Hemifacial Microsomia: Orthodontic Management in the UK

What is hemifacial microsomia?

Hemifacial microsomia (HFM) — also called craniofacial microsomia or first and second branchial arch syndrome — is a congenital condition characterised by unilateral (one-sided) underdevelopment of the lower face, jaw, ear, and adjacent soft tissues. The spectrum ranges from very mild, where only a small ear tag and subtle jaw asymmetry are present, to severe, with complete absence of the ear (anotia), profound mandibular hypoplasia, facial nerve palsy, and restricted mouth opening. Goldenhar syndrome represents the more severe end of the spectrum and may additionally include vertebral anomalies and epibulbar dermoids. HFM affects approximately 1 in 5,600 live births in the UK.

How is hemifacial microsomia classified?

Two classification systems are widely used. The SAT classification grades the severity of the skeleton (S), auricle or ear (A), and soft tissue (T) components independently, allowing a concise description of each element. The more comprehensive OMENS classification grades the orbit (O), mandible (M), ear (E), facial nerve (N), and soft tissue (S) on a scale of 0 to 3 for each structure. OMENS-Plus extends this further to include extracraniofacial anomalies. These systems allow the severity of each component to be communicated consistently between clinicians across the multidisciplinary team and are used in UK specialist craniofacial centres for treatment planning.

What orthodontic challenges does hemifacial microsomia cause?

The orthodontic challenges posed by HFM are substantial and arise from the underlying skeletal asymmetry. The affected mandible is shorter and may be hypoplastic to varying degrees, producing a midline deviation towards the affected side. The occlusal plane is canted — tilted so that one side is higher than the other — rather than horizontal. On the affected side, teeth may be missing or malformed. The temporomandibular joint on the affected side may be absent, rudimentary, or structurally abnormal, limiting mouth opening (trismus). The unaffected side undergoes compensatory overgrowth during development, increasing the asymmetry over time. Managing orthodontic tooth movement in this context requires three-dimensional planning and must be integrated with the surgical programme.

What is distraction osteogenesis in childhood?

Distraction osteogenesis (DO) is a surgical technique in which the bone is cut and slowly separated using a device (distractor) that incrementally lengthens the bone as it heals. For HFM, mandibular DO involves cutting the hypoplastic ramus and body of the mandible on the affected side and applying a device that advances the bone by approximately 1 millimetre per day. Over several weeks, new bone forms in the gap, lengthening the mandible. DO can be performed in infancy or early childhood and can be repeated as the child grows. It partially corrects the midline deviation and chin asymmetry, and may improve mouth opening. Orthodontic involvement before and after DO is required to manage the changing dental relationships. Distraction in childhood is preferable where airway compromise is present, but definitive jaw surgery is deferred until growth is complete.

What happens in pre-surgical orthodontics before jaw surgery?

For patients with HFM who are approaching skeletal maturity (usually age 17 to 20 for females, 18 to 21 for males), orthognathic surgery offers definitive correction of the facial asymmetry. Pre-surgical orthodontics aims to align and level the teeth within each arch, eliminate dental compensation for the skeletal discrepancy (decompensation), and coordinate the arch forms to allow the planned surgical movements. This phase typically takes 12 to 18 months. Surgical planning uses 3D CT imaging, digital occlusal analysis, and virtual surgical planning software. HFM cases may require multi-piece osteotomies to level the canted occlusal plane in addition to mandibular advancement on the affected side. Post-surgical orthodontics finalises the occlusion after bone healing.

How are ear reconstruction and oral rehabilitation sequenced?

Ear reconstruction or prosthetic rehabilitation of the ear is an important part of overall care for patients with severe auricular (ear) involvement. Autologous rib cartilage ear reconstruction (Nagata technique or similar) is typically carried out in two or more stages starting around age 7 to 10, when the contralateral ear has reached most of its adult size and rib cartilage is of sufficient quantity and quality. Osseointegrated ear prostheses supported by titanium implants in the mastoid are an alternative, particularly for older adolescents and adults. Oral rehabilitation — including dental implants for missing teeth, prosthodontic crowns, and soft tissue reconstruction — is usually sequenced to follow or accompany definitive jaw surgery. The timing of each component requires careful coordination across the team to avoid implants being placed in bone that will subsequently be moved.

Which UK specialist centres treat hemifacial microsomia, and is NHS funding available?

In the UK, complex craniofacial conditions including HFM are managed through a small number of specialist craniofacial units. These include: Alder Hey Children's NHS Foundation Trust (Liverpool), Great Ormond Street Hospital (London), Birmingham Children's Hospital, and the Oxford Craniofacial Unit. Each unit has a multidisciplinary craniofacial team and the specialist infrastructure for distraction osteogenesis, virtual surgical planning, and coordinated ear reconstruction. NHS England funds treatment for complex craniofacial conditions through specialised commissioning, and most patients with HFM in the UK are eligible for NHS-funded care for their craniofacial treatment. Referral is usually initiated by the GP or community paediatrician and should be made to the nearest specialist craniofacial unit.

Who is on the multidisciplinary team for HFM care?

Comprehensive HFM management involves a wide multidisciplinary team whose composition evolves with the patient's age and treatment phase. The core team includes an orthodontist, oral and maxillofacial surgeon (OMFS), and ENT surgeon. Restorative dentistry and implantology are involved for dental rehabilitation. Craniofacial nursing, clinical psychology, and speech and language therapy (SALT) support the patient and family throughout. Audiology involvement is essential for hearing assessment and management, as conductive hearing loss from middle ear anomalies is common in HFM. Ophthalmology input is required where orbital involvement is present. For patients with Goldenhar syndrome, spinal assessment is also indicated. Regular multidisciplinary team meetings, held at the specialist centre, coordinate the treatment plan and timing of each intervention.

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