Juvenile Idiopathic Arthritis (JIA) and Orthodontic Treatment

Why the TMJ matters in JIA

The temporomandibular joint — the jaw joint — is a synovial joint and therefore susceptible to the same inflammatory changes that affect knees, wrists, and other joints in JIA. TMJ involvement is estimated to occur in 40 to 70 percent of children with JIA, depending on subtype and study methodology. The oligoarticular and polyarticular RF-negative subtypes are particularly associated with TMJ disease. Crucially, TMJ arthritis in JIA is frequently subclinical: children may not report jaw pain, and clinical examination alone is unreliable at detecting early disease. MRI is the gold standard for TMJ assessment, and many paediatric rheumatology centres now include mandibular MRI in their baseline workup.

Condylar destruction and its consequences

The condyle is the rounded head of the mandible that sits in the TMJ fossa and is the primary growth site of the lower jaw. Persistent inflammation in the TMJ causes synovitis and pannus formation that erodes the condylar cartilage and bone. As the condyle is destroyed or remodelled, it loses height and the mandible rotates backwards. This produces retrognathia — a recessed lower jaw — and an anterior open bite. The severity depends on how long inflammation persists and how severely the condyles are affected. Children with bilateral condylar destruction can develop significant micrognathia: a markedly underdeveloped lower jaw that creates a steep mandibular plane angle, excessive lower face height, and limited mouth opening. The chin appears to recede and the upper teeth protrude by comparison.

Anterior open bite in JIA

As condyles flatten and lose height, the molar regions of the jaws are pushed apart. This forces the anterior teeth out of contact, creating an anterior open bite. Unlike open bites caused by digit habits or tongue thrusting, JIA-related open bite is skeletal in origin — caused by jaw bone changes rather than dentoalveolar tipping. This distinction is critical because dentoalveolar open bites may be correctible with orthodontics alone, whereas skeletal open bites from condylar destruction ultimately require orthognathic surgery once growth is complete.

The challenge of treatment during active disease

Orthodontic treatment during active TMJ inflammation is controversial. Applying orthodontic forces to a jaw with actively inflamed joints risks accelerating bone destruction or causing pain. Functional appliances that load the TMJ are generally contraindicated while disease is active. Fixed braces that do not exert significant forces on the mandible may be tolerable in mild disease. The general principle is to defer active orthodontic treatment that loads the TMJ until disease is in sustained remission. Paediatric rheumatologists manage disease activity with disease-modifying drugs (DMARDs), biologics such as adalimumab and tocilizumab, and intra-articular corticosteroid injections directly into the TMJ. Achieving remission before orthodontic intervention is the priority.

Functional appliances and fixed braces in JIA

Twin blocks and other functional appliances work by repositioning the mandible forward to stimulate condylar growth. In a child without JIA, this can effectively advance a retrognathic lower jaw. In a child with JIA and TMJ disease, functional appliances are used cautiously: advancing the mandible loads a damaged joint, and the condylar growth response may be impaired or absent because the growth centre has been damaged by arthritis. Some specialist centres use functional appliances in JIA patients during remission with close joint monitoring, but outcomes are less predictable than in non-JIA patients. Fixed braces can be used to align teeth and manage the dental aspects of the malocclusion in preparation for surgery, but cannot correct the underlying skeletal discrepancy.

Orthognathic surgery as definitive treatment

For many JIA patients with significant condylar destruction and skeletal retrognathia, orthognathic surgery is the definitive treatment once facial growth is complete — typically late teenage years. Combined orthodontic-surgical treatment involves preparing the teeth with fixed braces, then advancing the mandible surgically (bilateral sagittal split osteotomy), sometimes combined with maxillary movements. If condylar destruction is progressive and unpredictable, total joint replacement with prosthetic TMJ implants may be considered in adult life. Surgery is planned collaboratively between orthodontists, maxillofacial surgeons, and the patient's rheumatology team.

NHS multidisciplinary pathway in the UK

Children with JIA and significant jaw involvement are ideally managed through specialist paediatric rheumatology centres with access to multidisciplinary teams including orthodontists. Centres with established joint expertise include Great Ormond Street Hospital, Birmingham Children's Hospital, the Leeds and Newcastle paediatric rheumatology services, and several other regional hubs. NHS orthodontic treatment for JIA patients qualifies under IOTN criteria due to the severity of malocclusion and the functional impact. Parents should ensure the rheumatology team and orthodontist are communicating, as joint management decisions should incorporate both perspectives. Referral to a regional cleft and craniofacial unit may also be appropriate for complex cases.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.