Quantitative electron spectroscopic diffraction analyses of the crystal formation in dentine

Area of Science:

• Biomineralization
• Materials Science
• Crystallography

Background:

• Hard tissues like dentine feature apatitic crystallites crucial for structural integrity.
• Understanding the initial formation and nanoscale organization of these crystallites is key to comprehending tissue development and properties.

Purpose of the Study:

• To investigate the formation process and nanoscale structure of apatitic crystallites in dentine.
• To determine the relationship between crystallite formation and the underlying matrix macromolecules.
• To quantify the degree of crystal disorder during dentine mineralization.

Main Methods:

• Utilized energy-filtering transmission electron microscopy (EFTEM) in selected area electron diffraction mode.
• Analyzed various stages of crystal formation in dentine.
• Applied paracrystal theory to quantify crystal disorder.

Main Results:

• Newly formed apatitic crystallites consist of chains of nanometre-sized particles (islands) originating from matrix nucleation sites.
• In dentine, these islands coalesce longitudinally into needle-like and then ribbon-like crystallites.
• The center-to-center distances between islands correlate with matrix macromolecule nucleation site distances.
• Crystal disorder, measured by lattice plane distance fluctuations in the c-axis direction, decreases from the dentine/predentine border towards the dentine/enamel border.

Conclusions:

• Dentine crystallite formation involves the coalescence of nanoparticle chains originating from specific matrix nucleation sites.
• The spatial arrangement of these nucleation sites dictates the crystallite morphology and organization.
• Mineralization progresses with an increasing degree of crystal order towards the enamel interface.