Chewing Affects Structural and Material Coupling, and Age-Related Dentoalveolar Joint Biomechanics and Strain

Area of Science:

• Biomechanics
• Biomaterials Science
• Developmental Biology

Background:

• Understanding how primary structural features and secondary material properties adapt to functional loads is essential to determining their effect on changes in joint biomechanics over time.
• The dentoalveolar joint (DAJ) is crucial for mastication, and its long-term health is influenced by diet and aging.

Purpose of the Study:

• To map and correlate spatiotemporal changes in primary structural features, secondary material properties, and DAJ stiffness with age.
• To investigate how loading history (soft vs. hard food diets) shapes the balance between primary and secondary features in the DAJ.

Main Methods:

• Rats were fed either a hard-food (HF) or soft-food (SF) diet from four weeks of age for up to 20 weeks.
• Functional imaging of intact mandibular DAJs was performed at multiple time points (8, 12, 16, 20, and 24 weeks).
• Quantification of primary structural determinants (periodontal ligament space, contact area, socket morphology) and secondary material/microstructural determinants (tissue-level stiffness, bone/cementum volume fractions, pore architecture, bone microarchitecture).

Main Results:

• Bone and cementum volume fractions increased differently in HF and SF groups, correlating with decreased PDL space.
• Older HF rats maintained wider PDL spaces than SF rats; SF group showed increased contact ratio with age.
• DAJ stiffness was higher in SF than HF animals at younger ages, indicating diet-dependent remodeling altered structural vs. material contributions.
• Bone strains (volumetric and von Mises) increased with age in both groups, with SF bone exhibiting higher and more variable strain values.
• Changes in joint space, contact area, and bone strain correlated with DAJ biomechanics.

Conclusions:

• Spatiotemporal shifts in primary (structure) and secondary (material properties, microarchitecture) features define divergent mechanobiological pathways for the DAJ.
• Altered loading histories can bias DAJs toward early maladaptation and potential degeneration.
• Dietary hardness significantly influences DAJ development, adaptation, and long-term biomechanical function.