Demineralisation of human dental enamel observed by operando X-ray tomography

Session

Stream 4: Diamond Light Source Session 2

Authors

Professor Alexander M. Korsunsky (3), Dr Cyril Besnard (3), Dr Ali Marie (3), Dr Sisinii Sasidharan (3), Dr Robert Harper (1), Mr Jonathan James (1), Professor Gabriel Landini (1), Dr Richard Shelton (1), Dr Shashidara Marather (2)

Affiliations

1. Birmingham Dental School
2. Diamond Light Source
3. University of Oxford

Keywords

X-ray tomography, synchrotron, demineralisation, dental enamel, caries

Abstract text

Human dental enamel is mainly composed of hydroxyapatite (HAp, 96 wt%), bonded with organic matter [1]. It is a hierarchical acellular tissue, formed by ameloblasts in the course of biomineralisation process. During this process, nanocrystals of HAp are assembled into rods of  ̴ 5 μm diameter separated by inter-rod regions of  ̴ 2 μm thickness [2]. The content, orientation and arrangement of HAp crystallites is different in these two phases, leading to different properties. The complex organisation and mineral composition confer high mechanical properties, but leave enamel structure susceptible to acid demineralisation. Dental caries involves demineralisation of enamel by acid produced by bacteria. Caries process is a dynamic phenomenon that involves demineralisation and remineralisation phases [3]. Previous synchrotron tomography and X-ray diffraction studies demonstrated the ability to resolve rod and inter-rod regions, and HAp structure [4,5], and will be further studied using Dual Imaging And Diffraction (DIAD) accepted beamtime at DLS. Our most recent operando synchrotron tomography studies at DLS beamline I13 revealed real time demineralisation of enamel using the combination of fast acquisition and high spatial resolution. In combination with laboratory characterisation and statistical analysis, the results provide spatially resolved data for the rate of demineralisation used as input for multi-scale modelling of demineralisation [6]. This technique offers great potential for other applications, such as the evaluation of oral health benefits from remineralising treatments, analysis of pitting corrosion and scale formation, weathering phenomena, etc.

References

[1] - T. Baumann et al., Sci. Rep. 5, 15194 (2015). 

[2] - S. Risnes and C. Li, Microscopy Research and Technique 82(10), 1668-1680 (2019).

[3] - J. D. B. Featherstone, Australian Dental Journal 53, 286-291 (2008).

[4] - C. Besnard et al., Poster-Workshop on Neutron and X-Ray Imaging in Life Sciences and Biology (2020).

[5] - T. Sui et al., Acta Biomater. 77, 333-441 (2018).

[6] - E. Salvati et al., Journal of Advanced Research, (2020).