Last checked: October 2026. Written by Clockwork, which makes a nano-hydroxyapatite toothpaste.
"Contains nano-hydroxyapatite" is easy to put on a box. Six questions show whether a brand knows what's inside its toothpaste. Ask them of any brand, ours included. If a brand won't answer, ask why.
Why it matters: the EU's 2023 safety review (SCCS/1648/22) covers rod-shaped nano-hydroxyapatite only, with at least 95.8% of particles at aspect ratio below 3. Needle-shaped particles are outside it.
A good answer: "Rod-shaped", ideally with the aspect-ratio figure.
Clockwork: rod-shaped, 95.8% of particles at aspect ratio below 3.
Why it matters: "nano" means under 100 nanometres. Some clinical trials used larger "micro" particles, so the size tells you which evidence applies.
A good answer: a stated size, such as "under 100 nm".
Clockwork: under 100 nm.
Why it matters: hydroxyapatite is made by a handful of specialist manufacturers to very different specifications. A named maker means there is a specification sheet behind the claim.
A good answer: a company and a country.
Clockwork: Fluidinova, Portugal. The ingredient is nanoXIM·CarePaste.
Why it matters: a "10%" can mean 10% nano-hydroxyapatite, or 10% of a named ingredient that contains it. The two are not the same. A bare number with no ingredient attached can't be checked.
A good answer: a percentage with the exact ingredient name next to it.
Clockwork: 10% nanoXIM·CarePaste, a named ingredient whose specification is public.
Why it matters: a REACH registration number identifies the exact substance in the EU chemicals database. The SCCS review sets the conditions under which it is assessed as safe.
A good answer: a registration number you can search.
Clockwork: REACH 01-2119490075-38-0021. Reviewed by the SCCS in 2023.
Why it matters: "excipients q.s." or a list that only names the hero ingredients hides the rest of the formula: the foaming agent, the thickener, the sweetener.
A good answer: every ingredient, on the pack and on the website.
Clockwork: every ingredient, on the pack and on The Formula. That includes carrageenan, our thickener, which some people ask about. Ours is refined carrageenan, not the degraded form.
| Question | What to look for |
|---|---|
| 1. Shape | Rod-shaped, with an aspect ratio |
| 2. Size | Under 100 nm, stated |
| 3. Maker | A named manufacturer and country |
| 4. Percentage of what | A number with the ingredient name attached |
| 5. Registration | A REACH number or a safety review you can look up |
| 6. Ingredients | The full list, not "excipients q.s." |
See how nHAp toothpastes sold in India answer these →
Read the complete guide to nano-hydroxyapatite →