Discrete element models of tooth enamel, a complex three-dimensional biological composite

Area of Science:

• Biomaterials Science
• Computational Mechanics
• Dental Materials

Background:

• Tooth enamel, a biological composite, exhibits remarkable hardness and toughness due to its complex 3D microstructure of mineral rods and protein interfaces.
• Understanding the structure-property relationships in enamel is challenging due to its intricate architecture, often requiring computationally intensive models.
• Existing models struggle to capture the full mechanical behavior of enamel, limiting the development of advanced dental restorative materials.

Purpose of the Study:

• To develop computationally efficient discrete element models (DEM) for simulating tooth enamel's mechanical properties.
• To investigate the influence of rod decussation and stiffness contrast on enamel's modulus, hardness, and fracture resistance.
• To provide insights for designing improved reconstructive dental materials and bioinspired composites.

Main Methods:

• Generated idealized enamel microstructures using a biological growth model to simulate rod decussation.
• Employed discrete element models (DEM) to simulate mechanical properties, including elastic moduli via unit cell analysis and hardness via virtual indentation tests.
• Modeled macroscopic crack growth in virtual fracture specimens to assess fracture resistance and toughness mechanisms.

Main Results:

• Efficient DEM models accurately captured enamel's mechanical properties, including modulus, hardness, and fracture resistance.
• Rod decussation was found to increase crack resistance and inelastic region size while decreasing axial modulus and hardness.
• Higher stiffness contrast between rods and interfaces resulted in enhanced overall stiffness, hardness, and crack resistance.

Conclusions:

• The study provides a computationally efficient method to model tooth enamel's complex micromechanics.
• Findings highlight the critical roles of rod decussation and stiffness contrast in determining enamel's superior mechanical performance.
• These insights can inform the development of novel biomimetic materials with tailored mechanical properties for dental and other applications.