Forceful mastication activates osteocytes and builds a stout jawbone

Area of Science:

• Bone biology and biomechanics
• Craniofacial development
• Mechanotransduction in bone tissue

Background:

• Bone remodeling is crucial for adapting to mechanical loads.
• Masticatory force is thought to influence jawbone shape, but mechanisms are unclear.
• Understanding this relationship is key to jawbone morphology.

Purpose of the Study:

• To investigate the causal link between masticatory force and jawbone morphology.
• To elucidate the molecular mechanisms underlying jawbone adaptation to mechanical loading.
• To establish a mouse model for studying increased mastication effects.

Main Methods:

• Developed a mouse model with a hard diet to increase masticatory force.
• Utilized in silico computer simulations to model masticatory load.
• Employed in vivo micro-computed tomography (micro-CT) for bone analysis.
• Analyzed molecular changes in osteocytes, including Insulin-like growth factor-1 (IGF-1) and sclerostin levels.

Main Results:

• Computer simulations predicted jawbone profiles based on masticatory load.
• In vivo micro-CT confirmed these predictions in mice with increased mastication.
• Increased mastication upregulated IGF-1 and downregulated sclerostin in osteocytes.
• IGF-1 promoted osteoblastogenesis from tendon-derived cells.

Conclusions:

• Osteocytes regulate cytokine expression in response to mechanical loading from increased mastication.
• This process enhances bone formation, leading to jawbone morphological changes.
• Jawbone adapts its shape to accommodate altered mechanical environments, demonstrating mechanotransduction.