title: The value of the PM reference line for estimating natural head position.
mesh_terms: D000293:Adolescent; D000328:Adult; D002508:Cephalometry; D003756:Dental Hygienists; D005145:Face / Q000033:anatomy & histology; D005260:Female; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D008310:Malocclusion; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000033:anatomy & histology / Q000473:pathology; D008722:Methods; D011187:Posture; D011378:Prognathism / Q000473:pathology; D011859:Radiography; D063173:Retrognathia; D013100:Sphenoid Bone / Q000033:anatomy & histology