Analysis of in vitro demineralised human enamel using multi-scale correlative optical and scanning electron microscopy, and high-resolution synchrotron wide-angle X-ray scattering

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  • Cyril Besnard
  • Enrico Salvati
  • Thomas E.j. Moxham
  • León Romano Brandt
  • Alexander M. Korsunsky

Colleges, School and Institutes


Enamel caries is a highly prevalent worldwide disease that involves the demineralisation of the outer tooth structure. In this study, we report the analysis of artificially demineralised human enamel sections (‘slices’) etched using lactic acid (2% v/v) in comparison with healthy enamel using correlative techniques of optical and electron microscopy, as well as scanning diffraction. Demineralisation of the enamel was characterised at the micron to sub-micron scale. The structure of the healthy enamel was investigated using Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) and compared with an etched sample to reveal their structural differences. Additional chemical analysis using energy-dispersive X-ray spectroscopy (EDS) was performed and a decrease in the Ca/P atomic % ratio was found in etched samples in comparison with healthy enamel, suggesting greater loss of calcium compared with phosphorus. Synchrotron wide-angle X-ray scattering (WAXS) was performed on the samples to reveal the differences in the diffraction patterns before and after etching in terms of lattice structure and preferred orientation (texture). Texture maps were extracted from diffraction analysis at 500 nm spatial resolution. These maps were correlated with the dimension of the enamel structure. The multi-scale correlative approach provided insights into the demineralisation-induced enamel structure alteration at a resolution approaching 500 nm.

Bibliographic note

Funding Information: This work was funded by The Engineering and Physical Sciences Research Council (EPSRC) entitled “Tackling human dental caries by multi-modal correlative microscopy and multi-physics modelling” (EP/P005381/1). The access to Diamond Light Source was under the proposal MT21419-1. Thanks to Diamond Light Source and particularly the team of B16 Dr. Igor Dolbnya and Dr. Oliver Fox, for beamline support and Dr. Jacob Filik for his support with the DAWN software. Thanks to Dr. Jonathan D. James (School of Dentistry, University of Birmingham) for support with preparation of the samples and optical imaging. Thanks to Petr Buček (Tescan, U.K.) for support with FIB-SEM and Dr. Marzena Tkaczyk (Laboratory for In-situ Microscopy & Analysis, University of Oxford, U.K.) for support with sample coating. Publisher Copyright: © 2021 The Authors


Original languageEnglish
Article number109739
Number of pages13
JournalMaterials and Design
Early online date23 Apr 2021
Publication statusPublished - Aug 2021


  • Enamel, Energy-dispersive X-ray spectroscopy, In vitro demineralisation, Scanning electron microscopy, Synchrotron, X-ray diffraction

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