Hydroxyapatite
Calcium hydroxyapatite (Ca10(PO4)6(OH)2)
TL;DR
Hydroxyapatite is the mineral of bone and enamel. In toothpaste, trials show it eases tooth sensitivity and may match fluoride for cavity prevention. As an oral bone supplement, the evidence is old, small and mostly open-label.
Ideal For
- Adults with tooth sensitivity who want a fluoride-free or additional desensitizing toothpaste
- People who prefer fluoride-free toothpaste and accept that its cavity evidence is shorter than fluoride's
Avoid If
- You are at high cavity risk and your dentist has advised fluoride: do not swap it out without asking
- You take levothyroxine, a quinolone antibiotic, dolutegravir, lithium or an oral bisphosphonate and plan an oral supplement: separate or ask first
- You have high blood calcium, hyperparathyroidism or calcium kidney stones and are considering oral supplements
- You are relying on it instead of prescribed osteoporosis treatment
Frequently Asked Questions
What is hydroxyapatite?
Does hydroxyapatite toothpaste help sensitive teeth?
Can hydroxyapatite replace fluoride for cavity prevention?
Is nano-hydroxyapatite safe?
Does oral hydroxyapatite build bone?
Overview
Hydroxyapatite is the calcium phosphate mineral that gives bone and teeth their hardness. The NIH Office of Dietary Supplements notes that more than 99% of the body's calcium is stored as calcium hydroxyapatite in bones and teeth. The name covers two very different kinds of product. One is synthetic hydroxyapatite, in nano-sized or microcrystalline particles, added to toothpaste, gels and mouthwash. The other is bone-derived oral hydroxyapatite, sold as microcrystalline hydroxyapatite compound (MCHC) or ossein-hydroxyapatite complex (OHC), which supplies calcium, phosphorus and, in the ossein form, non-collagen peptides.
The dental evidence is the stronger. A meta-analysis of six randomized trials found hydroxyapatite-containing treatments relieved dentin hypersensitivity more than other treatments or placebo over 4 weeks (SMD -0.93), and a later review of 44 trials found a 39.5% larger reduction than placebo. For cavities, non-inferiority trials in children, adults and orthodontic patients found fluoride-free hydroxyapatite toothpaste performed about as well as fluoride toothpaste over 6 to 18 months. Caveats apply: the sensitivity trials are short, several share authors, and the American Dental Association requires fluoride in a toothpaste before it can be accepted for anticaries claims.
The bone evidence is thinner and older. Small trials of ossein-hydroxyapatite and microcrystalline hydroxyapatite in postmenopausal women and people on corticosteroids reported less bone loss than no treatment or calcium carbonate, but most were open-label, none measured fractures as the main result, and the one modern randomized, placebo-controlled trial (100 women, 3 months) measured bone turnover markers rather than density. Current guidelines put bisphosphonates first for osteoporosis, with calcium and vitamin D as the base.
Safety depends on the form. Regulators reviewing nano-hydroxyapatite in oral products found no mutagenic, cytotoxic or inflammatory signal in cell models at the particle sizes assessed. Oral hydroxyapatite supplements are calcium supplements, so total calcium limits, constipation and drug interactions (levothyroxine, quinolone antibiotics, dolutegravir, lithium) apply, and lead has been found in bone-meal and other calcium products, so third-party testing matters.
How It Works
- In teeth, hydroxyapatite particles are the same mineral as enamel and dentin; in laboratory studies they block the open dentinal tubules that carry cold, air and touch to the tooth nerve.
- Sensitivity is most widely explained by the hydrodynamic theory: fluid moving in exposed tubules stimulates nerve endings. Plugging the tubules is the proposed way hydroxyapatite helps, but plugging in the laboratory does not prove clinical benefit.
- For cavities, hydroxyapatite is proposed to supply calcium and phosphate to early enamel lesions; in situ trials measured lesion size and fluorescence rather than new cavities.
- Taken by mouth as MCH or OHC, it is a calcium and phosphate source; in a 100-woman trial it lowered bone turnover markers about as much as calcium citrate or carbonate while raising blood ionised calcium less.
- Ossein-hydroxyapatite also contains non-collagen peptides, and the trials cannot say whether those add anything beyond the calcium and phosphate.
Quick Facts
- Mineral that makes up bone and tooth enamel
- Toothpaste trials show relief of tooth sensitivity
- Cavity trials: non-inferior to fluoride, mostly short
- ADA anticaries acceptance requires fluoride
- Oral bone forms: small, mostly open-label trials
- Lead has been found in bone-meal calcium products
Health Concerns Addressed
Dentin Hypersensitivity
Likely helps: pooled randomized trials favour hydroxyapatite over placebo and fluoride over 4 to 8 weeks, but it is not shown to beat the other proven desensitizers.
