Articular eminence inclination as a morphological marker for temporomandibular joint disc displacement: a...

To investigate the association between the morphology of the articular eminence (AE) and mandibular fossa (MF) and the presence of temporomandibular joint (TMJ) disc displacement with reduction (DDwR) using cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI).

This retrospective cross-sectional study analyzed 60 TMJs from 30 patients with intra-articular disorders treated at two Vietnamese centers (2022-2024). MRI classified joints as DDwR or normal disc position (No DD). CBCT provided morphometric measurements: AE inclination (top-roof line [TR] and best-fit line [BF] angles), AE height and width, and MF width. Intra-observer reliability was assessed using the intraclass correlation coefficient (ICC). Group differences were tested using t-tests or Mann-Whitney U tests (p < 0.05).

MRI identified 50 DDwR joints (83.3%) and 10 No DD joints (16.7%). Measurement reliability was excellent (ICC = 0.86). AE inclination was significantly lower in DDwR joints (TR: 37.85 ± 7.13 ° vs. 46.44 ± 6.41 °, p = 0.001; BF: 53.80 ± 6.70 ° vs. 60.64 ± 7.16 °, p = 0.003). No significant differences were found for AE height (6.88 ± 1.51 mm vs. 6.91 ± 1.00 mm), AE width (9.37 ± 1.63 mm vs. 9.48 ± 1.54 mm), or MF width (15.24 ± 1.40 mm vs. 15.85 ± 1.00 mm) (all p > 0.05).

A flatter AE inclination is significantly associated with DDwR, challenging the traditional view that a steeper eminence predisposes to disc displacement. These findings suggest AE flattening may be a secondary change linked to degenerative remodeling. CBCT-based AE inclination assessment could aid in risk evaluation and early diagnosis of TMJ internal derangement.