Structural characterization of salivary calculi

The microstructure, local chemistry, crystallography and mechanical properties of submandibular sialoliths have been characterized by powder X-ray diffraction, electron microscopy combined with X-ray spectroscopy and ultramicro-indentation assays. The sialoliths presented highly mineralized, lamellar and globular regions. The fairly homogeneous mineralized regions are constituted by hydroxyapatite, whitlockite and brushite. Lamellar regions consisted of alternating layers of mineralized material and organic matter, with a concentric morphology pointing to a chronologic cyclic formation. Globular regions are composed of organic matter globules presenting high sulphur content. The Young modulus and hardness increased with the mineralization degree of the sialoliths. Nevertheless the relatively high amounts of compliant and soft organic matter present in the sialoliths may play a major role in the relatively low success of shock wave therapeutics for sialolith fragmentation.