Osteoporosis
Pooled trials show slightly less bone loss than calcium carbonate, but no evidence of fewer fractures, and the independent trials are small.
Dental Caries
Not yet proven: fluoride-free hydroxyapatite matched fluoride in small, short trials, while the much larger fluoride evidence base keeps fluoride the default.
Supporting Research32 studies
Clinical efficacy of nano-hydroxyapatite in dentin hypersensitivity: A systematic review and meta-analysis
de Melo Alencar C, de Paula BLF, Guanipa Ortiz MI +3 more
n-HAP-containing treatment showing the most significant desensitizing effect
Efficacy of ossein-hydroxyapatite complex compared with calcium carbonate to prevent bone loss: a meta-analysis
Castelo-Branco C, Ciria-Recasens M, Cancelo-Hidalgo MJ +4 more
OHC is significantly more effective in preventing bone loss than CC
Comparison of the treatment effects of ossein-hydroxyapatite compound and calcium carbonate in osteoporotic females
Rüegsegger P, Keller A, Dambacher MA
OHC is more effective than CC in slowing peripheral trabecular bone loss
Raloxifene plus ossein-hydroxyapatite compound versus raloxifene plus calcium carbonate to control bone loss in postmenopausal women: a randomized trial
Pelayo I, Haya J, De la Cruz JJ +4 more
RLX plus OHC appears to be more effective in controlling bone loss than RLX plus CC
Efficacy and safety of ossein-hydroxyapatite complex versus calcium carbonate to prevent bone loss
Castelo-Branco C, Cancelo Hidalgo MJ, Palacios S +4 more
OHC showed greater efficacy and tolerability than CC for bone loss prevention
Prospective trial of ossein-hydroxyapatite compound in surgically induced postmenopausal women
Stĕpán JJ, Pospíchal J, Presl J +1 more
preventing cortical bone loss in a portion of at-risk postmenopausal women
Clinical Evidence of Biomimetic Hydroxyapatite in Oral Care Products for Reducing Dentin Hypersensitivity: An Updated Systematic Review and Meta-Analysis
Limeback H, Enax J, Meyer F
HAP significantly reduced dentin hypersensitivity compared to placebo
Efficacy of nano-hydroxyapatite on caries prevention-a systematic review and meta-analysis
Wierichs RJ, Wolf TG, Campus G +1 more
do not allow for conclusive evidence on the efficacy of nHA
Desensitizing Toothpastes for Dentin Hypersensitivity: A Network Meta-analysis
Martins CC, Firmino RT, Riva JJ +4 more
potassium + hydroxyapatite
Biomimetic hydroxyapatite and caries prevention: a systematic review and meta-analysis
Limeback H, Enax J, Meyer F
HAP provided 17% protection against caries
Effectiveness of nano-hydroxyapatite toothpaste in reducing dentin hypersensitivity: a double-blind randomized controlled trial
Vano M, Derchi G, Barone A +1 more
encourage the application of nano-hydroxyapatite in fluoride-free toothpaste as an effective desensitizing agent
Hydroxyapatite-Fluoride Toothpastes on Caries Activity: A Triple-Blind Randomized Clinical Trial
Cocco F, Salerno C, Wierichs RJ +4 more
may be better for children with active caries lesion in primary dentition
Reducing dentine hypersensitivity with nano-hydroxyapatite toothpaste: a double-blind randomized controlled trial
Vano M, Derchi G, Barone A +3 more
nano-hydroxyapatite in gel toothpaste fluoride free is an effective desensitizing agent
Fluoride-Free Toothpastes for Caries Prevention: A Systematic Review of Clinical Evidence on Active Ingredients
Unterbrink P, Schulze Zur Wiesche E, Amaechi BT +1 more
Three trials evaluated the caries-preventing efficacy of fluoride-free hydroxyapatite toothpastes
Clinical efficacy of nanohydroxyapatite-containing toothpaste at relieving dentin hypersensitivity: an 8 weeks randomized control trial
Amaechi BT, Lemke KC, Saha S +2 more
as effective as CSPS for relief of DHS symptoms
The effect of nano-hydroxyapatite on white spot lesions: A systematic review and meta-analysis
Alajlan S, et al.
