Hydroxyapatite vs fluoride toothpaste for children

There is one clinical trial. It ran for 336 days in 207 children aged three to seven, it compared a fluoride-free hydroxyapatite toothpaste with a 500 ppm fluoride one, and it found the hydroxyapatite paste non-inferior. It was funded by the company that makes the hydroxyapatite paste. Those three facts belong in the same sentence, which is why they are.

That trial is the strongest evidence that exists for using hydroxyapatite instead of fluoride in a child’s mouth. It is real, it was properly randomised and double-blinded, and it is also a single study. No national guideline anywhere has changed as a result, and the scoping review published this year concluded that no fluoride-free category yet has evidence comparable to fluoride for long-term caries prevention in children.

Here is what the trial did, what “non-inferior” means when you look at it closely, and what the actual decision in front of a parent is.

What the trial measured

Paszynska and colleagues, published in Scientific Reports in 2021, recruited children aged three to seven who already had at least one filled primary molar — that is, a group already known to develop caries. The test group brushed three times a day with a fluoride-free microcrystalline hydroxyapatite paste; the control group used a children’s toothpaste with 500 ppm amine fluoride. Neither the children nor the examiners knew which was which.

The outcome was whether new caries lesions appeared on the primary teeth, scored using ICDAS — a visual scale where code 1 is the very first visible change in enamel, long before a hole. Over 336 days:

207 children were in the intention-to-treat analysis and 177 finished per protocol. The difference between the groups was −1.4 percentage points, and the one-sided upper 95% confidence limit on that difference was 9.8 points — comfortably inside the 20-point non-inferiority margin the researchers set before starting. So: non-inferior, on the terms the trial declared in advance.

The number nobody puts in the headline

Look at the table again. Roughly three-quarters of the children in both groups developed a new lesion within a year.

This was not a trial in which one toothpaste kept children caries-free and the other did slightly better or worse. It was a trial in which both toothpastes were followed by a great deal of new enamel damage in a high-risk group, and the two were indistinguishable in how much. That is a genuine result, and it is a much less exciting one than “hydroxyapatite works as well as fluoride”.

It also puts the choice of tube in proportion. In children who already have fillings, brushing with either paste three times a day did not stop most of them acquiring new early lesions over a year. What is going into their mouths between brushes is doing more work than what is on the brush — which is the same conclusion the remineralisation evidence keeps arriving at, from the other direction.

What a non-inferiority margin actually is

This is worth understanding, because it turns up all over health marketing and almost nobody explains it.

A non-inferiority trial does not ask “is A as good as B?” — that question cannot be answered statistically. It asks “can we rule out that A is worse than B by more than this much?” The “this much” is the margin, and researchers must choose it before the trial and justify it. Here it was 20 percentage points.

So the finding is precisely this: the data rule out hydroxyapatite being more than 20 points worse. They do not rule out it being, say, 9 points worse, because 9.8 is still inside the confidence interval. Fig. 1 shows the whole claim in one line: the interval’s upper end has to land left of the dashed margin, and it does.

Whether a 20-point margin is a reasonable thing to accept in a child’s mouth is a judgement, not a calculation, and reasonable people disagree about it. It is not a flaw in the trial — the margin is stated openly — but it is the hinge the conclusion turns on, and it disappears entirely from the phrase “proven as effective as fluoride”.

Who paid for it

The funding statement is short and worth quoting exactly: “This study was funded by Dr. Kurt Wolff GmbH & Co. KG, Bielefeld, Germany. The funders had no role in recruiting, conduction of the study, data collection, and statistical analysis.” The authors declared no competing interest.

Dr. Kurt Wolff makes the hydroxyapatite toothpaste the trial tested — the paper says the test product was identical in composition to a commercially available children’s paste of theirs. The fluoride comparator was an off-the-shelf children’s toothpaste from a different manufacturer.

None of that makes the result wrong. Company-funded trials are not automatically invalid, and the funder’s stated distance from data collection is a real safeguard. It does mean the strongest paediatric evidence for hydroxyapatite was paid for by a hydroxyapatite manufacturer, and a parent deciding what to buy is entitled to know that before they weigh it. The same pattern runs through the adult evidence, which we set out on who paid for the hydroxyapatite research.

What the independent reviews say

Two recent appraisals with no manufacturer among their authors:

• A 2025 systematic review and meta-analysis in the Journal of Dentistry searched six databases, retrieved 68 studies and found four eligible. Its conclusion on caries outcomes: development of new lesions and progression of existing ones, recorded by DMFS or ICDAS, showed no significant differences between hydroxyapatite and fluoride toothpastes. Differences did show up in lesion size.
• A 2026 scoping review in the European Journal of Pediatrics mapped 122 studies of fluoride-free toothpastes, of which only 20 gave direct paediatric evidence. Its conclusion, verbatim: “While hydroxyapatite-based products have the most consistent evidence base, no fluoride-free category currently has evidence comparable to fluoride for long-term caries prevention in children.”

