A Primer on Hydroxyapatite

Although enamel is extremely hard, it is not chemically static.

After exposure to acids, minerals can move out of the tooth surface — a process known as demineralization. These acids may come directly from acidic foods and drinks or be produced when oral bacteria metabolise fermentable carbohydrates.

Saliva normally helps the mouth recover. It dilutes and buffers acids while supplying calcium and phosphate that support remineralization, the return of minerals to weakened areas of the tooth.

Synthetic hydroxyapatite is used in products such as toothpastes, gels and professional dental materials.

Depending on particle size and formulation, hydroxyapatite may attach to the tooth surface, deposit within microscopic irregularities and provide calcium-phosphate material around areas affected by demineralization. Smaller hydroxyapatite particles are also studied for their ability to enter surface defects and partially block open dentinal tubules — the tiny channels associated with tooth sensitivity.²

Researchers have investigated hydroxyapatite for several oral-care applications:

• supporting enamel remineralization;
• helping prevent early caries progression;
• reducing dentine hypersensitivity;
• smoothing microscopic surface defects;
• supporting the management of dental biofilm.

These effects depend on the complete product formulation, hydroxyapatite concentration, particle characteristics and how consistently the product is used. Hydroxyapatite is not simply a universal repair ingredient that works identically in every product.

Laboratory research has long shown that hydroxyapatite can deposit on enamel and dentine. More importantly, clinical evidence is also developing.

An 18-month, double-blind randomized trial in adults compared a fluoride-free hydroxyapatite toothpaste with a standard toothpaste containing 1,450 ppm fluoride. The hydroxyapatite toothpaste met the study's criterion for non-inferiority in preventing caries progression, meaning its performance was not clinically worse than the fluoride control within the trial's defined margin.³

A 2024 systematic review and meta-analysis concluded that evidence supporting hydroxyapatite-containing oral-care products for caries prevention has expanded, although results still depend on the populations, products and study designs examined.⁴

Research also suggests a role in sensitivity management. Hydroxyapatite particles may reduce sensitivity by depositing over exposed dentine and blocking open tubules. A clinical meta-analysis reported meaningful reductions in dentine hypersensitivity with hydroxyapatite-containing products, though product formulations and comparison treatments differed across studies.⁵

No.

Both may support the tooth surface, but they work through different chemical pathways.

Fluoride encourages the formation of a more acid-resistant mineral phase and remains an established ingredient in caries prevention. Hydroxyapatite acts more directly as a biomimetic calcium-phosphate material that can deposit on enamel and dentine.

They should not automatically be presented as interchangeable in every person or every clinical situation. Individual caries risk, age, diet, saliva, existing dental disease and professional advice still matter.

HAp⁺, as used by UNBTN, should not be confused with simply adding hydroxyapatite particles to a conventional toothpaste.

Its principle centres on the mineral relationship between acidity, calcium, saliva and hydroxyapatite. Acidity produces a strong mouth-watering stimulus, while calcium is used to modify the formulation's mineral balance.

According to IceMedico, the formulation is designed to stimulate saliva while remainingsupersaturated with respect to hydroxyapatite under its validated test conditions. In practical terms, the aim is to create a saliva-stimulating lozenge without behaving like an ordinary erosive sour sweet.

This does not mean that the lozenge repairs damaged teeth, reverses caries or neutralizes every acidic sports product. Its primary role is different:

To stimulate natural saliva and support oral comfort through a calcium-balanced formulation.

Hydroxyapatite is not foreign to the mouth. It is closely related to the mineral from which teeth are already built.

That biological similarity explains why it has attracted increasing interest in modern oral care. Research supports promising applications in remineralization, caries prevention and sensitivity management, while also showing why claims must remain specific to the formulation and evidence being discussed.

The mouth is not an inert gateway for fuel. It is a mineral, chemical and biological environment — and saliva is central to protecting that environment.