title: Three-dimensional evaluation of dentoskeletal changes after posterior cross-bite correction by quad-helix or removable appliances.
abstract: The aim of the study was to evaluate in a three-dimensional manner the dentoskeletal changes after slow maxillary expansion. The sample consisted of 34 children with a unilateral, symmetrical posterior cross-bite. Half of the children were treated with a quad-helix and the rest with a removable appliance. Assessment of the changes was made with study casts, and frontal and lateral cephalograms, before treatment, at the end of the expansion, after a retention period of 3 months, and after a post-retention period of 3 months. The results showed that sufficient expansion of the dental arches took place in both groups. The expansion expressed in the molar region in the quad-helix group was mostly due to buccal translation of the teeth and in the removable appliance group due to buccal tipping. The quad-helix group showed somewhat greater basal expansion than the removable appliance group, though the basal expansion in both groups was rather small. A tendency towards an increase of the NL/ML angle characterized the removable appliance group, but the opposite pattern was present in the quad-helix group.
authors.affiliation: Department of Orthodontics, Royal Dental College, Aarhus C, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Boysen
authors.forename: K
authors.initials: K
authors.lastname: La Cour
authors.forename: A E
authors.initials: AE
authors.lastname: Athanasiou
authors.forename: P E
authors.initials: PE
authors.lastname: Gjessing
mesh_terms: D000202:Activator Appliances; D002508:Cephalometry; D002648:Child; D005069:Evaluation Studies as Topic; D005147:Facial Bones / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy*; D008334:Mandible / Q000473:pathology; D008437:Maxilla / Q000473:pathology; D003765:Models, Dental; D009915:Orbit / Q000473:pathology; D016382:Orthodontic Appliance Design; D009968:Orthodontic Appliances, Removable; D009969:Orthodontic Wires; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D012886:Skull / Q000473:pathology; D013193:Stainless Steel; D014070:Tooth / Q000473:pathology*
chemical_list: D013193:Stainless Steel