A Calcium-Phosphate System
Its oral-care rationale begins with mineral chemistry related to enamel and dentin—not with a marketing percentage.
A Material Guide for Oral-Care Product Development
Nano-Hydroxyapatite: A Biomimetic Mineral for Modern Oral Care
Nano-hydroxyapatite, commonly shortened to nHA, is a calcium-phosphate material designed around the mineral chemistry of teeth. It can be considered for toothpastes, tablets, gels, serums, mousses, powders, mouth rinses and other daily or professional oral-care formats.
nHA performance depends on more than particle size or the percentage printed on a label. Chemical composition, morphology, surface characteristics, active content, dispersion, product format and contact with tooth surfaces all influence its behavior in an oral-care formula.
Start with its identity
What Nano-Hydroxyapatite Actually Is
Hydroxyapatite is a calcium-phosphate mineral commonly written as Ca10(PO4)6(OH)2. Natural enamel and dentin contain apatite crystals within highly organized biological structures. Synthetic nHA is not identical to a living tooth, but its related mineral chemistry provides the rationale for describing it as a biomimetic oral-care material.
The nano scale increases surface area relative to mass and can influence how particles contact mineral-deficient or porous tooth surfaces. It may also change dispersion, aggregation, rheology and sensory behavior. For this reason, the ingredient name alone does not fully describe how an nHA material will behave.
A complete technical description therefore includes chemical composition, particle morphology, size distribution, aspect ratio, crystallinity, surface treatment, purity, active content and the physical form in which the material enters a product.
A Particulate Material
Particles can deposit, aggregate, suspend or settle. Their physical character influences both tooth interaction and product design.
A Grade-Specific Nanoform
Different grades may not share the same size, morphology, coating, assay or regulatory relevance.
A Formulation Input
The final user experience depends on the complete oral-care formula, delivery format, contact time and directions for use.
Read beyond the word “nano”
The Material Characteristics That Change Its Behavior
nHA can form short rod-like nanoscale particles as well as larger agglomerates. A rod-shaped, non-needle oral-care grade can have a median particle length of 27.6 ± 3.1 nm and a median width of 15.4 ± 2.8 nm, with at least 95.8% of particles having an aspect ratio below 3. Size, shape and aggregation all influence surface contact, dispersion and product texture.
MorphologyRod, plate, spherical and needle-like forms should not be treated as equivalent.
Size DistributionA single average or “below 100 nm” statement does not describe the entire population.
Aspect RatioLength-to-width distribution is part of the identity of a safety-evaluated nanoform.
CrystallinityHigh crystallinity supports a stable apatite structure and helps distinguish nHA from less ordered calcium-phosphate phases.
Surface StatusCoating or chemical modification can change compatibility and the relevance of a published safety opinion.
AggregationPrimary particles can cluster, affecting suspension, texture, delivery and available contact area.
What it can contribute
How nHA May Support Teeth and Oral-Care Performance
The most defensible explanation is a sequence of physical and mineral interactions. The strength of a finished-product claim depends on the selected material, the complete formula, the test method and the intended market.
Mineral Deposition on Tooth Surfaces
Particles can attach to rough, porous or demineralized areas. Laboratory methods may visualize deposits, filled micro-irregularities or a more continuous mineral-rich surface after treatment.
A Local Calcium-Phosphate Source
At the tooth interface, hydroxyapatite contributes calcium-phosphate material to an environment controlled by saliva, pH, acids, contact time and repeated oral-care use.
Coverage of Exposed Dentin Tubules
Particles and deposited mineral can cover or enter exposed tubules. Reduced tubule openness can lower fluid movement in laboratory models used to study desensitizing potential.
Surface Feel and Optical Appearance
Mineral deposition and cleaning-system design may influence surface smoothness and the way light reflects from teeth. Whitening or polishing claims still require testing of the final product.
A useful wording boundary: biomimetic mineral deposition, surface support and tubule coverage can be explained without reducing these mechanisms to a promise that an oral-care product “grows new enamel” or cures a dental condition.
One material, different delivery systems
Where nHA Can Fit in an Oral-Care Portfolio
nHA is not limited to conventional toothpaste. It can be evaluated in solid, semi-solid and liquid oral-care products, but the same raw material will not behave identically in every format. Each product needs its own dispersion strategy, active-content calculation, stability program, packaging review and claim support.
