Walk down any supermarket aisle and you'll find dozens of toothpastes promising a brighter, whiter smile. Most of them get there the same way: oxidising chemicals hydrogen peroxide and its derivatives, that chemically break down the molecules causing discolouration.

It works. But it comes with trade-offs most brands won't tell you about.

The distinction matters more than it might seem. 

Bleaching: targets chromophores, the pigment molecules that make teeth appear yellow or grey. Peroxide agents break those molecules at their double bonds, producing shorter fragments that no longer absorb visible light. Colour gone. Effect achieved.

Whitening: in the true sense, works differently. Rather than altering what's inside the tooth, it increases the brightness of the tooth's surface by encouraging it to reflect more light. Hydroxyapatite: the same mineral that makes up 96% of your enamel; can achieve exactly this, without any oxidising chemistry involved.

"Hydroxyapatite materials adhere to the tooth surface without affecting or chemically altering the deeper tooth tissue."

A peer-reviewed study published in the American Journal of Dentistry (Dabanoglu et al., 2009) tested hydroxyapatite suspensions on extracted human teeth, measuring colour change before and after treatment using a clinical spectrophotometer.

The results were clear. After three applications, all hydroxyapatite groups achieved ΔE values between 3.0 and 3.3: at or above the threshold a trained eye can detect as a visible colour difference. Critically, scanning electron microscope imaging confirmed that the enamel surface showed no structural damage. The hydroxyapatite particles adhered to the enamel, remained after simulated brushing forces, and left no surface etching.

Not all hydroxyapatite is equal. The particle size, crystal structure, and grade of the material determine both how it behaves on your enamel and whether its safety profile holds up under regulatory scrutiny. These distinctions matter and they are precisely why we chose pharmaceutical-grade micro-hydroxyapatite.

Micro-hydroxyapatite (micro-HA) is structurally biomimetic, meaning its crystalline form closely mirrors the hydroxyapatite that naturally makes up your enamel. Research into microcrystalline hydroxyapatite has demonstrated that it can promote remineralisation of enamel and dentine surfaces, with studies showing a measurable regain of mineral content and an increase in microhardness in demineralised enamel following exposure to microcrystalline HAP particles. This remineralisation effect occurs through a straightforward mechanism: micro-HA particles deposit into the microscopic voids and prism-sheath interfaces of enamel, rebuilding mineral structure from the outside in, without altering the deeper tooth tissue. biorxiv

The clinical evidence base is substantial. A randomised, double-blind, non-inferiority trial demonstrated that the caries-preventive efficacy of a microcrystalline hydroxyapatite dentifrice was not inferior to the protection provided by a fluoridated control. A separate study published in Scientific Reports reached the same conclusion in a paediatric population: a double-blinded randomised controlled trial comparing microcrystalline hydroxyapatite toothpaste against fluoride toothpaste found comparable rates of caries prevention over a 336-day observation period. These are peer-reviewed, randomised controlled trials — the gold standard of clinical evidence. bioRxivnih

Then there is the regulatory picture. EU Regulation 2024/858, published in March 2024 and applicable from February 2025, introduced new restrictions on nano-hydroxyapatite in cosmetic products. The EU's Scientific Committee on Consumer Safety concluded that nano-hydroxyapatite is only considered safe at concentrations up to 10% in toothpaste and 0.465% in mouthwash, and only when composed of rod-shaped, uncoated particles meeting specific dimensional criteria. The primary concern driving the restriction was preventing potential lung exposure through inhalation. CosmeticOBS + 2

Micro-hydroxyapatite sits entirely outside these restrictions. The regulation applies specifically to nano-form particles, a different particle size category with different behaviour and a different risk profile. Our pharmaceutical-grade micro-HA formulation is not subject to these limitations, and was never the subject of the safety concerns that prompted them.