Mandibular prognathism develops as a result of several factors including infant osteogenetic disturbance, mechanical factors such as malocclusion, and heredity. The condition is characterized by an enlarged mandible, an increased mandibular angle and arch of the circle of the sigmoid notch, and masticatory and phonetic disturbances. Curative treatment involves surgery using Castro's technique, which makes use of an extra-oral approach that leaves an inconspicuous scar.