In production
The Fluoride Decision
A quarter of a tooth, and everything it was traded for
Environment & exposure
Nano-hydroxyapatite
The fluoride-free alternative, and a synthetic one: manufactured apatite rods, cleared by one regulator on a specification no tube prints, with four eligible trials behind the efficacy claim.
What we are reading
Gathered for the investigation and not yet written up. Each note says what the paper does and does not show.
- Chatzidimitriou K, Theodorou K, Seremidi K, Kloukos D, Gizani S, Papaioannou W. The role of hydroxyapatite-based, fluoride-free toothpastes on the prevention and the remineralization of initial caries lesions: a systematic review and meta-analysis.10.1016/j.jdent.2025.105691 · PMID 40107597
THE SIZE OF THE EVIDENCE BASE, from an independent group in Athens and Bern. The search retrieved 68 studies and FOUR were eligible. Pooled against fluoride toothpaste: risk ratio 0.98 (95% CI 0.85 to 1.12, p = 0.61) and odds ratio 0.90 (95% CI 0.57 to 1.42, p = 0.68) for new and progressing lesions — no difference detected, which on four studies and confidence intervals that wide is also no equivalence demonstrated. The review's own closing line calls hydroxyapatite's biocompatibility 'superior' and says it lacks toxicity; it measured neither, and that sentence should not be repeated as though it did.
- 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.10.1038/s41598-021-81112-y · PMID 33514787
The one fluoride-FREE head-to-head, and it is worth reading past the headline. 207 children, 336 days, hydroxyapatite paste against a fluoride paste, and the conclusion was non-inferiority. READ THE MARGIN: non-inferiority was declared against a pre-set margin of 20 percentage points, and new lesions appeared in 72.7% of the hydroxyapatite group against 74.2% of the fluoride group. Three quarters of the children in each arm got new caries; the trial shows the two pastes were within 20 points of each other, not that either worked. The material was also MICROcrystalline, not nano.
- Wierichs RJ, Kuruparan M, Ruthiraswaran A, Meyer-Lueckel H, Carvalho TS, Niemeyer SH. Fluoride dose-response and anticaries effect of herbal antibacterial agents and (nano-)hydroxyapatite on dentin caries: an in vitro study.10.1159/000542953 · PMID 39681101
The mechanism test, run as a dose-response. Bovine dentin, 28 days of pH cycling, eleven pastes. Fluoride showed a clean dose-response at 0, 500 and 1,100 ppm. Fluoride-free (nano-)hydroxyapatite was NOT significantly different from the 0 ppm control, and the fluoride-free pastes that did something were grape seed extract and melaleuca oil, not the apatite. A hypermineralized surface layer formed, and surface loss was prevented, ONLY where fluoride was present. In vitro and bovine, so not an outcome in a person — but it is the mechanism the sales case rests on, measured directly.
- Cocco F, Salerno C, Wierichs RJ, Wolf TG, Arghittu A, Cagetti MG, Campus G. Hydroxyapatite-fluoride toothpastes on caries activity: a triple-blind randomized clinical trial.10.1016/j.identj.2024.09.037 · PMID 39971658
The largest trial in this space: 610 children aged 4 to 7, 518 completing, 24 months, triple-blind. Hydroxyapatite-plus-fluoride pastes beat conventional monofluorophosphate pastes on enamel lesions (p < 0.01); of 78 active lesions at baseline in the hydroxyapatite arm, 58 were inactive at two years. NOTE WHAT IT IS AND IS NOT: all four arms contained fluoride, at 1,000 or 1,450 ppm. It tests hydroxyapatite as an ADDITION to fluoride, and says nothing about using it instead.
- Pawinska M, Paszynska E, Amaechi BT, Meyer F, Enax J, Limeback H. Clinical evidence of caries prevention by hydroxyapatite: an updated systematic review and meta-analysis.10.1016/j.jdent.2024.105429 · PMID 39471896
The review most often cited FOR replacing fluoride, and the one to read the author list on. Two of its six authors, Frederic Meyer and Joachim Enax, are in the Research Department of Dr. Kurt Wolff GmbH & Co. KG, which manufactures hydroxyapatite toothpaste. Its conclusion is that hydroxyapatite is 'an ideal substitute for fluoride in toothpaste and mouthwash tailored for young children'. Its own numbers are more modest: pooled odds ratio 2.51 against placebo, and 1.1 against fluoride, NON-SIGNIFICANT. A manufacturer-authored recommendation standing on a non-significant comparison is a conflict to state out loud, not a verdict to quote.
