I22-Small angle scattering & Diffraction
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Tayyaba
Rabnawaz
,
Nathanael
Leung
,
Leonard C.
Nielsen
,
Robert A.
Harper
,
Richard M.
Shelton
,
Gabriel
Landini
,
Tim
Snow
,
Andy
Smith
,
Nick
Terrill
,
Marianne
Liebi
,
Tan
Sui
Diamond Proposal Number(s):
[20285]
Abstract: Dental caries, one of the most prevalent non-communicable diseases worldwide, is characterised by the progressive deterioration of the structure and mechanical properties of dental hard tissues. In human teeth, dentine is the most abundant mineralised tissue, forming the primary support material. To assess changes in the mechanical properties of dentine caused by dental caries and acid erosion, it is crucial to understand the relationship between organic and inorganic dentine components and their organisation into a 3D anisotropic structure at the nanoscale. Over the past 20 years, alterations in dentine structure caused by caries and artificial demineralisation have been reported using conventional microscopy techniques. However, due to the limited spatial resolution of these techniques, the 3D structural organisation including orientation and degree of alignment of mineralised collagen fibrils at the nanoscale, has not been fully explored. This study investigated alterations in the 3D structure of normal, carious and artificially demineralised dentine using SAXS tensor tomography (SASTT). This technique enabled the observation of differences in the local orientation of organic and inorganic components, as well as variations in local scattering intensity, resulting from natural caries and artificial demineralisation. In comparison to normal dentine, caries caused minor orientational differences of both components but had a major impact on the local X-ray scattering intensity. After artificial demineralisation of the dentine, most of the mineral was lost in the outer layers, resulting in a greater reduction in scattering intensity than that caused by caries.
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Mar 2026
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[23724]
Abstract: Dental caries is the most prevalent oral disease that causes structural and compositional changes of the dental hard tissues due to a chronic demineralisation (combined with possible phases of remineralisation) process. The changes can affect most important oral functions and aesthetics, as well as causing pain and discomfort. Though considerable efforts have been directed at studying natural and artificial carious lesions, most characterisations remain either constrained to 2D analyses or have been unable to achieve fine resolution in 3D due to limited field of view. To overcome this challenge, the present study combined X-ray diffraction (XRD) and scanning transmission X-ray microscopy (STXM) tomography techniques to analyse the mineral density, scattering intensity, and crystallite size in normal, carious, 30 % artificially demineralised, and 50 % artificially demineralised dentine. Combined XRD and STXM tomography was performed on the I18 beamline at Diamond Light Source, using a 15 keV monochromatic beam with 2 × 2 μm spotsize and scanning with translation steps of 2 μm, providing a reconstructed voxel size of 2 × 2 × 2 μm. Natural carious dentine showed a reduction in hydroxyapatite (HAp) crystallite size due to chronic demineralisation. This was unlike artificially demineralised dentine samples that underwent short, continuous demineralisation, which created a zone of fully demineralised dentine, near the sample surface, and a zone of partially demineralised dentine that had a reduced mineral density but an increased average crystallite size.
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May 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[29256]
Open Access
Abstract: High-resolution spatial and temporal analysis and 3D visualization of time-dependent processes, such as human dental enamel acid demineralization, often present a challenging task. Overcoming this challenge often requires the development of special methods. Dental caries remains one of the most important oral diseases that involves the demineralization of hard dental tissues as a consequence of acid production by oral bacteria. Enamel has a hierarchically organized architecture that extends down to the nanostructural level and requires high resolution to study its evolution in detail. Enamel demineralization is a dynamic process that is best investigated with the help of in situ experiments. In previous studies, synchrotron tomography was applied to study the 3D enamel structure at certain time points (time-lapse tomography). Here, another distinct approach to time-evolving tomography studies is presented, whereby the sample image is reconstructed as it undergoes continuous rotation over a virtually unlimited angular range. The resulting (single) data set contains the data for multiple (potentially overlapping) intermediate tomograms that can be extracted and analyzed as desired using time-stepping selection of data subsets from the continuous fly-scan recording. One of the advantages of this approach is that it reduces the amount of time required to collect an equivalent number of single tomograms. Another advantage is that the nominal time step between successive reconstructions can be significantly reduced. We applied this approach to the study of acidic enamel demineralization and observed the progression of demineralization over time steps significantly smaller than the total acquisition time of a single tomogram, with a voxel size smaller than 0.5 μm. It is expected that the approach presented in this paper can be useful for high-resolution studies of other dynamic processes and for assessing small structural modifications in evolving hierarchical materials.
