Retrogenia and Retrognathia

RETROGENIA, RETROGNATHIA. Retrogenia (or opisthogenia or microgenia) is the distal deviation of the mandible, usually resulting from its underdevelopment. Retrognathia (or opisthognathia or micrognathia) is the same deviation of the maxilla. Retrogenia can involve the entire jaw or individual parts: the chin region, the alveolar region, etc. In the first case, the face acquires a characteristic bird-face profile. The lower part of the face recedes, while the middle part of the face appears elongated forward along with the nose compared to it. In alveolar retrogenia, the chin sometimes protrudes forward instead. Retrogenia can be expressed symmetrically on the right and left sides of the jaw or be unilateral. True retrogenia should be distinguished from "false" retrogenia, i.e., cases where a fully developed mandible gives the impression of being underdeveloped due to excessive development of the maxilla. Sagittal deviations of the dental arches with normally developed jaws are more correctly designated by the terms prodentia and retrodentia. Dental deviation rarely occurs parallel to their physiological axes; combinations of coronal protrusion with apical retrusion and vice versa are more frequently observed. Retrognathia can be complete or partial. Underdevelopment of the entire maxilla is observed rarely. In such cases, the tip of the nose and the upper lip are usually displaced distally, creating the picture of false prognathism. Underdevelopment of the intermaxillary bone and the alveolar region is more common. Such cases are usually combined with compression of the jaw in the premolar region, narrowing and elevation of the palatal vault, and frequently with an open bite. At the same time, the axes of the incisors are usually deviated from their normal position. The following cases are distinguished: 1) underdevelopment may involve both jaws, in which case occlusion may be correct and functional impairment insignificant; 2) one of the jaws may be underdeveloped while the second jaw is normal, leading to a mismatch of the dental arches and greater or lesser functional impairment; 3) underdevelopment of one jaw may be accompanied by excessive development of the other, in which latter case functions are impaired particularly severely. For the etiology, diagnosis, and treatment of occlusion anomalies in retrognathia, retrogenia, progenia, and prognathism, see Orthodontics and Progenia, prognathism, surgical treatment. G. Verkoch. RETROPOSITIO UTERI (retroposition of the uterus), an abnormal position of the uterus in which the latter is entirely displaced posteriorly; retropositio uteri is usually combined with anterior inclination of the uterus. The origin of retropositio uteri is most frequently associated with inflammatory processes behind the uterus (inflammation of the peritoneum, Douglas' pouch, ovaries, tubes, parametritis behind the uterus); less frequently, the origin of retropositio uteri is connected with ovarian tumors located in front of the uterus, tumors developing from the anterior wall of the uterus, tumors of the bladder, and the anterior wall of the pelvic ring. Retropositio uteri, due to tissue rigidity behind the uterus, is often observed in the infantile state of the pelvic organs; frequently, retropositio uteri develops in the climacteric period, after treatment with radium or X-rays as a result of wrinkling and shortening of the tissues behind the uterus. Symptoms and treatment depend on the underlying condition (see Uterus, displaced positions of the uterus, Parametritis, Pelveoperitonitis).