title: Non-invasive imaging of the crystalline structure within a human tooth.
abstract: The internal crystalline structure of a human molar tooth has been non-destructively imaged in cross-section using X-ray diffraction computed tomography. Diffraction signals from high-energy X-rays which have large attenuation lengths for hard biomaterials have been collected in a transmission geometry. Coupling this with a computed tomography data acquisition and mathematically reconstructing their spatial origins, diffraction patterns from every voxel within the tooth can be obtained. Using this method we have observed the spatial variations of some key material parameters including nanocrystallite size, organic content, lattice parameters, crystallographic preferred orientation and degree of orientation. We have also made a link between the spatial variations of the unit cell lattice parameters and the chemical make-up of the tooth. In addition, we have determined how the onset of tooth decay occurs through clear amorphization of the hydroxyapatite crystal, and we have been able to map the extent of decay within the tooth. The described method has strong prospects for non-destructive probing of mineralized biomaterials.
authors.affiliation: School of Materials, The University of Manchester, Manchester M13 9PL, UK. christopher.egan@manchester.ac.uk
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Egan
authors.forename: Simon D M
authors.initials: SD
authors.lastname: Jacques
authors.forename: Marco
authors.initials: M
authors.lastname: Di Michiel
authors.forename: Biao
authors.initials: B
authors.lastname: Cai
authors.forename: Mathijs W
authors.initials: MW
authors.lastname: Zandbergen
authors.forename: Peter D
authors.initials: PD
authors.lastname: Lee
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Beale
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Cernik
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D006801:Humans; D008964:Molar, Third / Q000000981:diagnostic imaging* / Q000648:ultrastructure*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Computed tomography; EDX; Enamel; Hydroxyapatite; XRD