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Feb 2024
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E01-JEM ARM 200CF
I08-1-Soft X-ray Ptychography
I13-2-Diamond Manchester Imaging
I14-Hard X-ray Nanoprobe
I18-Microfocus Spectroscopy
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Cyril
Besnard
,
Ali
Marie
,
Sisini
Sasidharan
,
Petr
Buček
,
Jessica M.
Walker
,
Julia E.
Parker
,
Matthew C.
Spink
,
Robert A.
Harper
,
Shashidhara
Marathe
,
Kaz
Wanelik
,
Thomas E. J.
Moxham
,
Enrico
Salvati
,
Konstantin
Ignatyev
,
Michal M.
Klosowski
,
Richard M.
Shelton
,
Gabriel
Landini
,
Alexander M.
Korsunsky
Diamond Proposal Number(s):
[27749, 30684, 30691, 31005, 29256, 23873]
Open Access
Abstract: Caries, a major global disease associated with dental enamel demineralization, remains insufficiently understood to devise effective prevention or minimally invasive treatment. Understanding the ultrastructural changes in enamel is hampered by a lack of nanoscale characterization of the chemical spatial distributions within the dental tissue. This leads to the requirement to develop techniques based on various characterization methods. The purpose of the present study is to demonstrate the strength of analytic methods using a correlative technique on a single sample of human dental enamel as a specific case study to test the accuracy of techniques to compare regions in enamel. The science of the different techniques is integrated to genuinely study the enamel. The hierarchical structures within carious tissue were mapped using the combination of focused ion beam scanning electron microscopy with synchrotron X-ray tomography. The chemical changes were studied using scanning X-ray fluorescence (XRF) and X-ray wide-angle and small-angle scattering using a beam size below 80 nm for ångström and nanometer length scales. The analysis of XRF intensity gradients revealed subtle variations of Ca intensity in carious samples in comparison with those of normal mature enamel. In addition, the pathways for enamel rod demineralization were studied using X-ray ptychography. The results show the chemical and structural modification in carious enamel with differing locations. These results reinforce the need for multi-modal approaches to nanoscale analysis in complex hierarchically structured materials to interpret the changes of materials. The approach establishes a meticulous correlative characterization platform for the analysis of biomineralized tissues at the nanoscale, which adds confidence in the interpretation of the results and time-saving imaging techniques. The protocol demonstrated here using the dental tissue sample can be applied to other samples for statistical study and the investigation of nanoscale structural changes. The information gathered from the combination of methods could not be obtained with traditional individual techniques.
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Jul 2023
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B16-Test Beamline
DIAD-Dual Imaging and Diffraction Beamline
E01-JEM ARM 200CF
E02-JEM ARM 300CF
I08-Scanning X-ray Microscopy beamline (SXM)
I12-JEEP: Joint Engineering, Environmental and Processing
I13-1-Coherence
I13-2-Diamond Manchester Imaging
I14-Hard X-ray Nanoprobe
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Open Access
Abstract: Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical–chemical–structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health.
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Apr 2023
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E01-JEM ARM 200CF
I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[29256, 30666]
Open Access
Abstract: Dental caries is a widespread disease that damages teeth by heterogeneous dissolution. Conventional histology identifies different zones within carious lesions by their optical appearance, but fails to quantify the underlying nanoscale structural changes as a function of specific location, impeding better understanding of the demineralisation process. We employ detailed collocative analysis using different imaging modalities, resolutions and fields of view. Focused ion beam-scanning electron microscopy (FIB-SEM) reveals subsurface 3D nanostructure within milled micro-sized volumes, whilst X-ray tomography allows less destructive 3D imaging over large volumes. Correlative combination of these techniques reveals fine detail of enamel rods, inter-rod substance, sheaths, crystallites and voids as a function of location. The degree of enamel demineralisation within the body of the lesion, near its front, and at the surface is visualized in 3D. We thus establish the paradigm of dental 3D nano-histology as an advanced platform for quantitative evaluation of caries-induced structural modification.