Read together: hydroxyapatite is the best-supported fluoride-free option, and “best of the alternatives” is not the same claim as “equal to fluoride”. The second review is unusually useful because it counted what kind of evidence exists rather than pooling effects — and found it dominated by laboratory work and surrogate outcomes.

What the guidance still says

England’s Delivering better oral health toolkit, the guidance NHS dental teams work from, is unambiguous: there is moderate to high-certainty evidence that fluoride toothpaste of 1,000 ppm or above prevents caries in both primary and permanent teeth, and for children at higher risk, 1,350 to 1,500 ppm is advocated, as it is for everyone from seven years upwards.

Note the strength of evidence attached to that: moderate to high certainty. The hydroxyapatite paediatric evidence is one trial and a handful of short in-situ studies. Those are not the same tier, and no honest comparison can present them as though they were.

The question underneath: fluorosis

Most parents asking about hydroxyapatite are not really asking about remineralisation chemistry. They are asking whether swallowed fluoride will mark their child’s adult teeth. That is a legitimate question with a specific answer.

Dental fluorosis happens when a child ingests excess fluoride while the enamel is still forming. The toolkit is precise about the windows: the risk to the appearance of permanent incisors is relevant only to ingestion under three years old, because the crowns of those teeth finish calcifying by 30 months; the risk to premolars is relevant only under six.

And the doses involved are small when the amount is controlled:

The practical upshot is that the amount on the brush matters more than the number on the tube. A smear of strong toothpaste delivers less fluoride than a generous squeeze of weak toothpaste, and the guidance is built around exactly that.

If your worry is fluorosis specifically, controlling the quantity and teaching a child to spit addresses it directly, and does so without giving up an intervention with moderate to high-certainty evidence behind it. We go through the swallowing question in more detail on is hydroxyapatite toothpaste safe to swallow.

So when does hydroxyapatite make sense for a child?

Three situations, honestly stated.

1. A child who genuinely cannot spit yet, and swallows everything Under about three, some children swallow the lot no matter what you do. The guidance answer is still a smear of fluoride paste, because the dose that reaches them is tiny. But this is the case where a parent’s instinct to reach for something swallowable is most understandable.
2. A family that has already decided against fluoride This is the situation the paediatric literature actually addresses. If the alternative is a toothpaste with no anti-caries ingredient at all, hydroxyapatite is the fluoride-free option with the most evidence behind it, and that is a meaningfully better choice than nothing. It is a second-best that is worth having.
3. Alongside fluoride rather than instead of it Nothing requires you to pick one tube for all time. Some families use fluoride at night, when it matters most, and hydroxyapatite in the morning. There is no trial of that arrangement, so we are not going to pretend it is evidence-based — but it is not risky either.

What does not hold up is the framing that hydroxyapatite is the proven equal of fluoride and the obvious choice for children. One company-funded trial and a set of short surrogate studies do not carry that.

The things that outrank the choice of tube

• Brushing twice a day, one of them last thing at night. Nothing on this page matters as much as this.
• Spit, do not rinse. Rinsing with water washes the active ingredient straight out — whichever ingredient it is.
• An adult brushing or supervising until about seven. Small children do not have the manual control, and the difference is visible.
• How often sugar arrives, not how much. Frequency is what drives the acid cycle; see can teeth remineralise.
• Actually going to the dentist. Early lesions are reversible and invisible to you at home.

See a dentist if

• You can see a white, chalky or brown patch on a tooth, particularly at the gum line.
• Your child complains of sensitivity to cold or sweet things.
• Your child has had a filling before — that is the strongest predictor of the next one, and it changes what the dentist will recommend.
• You are unsure what concentration is right for your child. It depends on their risk, and a dentist can tell you in one appointment.

Our illustrations, including Fig. 1, are free to reuse under CC BY 4.0 — see the diagrams page.

References

1. Paszynska E, Pawinska M, Gawriolek M, et al. Impact of a toothpaste with microcrystalline hydroxyapatite on the occurrence of early childhood caries: a 1-year randomized clinical trial. Sci Rep 2021;11:2650. DOI · PubMed · Funding: see ledger
2. Office for Health Improvement and Disparities. Delivering better oral health: an evidence-based toolkit for prevention (chapter on fluoride). Official page, accessed 15 Sep 2026. · Funding: see ledger