Multi-resolution Correlative Ultrastructural and Chemical Analysis of Carious Enamel by Scanning Microscopy and...

Area of Science:

• Biomineralization research
• Materials science
• Dental research

Background:

• Dental caries is a global health issue with poorly understood ultrastructural changes in enamel.
• Nanoscale characterization of chemical spatial distributions is crucial for understanding demineralization.
• Current techniques lack the resolution to fully characterize carious enamel at the nanoscale.

Purpose of the Study:

• To demonstrate the efficacy of correlative analytical methods for nanoscale characterization of human dental enamel.
• To compare the accuracy of different techniques on a single enamel sample.
• To map hierarchical structures and chemical changes in carious enamel.

Main Methods:

• Correlative microscopy combining focused ion beam scanning electron microscopy (FIB-SEM) and synchrotron X-ray tomography.
• Scanning X-ray fluorescence (XRF) and X-ray wide-angle/small-angle scattering (WAXS/SAXS) with sub-80 nm beam size.
• X-ray ptychography for studying enamel rod demineralization pathways.

Main Results:

• Subtle variations in calcium (Ca) intensity gradients were identified in carious enamel compared to healthy enamel using XRF.
• Hierarchical structures and chemical modifications within carious enamel were mapped at the nanoscale.
• Pathways of enamel rod demineralization were visualized using X-ray ptychography.

Conclusions:

• Multi-modal nanoscale analysis is essential for interpreting material changes in complex hierarchical structures like dental enamel.
• The developed correlative characterization platform provides confidence in nanoscale analysis of biomineralized tissues.
• This protocol can be extended to other biomineralized samples for statistical studies and nanoscale investigation.