The retroclined upper incisor.
D000293:Adolescent; D000539:Alveolar Process / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007180:Incisor / Q000254:growth & development*; D008046:Lip / Q000503:physiopathology*; D008310:Malocclusion / Q000209:etiology*; D008437:Maxilla; D063173:Retrognathia; D014079:Tooth Eruption, Ectopic