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Jun 2022
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[20155]
Abstract: Objective: Dental erosion is a common oral condition caused by chronic exposure to acids from intrinsic/extrinsic sources. Repeated acid exposure can lead to the irreversible loss of dental hard tissues (enamel, dentine, cementum). Dentine can become exposed to acid following severe enamel erosion, crown fracture, or gingival recession. Causing hypersensitivity, poor aesthetics, and potential pulp involvement. Improving treatments that can restore the structural integrity and aesthetics are therefore highly desirable. Such developments require a good understanding of how acid demineralisation progresses where relatively little is known in terms of intertubular dentine (ITD) and peritubular dentine (PTD) microstructure. To obtain further insight, this study proposes a new in vitro method for performing demineralisation studies of dentine. Methods: Advanced high-speed synchrotron X-ray microtomography (SXM), with high spatial (0.325 μm) and temporal (15 min) resolution, was used to conduct the first in vitro, time-resolved 3D (4D) study of the microstructural changes in the ITD and PTD phases of human dentine samples (∼0.8 × 0.8 × 5 mm) during 6 h of continuous acid exposure. Results: Different demineralisation rates of ITD (1.79 μm/min) and PTD (1.94 μm/min) and their progressive width-depth profiles were quantified, which provide insight for understanding the mechanisms of dentine demineralisation. Significance: Insights obtained from morphological characterisations and the demineralisation process of ITD and PTD during acid demineralisation would help understand the demineralisation process and potentially aid in developing new therapeutic dentine treatments. This method enables continuous examination of relatively large volumes of dentine during demineralisation and also demonstrates the potential for studying the remineralisation process of proposed therapeutic dentine treatments.
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Sep 2021
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[20479]
Open Access
Abstract: We report major advances in the analysis of synchrotron 3D datasets acquired from human healthy and carious dental enamel. Synchrotron tomographic data for three human carious samples and a non-carious reference tooth sample were collected with the voxel size of 325 nm for a total volume of 815.4 × 815.4 × 685.4 μm3. The results were compared with conventional X-ray tomography, optical microscopy, and focused ion beam-scanning electron microscopy. Clear contrast was seen within demineralised enamel due to reduced mineral content using synchrotron tomography in comparison with conventional tomography. The features were found to correspond with the rod and inter-rod structures within prismatic enamel. 2D and 3D image segmentation allowed statistical quantification of important structural characteristics (such as the aspect ratio and the cross-sectional area of voids, as well as the demineralised volume fraction as a function of lesion depth). Whilst overall carious enamel predominantly displayed Type 1 etching pattern (preferential demineralisation of enamel rods), a transition between Type 2 (preferential inter-rod demineralisation) and Type 1 was identified within the same lesion for the first time. This study does not intend to give extensive results on the different lesions studied, but to illustrate a new method and its potential application.
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May 2021
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B16-Test Beamline
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Diamond Proposal Number(s):
[19192]
Open Access
Abstract: Enamel caries is a highly prevalent disease that involves demineralisation of the enamel structure. In this study, we report the analysis of artificially demineralised human enamel 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 within 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 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 more 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.
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Apr 2021
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I13-2-Diamond Manchester Imaging
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Open Access
Abstract: In the past years, a significant amount of effort has been directed at the observation and characterisation of caries using experimental techniques. Nevertheless, relatively little progress has been made in numerical modelling of the underlying demineralisation process.
The present study is the first attempt to provide a simplified calculation framework for simulating the demineralisation process at the length scale of enamel rods and its validation by comparing the data with statistical analysis of synchrotron X-ray CT results. The local orientation of the hydroxyapatite crystals is accounted to solve a time-dependent reaction-diffusion equation, in which H ions diffuse and demineralise the enamel. insights into the pH level of the etchant solution and origin of different etching morphology were obtained by simulating these processes through the newly developed model.
The implications of this study itself pave the way for simulations of enamel demineralisation within different complex scenarios and higher length scales. Indeed, the framework proposed can incorporate the presence of chemical species other than H ions and their diffusion and reaction leading to dissolution and re-precipitation of hydroxyapatite. It is the authors’ hope and aspiration that ultimately this work will help identify new ways of controlling and preventing caries.
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Sep 2020
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