The development plan starts with how the format will be used, how long it contacts the teeth, whether it is brushed or rinsed, and how the material will remain uniformly delivered throughout its shelf life.
Toothpastes and Brush-On Pastes
A structured paste can hold mineral particles during storage and provide controlled delivery during brushing. Abrasivity, extrusion, foam, flavor and after-feel must be balanced.
Toothpaste Tablets and Solid Doses
Dry formats need good dose uniformity, moisture control, mechanical strength and rapid breakup so particles can disperse during use rather than remain in hard agglomerates.
Gels, Serums and Mousses
Topical formats can be designed around contact, spreadability and targeted use. Rheology, applicator design, flavor intensity and compatibility with other actives become central.
Mouth Rinses and Liquid Concentrates
Liquid systems require careful control of suspension, sedimentation, redispersibility, mouthfeel and preservation. European concentration conclusions also differ between rinse and paste formats.
Tooth Powders
Powders avoid an aqueous base but demand strong control of dust, flow, segregation, dose consistency and wetting when the consumer introduces water.
Professional or Kit-Based Care
Polishing pastes, post-cleaning topical products and multi-step kits may use different contact times and instructions. Testing and product classification must match the exact intended use.
European safety context
The SCCS Limits Apply to a Defined Nanoform
In its 2025 final opinion, the EU Scientific Committee on Consumer Safety considered hydroxyapatite (nano) safe up to 29.5% in toothpaste and 10% in mouthwash. These figures are often quoted as if they applied to every material sold under the same ingredient name, but the opinion is tied to the nanoform described in the submission.
The SCCS-assessed nanoform is rod-shaped, uncoated and unmodified. At least 87% of particles have an aspect ratio at or below 3, while the remaining fraction is at or below 9; the maximum particle length is 122 ± 43 nm. The conclusion does not apply to material containing needle-shaped particles.
The SCCS opinion must therefore be matched to the actual nanoform rather than treated as a blanket approval. Particle characteristics, intended product type, active percentage and the destination-market pathway all remain part of the assessment.
What Must Be Checked for a European Project
✓Whether the particles are rod-shaped and non-needle
✓Size and aspect-ratio distribution, not only one average
✓Whether the material is coated, modified or otherwise outside the assessed nanoform conditions
✓Actual hydroxyapatite content in the finished product
✓Whether the product is a paste, rinse or another format with its own regulatory pathway
Chemistry and material profile
Key Technical Properties of Nano-Hydroxyapatite
The performance of nHA is shaped by its calcium-phosphate chemistry, particle dimensions, morphology, crystallinity, purity and active concentration. These properties also affect dispersion, processing and compatibility with different oral-care formats.
| Property | Technical Value | Why It Matters |
|---|---|---|
| Chemical formula and Ca/P ratio | Ca10(PO4)6(OH)2; Ca/P 1.67 ± 0.02 | Connects the material to the calcium-phosphate chemistry of tooth mineral. |
| Oxide composition | CaO 51.8 wt%; P2O5 39.6 wt% | Provides an additional way to describe the calcium and phosphate composition. |
| Particle dimensions | Average particle size ≤100 nm; median rod length 27.6 ± 3.1 nm and width 15.4 ± 2.8 nm | Influences surface area, tooth-surface contact, dispersion and sensory behavior. |
| Morphology and aspect ratio | Rod-shaped, non-needle; at least 95.8% of particles have an aspect ratio below 3 | Shape and elongation affect aggregation, flow and regulatory relevance. |
| Crystallinity | ≥95% | Indicates a highly ordered hydroxyapatite crystal structure. |
| Liquid suspension concentration | 15.4 wt% hydroxyapatite | Shows why suspension addition rate and active nHA percentage are not the same number. |
| Aqueous-system pH and viscosity | pH 9.5–10.5; viscosity 50–400 cP at 25°C | Influences ingredient order, thickener response, pumping and compatibility with the finished base. |
| Water solubility | Approximately 0.00657 g/L at 20°C | Shows why liquid products rely on particle dispersion and suspension rather than complete dissolution. |
| Powder density and stability | Relative density 3.14–3.21; non-combustible and stable under normal conditions | Affects volumetric dosing, dust control, wetting and material handling. |
| Elemental and microbiological control | Pb ≤10 mg/kg; Hg ≤1 mg/kg; As ≤2 mg/kg; Cd ≤5 mg/kg; total microbial count <3 cfu/g | Supports raw-material purity, hygiene and controlled oral-care manufacturing. |
nHA grades can differ in particle profile, active concentration and physical form. The complete oral-care formula determines how these material properties translate into stability, delivery and finished-product performance.
