Elastic modulus variation in mandibular bone: a microindentation study of Macaca fascicularis

Area of Science:

• Biomechanical Engineering
• Materials Science
• Comparative Anatomy

Background:

• Understanding the mechanical properties of bone is crucial for biomechanical analysis and implant design.
• The mandible's complex structure suggests heterogeneous material properties that require detailed investigation.

Purpose of the Study:

• To characterize the heterogeneous anisotropic elastic properties of Macaca fascicularis mandibular bone.
• To investigate localized variations in bone structure and material properties using microindentation.

Main Methods:

• Microindentation was employed to measure bone hardness at a high spatial resolution (approx. 100 µm).
• Hardness values were converted to elastic modulus using empirical regression.
• Properties were assessed in alveolar, midcorpus, and basal regions across coronal and transverse sections, including endosteal, midcortical, and periosteal layers.

Main Results:

• Regional variations in bone structure were identified, including circumferential lamellar bone and transversely isotropic osteonal bone.
• Compliant bone was observed in the anterior corpus and ramus.
• Basal cortical bone showed greater longitudinal stiffness, while alveolar bone was generally more compliant than midcorpus or basal regions.

Conclusions:

• Mandibular bone exhibits significant localized heterogeneity in its elastic properties and structure.
• Microindentation provides a detailed scale for assessing material property variations beyond conventional methods.
• These findings contribute to a deeper understanding of jawbone biomechanics and structural integrity.