How much hydroxyapatite must a toothpaste contain to be effective? 5%, 10%, or 15%?

“With hydroxyapatite” on the packaging doesn’t say much. One toothpaste has 15%, another 10%, and many don't list it at all, so it could just be 1% added for the label. This article organizes the topic: what concentrations have been studied, what the European safety committee says, how to read the ingredients when the manufacturer doesn't list a number, and which toothpastes from our selection declare how much.

How do we even know that concentration matters

Hydroxyapatite works physically, not chemically: its particles deposit on the surface of the enamel and exposed dentin, supporting surface remineralization. The logic is simple — the more particles in the paste, the more material can deposit during a two-minute brushing session. But the relationship is not linear: above a certain threshold, more hydroxyapatite doesn't yield a significantly better effect, and it starts to change the consistency and price of the paste.

Laboratory studies on enamel and dentin usually compare concentrations in the 5–15% range. In most of them, 10% performs significantly better than 5%, while the difference between 10% and 15% is smaller. This is why 10% has become the unofficial standard in nano-hydroxyapatite (nHAp) toothpastes, and manufacturers who declare the concentration usually state 10% or 15%.

What clinical studies say

Three papers that manufacturers most often refer to:

• 18-month study in adults (Amaechi et al., 2019) — hydroxyapatite toothpaste compared to fluoride toothpaste in preventing caries; the authors deemed it "non-inferior" in this group. This is one study, on one formula, in adults.
• Study in adolescents with orthodontic braces (Schlagenhauf et al., 2019) — a similar "non-inferior to fluoride" result in preventing white spot lesions around brackets.
• Study in children (Paszyńska et al., 2021) — 18 months, hydroxyapatite toothpaste vs. fluoride, no significant difference in caries increment.

Important caveat: in these studies, manufacturers did not always disclose the exact concentration, and the results apply to specific formulas. They cannot be transferred to every “hydroxyapatite” toothpaste from a drugstore. More on the evidence: Hydroxyapatite or fluoride — what to choose?

How much is too much? SCCS opinion

The Scientific Committee on Consumer Safety (SCCS) of the European Commission issued an opinion in 2023 on nano-hydroxyapatite in cosmetics. The conclusion: nHAp in the form of rod-shaped particles, without coating, is safe in toothpastes at a concentration of up to 29.5% and in mouthwashes up to 10%. In other words, all the toothpastes in our selection are well within this range, and the upper limit is far from what makes technological sense.

Note on the form: the opinion applies to rod-shaped particles. Manufacturers who refer to the SCCS should use exactly this form — Ollie states this explicitly.

Nano or regular hydroxyapatite

Hydroxyapatite in toothpaste comes in two forms. Nano (nHAp, n-Ha) has particles on the order of tens to hundreds of nanometers; this is the form studied for remineralization and hypersensitivity, as it fits into enamel micro-defects and dentinal tubules. Micro (regular hydroxyapatite, sometimes "HAP") has larger particles; it acts more as a mild abrasive and a source of calcium and phosphates. On the INCI label, both forms can appear as "Hydroxyapatite" — that is why what the manufacturer declares on their website matters. If they don't write "nano," assume it is the micro form.

How to read ingredients when the manufacturer doesn't provide a percentage

INCI lists ingredients from highest to lowest content (for ingredients above 1%). This provides a simple test:

• Hydroxyapatite in the top six, right after water, abrasives, and humectants — likely several to over a dozen percent. This is the case with BOKA (sixth position, after water, glycerin, abrasives, and sorbitol).
• Hydroxyapatite in the middle of the list, after flavorings and thickeners — likely 1–3%.
• Hydroxyapatite at the end of the list, next to preservatives — an addition for the label, below 1%.

This is an approximation, not a measurement. But it is enough to distinguish a toothpaste built on hydroxyapatite from a toothpaste that "also" contains it.

Toothpastes from our selection — who discloses what

• PrevDent nHAp — 15%. The highest declared concentration we carry, plus potassium nitrate for hypersensitivity. The choice when remineralization and sensitive teeth are the main problem.
• Ollie Clean Mint — 10%. The middle of the range studied in literature, rod-shaped, 11 ingredients. A choice for those who want to know the number and have a short ingredient list.
• BOKA — does not disclose. Hydroxyapatite is sixth in the INCI, in the first group of ingredients, so the concentration is significant, but the brand does not declare a number. It makes up for it with flavors and a formula that is easy to like.
• LEBON — does not disclose, form unspecified. Hydroxyapatite is one of several active ingredients here alongside xylitol, aloe, and green tea; this is a toothpaste bought mainly for its taste and natural composition, not for nHAp.

All four brands are in the hydroxyapatite toothpaste collection.

What this means when shopping

If you are buying a toothpaste for the hydroxyapatite — for hypersensitivity, to support remineralization, as an alternative to classic formulas — choose a product that lists the concentration (10–15%) and the nano form. If hydroxyapatite is meant to be a nice addition to a toothpaste you like for its taste and ingredients, the number is not crucial. And in every case: do not rinse thoroughly after brushing, because hydroxyapatite works longer when it remains on the teeth.

Most common questions

Is 5% hydroxyapatite not enough?

In laboratory studies, 5% works, but less effectively than 10%. Toothpastes declaring 5% are rare; more often, the manufacturer doesn't list a number at all.

Does more than 15% make sense?

Technologically, little: the difference between 10% and 15% is already small, and high concentrations change the paste's consistency. The SCCS considers up to 29.5% to be safe, but that is a safety limit, not a recommendation.

How do you know if a toothpaste is in the nano form?

From the manufacturer's declaration — INCI does not distinguish this. BOKA, Ollie, and PrevDent write "nano" explicitly.

Is hydroxyapatite safe?

It is a biocompatible mineral, identical to the building block of enamel and bone. The SCCS deemed nHAp safe in toothpastes up to 29.5% (rod-shaped particles, without coating). Like any toothpaste, nHAp should be spat out — accidental swallowing of a small amount is not dangerous, but this is not an encouragement to swallow it.