Hydroxyapatite’s adhesion to enamel and dentin tubule occlusion depends greatly on its particle size, with nanoparticles and small microparticles being much more effective than conventional micron-sized particles.

In the following diagram, we can see the difference in particle size between nanoXIM nano-HAp, nanoXIM micro-HAp and conventional micro-HAp, bearing in mind that dentin tubules have an average diameter of 2.5 μm.

When it comes to dentin tubule occlusion, conventional micro-HAp is too large to be effective at sealing dentin tubules.

On the other hand, nanoXIM nano-HAp, which is 50x smaller than the average diameter of dentin tubules, and nanoXIM micro-HAp (1.1 μm), which is also smaller than dentin tubules, are both able to effectively occlude the dentin tubules, strongly reducing dental hypersensitivity.Fabritius-Vilpoux et al. (2019) found that effective adhesion to enamel only occurs with particles up to 1.3 μm in diameter. Because conventional micro-HAp size is excessively large, above 5 μm, it results in poor or nonexistent adhesion to the enamel. On the other hand, nanoXIM nano-HAp size is 25x smaller than the upper limit of 1.3 μm determined by Fabritius-Vilpoux et al., and nanoXIM micro-HAp size is about 1.1 μm, which is also below the 1.3 μm mentioned. As a result, both nanoXIM nano-HAp and micro-HAp are capable of adhering effectively to the enamel surface, remineralizing it and protecting the tooth surface, thereby preventing the appearance of new cavities.