Orthopaedic splint treatment can reduce mandibular asymmetry caused by unilateral temporomandibular involvement in juvenile idiopathic arthritis.

Unilateral temporomandibular joint (TMJ) arthritis in juvenile idiopathic arthritis (JIA) patients often induces asymmetric dentofacial growth. This study evaluates the effects of an orthopaedic functional appliance worn full time to reduce asymmetric mandibular growth in JIA patients. Twenty-two JIA patients with unilateral TMJ involvement were included in the study (mean age 7.5 years, range: 3.8-13.8 years). They all received orthopaedic treatment with a functional appliance, a so-called distraction splint (mean treatment time 57 months). Panoramic tomograms or cone beam-computerized tomograms were taken before and within 12 months after treatment cessation. At both time points, the ratio between the healthy and the affected side of the mandible was evaluated in terms of inter-side differences in condylar height, ramus height, and total vertical mandibular height. Orthopaedic functional treatment reduced mandibular asymmetries in terms of ramus height and total vertical mandibular height (P < 0.05). Mandibular growth rates in the affected and the non-affected sides were comparable in most patients. Our study finds evidence to support that a distraction splint can normalize mandibular vertical growth in the affected side. We therefore suggest implementation of distraction splint therapy in the treatment of JIA patients with unilateral TMJ arthritis.