Quick facts
- Cavity varnish is a compound applied to a prepared cavity before the restorative material is placed; its stated job is to stop the restorative, such as amalgam, from penetrating the dentinal tissue.
- In the United States it is a named entry at Class II (special controls). 21 CFR 872.3260 carries product codes LBH (cavity varnish), PHR (diammine silver fluoride dental hypersensitivity varnish) and PME (external cleaning solution) read from the openFDA classification database.
- The companion material has its own entry. 21 CFR 872.3250, Calcium hydroxide cavity liner, is Class II, product code EJK, and is applied to the interior of a prepared cavity to protect the pulp.
- Canada keeps no entry for either. A material placed inside a prepared cavity is an invasive device, and Rule 1(1) of Schedule 1 places all surgically invasive devices at Class II.
- The rule that does not apply is worth naming: Rule 3(a) covers denture materials and orthodontic appliances, and Rule 3(b) covers surgical or dental instruments - neither describes a restorative material placed into a tooth.
- Sections, classes and product codes below were checked against the eCFR, the Regulations and the openFDA classification database on 2026-10-16.
A cavity varnish is a thin film with a narrow job: it goes into a prepared cavity before the filling, and it is there to stop the filling from reaching the dentine. The United States names the material and its companion liner; Canada derives the class from where the material is placed. This article sets out both routes and the records a restorative workflow needs, with the 3-layer paper and PE dental bibs, 500 per pack that cover the patient.
What is a cavity varnish or a cavity liner?
They are two materials that do different jobs in the same place. A cavity varnish is a compound that coats the prepared cavity before the restorative is inserted; its stated purpose is to prevent the restorative material, such as amalgam, from penetrating the dentinal tissue. A calcium hydroxide cavity liner is applied to the interior of the prepared cavity before the restorative is placed, to protect the pulp. Both are placed after the cavity is prepared and before it is filled, and both sit between the tooth and everything that comes afterwards.
The family also includes materials whose names describe a different job but whose position in the mouth is the same. A hypersensitivity varnish based on diammine silver fluoride sits on the same US regulation number as a cavity varnish, which tells the buyer that the regulator reads the placement and the claim together rather than reading the trade name.
Because these materials are placed inside the body and stay there, the biological evaluation is the document that carries the most weight in a purchasing file. ISO 10993-1:2025 sets out how a device is evaluated for biological safety, and it turns on the nature and the duration of body contact - which for a material under a filling is a long contact with living tissue.
How does the United States classify cavity varnish?
21 CFR 872.3260 is titled Cavity varnish, and the identification describes a device consisting of a compound intended to coat a prepared cavity of a tooth before insertion of restorative materials, to prevent penetration of restorative materials such as amalgam into the dentinal tissue. The regulation sets Class II (special controls), with the clarification that the device, when it is an external cleaning solution, is exempt from premarket notification under subpart E of part 807 subject to section 872.9.
The openFDA device classification API returns LBH for cavity varnish, PHR for a diammine silver fluoride dental hypersensitivity varnish, and PME for an external cleaning solution. The companion liner is 21 CFR 872.3250, also Class II, product code EJK.
| US regulation | Device | Class | Product code |
|---|---|---|---|
| 21 CFR 872.3260 | Cavity varnish | Class II (special controls) | LBH |
| 21 CFR 872.3260 | Diammine silver fluoride dental hypersensitivity varnish | Class II | PHR |
| 21 CFR 872.3260 | External cleaning solution | Class II, with a premarket exemption for that variant | PME |
| 21 CFR 872.3250 | Calcium hydroxide cavity liner | Class II | EJK |
How does Canada classify cavity varnish and liner?
Canada keeps no entry, so the class is derived from Schedule 1 of the Medical Devices Regulations, and the derivation turns on where the material goes. A varnish or a liner that is placed into a prepared cavity passes into the body, which makes it an invasive device. Rule 1(1) reads: \\"Subject to subrules (2) and (3), all surgically invasive devices are classified as Class II.\\" The two subrules that could lift the class cover a device intended to diagnose, monitor, control or correct a defect of the central cardiovascular system, the central nervous system or a fetus in utero (Class IV), and a device intended to be absorbed by the body or to remain in the body for at least 30 consecutive days (Class III). A dental varnish used under a filling does not reach either.
The two rules that a reader might expect to apply do not. Rule 3(a) classifies denture materials and orthodontic appliances and their accessories as Class II; a cavity varnish is not denture material. Rule 3(b) classifies surgical or dental instruments as Class I; a varnish is a material, not an instrument. The class therefore comes from Rule 1(1), and it lands in the same place as the US entry - but for a different reason, and with a different consequence, because the Canadian route is a licence requirement rather than an entry with special controls.
A material that only coats an intact tooth surface, without entering the body, is a different case. It is non-invasive, and Rule 7(1) places all other non-invasive devices at Class I. That is why the intended-use statement decides the class here: the same bottle is a Class II invasive device when it is placed into a prepared cavity and a Class I non-invasive device when it is wiped onto enamel.
| Item | Canada | United States |
|---|---|---|
| Named entry | None; classified by rule | 872.3260 (varnish); 872.3250 (liner) |
| Class, placed in a prepared cavity | Class II (Rule 1(1), invasive device) | Class II |
| Class, coating intact enamel only | Class I (Rule 7(1), non-invasive device) | Class II on the named entry |
| Rule 3(a) denture materials | Does not apply to a restorative material | Not applicable |
| Rule 3(b) instruments | Does not apply to a material | Not applicable |
| Governing text | Schedule 1, Part 1, Rules 1(1) and 7(1) | 21 CFR 872.3260 and 872.3250 |
| Licence route | Device licence for the Class II material | Class II with special controls |
Why is the drug and device line part of this question?
