Prognathism (PROGENIA, excessive forward projection of the)

PROGNATHISM, PROGENIA, excessive forward projection of the facial skeleton, caused by significant development of the jaws (lower jaw prognathism, both upper jaws or one of them - prognathy). 'True prognathism should be distinguished from "false prognathism," i.e., forward projection of the lower jaw without an increase in its size. False prognathism appears secondarily as a result of retrognathism or displacement of the lower jaw forward. Prognathism can be complete or partial. The latter can involve the chin, alveolar, and dental areas. Prognathism most often represents an anomaly of development of the lower jaw, sometimes of hereditary origin. In the Habsburg dynasty, prognathism was inherited for 400 years, i.e., during the period when blood marriages predominated among the Habsburgs. Prognathism can also have a pathological origin. In acromegaly, prognathism and the resulting diastemas are early symptoms of this disease. In macroglossia, enlargement of the tongue also contributes to an increase in the lower jaw. After surgical treatment of acromegaly, prognathism decreases and the teeth come closer together. In prognathy, the shape of the lower jaw approaches a right angle, while in prognathism an obtuse angle is usually observed. The chin prominence, absent in newborns, increases with age. Cases where normal occlusion is preserved in prognathism are of no importance for orthodontics. Only those anomalies of jaw development that are accompanied by a decrease in the efficiency of the chewing organ should be treated orthodontically. This occurs to a particularly strong degree when prognathy is combined with retrogenia or prognathism with retrognathism. For etiology, diagnosis, and treatment of anomalies of closure in prognathism, prognathy, retrogenia, and retrognathism - see below. Prognathy. True prognathy or macrognathy should be distinguished from "false prognathy," i.e., forward projection of the upper jaw without an increase in its size. False prognathy...