Physical form changes processing
Dry nHA Powder vs. a Pre-Dispersed Aqueous System
nHA is only sparingly soluble in water, so an aqueous product contains dispersed mineral particles rather than a conventional dissolved active. This distinction explains why wetting, agglomeration, sedimentation and redispersibility matter in liquid and semi-solid oral-care products.
The same ingredient name can therefore enter a formula through two very different manufacturing routes. Dry powder offers a high mineral fraction, while a pre-dispersed system introduces water, electrolyte and its own pH and viscosity into the formula.
Dry Powder Route
Maximum Mineral Fraction, More Wetting Work
With a relative density of about 3.14–3.21, nHA powder carries substantial mass in a small solid volume. Accurate gravimetric dosing is preferable to relying on scoop volume.
Manufacturing must control dust, powder addition rate, wetting and mixing energy. Adding fine particles too quickly can create dry pockets or persistent agglomerates that later appear as grit, poor uniformity or unstable sediment.
Pre-Dispersed Route
Easier Initial Dispersion, More Formula Inputs
A pre-dispersed oral-care system can contain 15–16 wt% hydroxyapatite and 4–5 wt% potassium chloride, with pH 9.5–10.5 and viscosity of 50–400 cP at 25°C.
Its full mass enters the water and electrolyte balance, even though only the assayed HAp fraction counts toward the target active level. The system should be protected from freezing and re-homogenized before dosing so settled particles do not create concentration variation.
Why “Dispersed” Is Not the Same as “Dissolved”
A clear solution contains molecules or ions distributed at the molecular scale. An nHA dispersion contains solid particles in a continuous phase. A product may look uniform after mixing but still settle during storage; stability must therefore be checked through top-middle-bottom sampling, redispersibility, particle or active-content uniformity, viscosity and pack testing.
Dentin tubule interaction
How nHA Interacts with Dentin In Vitro
Exposed dentin contains open microscopic tubules. nHA particles can deposit on the surface, cover tubule openings and reduce fluid movement in laboratory models. Tubule-occlusion imaging and dentin-permeability testing measure different aspects of this physical interaction.
Tubule Occlusion
81.63% Occlusion with 8% HAp Toothpaste
In an in-vitro bovine-dentin method, acid-etched specimens were brushed for two minutes with a 1:1.5 toothpaste slurry and examined by SEM at 2,000×. The 8% HAp toothpaste produced an 81.63% tubule-occlusion rate.
Interpretation: this is a controlled laboratory result, not a guaranteed clinical sensitivity outcome.
Dentin Permeability
49.88% Relative Permeability with 20% HAp
In a dentin-permeability method using a 20% HAp dispersion, mean permeability decreased from 0.1037 ± 0.0171 to 0.0521 ± 0.0147 μL·min−1·cm−2·cmH2O−1, with P<0.05.
Interpretation: permeability and tubule occlusion are different laboratory endpoints and should not be compared numerically.
From material to delivery system
Formulating nHA Across Oral-Care Formats
A raw-material percentage does not reveal whether particles are uniformly dispersed, physically stable, compatible with the base or available at the tooth surface during use. The delivery system must be designed around the selected nHA grade and the way the consumer will use the product.
Each format creates different technical demands: a rinse must manage sedimentation and redispersibility; a gel needs suitable contact and extrusion; a tablet needs dose uniformity and breakup; a powder needs flow and wetting; and a paste must balance suspension, cleaning, texture and packaging.
Why Active-Content Math Matters
A liquid nHA suspension may contain 15.4 wt% hydroxyapatite, with water and potassium chloride making up most of the balance. Adding 10 kg of this suspension to a 100 kg formula contributes 1.54 kg of hydroxyapatite—not 10 kg.
The ingredient addition rate must therefore be distinguished from the target percentage of active hydroxyapatite. Active concentration, carrier ingredients, final formula weight, stability and processing controls all form part of the calculation.
01. Powder or Suspension
The physical form changes active-content math, wetting, water balance, addition order, transport and processing requirements. A suspension must be re-homogenized before accurate dosing.
