X-ray microdiffraction, TEM characterization and texture analysis of human dentin and enamel.

Area of Science:

• Materials Science
• Biomaterials
• Crystallography

Background:

• Human teeth are complex bioceramic composites comprising enamel, dentin, and the dentin-enamel junction (DEJ).
• Understanding the crystallographic and microstructural properties of tooth components is crucial for explaining their mechanical resilience.

Purpose of the Study:

• To investigate the crystal properties and ultrastructure of the inorganic phase across the thickness of healthy human molar teeth.
• To compare the crystallite size and texture in enamel and dentin using advanced analytical techniques.

Main Methods:

• Utilized X-ray microdiffraction (μXRD), electron diffraction, and transmission electron microscopy (TEM).
• Analyzed XRD data using the Le Bail profile fitting approach.
• Measured and compared crystallite size and texture in enamel and dentin.

Main Results:

• Dentin crystallite thickness decreased towards the DEJ, while enamel crystallite thickness increased away from the DEJ.
• Enamel showed increased texture in 002 and 102 lattice planes from the DEJ outwards; similar texture effects were observed in dentin.
• Observed variations in lattice parameters and non-uniform microstrain (1.40 × 10⁻⁶% to 4.44 × 10⁻⁵%) in both enamel and dentin crystallites.

Conclusions:

• μXRD is a valuable technique for studying the crystallography and microstructure of heterogeneous dental tissues.
• Gradient characteristics in texture and crystallite size within enamel and dentin likely evolved to enhance resistance to wear and fracture.
• These microstructural features contribute to the exceptional mechanical properties of human teeth.