Bilateral Temporomandibular Joint Changes Following Unilateral Posterior Occlusal Alteration in Rats: A Longitudinal MRI and Histomorphometric Study

Background/Objectives: Whether a unilateral posterior occlusal alteration produces bilateral temporomandibular joint (TMJ) changes, and how imaging findings relate to tissue-level alterations, remains incompletely characterised. This study aimed to characterise the bilateral TMJ response to a sustained unilateral posterior occlusal alteration in rats using longitudinal magnetic resonance imaging (MRI) and endpoint histological and histomorphometric assessment.

Methods

Twenty-eight female Wistar rats were allocated to an experimental group (n = 12), a baseline control group (n = 4) and an age-matched control group (n = 12). Light-cured composite resin was applied to the three right maxillary molars of experimental animals and maintained for 16 weeks. Baseline MRI was obtained from the separate 8-week control group, whereas experimental and age-matched control animals underwent bilateral MRI at 16 and 24 weeks of age. Cartilage and disc structure, thickness and cell density were assessed histologically at the endpoint.