promising remineralisation effect on WSLs in comparison to fluoride alone
A double-blind randomized-controlled trial comparing the desensitizing efficacy of a new dentifrice containing carbonate/hydroxyapatite nanocrystals and a sodium fluoride/potassium nitrate dentifrice
Orsini G, Procaccini M, Manzoli L +3 more
significantly reduced dentinal hypersensitivity after 4 and 8 weeks
Efficacy of a Toothpaste Based on Microcrystalline Hydroxyapatite on Children with Hypersensitivity Caused by MIH: A Randomised Controlled Trial
Ehlers V, Reuter AK, Kehl EB +4 more
hydroxyapatite group tended to be less hypersensitive in both populations
Impact of a toothpaste with microcrystalline hydroxyapatite on the occurrence of early childhood caries: a 1-year randomized clinical trial
Paszynska E, Pawinska M, Gawriolek M +4 more
is not inferior to a fluoride control toothpaste
Caries-preventing effect of a hydroxyapatite-toothpaste in adults: a 18-month double-blinded randomized clinical trial
Paszynska E, Pawinska M, Enax J +4 more
not statistically inferior to a fluoride toothpaste
Clinical evidence of caries prevention by hydroxyapatite: An updated systematic review and meta-analysis
Pawinska M, Paszynska E, Amaechi BT +3 more
hydroxyapatite is effective as an anti-caries active ingredient in the absence of fluoride
The role of hydroxyapatite-based, fluoride-free toothpastes on the prevention and the remineralization of initial caries lesions: A systematic review and meta-analysis
Chatzidimitriou K, Theodorou K, Seremidi K +3 more
no significant differences between HAP and fluoride toothpastes
Impact of a non-fluoridated microcrystalline hydroxyapatite dentifrice on enamel caries progression in highly caries-susceptible orthodontic patients: A randomized, controlled 6-month trial
Schlagenhauf U, Kunzelmann KH, Hannig C +4 more
not significantly different from the use of a 1400 ppm fluoride toothpaste
Efficacy of HAF toothpastes in primary and permanent dentitions. A 2-years triple-blind RCT
Cagetti MG, Cocco F, Wierichs RJ +4 more
reduces caries increment in children over a period of 2 years more than traditional fluoridated toothpastes
Acute and 3-month effects of microcrystalline hydroxyapatite, calcium citrate and calcium carbonate on serum calcium and markers of bone turnover: a randomised controlled trial in postmenopausal women
Bristow SM, Gamble GD, Stewart A +4 more
comparable decreases in bone resorption
Microcrystalline hydroxyapatite compound in prevention of bone loss in corticosteroid-treated patients with chronic active hepatitis
Stellon A, Davies A, Webb A +1 more
results overall were consistent with a beneficial effect from MCHC
Clinical trial of microcrystalline hydroxyapatite compound ('Ossopan') in the prevention of osteoporosis due to corticosteroid therapy
Pines A, Raafat H, Lynn AH +1 more
much more marked decreases in the control group
Preventing postmenopausal bone loss with ossein-hydroxyapatite compounds. Results of a two-year, prospective trial
Castelo-Branco C, Pons F, Vicente JJ +2 more
Continuous administration of OHC prevents bone loss in postmenopausal women
Comparison of the effects of ossein-hydroxyapatite complex and calcium carbonate on bone metabolism in women with senile osteoporosis: a randomized, open-label, parallel-group, controlled, prospective study
Ciria-Recasens M, Blanch-Rubió J, Coll-Batet M +4 more
OHC had a greater anabolic effect on bone than calcium carbonate
Prevention of osteoporosis: four-year follow-up of a cohort of postmenopausal women treated with an ossein-hydroxyapatite compound
Fernández-Pareja A, Hernández-Blanco E, Pérez-Maceda JM +3 more
progressive and statistically significant increase in BMD
Comparison of the effects of two different types of calcium supplementation on markers of bone metabolism in a postmenopausal osteopenic population with low calcium intake: a double-blind placebo-controlled trial
Albertazzi P, Steel SA, Howarth EM +1 more
the effect of ossein-hydroxyapatite seems slightly superior to that of tricalcium phosphate
Ossein-hydroxyapatite compounds for preventing postmenopausal bone loss. Coadjuvant use with hormone replacement therapy
Castelo-Branco C, Martínez de Osaba MJ, Pons F +4 more
combined regimen of OHC and HRT increased vertebral bone mass
Safety Information
Potential Side Effects
Toothpaste: the trial reports reviewed did not highlight adverse effects, and EU reviewers found no mutagenic, cytotoxic or inflammatory signal for nano-sized particles in mouth-cell models. Oral supplements: mild constipation in 3.2% of 112 women over 4 years in one cohort; NIH lists gas, bloating and constipation for calcium supplements generally.
