Longitudinal evaluation of prognostic factors influencing the outcomes of functional appliance therapy in juvenile idiopathic arthritis patients with temporomandibular joint involvement

Introduction

Temporomandibular joint (TMJ) involvement is a common yet under-recognized manifestation of Juvenile Idiopathic Arthritis (JIA) which can impair craniofacial growth and oral function. While early functional orthopaedic intervention holds promise, evidence from long-term studies evaluating outcomes and predictors of treatment response remains sparse.

Materials and Methods

This prospective longitudinal study included 84 children (mean age: 12.3 ± 2.1 years) diagnosed with JIA and clinical TMJ involvement. All participants were treated with a standardized modified twin-block appliance over a 2-year period. Clinical, skeletal, inflammatory and quality-of-life assessments were performed at six time points using Maximum Interincisal Opening (MIO), Visual Analog Scale (VAS) for pain, cephalometry (SNB angle), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), autoantibodies (RF, ANA, anti-CCP), cone-beam computed tomography (CBCT) and the OHIP-14 questionnaire. Prognostic factors and relapse were evaluated using multivariate regression and Kaplan–Meier survival analysis.

Results

Over 24 months, patients demonstrated statistically significant improvement in MIO (+7.6 mm), VAS pain score (–3.9), SNB angle (+3.6°), ESR (–14.7 mm/hr) and CRP (–6.9 mg/L) (p < 0.001). Poorer outcomes were associated with RF/anti-CCP positivity, elevated baseline ESR/CRP, severe TMJ changes on CBCT and extra-articular involvement. In contrast, children aged ≤12 years with overjet ≤5 mm, SNB angle ≥76° and mild radiographic findings showed better therapeutic response. The 2-year relapse-free survival rate was 63.1 %.

Conclusion

Modified twin-block therapy appears to be a promising adjunct for managing TMJ involvement in JIA. Early intervention, mild radiographic pathology and absence of seropositivity were strong predictors of sustained improvement highlighting the need for timely diagnosis and individualized orthopaedic planning.