Eccentric Occlusal Loads Remodel the Dentoalveolar and Temporomandibular Biomechanical Unit in Rats

Altered occlusal mechanics are critical regulators of the structure and function of the dentoalveolar and temporomandibular joints (DAJ, TMJ); however, the multiscale biological and mechanical consequences of sustained occlusal rise on the TMJ are not understood.

This study establishes a proof-of-concept for using an occlusal rise (OR) to investigate how the resulting chronic eccentric loading influences the DAJ and TMJ across mechanical, structural, and metabolic domains.

Rats were subjected to increased occlusal forces by placing a 0.5 mm metal wire and dental composite on the maxillary molars, producing a total occlusal rise of 1-1.5 mm. The DAJ and TMJ condylar bones in OR (N = 7) and control (N = 3) groups were evaluated using in vivo micro-CT at days 1, 14, and 35. One rat/group underwent ¹⁸F-NaF PET, complemented by autoradiography and histology. Finite element modelling (FEM) based on CT-derived geometries was used to evaluate TMJ reaction forces and stress under OR-loads.

Widened PDL space and interradicular bone remodelling were accompanied by reduced BMD with relatively preserved BV/TV, indicating redistribution rather than uniform loss of mineralized tissue in the DAJ. Progressive changes in condylar physical properties, with deviations between anatomical and mechanical axes, reflected adaptive load transmission. Increased ¹⁸F-NaF in TMJ indicated elevated metabolic activity. Histology confirmed ectopic cartilage-like tissue formation. FEM demonstrated buffering of TMJ stresses followed by temporal structural reorganisation.

Sustained OR drives coordinated, time-dependent remodelling across the DAJ-TMJ biomechanical unit through coupled mechanobiological adaptation, providing a mechanistic framework linking eccentric occlusal loading to TMJ remodelling and pathophysiology.