Quick facts
- A plaque disclosing kit carries a dye that stains dental plaque so that a patient or a clinician can see where the plaque sits.
- In the United States it is filed under 21 CFR 872.1740, titled Caries detection device, at Class II, product code NYH (Plaque Disclosing Kit).
- In Canada it is a non-invasive device with no named entry, so Rule 7(1) of the Medical Devices Regulations places it at Class I.
- That is a real cross-border gap on the same tablet or solution: Class II in the United States, Class I in Canada.
- The disclosing kit shares a US regulation number with light-based caries detection devices, but the two are different products with different product codes.
- Entries, classes and product codes were checked against the current eCFR text, the Regulations and the openFDA classification database on 2026-10-12.
A plaque disclosing kit is the tablet, gel or solution a clinician uses to colour plaque so that a patient can see it and a clinician can score it. It is one of the simplest products on a hygiene shelf, and it is a useful example of how the two countries classify the same item differently: a named Class II US entry against a Canadian catch-all rule for non-invasive devices at Class I. This article sets out both routes and the practical effect on an order. The cotton rolls used for isolation in the same appointment come from the same dental range.
What is a plaque disclosing kit and how is it used?
A disclosing agent carries a dye - historically erythrosine, now usually a two-tone dye that stains old plaque one colour and new plaque another - and it is delivered as a tablet to be chewed, a solution to be painted on with a small brush, or a gel applied to the teeth. The dye binds to plaque and not to clean enamel, so the stained areas show the patient where brushing has missed.
The kit is used in hygiene appointments, in orthodontic monitoring, in paediatric coaching and in home use where a clinician has taught the patient to check a site. The disclosing agent contacts the teeth and the oral mucosa and is rinsed away; it does not cut tissue, does not enter the body, and does not deliver energy. Those three negatives decide its class in Canada.
Is a plaque disclosing kit a Class II device in the United States?
Yes. 21 CFR 872.1740 is titled Caries detection device, and the entry sits at Class II. The openFDA device classification API lists a Plaque Disclosing Kit under product code NYH within that regulation number, alongside LFC for a Device, Caries Detection.
Two products under one regulation number is the detail to hold on to. The regulation number is the same, but the product code tells the regulator which device it is looking at, and a disclosing tablet is not a light-based caries scanner. A supplier quoting only the regulation number can therefore describe both products with the same number and leave the buyer unsure which one is on the shelf.
How does Canada classify a plaque disclosing kit?
Canada keeps no named entry. It applies the rules in Schedule 1 of the Medical Devices Regulations. A disclosing tablet or solution is non-invasive; it does not contact injured skin, it does not channel or store fluids for introduction into the body, and it does not modify blood or tissue. It therefore falls to Rule 7(1): "Subject to subrule (2), all other non-invasive devices are classified as Class I."
Rule 7(2) is the subrule that can change the answer: a device is Class II if it is intended to act as a calibrator, tester or quality control support to another medical device, or to be connected to an active device that is Class II or higher. A disclosing tablet does neither. Rule 2(1), the rule that catches devices penetrating a body orifice or contacting the surface of the eye, does not apply either, because a tablet that is chewed and rinsed is not an invasive device.
| Item | Canada | United States |
|---|---|---|
| Named entry | None; classified by rule | 872.1740, Class II |
| Product code | Not applicable | NYH (Plaque Disclosing Kit) |
| Class | Class I (Rule 7(1)) | Class II (special controls) |
| Governing text | Schedule 1, Rule 7(1) | 21 CFR 872.1740 |
| Lift to Class II? | Only under Rule 7(2): calibrator or connected to a Class II+ active device | Not applicable |
| Route to market | Establishment licence; no device licence for Class I | Premarket notification with special controls |
Why does the US place a disclosing tablet at Class II?
The US entry is written around the intended use of the regulation number rather than around the chemistry of one product. A device used in the mouth to detect or monitor disease is placed where a wrong reading matters, and Class II brings special controls in addition to general controls. The disclosing kit earns that place because the thing it shows is used to make a clinical judgement about the patient's disease risk.
Canada reads the same product and asks a different question first: is it invasive, does it carry a fluid into the body, does it modify blood, is it a calibrator? A disclosing tablet answers no to all four, so it falls to the catch-all rule at Class I. Neither reading is unreasonable; they are answers to different questions.
Which formats and related products sit in the same family?
The class follows the intended use and not the format. A tablet, a two-tone tablet, a painted solution and a gel all do the same job, so in the United States they sit under the same product code and in Canada under the same rule. What changes between them is how the dye is delivered and how long it takes to rinse away.
| Format | Typical use | Class, Canada | Class, US |
|---|---|---|---|
| Single-tone tablet | Patient coaching in a hygiene visit | I (Rule 7(1)) | II (872.1740) |
| Two-tone tablet | Distinguishes old from new plaque | I (Rule 7(1)) | II (872.1740) |
| Disclosing solution | Painted on a site with a brush | I (Rule 7(1)) | II (872.1740) |
| Disclosing gel | Applied to a full arch | I (Rule 7(1)) | II (872.1740) |
| Light-based caries detector | Different product, same US regulation number | II (Rule 10(1)) | II (872.1745) |
The last row is the one to keep separate. Light-induced fluorescence caries detection is a different device with a different US entry and a different Canadian analysis, and it should not be quoted from the same line as a disclosing tablet.