Because a varnish with a preventive claim can stop being a device. In Canada a product that is represented for preventing or treating a disease through a pharmacological action is a drug, not a device, and the route to market is a drug identification number rather than a device licence. A fluoride varnish used to prevent caries sits on that line, and manufacturers answer it with the wording of the claim rather than with the formulation.
The US side shows the same tension inside one regulation number. 21 CFR 872.3260 carries product code PHR, a diammine silver fluoride varnish for dentine hypersensitivity, alongside LBH, a cavity varnish, because the FDA reads both as devices when the stated use is physical rather than pharmacological. A manufacturer that changes the claim can change the regime in one country and not in the other.
For a practice, the practical rule is simple. Buy the material for the job it is labelled for, keep the label, and keep the safety data and the biological evaluation with it. If the claim on the bottle is the reason it was chosen, the claim belongs in the purchasing file.
What should a practice check before ordering?
Four checks. First, confirm the intended-use statement and whether the material is placed into a prepared cavity or applied to a surface, because that is the line between Rule 1(1) and Rule 7(1) in Canada. Second, confirm the biological evaluation under ISO 10993-1:2025 and the contact duration it covers. Third, confirm whether the product is supplied and represented as a device or as a drug in Canada, since the two carry different identifiers and different record requirements. Fourth, confirm the handling instructions and the shelf-life for the specific variant, because a cleaning solution on the same US regulation number as a varnish has its own exemption and its own labelling.
| Check | What to ask for | Why it matters |
|---|---|---|
| Intended-use statement | Placed in a cavity or applied to a surface | Decides Rule 1(1) or Rule 7(1) in Canada |
| Drug or device status | Canadian identifier and the claim that supports it | A preventive drug claim moves the product out of the device regime |
| Biological evaluation | Report against ISO 10993-1:2025 with the contact duration | Material changes reopen the evaluation |
| Variant labelling | Which product code the variant matches | An external cleaning solution carries its own premarket treatment |
| Shelf-life and storage | Expiry date and storage condition per lot | An expired varnish is not a compliant one |
| Records | Lot number on the patient record | Recall handling depends on it |
Restorative work runs on consumables that are easy to overlook. The 3-layer paper and PE dental bibs, 500 per pack, the hypoallergenic paper tape and the pre-cut sterilisation roll sit in the same ordering line as the materials themselves.
A dental practice also reorders the consumables used at the same treatment chair. Clinics that stock for a whole practice can order through the wholesale programme and request a bulk quote for a standing or annual order; the hypoallergenic paper tape, 1 inch by 10 yards sits in the same catalogue. Consumables for this line are listed under dental practices. Reselling? become a distributor.
Sources
- openFDA device classification API
- Medical Devices Regulations, SOR/98-282, full text and Schedule 1
- US FDA, medical device databases
- US FDA, overview of device regulation
- Health Canada, medical devices
- Health Canada, establishment licensing
- ISO 10993-1:2025, biological evaluation of medical devices
- ISO 17664-1:2021, processing of health care products
- ISO 11607-1:2019, packaging for terminally sterilized medical devices
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, application of risk management to medical devices
- Royal College of Dental Surgeons of Ontario, standards and guidelines
- Canadian Dental Association
- Public Health Ontario, infection prevention and control
- CSA Group
- CCOHS, OSH answers
Printable record sheet. A restorative record is only useful if it carries the material and the lot that went into the tooth. print the restorative material log — the pack contains a material use log, a lot traceability page and a storage check line, printable in any browser with no account and no sign-up required
Log generator. Enter the material, the tooth reference and your province, and the page builds a dated restorative record with the lot field on every line. build a restorative record sheet — the generated sheet keeps the material name, the lot number and the tooth reference in fixed columns, so a later recall check takes minutes rather than an afternoon
Ask a compliance specialist. A classification question usually turns on how the device is used, not only on its name. Ask a compliance specialist — you get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Dental cements: class in Canada and the US
- Dental sealants in Canada vs the US
- Dental amalgam: which class applies in each country
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 a practice keeps belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
What class is cavity varnish in the United States?
It is 21 CFR 872.3260 at Class II (special controls) with product code LBH. The section also carries PHR for a diammine silver fluoride dental hypersensitivity varnish and PME for an external cleaning solution.
What class is a cavity liner in the United States?
A calcium hydroxide cavity liner is 21 CFR 872.3250 at Class II with product code EJK.
How does Canada classify a cavity varnish?
A varnish placed into a prepared cavity is an invasive device and Rule 1(1) of Schedule 1 of the Medical Devices Regulations places it at Class II. A varnish that only coats an intact surface is non-invasive at Class I under Rule 7(1).
Does the denture material rule apply to a cavity varnish?
No. Rule 3(a) covers denture materials and orthodontic appliances and their accessories, and Rule 3(b) covers surgical or dental instruments. A restorative material placed into a tooth is neither.
Can a cavity varnish be a drug in Canada?
It can, if it is represented for preventing or treating a disease through a pharmacological action. In that case the product is regulated as a drug rather than as a device, and the claim wording decides the question.
What records should a practice keep for these materials?
The material name, the lot number on the patient record, the biological evaluation under ISO 10993-1:2025, the expiry date for the lot in use, and the manufacturer's handling instructions.