title: Factors that influence the proclination or retroclination of the lower incisors in children with prolonged thumb-sucking habits.
abstract: In some children with a prolonged finger-sucking habit, the lower incisors are retroclined, however, proclination of the lower incisors has been frequently observed. The purpose of this study was to determine how such differences develop in the child with a digit-sucking habit. Children with a prolonged thumb-sucking habit and proclination of the lower incisors (Ili/ML > 97 degrees) were cephalometrically and clinically compared to persistent thumb-suckers with retroclined lower incisors (Ili/ML < 89 degrees). In the group with retroclined lower incisors the angle between the thumb and the lower incisors was significantly smaller and the thickness of the lower lip significantly thinner than in the group with proclined incisors. A higher frequency of early loss of deciduous molars was also observed in the group with retroclined incisors. The tightness of the lower lip, early loss of deciduous molars and the angle between the teeth and the thumb are factors which have been identified to influence the inclination of the lower incisors in persistent digit suckers. The majority of children with prolonged thumb-sucking have proclined lower incisors rather than retroclined lower incisors.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Anita
authors.initials: A
authors.lastname: Afzelius-Alm
authors.forename: Erik
authors.initials: E
authors.lastname: Larsson
authors.forename: Claes-Göran V
authors.initials: CG
authors.lastname: Löfgren
authors.forename: Samir E
authors.initials: SE
authors.lastname: Bishara
mesh_terms: D000293:Adolescent; D002508:Cephalometry; D016009:Chi-Square Distribution; D002648:Child; D003679:Deglutition / Q000502:physiology; D005260:Female; D005386:Fingersucking / Q000009:adverse effects*; D006801:Humans; D007180:Incisor / Q000473:pathology*; D008046:Lip / Q000473:pathology; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000473:pathology*; D008334:Mandible; D008963:Molar / Q000503:physiopathology; D013933:Thumb; D014059:Tongue / Q000473:pathology; D014061:Tongue Habits; D014080:Tooth Exfoliation / Q000503:physiopathology; D014094:Tooth, Deciduous / Q000503:physiopathology