Hydroxyapatite Powder Morphologies in Oral Care: Production Routes, Particle Structure, and Characterization

Introduction

Hydroxyapatite (HAp) is widely recognized as one of the most important active ingredients in modern oral care formulations, particularly in products for enamel remineralization, tooth sensitivity relief, whitening, and fluoride-free daily care. At the same time, not all HAp powders are structurally identical. Different grades may exhibit significant differences in particle morphology, crystal dimensions, agglomeration behavior, and particle size distribution.

In oral care applications, hydroxyapatite is commonly supplied in rod-shaped, spherical, or irregular nanoparticle forms. These differences are not merely visual or descriptive. They are closely linked to the material’s synthesis route, downstream processing, drying history, and characterization method, and they can influence how the powder is interpreted and evaluated as an oral care raw material.