title: Synchrotron x-ray microtomographic investigation of mineral concentrations at micrometre scale in sound and carious enamel.
abstract: Synchrotron X-ray microtomography (XMT) was used to measure the linear attenuation coefficient (LAC) for 1.9-microm sidelength voxels within approximal brown spot lesions and sound human enamel. XMT demonstrated three-dimensional features, notably sheets with approximately 30 microm periodicity having low LAC, identified as regions of demineralization corresponding to Retzius lines. Quantitative three-dimensional measurements of mineral concentration, derived from LAC with assumption of a single model composition, were consistent with previous measurements of sound and carious enamel from microradiographic projections. The uncertainty in measurements of mineral concentration and mineral fraction volume was investigated by modelling enamel with a range of composition and component densities. This analysis showed that, although mineral concentration can be determined from LAC with an error of <0.2 g cm(-3), the variation in pore fraction volume within caries lesions cannot be reliably determined from X-ray attenuation measurements alone.
authors.affiliation: Institute of Dentistry, Barts and The London, Queen Mary's School of Medicine and Dentistry, London, UK. s.e.p.dowker@qmul.ac.uk
authors.forename: S E P
authors.initials: SE
authors.lastname: Dowker
authors.forename: J C
authors.initials: JC
authors.lastname: Elliott
authors.forename: G R
authors.initials: GR
authors.lastname: Davis
authors.forename: R M
authors.initials: RM
authors.lastname: Wilson
authors.forename: P
authors.initials: P
authors.lastname: Cloetens
mesh_terms: D001031:Apatites / Q000032:analysis; D016477:Artifacts; D001641:Bicuspid / Q000737:chemistry / Q000000981:diagnostic imaging; D003731:Dental Caries / Q000000981:diagnostic imaging* / Q000473:pathology; D003743:Dental Enamel / Q000737:chemistry* / Q000000981:diagnostic imaging*; D006801:Humans; D008852:Microradiography / Q000379:methods; D008903:Minerals / Q000032:analysis; D016062:Porosity; D011861:Radiography, Dental / Q000295:instrumentation / Q000379:methods*; D017356:Synchrotrons; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D001031:Apatites; D008903:Minerals