Retrognathous

Retrognathous is an adjective used in dentistry and orthopedics to describe a jaw that is positioned posteriorly relative to the cranial base or facial skeleton. The term most often refers to mandibular retrognathia, a retruded lower jaw, but it can also describe maxillary retrognathia when the upper jaw sits behind its normal position. Clinically, retrognathous individuals may have a convex or retruded facial profile, reduced chin projection, and an increased overjet; it is commonly associated with Class II malocclusion but can occur in isolation.

Diagnosis relies on imaging and cephalometrics. Lateral skull radiographs (cephalograms) are analyzed using metrics such as the SNA, SNB, and ANB angles to distinguish maxillary versus mandibular retrusion. A decreased SNB angle indicates mandibular retrognathia, while an increased ANB reflects a maxillomandibular discrepancy. In growing patients, clinical assessment of growth direction guides treatment planning.

Causes include genetic predisposition and growth disturbances; it may be an isolated dental-skeletal finding or part of congenital syndromes (e.g., craniofacial anomalies). Acquired causes include facial trauma or severe dentoalveolar compensations that mask the underlying skeletal pattern.

Management depends on severity and age. In children, orthodontic appliances and functional devices aim to modify growth. In adults or severe cases, orthognathic surgery—typically mandibular advancement (bilateral sagittal split osteotomy) and/or maxillary advancement (Le Fort I osteotomy)—is combined with comprehensive orthodontics. Impacts include bite irregularities, speech effects, and potential airway concerns; long-term prognosis is favorable with appropriate treatment. See also prognathism and cephalometrics.