Recessed Lower Jaw (Retrognathia): Orthodontic and Surgical Treatment in the UK

What is retrognathia?

Retrognathia describes a lower jaw — the mandible — that is positioned further back than ideal relative to the upper jaw and the rest of the face. In clinical terms, this typically manifests as a skeletal Class II pattern: the lower jaw sits posterior to where it should be, creating a retrusive chin profile and, in many cases, an increased overjet — a horizontal gap between the upper and lower front teeth. Retrognathia may involve a genuinely small or short lower jaw, a jaw that is appropriately sized but sits too far back, or a combination of both. It is distinct from cases where the overjet is caused primarily by upper teeth that protrude.

How retrognathia differs from a dental overjet

An overjet is the measurement of how far upper front teeth project horizontally beyond lower front teeth. A large overjet can have a skeletal cause — the lower jaw is too far back — or a dental cause — the upper front teeth protrude forwards or the lower front teeth are tipped inwards without a significant jaw discrepancy. Distinguishing between these causes is critical because the treatment is entirely different. A cephalometric X-ray and clinical assessment allow the clinician to establish whether the overjet is primarily skeletal, primarily dental, or a combination of both, and this determines the treatment approach.

Clinical assessment: cephalometry and Wits appraisal

A lateral cephalometric radiograph — an X-ray taken from the side with the teeth in occlusion — is the standard tool for measuring jaw relationship. Key measurements include the ANB angle, which reflects the horizontal relationship between the upper and lower jaw bases, and the Wits appraisal, which measures the relationship between the jaw bases independent of the cranial base. A large ANB angle and a positive Wits value confirm a skeletal Class II pattern. These measurements, combined with clinical examination, guide the choice of treatment and allow comparison at different stages to monitor progress.

Treatment in growing children: functional appliances

In patients who are still growing — typically aged 9 to 14 — functional appliances can harness the growth potential of the lower jaw to encourage forward development. The twin block appliance is the most widely used in the UK: a two-piece removable appliance that postures the lower jaw forwards, stimulating condylar growth and remodelling of the glenoid fossa. The Herbst appliance provides the same effect but is fixed, removing compliance requirements. Wearing functional appliances during the growth spurt — when bone remodelling is fastest — produces the best skeletal changes. Treatment typically takes 9 to 15 months and is usually followed by fixed braces to detail the final occlusion.

The growth spurt window

The timing of functional appliance therapy matters considerably. The peak pubertal growth spurt — when the lower jaw is growing most rapidly and responds best to functional stimulation — typically occurs around age 12 to 13 in girls and 13 to 14 in boys. Starting treatment just before or during this window maximises skeletal change. Starting too early means treatment may be complete before growth is sufficient to produce meaningful change; starting too late, after the growth spurt has passed, significantly reduces the skeletal effect. Clinicians may use hand-wrist radiographs or cervical vertebral maturation staging to time treatment optimally.

Adult options: orthodontic camouflage and its limits

In adults who have completed growth, functional appliances have little or no skeletal effect. The options are orthodontic camouflage — moving teeth within the existing jaw structure to improve appearance and occlusion without correcting the jaw discrepancy itself — or orthognathic surgery to reposition the jaw. Camouflage typically involves retracting upper front teeth, advancing lower front teeth, or both, to reduce the visible overjet. This approach works well for mild to moderate skeletal Class II cases but has limits: if the jaw discrepancy is severe, attempting to camouflage it fully will move teeth to positions outside the bone or create an unstable bite.

Orthognathic surgery: BSSO mandibular advancement

For adults with a significant skeletal Class II discrepancy who cannot or do not wish to accept camouflage, bilateral sagittal split osteotomy (BSSO) is the surgical procedure used to advance the lower jaw. The mandible is cut and moved forwards, then held in the new position with titanium plates and screws. The procedure requires general anaesthesia and typically an overnight hospital stay. Recovery involves swelling, restricted jaw movement, and a modified diet for several weeks. Orthodontic treatment is required before surgery to align the teeth within each arch and after surgery to achieve the final occlusal detail — total treatment time is typically 2 to 3 years.

Combined upper and lower jaw surgery

Where the skeletal discrepancy involves both a retrusive lower jaw and an excess or deficiency of the upper jaw, combined bimaxillary surgery — operating on both jaws simultaneously — produces the most balanced facial result. This is a more complex procedure but allows the surgeon to adjust both jaw positions together, optimising both the occlusal and facial aesthetic outcome. It is planned collaboratively between the orthodontist and maxillofacial surgeon using cephalometric and dental model analysis, and increasingly through digital 3D surgical planning.

NHS access via the SCAN pathway

Patients with significant skeletal Class II retrognathia may qualify for NHS treatment if their IOTN (Index of Orthodontic Treatment Need) score is in the definite treatment need range (grades 4 to 5) and they are referred through the SCAN (Specialist Care Assessment Network) pathway for combined orthodontic and orthognathic surgical treatment. Eligibility requires functional impairment — not just cosmetic concern — and NHS treatment is typically only funded for patients under 18 at the point of referral, although some adults may access surgical treatment via NHS maxillofacial surgery on medical grounds.

Realistic outcomes and expectations

Treatment of retrognathia — whether by functional appliances, camouflage, or surgery — produces real and meaningful improvements to bite function and facial profile. Functional appliance treatment in growing patients can reduce skeletal discrepancy by several millimetres, though rarely eliminates it entirely; some residual dental camouflage is almost always needed. Surgical advancement in adults can produce dramatic profile improvement with stable long-term results. The most important thing is aligning the treatment approach with the degree of the problem — mild cases respond well to camouflage, while attempting to camouflage a severe skeletal discrepancy produces compromised outcomes that neither the patient nor the clinician will be satisfied with.

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.