Viktória Kis

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1 INTRODUCTION Tooth enamel is the hardest and most mineralized tissue of vertebrates. The complex microstructure of enamel contains needle-shaped hydroxyapatite (HAP) crystals of about 68 × 26 nm size in cross section (Daculsi & Kerebel, 1978) with length up to 10 μm (Daculsi et al., 1984). Nanocrystals are arranged on several structural levels to form the most characteristic unit of mammalian dental enamel, the enamel prism (Cui & Ge, 2007; Nanci, 2017).