02. Dispersion and Sedimentation
Mixing energy, particle interactions and the continuous phase influence agglomeration, settling and redispersibility.
03. pH and Electrolytes
A pre-dispersed system can arrive at pH 9.5–10.5 and contain potassium chloride. Both pH and ionic strength can change thickener hydration, flavor perception and compatibility with other actives.
04. Rheology and Delivery
A product must remain uniform but still pour, pump, spray, foam, dissolve or extrude as the package and instructions require.
05. Sensory and Cleaning Balance
Mineral loading can change taste, opacity, slip, after-feel and perceived dryness. The whole system must be tuned rather than masked at the end.
06. Stability, Microbiology and Pack
Physical stability, top-middle-bottom uniformity, redispersibility, pH, microbial quality, active content, freeze sensitivity, packaging interaction and appearance are checked for the chosen format.
Featured toothpaste application
Our Custom 10% Nano-Hydroxyapatite Toothpaste
Among the many possible formats, 10% nHA toothpaste is a frequently requested private-label project. Ten percent is a useful development benchmark because it has appeared in controlled toothpaste research, including an 18-month adult caries-prevention trial.
The trial reported no increase in DMFS for 89.3% of the per-protocol hydroxyapatite group and 87.4% of the fluoride-control group. Under the defined study conditions, the hydroxyapatite toothpaste met the non-inferiority criterion.
A concentration figure cannot reproduce a clinical study by itself. We use 10% as one design input, then develop the selected nHA grade, dispersion, cleaning system, texture, flavor, tube, carton and agreed verification package around the brand brief.
- ✓Target nHA level and raw-material route
- ✓Fluoride-free or market-specific active system
- ✓Flavor, foam, viscosity, tube and carton customization
- ✓Stability, microbiological quality and agreed finished-product testing
Technical FAQ
Frequently Asked Questions About nHA
Is nano-hydroxyapatite only used in toothpaste?
No. It can be evaluated for tablets, gels, serums, mousses, powders, mouth rinses and professional-care formats. Each delivery system needs its own dispersion, stability, sensory, packaging and regulatory review.
Is every hydroxyapatite below 100 nm equivalent?
No. Size is only one parameter. Shape, aspect ratio, surface modification, crystallinity, purity, aggregation, assay and material traceability also matter.
How may nHA help enamel and dentin?
Research supports mineral deposition on tooth surfaces and physical coverage of exposed dentin tubules. The resulting claim must be based on the final product and should not be simplified into a promise that the product grows new biological enamel.
Does the European 29.5% conclusion apply to every nHA grade?
No. The SCCS opinion applies to a rod-shaped, uncoated and unmodified nanoform and excludes material containing needle-shaped particles. The actual particle profile must fit these conditions.
Why is the mouthwash figure different from the toothpaste figure?
The SCCS final opinion considered up to 29.5% in toothpaste and 10% in mouthwash for the specified material. Product type, exposure and the assessed use conditions are part of the conclusion, so the paste figure should not be transferred to a rinse.
Is 10% always the best concentration for toothpaste?
Ten percent is a clinically studied and commercially useful benchmark, but concentration alone does not determine performance. Particle properties, active-content calculation, dispersion, base formula, contact and test method all influence the result.
Can an 81.63% in-vitro occlusion result support every product claim?
No. The 81.63% value comes from an 8% HAp toothpaste under a defined bovine-dentin laboratory method. A market claim must be supported by testing relevant to the final formula and reviewed for its destination.
Why can a liquid nHA product be harder to stabilize?
Mineral particles may settle or form aggregates. A liquid system must manage suspension, redispersibility, viscosity, electrolytes, mouthfeel and preservation without changing the selected material’s intended role.
Which nHA properties matter during product development?
Chemical composition, active concentration, particle size, morphology, aspect ratio, crystallinity, surface status, purity, aggregation and physical form all affect formulation choices and regulatory assessment.
Science-led oral-care development
Develop an nHA Format That Fits Your Brand and Market
Tell us the product format, target market, intended nHA level, active system, sensory brief, packaging and claim direction. We can align the material profile, formulation pathway, testing plan and manufacturing requirements before scale-up.
Explore Our nHA Knowledge Library
Our articles examine science, safety, regulation, raw-material options and product development from different angles. They extend this material guide without repeating the same explanation.
