pre-vacuum unit, the three Bowie-Dick results.
- After a failure: the cause that was determined and the correction that was made.
- Back in service: the date, and who released the sterilizer.
Dental Logbook keeps these fields on one requalification record per sterilizer, with the chamber state on every cycle, and it never asks for patient names.
Where these sources are silent
- What counts as a “major repair”. The trigger sentence names it and stops there (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
- Counts for non-steam units. The trigger sentence covers steam, ETO and other low-temperature sterilizers, but the three-cycle protocol after it is written in steam terms (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices). These sources give no separate requalification count for dry heat or ethylene oxide units.
- State rules. No state rule in this page's source pack sets its own requalification test counts. Routine spore-test schedules are a separate question.
- Where a source keeps a limit, so does this page: the three cycles use “an appropriate test package or tray” (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices), and the cycle-type sentence lists “e.g., vacuum-assisted, gravity” as examples, not as a complete list (CDC, 2008 guideline for disinfection and sterilization, sterilizing practices).
This page is not legal advice; check your state board's current rules.
Guides and tools that go with this one
- What to do when a dental sterilizer fails a spore test — the failure path that can end in requalification.
- The Bowie-Dick test: which dental sterilizers need it, and how often — the air-removal test in the series.
- Free dental sterilizer maintenance log — a printable sheet for the maintenance and service side of the file.
A requalification record that keeps its own history
Dental Logbook is being built to keep these records in one place for US dental offices. Pilot offices shape what it records.
Dental Logbook is in development: join the free pilot