How Enamel Toothpaste Works: Fluoride, HAp, and More

Quick answer

Enamel is mostly hydroxyapatite, a calcium phosphate mineral. Acid from plaque bacteria, food, and drink pulls calcium and phosphate out of it. Saliva puts some back. Enamel-protecting toothpaste tips that balance in one of three ways: it helps minerals redeposit into early weak spots, it leaves the surface more resistant to the next acid attack, or it cleans with low enough abrasion that it doesn't wear enamel away.

Fluoride has by far the most evidence, and the ADA recommends fluoride toothpaste. Hydroxyapatite, CPP-ACP, and NovaMin work through calcium and phosphate instead, and arginine works through plaque pH. Their records are smaller and more mixed. None of the studies below tested Klyyr One+.

01
Minerals move both ways
Acid pulls calcium and phosphate out of enamel. Saliva puts some back. Toothpaste tilts the balance.
02
Fluoride leads the evidence
Decades of trials back fluoride toothpaste for cavities. The ADA recommends it.
03
Gentle matters too
An enamel paste that scrubs hard works against itself. Check the RDA where the brand publishes one.

Enamel-protecting toothpaste ingredients, how each works, and what studies show
Topic	Mechanism How it works	Evidence What studies show
Sodium fluoride / MFP	Forms acid-resistant fluorapatite and speeds mineral redeposit	Strongest record; the ADA recommends fluoride toothpaste
Stannous fluoride	Fluoride plus tin, which forms surface deposits and acts on plaque bacteria	Reduces caries like other fluorides; several studies favor it for erosion
Hydroxyapatite (nano + micro)	Supplies the calcium phosphate mineral enamel is made of	One 18-month adult trial: 10% HAp non-inferior to 1450 ppm fluoride; different formula
CPP-ACP	A milk-protein complex that holds calcium and phosphate at the tooth surface	2025 review: effective on white spot lesions, results inconsistent
Arginine	An amino acid that helps plaque produce alkali instead of acid	2016 review: insufficient evidence for caries prevention
Calcium sodium phosphosilicate (NovaMin)	Bioactive glass that releases calcium and phosphate in saliva	2020 review: limited clinical evidence
Low abrasivity (RDA)	Cleans without scrubbing away enamel or exposed dentin	ADA Seal requires RDA 250 or less; One+ publishes RDA 62

Mechanisms are summarized from the sources below. Each study tested its own formula, not One+. One+ facts come from its current label.

Sources behind this answer

Guidance for fluoride, then one review or trial for each other ingredient. Each tested its own formula. None tested One+.

American Dental Association
How fluoride works
The ADA explains that fluoride remineralizes enamel by forming calcium fluorapatite, which resists acid better, and that this can reverse the early decay process. Fluoride toothpaste is the most widely used self-applied fluoride.
Read the ADA fluoride overview
Narrative review · Journal of Functional Biomaterials · 2025
Stannous fluoride
A review of 65 years of literature found that stannous fluoride reduces caries like other fluorides, that tin species form on the enamel surface, and that several studies showed greater protection against erosion. It also reviews its effect on plaque. It is a literature survey, not a systematic review.
Read the review
18-month adult clinical trial · different formula
Caries endpoint
In one 18-month adult study, a 10% HAp toothpaste was non-inferior to 1450 ppm fluoride for the primary caries endpoint. The study tested a different formula.
Read the 18-month non-inferiority study
Systematic review · 2025 · white spot lesions
CPP-ACP
The review found CPP-ACP clinically effective at remineralizing white spot lesions, although results were inconsistent across studies. Adding fluoride appeared to enhance the effect.
Read the systematic review
Systematic review · Caries Research · 2016
Arginine
The review concluded that there is insufficient evidence for a caries-preventive effect from adding arginine to toothpaste, and it called for studies less dependent on commercial interests.
Read the abstract
Systematic review · 2020
Calcium sodium phosphosilicate (NovaMin)
The review found significantly less clinical evidence for NovaMin as a remineralizing agent for carious and non-carious lesions, and called for better-designed trials before firm recommendations.
Read the systematic review
American Dental Association
ADA Seal of Acceptance
Toothpastes with the Seal must have an RDA of 250 or less. Seal-accepted toothpastes that claim cavity protection must contain fluoride, and sugar is not permitted.
Read about the ADA Seal

