Spore Testing for Dental Clinics: Daily BI Monitoring in Ontario (RCDSO)

Friday afternoon is when it happens at most clinics: the last load comes out of the autoclave, and someone remembers the biological indicator still has to go in. It is the easiest task of the week to skip, and one of the most important. Spore testing dental clinics with a biological indicator (BI) is the only way to prove a sterilizer actually killed resistant microorganisms — not just reached a number on a gauge. Canadian dental regulators expect it every week, and they do not treat it as optional.

Why Canadian dental standards require a weekly biological indicator

Chemical indicators — the stripes that change colour on pouches and tape — show that the right conditions were present: heat, steam, time. They do not show that anything was actually killed. A biological indicator holds live bacterial spores, typically Geobacillus stearothermophilus, which are far harder to destroy than anything found on dental instruments. If the cycle kills those spores, it killed your load. That is why ISO 11138 governs how these indicators are manufactured, and why CSA Z314.8 — the Canadian standard for effective sterilization in health care settings — treats biological monitoring as the core of a sterilization program.

Health Canada and provincial dental colleges take the same position: a dental autoclave monitoring program without regular spore testing is incomplete. In practical terms, that means running a biological indicator weekly for every sterilizer in the office. If you run two autoclaves, each one gets its own test, its own control, and its own log entry.

The weekly spore test, step by step

Once you have done it a few times, the whole routine takes about ten minutes of hands-on time plus a 24-hour incubation. This sequence works in most Canadian clinics:

1. Place the BI in the hardest-to-sterilize location — usually the front of the chamber on the lower tray, inside a sealed pouch or wrapped cassette, exactly where steam has the toughest time reaching.
2. Run a normal cycle with a routine load. Do not run an empty or extended cycle; you want to test what actually happens during real use.
3. After the cycle, remove the BI, activate it according to the instructions, and place it in the incubator next to the positive control that came in the pack.
4. Read the result at 24 hours. A colour change in the growth medium means spores survived — that is a failed test.
5. Record the outcome in your sterilization log with the date, cycle number, operator, and load contents, even when the result is a pass.

When a spore test comes back positive

A positive result is not the end of the world, but it is a stop-everything moment. Everything from that cycle is considered non-sterile until proven otherwise. This is the sequence we walk clinics through:

• Isolate everything from the failed cycle. Do not return it to circulation, and do not reprocess it in the same machine until you understand what happened.
• Retest the sterilizer right away, ideally with a fresh biological indicator from a different lot.
• Look for root causes: overloading, poor steam quality, a worn door gasket, pouches sealed incorrectly, or a chamber that has not been cleaned in months.
• Notify the team and your sterilizer service provider, and document every step. The CDC Guidelines for Infection Control in Dental Health-Care Settings expect a written record of the investigation, and so do most provincial colleges.

Record keeping that stands up to an audit

CDC guidance is blunt on this point: if it was not documented, it did not happen. For dental autoclave monitoring, that means a log entry for every cycle, including the weekly biological indicator. Record the BI result, the lot number of the indicator, the incubator reading, and the name of the person who ran the test. Canadian dental colleges typically ask practices to keep sterilization records for a defined period — check your provincial requirement and hold on to the logs longer than you think you need to.

Why autoclaves fail spore tests (and how to avoid it)

• Overloading. When pouches are packed too tightly, steam cannot sweep past every surface, and trapped air protects the spores.
• Steam quality. Wet steam, low pressure, or a chamber that does not purge air fully will fail a BI even on a light load.
• Sealing and packaging. Pouches taped shut, torn paper, or instruments crammed past the seal line defeat the entire cycle.
• Skipped maintenance. A sterilizer that is never cleaned or serviced will eventually fail, and the spore test is usually the first sign.

None of this requires exotic equipment. A 24-hour rapid readout biological indicator, a small incubator, and a logbook are the whole kit. CliniEco's biological indicator pack gives you ten tests with controls — about two and a half months of weekly testing for one autoclave — and the 24-hour readout means you know the result before Monday's patients arrive. Pair it with CliniEco's class 4 sterilization pouches (ISO 11140-1 class 4 chemical indicators) and autoclave tape so your packaging is never the reason a good cycle fails. Compared to Medicom's or 3M's equivalent kits, the routine is identical — same incubation window, same controls — and switching brands does not change your protocol.

how often to do spore test in dental office rcdso

Every day the sterilizer is used. In Ontario, the RCDSO infection prevention and control standard requires a biological indicator in a process challenge device on each day the sterilizer is operated, and for each type of cycle used. Weekly testing is the United States CDC / AAMI ST79 baseline, not the Ontario requirement. Plan roughly 250 indicators per sterilizer per year on a five-day week.

Related reading: browse the dental compliance hub for more clinic-ready sterilization guides.

Related: Never re-order sterilization supplies again — monthly plan from $69/month.

read our dental sterilization monitoring compliance pillar for RCDSO rules.

Frequently Asked Questions

How Often to Do Spore Test in Dental Office RCDSO

In Ontario, follow the RCDSO: run a biological indicator for each sterilizer on every day the sterilizer is used, not once a week. A clinic that runs five days a week therefore needs roughly five indicators per sterilizer per week, about 250 a year. Test every cycle type you run, not only the standard load, and record each result the day it is read. The weekly baseline belongs to the CDC and AAMI ST79 in the United States; it does not satisfy the Ontario college requirement.

What Counts as a Spore Test for RCDSO Purposes

Only a biological indicator counts. A self-contained vial of Geobacillus stearothermophilus spores, manufactured to ISO 11138-3, is processed inside a process challenge device in a normally loaded cycle, then incubated and read. Autoclave tape, external chemical indicators, and Class 5 or Class 6 strips show that cycle conditions were met, but they cannot prove the spores died. Keep the incubator log beside the sterilizer so a positive result is caught the day it appears.

Last updated: September 2026