Contraindications
Oral supplements: ask a clinician first if you have high blood calcium, hyperparathyroidism, calcium kidney stones or kidney disease. The EU safety opinion covers only uncoated rod-shaped nanoparticles of about 120 nm and excludes needle-shaped or coated particles.
Drug Interactions
- Levothyroxine: calcium carbonate lowers its absorption and the label advises a 4-hour gap; no data for hydroxyapatite, so keep the same gap.
- Quinolone antibiotics (ciprofloxacin, moxifloxacin): calcium reduces absorption; take the antibiotic 2 hours before or after.
- Dolutegravir: calcium can cut drug levels; the label says take it 2 hours before or 6 hours after calcium.
- Lithium: long-term lithium can raise calcium, so added calcium may add to the risk; ask your prescriber.
- Oral bisphosphonates (alendronate): calcium supplements interfere with absorption; take the bisphosphonate first with plain water and wait at least 30 minutes before any calcium, as the label advises.
Pregnancy & Breastfeeding
Pregnancy: Not enough evidence to judge
Breastfeeding: Not enough evidence to judge
Dosage Guidelines
Dosage Used in Studies
Consult healthcare provider
Best Time to Take
Toothpaste: twice daily, as in the sensitivity trials. Oral supplements: split into smaller doses with meals.
Best Form
For teeth, toothpaste is the form with trial data. For bone, no hydroxyapatite form has been shown to prevent fractures.
Bioavailability
In a 100-woman randomized trial, microcrystalline hydroxyapatite raised ionised calcium less than calcium citrate or carbonate but raised phosphate and the calcium-phosphate product; both lowered bone turnover markers by similar amounts at 3 months.
Dosing by Goal
| Goal | Dose | Notes |
|---|---|---|
| Sensitivity (toothpaste) | Brush for 2 minutes, twice a day, with a 10-15% nano-hydroxyapatite toothpaste | Trials assessed relief at 2, 4 and 8 weeks. A 2% gel left on the teeth for 10 minutes twice daily also worked in one trial. |
| Cavity prevention (toothpaste) | Fluoride-free microcrystalline hydroxyapatite toothpaste, 2-3 times a day in trials | Fluoride-free trials ran 6 to 18 months; a 2-year trial used fluoride plus substituted hydroxyapatite. Ask a dentist before replacing fluoride if you are at high cavity risk. |
| Bone (oral, as studied) | About 1 g calcium a day as MCH for 3 months, or 3.32 g a day of OHC for 2 years | No dose has been shown to prevent fractures. Keep total calcium within the NIH upper limit of 2,000 mg a day (age 51 and over) or 2,500 mg (19-50). |
Forms Compared
Nano-hydroxyapatite toothpaste or gel
Best for Dentin hypersensitivity
Concentrations in sensitivity trials ranged from 2% (gel) to 15% (toothpaste). The EU scientific committee judged nano-hydroxyapatite safe up to 29.5% in toothpaste and 10% in mouthwash, for the particle specification it assessed.
Microcrystalline hydroxyapatite toothpaste (fluoride-free)
Best for People who avoid fluoride, with their dentist's agreement
Used in non-inferiority trials against fluoride toothpaste in children, adults and orthodontic patients. Cannot carry an ADA anticaries acceptance because the ADA requires fluoride for that claim.
Fluoride plus substituted hydroxyapatite toothpaste
Best for Caries prevention in children; sensitivity
Carbonate-, zinc- or fluoride-substituted hydroxyapatite complexes were tested in schoolchildren and in people with sensitivity.
Mouthwash
Best for No efficacy data summarised here
The EU scientific committee set 10% as the safe maximum for nano-hydroxyapatite in mouthwash.
Microcrystalline hydroxyapatite (MCH, MCHC) capsules or tablets
Best for Studied for bone loss; no fracture data
Bone-derived calcium and phosphate. A 3-month trial used MCH supplying 1 g calcium a day; an older steroid trial used 6 to 8 g of MCHC a day.
Ossein-hydroxyapatite complex (OHC)
Best for Studied for postmenopausal bone loss
Bone extract with calcium, phosphorus and non-collagen peptides. Doses in trials were 3.32 g a day or 1,660 mg twice daily.
Food & Timing
Oral supplements: take with meals; NIH advises smaller, more frequent calcium doses or taking them with food to ease stomach upset.
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.