macrognathism macrognathism macrognathism is an abnormally large or protruding jaw. the opposite condition is called micrognathia. macrognathismother namesmegagnathiaspecialtyent surgery causes heredity pituitary gigantism paget's disease of bone acromegaly fetal alcohol syndrome leontiasis ossea cleidocranial dysplasia treatment treatment is surgical. osteotomy may be done in case of maxillary macrognathia. mandibular macrognathia is generally managed by resection of a portion of the mandible.