Temporomandibular joint osteoarthritis (TMJ OA) in adolescents is clinically important because condylar degeneration during growth may adversely affect mandibular development. However, three-dimensional evidence regarding the effect of stabilization splints on joint remodelling remains limited.

This retrospective observational study included adolescents with unilateral TMJ OA and baseline condylar erosion who underwent baseline and follow-up cone-beam computed tomography over approximately two years. Patients were classified into splint and no-splint groups. Changes in condylar height (Δh₁), lateral and medial posterior eminence volumes (ΔEpost.lat.v1, ΔEpost.med.v1), and mandibular plane angle were quantified. Adjusted mean changes were estimated using analysis of covariance controlling for age, sex, and baseline pain intensity.

After adjustment, the no-splint group showed significantly greater loss of condylar height and posterior eminence volume on the affected side compared with the splint group. On the non-affected side, lateral posterior eminence volume increased significantly in the no-splint group, suggesting compensatory remodelling. A greater increase in mandibular plane angle was also observed in patients without splint therapy.

In this retrospective exploratory cohort, night-time stabilization splint use was associated with a more favorable pattern of condylar and posterior eminence remodeling. These findings should be interpreted cautiously and do not establish a causal treatment effect.