Dental Autoclave Spore Testing: Frequency, Results Log and What RCDSO Inspectors Check
Quick Summary: Written for Canadian dental office managers, IPAC leads and dentists. The Royal College of Dental Surgeons of Ontario (RCDSO) requires a biological indicator (BI) test every day the autoclave is used. This article covers the daily-frequency rule, the weekly-vs-daily distinction, the log sheet fields inspectors review, and the daily workflow that keeps an office audit-ready.
Spore testing — running a biological indicator strip through the autoclave cycle and confirming the spores were killed — is the most important quality check in a dental reprocessing room. A chemical indicator (Class 1 through Class 6) tells you the load reached sterilizing conditions; a biological indicator tells you the spores were actually killed. The two checks are not interchangeable. Canadian regulators and the Public Health Ontario reprocessing guidance both treat biological indicators as the daily load-release floor.
Daily-frequency rule for Canadian dental offices
The RCDSO standard requires a biological indicator test every day the autoclave is used. A practice that runs the autoclave five days a week runs five BI tests. The test must use Geobacillus stearothermophilus spores (the reference organism for steam sterilizers) and must be incubated for the full cycle recommended by the manufacturer — typically 24 hours for traditional readout or 3 hours for fluorescence. Reading the vial at the wrong time is one of the most common RCDSO inspection findings.
Weekly checks vs. daily BI
Weekly checks — Class 1 external indicator on every pack, Bowie-Dick test for vacuum autoclaves, chemical integrator inside each pouch — are not a substitute for the daily BI. The CDC Guideline for Disinfection and Sterilization in Healthcare Facilities and AAMI ST79 describe weekly checks as baseline process control, but they do not replace the daily BI requirement that Canadian dental regulators apply. The right framing: weekly checks are routine process control; the daily BI is the load-release criterion.
What RCDSO inspectors actually review
The most common inspection findings on dental reprocessing are:
- BI frequency gaps. Days the autoclave was used but no BI was logged. The fix is a daily-usage log that triggers a BI the same day.
- BI incubation time. The log records the BI placement time but not the read time. The fix is a two-timestamp entry.
- Missing control vial. Every BI run needs an unprocessed control vial from the same lot to confirm spore viability, incubated in parallel.
- Failure follow-up not documented. When a BI shows growth, the log must record the load recall, instrument reprocessing, and retest BI before the autoclave returns to service.
- Log signature gaps. The clinician or IPAC lead must sign each entry.
The log sheet fields that satisfy inspectors
The Public Health Ontario sterilization log fields are the practical reference. The minimum dataset on every entry:
- Date and time the BI was placed in the autoclave.
- Date and time the BI was transferred to the incubator.
- Date and time the BI was read and the result (pass / fail).
- Control vial result for the same lot.
- Autoclave identifier (Sterilizer A, B, C).
- Cycle type (wrapped / unwrapped / cassette).
- Operator initials.
- Failure follow-up if applicable.
Practical workflow for a dental office
A four-step daily routine keeps the log clean:
- Start of day. Run the Bowie-Dick test (vacuum autoclaves); record the result.
- First load. Include a BI in a process challenge device in the first load; record the BI placement time.
- End of day. Transfer the BI to the incubator; record the incubation start time.
- Next day, at read time. Read the BI and the control vial; record results and initials. File the log.
CliniEco Medical carries a 24-hour readout biological indicator 25-pack and a precision dry-block incubator with 24 wells for practices running multiple BIs per day. For the 3-hour fluorescence workflow, the 4-well fluorescence rapid reader returns results at 3 hours with our 3-hour rapid fluorescence BIs. To validate the cycle on a new sterilizer, the 5-pack biological indicator trial (CA $12.99, shipping included) gives the office five cycles of confirmation before a bulk PO.
For the full reference framework, the CSA Group Z314 standard is the Canadian backbone, and the Public Health Ontario reprocessing guidance is the practical field reference for the daily log.
Related Reading
- Setting Up Sterilization Monitoring From Scratch: A 90-Day Compliance Launch Plan for New Dental Clinics
- Spore Testing for Autoclaves: What Dental Clinics Need to Know
- The Audit-Ready Autoclave Log: 14 Fields Canadian Inspectors Look For
- Dental Compliance Hub
- dental clinic sterilization supplies
- free Ontario sterilization compliance log
Frequently Asked Questions
How often must a Canadian dental office run a biological indicator test?
Every day the autoclave is used. A practice running the autoclave five days a week runs five BI tests. The BI result is the load-release criterion for that day's instruments.
What is the difference between a biological indicator and a chemical indicator?
A chemical indicator (Class 1 through Class 6) changes colour to confirm the load reached sterilizing conditions. A biological indicator uses live Geobacillus stearothermophilus spores and confirms the spores were killed. The two are not interchangeable; the BI is the load-release criterion.
How long must a BI be incubated before it is read?
Traditional readout vials require 24–48 hours of incubation. Super-rapid fluorescence vials from some manufacturers return a result in under 3 hours; our 3-hour rapid fluorescence BIs return a result at 3 hours. Reading the vial early is one of the most common RCDSO inspection findings.
What should a dental office do if the BI shows growth?
Recall the load, sequester the instruments, reprocess through a confirmed-pass cycle, and retest with a fresh BI before returning the autoclave to service. The log must record all four steps.
Last updated: 2026-09-14. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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