Search "hydroxyapatite vs fluoride" and you'll find two camps talking past each other. One says hydroxyapatite is a miracle; the other says it's wellness marketing. Neither seems to have read the trials. We have, and our reading is straightforward: these are two different routes to the same goal, and on the evidence to date hydroxyapatite holds its own. It's why every toothpaste on our shelf is built on it.
Two routes to the same goal
Your enamel is under constant negotiation. Acid from plaque bacteria, and from food and drink, pulls mineral out of it; saliva puts some of that mineral back. Decay begins when the losses keep winning. Both ingredients are there to tip the balance the other way.
Fluoride changes the chemistry of the repair. When mineral redeposits with fluoride around, some of it forms fluorapatite, which resists acid better, and fluoride also slows plaque bacteria down. It has decades of population data behind it.
Hydroxyapatite supplies the mineral itself. Enamel is 96 to 97 per cent mineral by weight, and that mineral is hydroxyapatite, so a hydroxyapatite toothpaste delivers more of exactly what the tooth is made of. The particles settle into microscopic scratches and early weak spots, bind to the surface and act as a reservoir of calcium and phosphate. On exposed dentine they gather over the tiny channels that carry cold to the nerve. That is what "biomimetic" means: the same material, not a substitute chemistry.
Neither rebuilds a broken tooth or fills a cavity. Both work on the enamel you have, and they aren't opposites: some toothpastes combine them.
The evidence, trial by trial
Decay in adults: 18 months against 1,450 ppm fluoride
The biggest single piece of evidence is Paszynska and colleagues' double-blind randomised trial, published in Frontiers in Public Health in 2023. 189 adults brushed with either a 10% hydroxyapatite toothpaste or a 1,450 ppm sodium fluoride toothpaste, standard adult strength, for 18 months. At the end, 89.3% of the hydroxyapatite group and 87.4% of the fluoride group had no increase in decayed, missing or filled surfaces. It was a non-inferiority trial, built to find out whether hydroxyapatite was worse than fluoride. It wasn't.
Decay in children: a year on milk teeth
The same research group's one-year trial, published in Scientific Reports in 2021, followed 207 young children brushing with either hydroxyapatite toothpaste or a 500 ppm children's fluoride toothpaste. Early decay progressed in 72.7% of the hydroxyapatite group and 74.2% of the fluoride group, and hydroxyapatite again passed the non-inferiority test.
An independent review, 2025
University researchers in Athens and Bern, with no competing interests declared, reviewed the randomised trials in under-25s for the Journal of Dentistry. They found no significant difference between hydroxyapatite and fluoride toothpaste for new or worsening decay, and concluded that hydroxyapatite toothpaste could be an effective alternative to fluoride.
Sensitive teeth: 44 trials
For sensitivity, the key paper is Limeback, Enax and Meyer's 2023 meta-analysis in Biomimetics. It pooled 44 clinical trials, more than half of them rated high quality, and found hydroxyapatite reduced sensitivity significantly more than placebo and significantly more than fluoride, and about as well as other established sensitivity ingredients. Two of those trials were double-blind randomised studies of Biorepair Plus, and the reviewers graded both high quality.
Inside the mouth, in a fortnight
Shorter studies show the mechanism at work. In a 2019 study in BDJ Open, 30 adults wore mouth appliances holding enamel samples with early artificial decay. Over 14 days, a 10% hydroxyapatite toothpaste remineralised them as well as a 500 ppm fluoride toothpaste, and more evenly through the depth of the lesion.
| Study | Design | Compared with | Finding |
|---|---|---|---|
| Paszynska and colleagues, 2023 | 18-month randomised trial, 189 adults | 1,450 ppm fluoride | No worse than fluoride against new decay |
| Paszynska and colleagues, 2021 | One-year randomised trial, 207 children | 500 ppm fluoride | No worse than fluoride against early decay |
| Chatzidimitriou and colleagues, 2025 | Independent systematic review, under-25s | Fluoride toothpaste | No significant difference for new or worsening decay |
| Limeback, Enax and Meyer, 2023 | Meta-analysis of 44 trials | Placebo, fluoride, other desensitisers | Better than placebo and fluoride for sensitivity |
| Amaechi and colleagues, 2019 | 14-day study in 30 adults' mouths | 500 ppm fluoride | Remineralised early decay as well as fluoride |
The fine print fits in one sentence: both decay trials tested a 10% formula from Dr. Kurt Wolff, the German maker of Karex toothpaste, which funded them and employs two of the three meta-analysis authors, and non-inferior means "no worse than" rather than "better than".
Why we chose Biorepair
We wanted a toothpaste that states its dose, and states a serious one. Biorepair lists Plus Sensitive Teeth at 240 mg/g (24%) microRepair® and Plus Total Protection at 200 mg/g (20%). microRepair® is zinc-substituted carbonate hydroxyapatite: enamel-like mineral with a little zinc built into the crystal.
Biorepair Plus has a clinical record of its own. In an eight-week double-blind trial it cut air-blast sensitivity scores by 46%, against 29% for a potassium nitrate and fluoride sensitivity toothpaste. And at £6.99 a tube, using it twice a day, every day, is realistic, which is how any toothpaste actually works. Both tubes are in our hydroxyapatite toothpaste and fluoride-free toothpaste collections.
Choosing between them
If sensitivity is your main complaint, hydroxyapatite has the stronger evidence of the two. If you'd rather go without fluoride, hydroxyapatite at a stated, meaningful concentration is the evidence-backed way to do it. For young children and anyone at high risk of decay, NHS advice is built around fluoride toothpaste; for families who would rather go without, Biorepair states that children under six can use its toothpaste without adult supervision, and Total Protection is our everyday family tube.
Whichever you use, the habits around the tube matter as much as the tube: two minutes twice a day, a light touch, cleaning between the teeth and sugar kept to mealtimes. The Oral-B iO9 helps with the first two, with a built-in timer and a pressure sensor that shows you when you're pressing too hard. Our hydroxyapatite toothpaste guide covers safety, nano versus micro particles and how to choose.
Why buy from Onyx
We read the research before we chose the range, and every product we sell was chosen by practising dentists. Start with Total Protection for everyday care or Sensitive Teeth if cold is your trigger, both £6.99, or get the whole routine in a £180 Complete Care Bundle with the iO9 and four iO Ultimate Clean heads, £11.98 less than buying separately. Order before 4pm for same-day dispatch, delivery is free on UK orders over £50, unopened items can come back within 30 days, and if you have a question about the evidence, email hello@onyx-dental.co.uk and one of our dentists will reply.
Sources
- Paszynska and colleagues: 18-month trial in adults, Frontiers in Public Health (2023)
- Paszynska and colleagues: one-year trial in children, Scientific Reports (2021)
- Chatzidimitriou and colleagues: systematic review of hydroxyapatite toothpaste and early decay, Journal of Dentistry (2025)
- Limeback, Enax and Meyer: meta-analysis of 44 trials on sensitivity, Biomimetics (2023)
- Orsini and colleagues: eight-week trial of a zinc-carbonate hydroxyapatite toothpaste, Journal of Clinical Periodontology (2010)
- Amaechi and colleagues: in situ remineralisation study, BDJ Open (2019)
- Xu and colleagues: materials for enamel remineralisation, Frontiers in Bioengineering and Biotechnology (2022)
- Biorepair: microRepair® concentrations and use by children under six