title: Structure and growth of sialoliths: computed microtomography and electron microscopy investigation of 30 specimens.
abstract: Theories have been put forward on the etiology of sialoliths; however, a comprehensive understanding of their growth mechanisms is lacking. In an attempt to fill this gap, the current study has evaluated the internal architecture and growth patterns of a set of 30 independent specimens of sialoliths characterized at different scales by computed microtomography and electron microscopy. Tomography reconstructions showed cores in most of the sialoliths. The cores were surrounded by concentric or irregular patterns with variable degrees of mineralization. Regardless of the patterns, at finer scales the sialoliths consisted of banded and globular structures. The distribution of precipitates in the banded structures is compatible with a Liesegang-Ostwald phenomenon. On the other hand, the globular structures appear to arise from surface tension effects and to develop self-similar features as a result of a viscous fingering process. Electron diffraction patterns demonstrated that Ca- and P-based electrolytes crystallize in a structure close to that of hydroxyapatite. The organic matter contained sulfur with apparent origin from sulfated components of secretory material. These results cast new light on the mechanisms involved in the formation of sialoliths.
authors.affiliation: ICEMS, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Nolasco
authors.forename: Ana J
authors.initials: AJ
authors.lastname: Anjos
authors.forename: João M Aquino
authors.initials: JM
authors.lastname: Marques
authors.forename: Fernando
authors.initials: F
authors.lastname: Cabrita
authors.forename: Eduardo Carreiro
authors.initials: EC
authors.lastname: da Costa
authors.forename: António
authors.initials: A
authors.lastname: Maurício
authors.forename: Manuel F C
authors.initials: MF
authors.lastname: Pereira
authors.forename: António P Alves
authors.initials: AP
authors.lastname: de Matos
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Carvalho
mesh_terms: D002118:Calcium / Q000032:analysis; D055032:Electron Microscope Tomography; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D008903:Minerals / Q000032:analysis; D009930:Organic Chemicals / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D015494:Salivary Gland Calculi / Q000737:chemistry* / Q000648:ultrastructure*; D013457:Sulfur Compounds / Q000032:analysis; D014057:Tomography, X-Ray Computed
chemical_list: D008903:Minerals; D009930:Organic Chemicals; D010710:Phosphates; D013457:Sulfur Compounds; D002118:Calcium