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.

The aim of this investigation was to study the effect of intra-articular (i.a.) corticosteroid injections (IACIs) in the temporomandibular joint (TMJ) on mandibular development in antigen-induced TMJ arthritis. Ten-week-old female New Zealand white rabbits (n = 42) were randomly divided into four groups: group A, control (no injections); group B, placebo (repeated i.a. TMJ saline injections); group C, untreated arthritis (repeated induction of TMJ arthritis); and group D, steroid (repeated induction of TMJ arthritis + IACI). All animals had two tantalum implants inserted in the right side of the mandible serving as stable landmarks for later growth analysis. One implant was inserted close to the symphysis and one in the molar region. Computerized tomographic (CT) full-head scans were carried out at 14 (T1) and 26 (T2) weeks of age. (Dropout of animals at T2; group C, n = 7, and group D, n = 3.) Absolute and relative intra- and inter-group growth variations were evaluated during the growth period by comparison of CT scans. One-way analysis of variance was used for T1 statistical analysis, and absolute intra-group and relative inter-group growth differences between T1 and T2 were evaluated by Student's t-tests. At T2, the animals in the group A had greater sagittal and vertical mandibular growth compared with the other three groups. TMJ arthritis caused diminished mandibular growth. However, relative mandibular growth was significantly less in group D. The findings of this study do not indicate a positive long-term effect in the use of IACI in the TMJ as an early treatment intervention against TMJ inflammation in growing individuals.