title: New Insights on the Composition and the Structure of the Acellular Extrinsic Fiber Cementum by Raman Analysis.
abstract: Acellular extrinsic fiber cementum is a mineralized tissue that covers the cervical half of the tooth root surface. It contains mainly extrinsic or Sharpey's fibers that run perpendicular to the root surface to anchor the tooth via the periodontal ligament. Acellular cementum is continuously and slowly produced throughout life and exhibits an alternating bright and dark pattern under light microscopy. However, although a better understanding of the structural background of acellular cementum is relevant to many fields, such as cementochronology, periodontology and tissue engineering, acellular cementum remains rarely studied and poorly understood. In this work, we studied the acellular cementum at the incremental line scale of five human mandibular canines using polarized Raman spectroscopy. We provided Raman imaging analysis and polarized acquisitions as a function of the angular orientation of the sample. The results showed that mineral crystals were always parallel to collagen fibrils, and at a larger scale, we proposed an organizational model in which we found radial collagen fibers, "orthogonal" to the cementum surface, and "non-orthogonal" fibers, which consist of branching and bending radial fibers. Concerning the alternating pattern, we observed that the dark lines corresponded to smaller, more mineralized and probably more organized bands, which is consistent with the zoological assumption that incremental lines are produced during a winter rest period of acellular cementum growth.
authors.affiliation: Univ. Lille, CHU Lille, EA 7367-UTML-Unité de Taphonomie Médico-Légale, Lille, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Colard
authors.affiliation: Univ. Lille, EA 4490-PMOI-Physiopathologie des Maladies Osseuses Inflammatoires, Lille, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Falgayrac
authors.affiliation: Univ. Lille, CHU Lille, EA 7367-UTML-Unité de Taphonomie Médico-Légale, Lille, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Bertrand
authors.affiliation: CIRHUS-NYU, New York City, NY, United States of America.
authors.forename: Stephan
authors.initials: S
authors.lastname: Naji
authors.affiliation: Univ. Lille, CNRS, UMR 8516-LASIR-Laboratoire de Spectrochimie et Raman, Lille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Devos
authors.affiliation: Univ. Lille, CHU Lille, EA 7367-UTML-Unité de Taphonomie Médico-Légale, Lille, France.
authors.forename: Clara
authors.initials: C
authors.lastname: Balsack
authors.affiliation: Univ. Lille, CHU Lille, EA 7367-UTML-Unité de Taphonomie Médico-Légale, Lille, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Delannoy
authors.affiliation: Univ. Lille, EA 4490-PMOI-Physiopathologie des Maladies Osseuses Inflammatoires, Lille, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Penel
mesh_terms: D003094:Collagen / Q000032:analysis*; D003739:Dental Cementum / Q000737:chemistry*; D006801:Humans; D008903:Minerals / Q000032:analysis*; D013059:Spectrum Analysis, Raman; D014092:Tooth Root / Q000737:chemistry
chemical_list: D008903:Minerals; D003094:Collagen