title: Tooth-borne vs bone-borne rapid maxillary expanders in late adolescence.
abstract: OBJECTIVE
  To evaluate the immediate effects of rapid maxillary expansion (RME) on the transverse skeletal and dentoalveolar changes with bone-borne (C-expander) and tooth-borne type expanders using cone-beam computed tomography (CBCT) in late adolescents.
  
  
  METHODS
  A sample of 28 female late-adolescent patients was divided into two groups according to the type of expander: bone-borne (C-expander, n  =  15, age  =  18.1 ± 4.4 years) and tooth-borne (hyrax, bands on premolars and molars, n  =  13, age  =  17.4 ± 3.4 years). CBCT scans were taken at 0.2-mm voxel size before treatment (T1) and 3 months after RME (T2). Transverse skeletal and dental expansion, alveolar inclination, tooth axis, vertical height of tooth, and buccal dehiscence were evaluated on maxillary premolars and molars. Paired t-test, independent t-test, one-way analysis of variance, and Scheffé post hoc analysis were performed.
  
  
  RESULTS
  The C-expander group produced greater skeletal expansion, except in the region of the first premolar (P < .05 or < .01), which showed slight buccal tipping of the alveolar bone. The Hyrax group had more buccal tipping of the alveolar bone and the tooth axes, except in the region of the second molar (P < .05 or < .01 or < .001). Dental expansion at the apex level was similar in the banded teeth (the first premolar and the first molar). Vertical height changes were apparent on the second premolar in the hyrax group (P < .05 or < .01). Significant buccal dehiscence occurred at the first premolar in the hyrax group (P < .01 or < .001). There were no significant differences between tooth types for any variables in the C-expander group.
  
  
  CONCLUSIONS
  For patients in late adolescence, bone-borne expanders produced greater orthopedic effects and fewer dentoalveolar side effects compared to the hyrax expanders.
authors.affiliation: a Postgraduate Student, Department of Orthodontics, School of Dentistry, Kyung Hee University, Seoul, Korea.
authors.forename: Lu
authors.initials: L
authors.lastname: Lin
authors.forename: Hyo-Won
authors.initials: HW
authors.lastname: Ahn
authors.forename: Su-Jung
authors.initials: SJ
authors.lastname: Kim
authors.forename: Sung-Chul
authors.initials: SC
authors.lastname: Moon
authors.forename: Seong-Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: Gerald
authors.initials: G
authors.lastname: Nelson
mesh_terms: D000293:Adolescent; D000539:Alveolar Process / Q000000981:diagnostic imaging; D001641:Bicuspid / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000379:methods; D003393:Cranial Sutures / Q000000981:diagnostic imaging; D003724:Dental Arch / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008437:Maxilla / Q000000981:diagnostic imaging; D008963:Molar / Q000000981:diagnostic imaging; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation*; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D021362:Palate, Hard / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D019227:Tooth Apex / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: Alveolar bone; Bone-borne expander; C-implant; Cone-beam computed tomogram; Hyrax expander; Rapid maxillary expansion