retrognathia

Retrognathia is a skeletal jaw relationship in which the mandible is positioned posteriorly relative to the maxilla. The term comes from Latin retro- “behind” and gnathos “jaw.” It is distinct from prognathism, in which the mandible projects forward.

Clinical features commonly include a retrusive chin, a softer or diminished lower facial height, and a profile that appears convex. Functionally, retrognathia often contributes to a Class II malocclusion with increased overjet, and may be associated with a reduced or variable overbite. In some cases it is part of a broader syndrome or developmental pattern.

Causes can be congenital, developmental, or acquired. Congenital/syndromic forms occur with conditions such as Pierre Robin sequence or Treacher Collins. Non-syndromic retrognathia results from inherent jaw size discrepancies or remodeling during growth. Traumatic injury or tooth loss can also influence occlusion and facial balance.

Diagnosis relies on clinical examination and imaging. Lateral cephalometric radiographs commonly show a retrusive mandible with a decreased SNB angle, and an increased ANB angle indicating relative maxillary protrusion or mandible retrusion.

Treatment is tailored to severity, age, and functional impact. Mild cases may require observation. Orthodontic approaches address dental alignment and occlusion; functional appliances can encourage mandibular growth in growing patients. In adults or more pronounced cases, orthognathic surgery to advance the mandible (for example, bilateral sagittal split osteotomy) or, less commonly, maxillary advancement, may be indicated. Management of airway concerns is important when sleep-disordered breathing is present.

Prognosis depends on the underlying cause and treatment plan; combined orthodontic and surgical approaches can improve aesthetics, occlusion, and airway function.