Every steam sterilization cycle in a dental office has to be verified three ways: mechanically, chemically, and biologically. Chemical indicators are the part staff handle most, on every pouch and inside every pack, and it is easy to treat the little colour-change marks as interchangeable. They are not. Under ISO 11140-1 they fall into distinct classes with very different jobs, and Ontario regulators are specific about which one belongs where. This guide explains the difference between a Class 4 multi-parameter indicator and a Class 5 integrator, why every pouch already carries a Class 4, when a Class 5 goes inside the pack, and how often you actually need to run a biological (spore) test in an Ontario practice.
Three layers of monitoring: mechanical, chemical, biological
Ontario's Royal College of Dental Surgeons of Ontario (RCDSO) requires that sterilization be monitored through a combination of mechanical, chemical, and biological means, because each catches a different kind of failure. Mechanical monitoring, the sterilizer's own gauges, display, or printout, must be checked and recorded for each load. Chemical indicators confirm the sterilizing conditions reached the instruments. Biological indicators, the spore tests, are the only method that directly proves the process killed highly resistant micro-organisms. The RCDSO is explicit that mechanical and chemical indicators do not on their own prove that sterilization occurred, which is why all three layers are used together (RCDSO, Infection Prevention and Control in the Dental Office).
The ISO 11140-1 indicator classes, in plain language
ISO 11140-1:2014 sorts chemical indicators by what they respond to. The current standard uses the word Type; older AAMI documents and the RCDSO glossary say Class, and they mean the same thing. The numbering is not a ranking, a higher number is not automatically better, it simply describes a different intended use (ISO 11140-1:2014).
- Class 1 (process indicator). Goes on the outside of a pack. It only distinguishes a pack that has been through a process from one that has not, the classic pouch colour stripe or autoclave tape. It says nothing about whether the cycle was adequate.
- Class 2 (specific-test indicator). Used for a defined equipment test rather than a routine load. The best-known example is the Bowie-Dick test for steam penetration in a dynamic-air-removal (pre-vacuum) sterilizer.
- Class 4 (multi-parameter indicator). Reacts to two or more of the critical variables of the cycle, such as time and temperature. The RCDSO defines it as an internal indicator that responds to two or more critical parameters of the sterilization process. This is the minimum indicator that belongs inside a pack.
- Class 5 (integrating indicator). Reacts to all of the critical variables, time, temperature, and the presence of saturated steam, and is engineered so that its response is correlated to the performance of a biological indicator. That correlation to spore-kill behaviour is what sets it apart from a Class 4 (Infection Control Today).
- Class 6 (emulating, or cycle-verification, indicator). Also responds to all critical variables, but is calibrated to one specific cycle (for example a 134 C, 3.5-minute program) and will fail if the load is run on a different cycle. It is the most cycle-specific of the group.
Why every pouch already has a Class 4
Public Health Ontario's (PHO) dental reprocessing checklist requires a chemical indicator inside every package (minimum Class 4) and a Class 1 process indicator on the outside, unless those indicators are already built into the pouch (PHO IPAC Dental Reprocessing Checklist). Most modern self-seal pouches solve this for you: they print a Class 1 external stripe and a Class 4 internal indicator right on the pouch, so a correctly loaded pouch is compliant out of the box. That is exactly how EBIKO's Class 4 self-seal sterilization pouches are built, with dual internal and external indicators, so every wrapped item carries the internal Class 4 the standard calls for. The practical takeaway: if you package instruments in anything without a built-in internal indicator (a wrap, cassette, or container), you have to add a Class 4 or higher indicator inside.
When a Class 5 integrator goes inside the pack
A Class 4 confirms the cycle hit two or more parameters, but its pass point does not have to track spore inactivation. A Class 5 integrator does, which is why it is used when you want load-level assurance that comes closer to a biological result. Two Ontario scenarios call for putting a Class 5 inside packs:
- Sterilizers that do not record physical parameters. PHO's checklist states that where a sterilizer cannot record its physical parameters, time and temperature are recorded manually during each cycle and a Class 5 CI is placed in every package as compensating assurance.
- Releasing loads before the spore result is back. Items should ideally be quarantined until the biological indicator result is available. Where that is not possible for routine (non-implant) loads, PHO allows evaluation of a Class 5 or Class 6 CI in a process challenge device (PCD), together with the cycle's physical parameters, to justify releasing the load.
Many offices also run a Class 5 integrator inside a representative pack or PCD on every load simply as a higher-confidence internal check. EBIKO's Class 5 chemical integrator strips are made for exactly this, drop one into the pack or challenge pack you use for load monitoring. A Class 5 does not replace the spore test; it bridges the gap between daily spore tests.
Biological (spore) testing: how often in Ontario
This is where Ontario is stricter than the common weekly rule of thumb. The U.S. CDC recommends spore testing at least weekly (CDC, Sterilization Monitoring). In Ontario, both the RCDSO and PHO set a daily expectation: include a biological indicator each day the sterilizer is used, and test each type of cycle used that day. On top of that, any load containing implantable devices must include a biological indicator in that specific load, and those devices must not be released until the spore result is known (RCDSO; PHO checklist, above).
Spore tests use a standardized population of resistant bacterial spores (Geobacillus stearothermophilus for steam). A control vial from the same lot is incubated alongside each day's test. EBIKO stocks 24-hour steam biological indicators (100 per box) so the daily result is available the next working day. Record the lot number, incubation time, and pass or fail outcome for every BI; PHO requires documentation of the date, load, and results for physical, chemical, and biological monitoring, and a positive (failed) spore test triggers your recall and re-testing procedure.
A simple compliant routine
- Every load: check and record the mechanical parameters (printout or gauges).
- Every package: internal Class 4 (built into the pouch or added) plus external Class 1.
- Every load, for higher assurance or to release without full quarantine: a Class 5 integrator in a pack or PCD.
- Every day the sterilizer runs: a biological indicator in a PCD, for each cycle type used.
- Every implant load: a dedicated biological indicator, quarantined until the result is read.
Frequently asked questions
Is a Class 5 integrator required in every pouch in Ontario? No. The standard requires a minimum Class 4 internal indicator in every package. A Class 5 is required in every package only where your sterilizer cannot record its physical parameters. Otherwise it is used selectively, in the pack or PCD you use for load monitoring, or to help justify releasing a load before the spore result is back.
Can a chemical indicator replace the spore test? No. Even a Class 5, whose response is correlated to biological performance, does not prove that micro-organisms were killed. Ontario requires a biological indicator each day the sterilizer is used, and chemical and mechanical monitoring do not substitute for it.
Weekly or daily spore testing, which applies to me? If you practise in Ontario, follow the RCDSO and PHO daily standard: a BI each day the sterilizer is used and for each cycle type, plus every implant load. Weekly is the CDC minimum in the United States and is not sufficient for Ontario compliance.
Disclaimer: This article is general guidance for Ontario dental teams and is not regulatory, legal, or clinical advice. Always follow the current RCDSO and Public Health Ontario standards, your local public health unit's direction, and your device and sterilizer manufacturers' instructions for use. Verify requirements against the official sources before setting or changing your protocols.
Written by the EBIKO Dental Team.