title: Ultrastructural examination of dentin using focused ion-beam cross-sectioning and transmission electron microscopy.
abstract: Focused ion-beam (FIB) milling is a commonly used technique for transmission electron microscopy (TEM) sample preparation of inorganic materials. In this study, we seek to evaluate the FIB as a TEM preparation tool for human dentin. Two particular problems involving dentin, a structural analog of bone that makes up the bulk of the human tooth, are examined. Firstly, the process of aging is studied through an investigation of the mineralization in 'transparent' dentin, which is formed naturally due to the filling up of dentinal tubules with large mineral crystals. Next, the process of fracture is examined to evaluate incipient events that occur at the collagen fiber level. For both these cases, FIB-milling was able to generate high-quality specimens that could be used for subsequent TEM examination. The changes in the mineralization suggested a simple mechanism of mineral 'dissolution and reprecipitation', while examination of the collagen revealed incipient damage in the form of voids within the collagen fibers. These studies help shed light on the process of aging and fracture of mineralized tissues and are useful steps in developing a framework for understanding such processes.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Nalla
authors.forename: A E
authors.initials: AE
authors.lastname: Porter
authors.forename: C
authors.initials: C
authors.lastname: Daraio
authors.forename: A M
authors.initials: AM
authors.lastname: Minor
authors.forename: V
authors.initials: V
authors.lastname: Radmilovic
authors.forename: E A
authors.initials: EA
authors.lastname: Stach
authors.forename: A P
authors.initials: AP
authors.lastname: Tomsia
authors.forename: R O
authors.initials: RO
authors.lastname: Ritchie
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000818:Animals; D003094:Collagen / Q000032:analysis / Q000648:ultrastructure; D003804:Dentin / Q000737:chemistry / Q000293:injuries / Q000502:physiology / Q000648:ultrastructure*; D004606:Elephants; D006801:Humans; D007477:Ions; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D014070:Tooth / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D014074:Tooth Calcification; D014082:Tooth Fractures / Q000473:pathology / Q000503:physiopathology
chemical_list: D007477:Ions; D003094:Collagen