- Gugnani N, Gugnani S. Do we have enough evidence to recommend hydroxyapatite toothpaste for preventing dental caries?10.1038/s41432-025-01123-w · PMID 39984606
An independent critical appraisal of the review above, in Nature's evidence-based dentistry journal, and the title is the question. It confirms the arithmetic: significantly better than placebo, pooled OR 1.1 and non-significant against fluoride.
- Yeh CH, Wang YL, Vo TTT, Lee YC, Lee IT. Fluoride in dental caries prevention and treatment: mechanisms, clinical evidence, and public health perspectives.10.3390/healthcare13172246 · PMID 40941599
A 2025 narrative review of the whole field, useful here for one sentence: nano-hydroxyapatite, fluoride-containing bioactive glass and probiotics are 'promising but currently supported by limited clinical data'. That is the mainstream reading, and it is where this topic sits.
- Epple M. Review of potential health risks associated with nanoscopic calcium phosphate.10.1016/j.actbio.2018.07.036 · PMID 30031162
The safety review this topic used to be argued from, and it needs describing accurately: a single-author narrative review by a calcium-phosphate materials chemist, covering calcium phosphate nanoparticles IN GENERAL rather than the rods in a tube of toothpaste. What it reports: no inherent toxicity; particles taken into a cell are digested in the lysosome and the calcium is cleared within hours unless the dose is very high; cytotoxicity in culture is largely agglomeration and sedimentation producing a huge local dose; oral uptake carries no nano-specific risk because the particles dissolve in gastric acid; the one real exposure route is inhalation. It is a literature review, not a toxicology program, and it contains no long-term human study of brushing with the material.
- Scientific Committee on Consumer Safety (SCCS), European Commission. Final opinion on hydroxyapatite (nano) — fourth submission.
THE REGULATORY POSITION, AND ITS CONDITIONS. The SCCS now considers hydroxyapatite (nano) safe in oral care up to 29.5% in toothpaste and 10% in mouthwash, raised from the 10% and 0.465% of its 2023 opinion. The clearance is conditional in four ways that matter to a buyer: it applies only to ROD-SHAPED particles, at least 87% of them with an aspect ratio of 3 or less and the remainder not above 9; only to particles that are NOT coated or surface-modified; NOT AT ALL to needle-shaped particles; and not to sprayable products, which could put the particles in someone's lungs. The reasoning is that buccal uptake is negligible, that epithelial cells holding particles are shed anyway, and that anything swallowed dissolves in gastric fluid. Two things to say with it. First, no tube prints an aspect ratio or a coating status, so a shopper cannot tell whether what they are holding is the material that was cleared. Second, this is the FOURTH dossier the industry submitted and the fourth assessment since 2015 — a specification-bounded risk assessment built on cell models and dissolution arguments, not decades of human outcome data of the kind fluoride toothpaste has. SOURCING NOTE: the SCCS documents are not PubMed-indexed and this container's network policy blocks health.ec.europa.eu, so the figures here were taken from several independent regulatory trackers and RIVM reporting in agreement, not read off the opinion itself. Verify against the opinion PDF before any of it is spoken on air.
- Amaechi BT, Alshareif DO, Azees PAA, et al. Anti-caries evaluation of a nano-hydroxyapatite dental lotion for use after toothbrushing: an in situ study.10.1016/j.jdent.2021.103863 · PMID 34743963
Randomized, double-blind, crossover; 30 adults wearing intra-oral appliances carrying human enamel blocks. 5% nano-hydroxyapatite remineralized early lesions, and adding a lotion afterwards took remineralization from 37.7% to 58.4%. An appliance study on 64 enamel blocks measures a surrogate, not caries in a population, and its first author co-authors the manufacturer-involved review above.
- Butera A, Gallo S, Pascadopoli M, et al. Home oral care with biomimetic hydroxyapatite vs. conventional fluoridated toothpaste for the remineralization and desensitizing of white spot lesions.10.3390/ijerph19148676 · PMID 35886524
40 patients, three months, hydroxyapatite against 1,450 ppm fluoride. Hydroxyapatite did better on sensitivity and pain; erosive wear did not move in either arm. Forty patients, three months, and an outcome that is not caries — a signal about comfort, and it should be labeled that way rather than carried over to decay.
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