How to choose

If you get cavities

Fluoride toothpaste has the strongest evidence. Ask your dentist before you switch to a fluoride-free paste.

If acid is the problem

Soda, citrus, and reflux soften enamel without help from bacteria. Stannous fluoride has the most erosion data. Wait 30 to 60 minutes after acidic food or drink before you brush. Why the wait matters.

If you want fluoride-free

Hydroxyapatite has the most clinical data among fluoride-free options. Check that the label discloses the percentage. See what HAp evidence shows.

The Klyyr One+ formula

One+ is fluoride-free toothpaste with a clearly disclosed 10% nano + micro hydroxyapatite blend, 16 listed ingredients, peppermint + spearmint, no SLS, and no artificial dyes.

01
10% hydroxyapatite
Combined nano + micro hydroxyapatite, disclosed on the label. Ten percent is not a universal efficacy threshold.
02
16 listed ingredients
Water, Sorbitol, Glycerin, Potassium Sorbate, Hydroxyapatite (nano & micro), Xylitol, Sodium Cocoyl Glutamate, Cellulose Gum, Xanthan Gum, Zinc Citrate, Aloe Vera, Mentha Piperita (Peppermint) Oil, Mentha Viridis (Spearmint) Leaf Oil, Menthol, Sodium Benzoate, Stevia Rebaudiana Leaf/Stem Extract.
03
What is not in it
0 ppm fluoride. No SLS. No artificial dyes. Sodium cocoyl glutamate is the surfactant.
04
120 g aluminum tube
4.23 oz, approximately 90 brushings. Aluminum tube, HDPE cap. Recycle where accepted locally.

In short

Enamel toothpaste works by helping minerals back into enamel, hardening it against acid, or cleaning gently enough not to wear it down. Fluoride has the most evidence for the first two. Read the label for the active and its strength, and for an RDA if the brand publishes one.

01 Can toothpaste rebuild enamel?

Toothpaste can't regrow enamel that is gone, because enamel has no living cells. It can help minerals redeposit into early, weakened spots before they become cavities. Fluoride has the most evidence for that. Hydroxyapatite, CPP-ACP, and NovaMin are studied for it with smaller records.

02 Which toothpaste ingredients rebuild enamel?

Fluoride actives (sodium fluoride, sodium monofluorophosphate, stannous fluoride) have the strongest evidence for remineralizing early lesions. Calcium phosphate ingredients, namely hydroxyapatite, CPP-ACP, and calcium sodium phosphosilicate, are also studied. Their evidence is smaller and depends on the formula.

03 Is hydroxyapatite as good as fluoride for enamel?

One 18-month adult study found a 10% HAp toothpaste non-inferior to 1450 ppm fluoride for its primary caries endpoint. The study tested a different formula, and one trial does not settle the question. Ask your dentist if your cavity risk is high.

04 Does enamel toothpaste help with erosion?

Erosion comes from dietary acid rather than bacteria. Several studies favor stannous fluoride for erosion. The usual advice is also to wait 30 to 60 minutes after acidic food or drink before brushing, and to rinse with water in the meantime.

Read the full FAQ →

ONE+

10% nano + micro hydroxyapatite, disclosed. RDA 62, published.

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How enamel toothpaste works.

Sources behind this answer

How fluoride works

Stannous fluoride

Caries endpoint

CPP-ACP

Arginine

Calcium sodium phosphosilicate (NovaMin)

ADA Seal of Acceptance