Variations in cortical material properties throughout the human dentate mandible

Area of Science:

• Biomechanics
• Materials Science
• Human Anatomy

Background:

• Bone material properties are vital for understanding bone adaptation and quality.
• Systematic studies on material property variations in individual bone organs, particularly the human mandible, are limited.
• Existing research faces limitations due to small sample sizes and restricted sampling regions.

Purpose of the Study:

• To investigate regional variability in mandibular material properties.
• To assess the impact of this variability on mandibular function modeling.
• To explore the relationship between material property variations, mandibular structure, and function.

Main Methods:

• 31 samples were collected from the facial and lingual cortices of 10 adult human mandibles.
• Cortical thickness, density, and direction of maximum stiffness were measured using pulse transmission ultrasonics.
• Elastic properties were calculated from ultrasonic velocities, revealing orthotropic behavior in all specimens.

Main Results:

• Significant regional variations were observed in mandibular elastic properties and cortical thickness.
• Cortical thickness decreased posteriorly and was greater on the facial than lingual side.
• Bone was substantially stiffer longitudinally (20-30 GPa) compared to circumferential/tangential directions.

Conclusions:

• Mandibular material properties exhibit unique regional variations impacting mechanical modeling accuracy.
• The accuracy of stress calculations depends on regional variations in stiffness direction and anisotropy.
• Observed property orientations may relate to cortical bone microstructure, but functional correlations require further investigation.