Which standards and practice rules apply to a disclosing kit?
The product side is covered by the usual quality and risk standards. A manufacturer works under ISO 13485:2016 and keeps a risk file under ISO 14971:2019. Where the agent is supplied in single-use sterile packaging, that packaging follows ISO 11607-1:2019.
The practice side is governed by the dental college. The Royal College of Dental Surgeons of Ontario publishes the infection prevention and control standard that an Ontario practice works to, and Public Health Ontario carries the wider infection prevention material. The Canadian Dental Association and the American Dental Association publish the patient-facing oral health material that many practices use when they explain what the dye is showing.
How should a practice order and store disclosing kits?
Order by format and flavour. A practice that teaches children keeps a palatable tablet; a practice that scores plaque at a recall keeps a two-tone tablet and a solution for site work. Standardise on one or two formats per room so that the hygiene team reaches for the same thing every time, and check the expiry date on the box at every restock.
Store away from heat and light. A dye is a chemical product and it degrades; keep the container closed and out of a sunny window, and rotate stock so that older lots are used first. The operatory consumables that travel with the hygiene room - dental bibs for the patient and cotton rolls for isolation - belong on the same restock list. Multi-site groups order at case level through the wholesale and multi-site ordering page, and the dental range is indexed under the dental compliance hub. Reselling? become a distributor.
Sources
- openFDA device classification API
- Medical Devices Regulations, SOR/98-282, full text and Schedule 1
- US FDA, medical devices
- US FDA, medical device databases
- US FDA, overview of device regulation
- Health Canada, medical devices
- Health Canada, establishment licensing
- Standards Council of Canada
- CSA Group
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, risk management of medical devices
- CCOHS, OSH answers
- Royal College of Dental Surgeons of Ontario, standards and guidelines
- Canadian Dental Association
- Public Health Ontario, infection prevention and control
- American Dental Association, oral health topics
- Ontario, laws and regulations
- ISO 3630-1:2019, endodontic instruments, general requirements
- ISO 17664, processing information supplied by the device manufacturer
- ISO 11607-1:2019, packaging for terminally sterilized medical devices
- 21 CFR 872.1740, caries detection device
- 21 CFR 872.1745, light-induced fluorescence caries detector
A hygiene room that uses a disclosing agent also keeps a sheet for every other product it applies. The printable blank operatory log at the compliance log centre carries a column for the product, the lot and the operator, and it prints without an account and no sign-up.
A practice with more than one hygiene room can use the log generator on the same page to lay out one sheet per chair before printing the set.
Have a question about your own facility? Send it in and you will get a written answer specific to your equipment and province, with the regulation or standard it is based on cited. Ask a compliance specialist about the device you are buying.
Related reading
- Caries detection devices in Canada vs the US: which class applies
- Gingival retraction cords and kits in Canada vs the US: which class applies
- Dental barrier film in Canada vs the US: which class applies
CliniEco Medical supplies eye care, laboratory and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and dental procurement professionals and is not legal advice; the class of a device and the records kept by a practice belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
What class is a plaque disclosing kit?
The United States lists it at 21 CFR 872.1740 as Class II under product code NYH. In Canada the same kit is a non-invasive device at Class I under Rule 7(1) of the Medical Devices Regulations.
Why does Canada class a disclosing tablet at Class I?
Because Rule 7(1) classes all other non-invasive devices as Class I, and a tablet that is chewed and rinsed is non-invasive, does not carry a fluid into the body, does not modify blood, and is not a calibrator or accessory to an active device.
Is a plaque disclosing kit the same as a caries detection device?
Both sit under 21 CFR 872.1740 in the United States, but they are different products with different product codes. A plaque disclosing kit is NYH; a light-based caries detection device uses its own code and, for light-induced fluorescence, its own section at 872.1745.
When would a disclosing product move to Class II in Canada?
Under Rule 7(2), a non-invasive device is Class II if it is intended to act as a calibrator, tester or quality control support to another medical device, or to be connected to an active device classified Class II, III or IV.
Does a Class I disclosing kit need a licence in Canada?
No. A Class I device does not receive a device licence of its own; the manufacturer holds an establishment licence and keeps the records the Regulations require. A Class II or higher device needs a licence under section 32.
How should disclosing kits be stored?
Keep the container closed, out of direct light and away from heat, and rotate stock so that older lots are used first. The dye degrades, so check the expiry date at every restock.
Where should a practice record what it applies in the operatory?
In the practice's operatory and instrument records for the visit. The compliance log centre provides a printable blank form and a log generator sized to the number of chairs a practice runs.
0 comments