title: Changes in hyoid bone position following rapid maxillary expansion in adolescents.
abstract: OBJECTIVE
  To examine changes in hyoid to mandibular plane distance (H-MP) and tongue length (TL) between children who had orthodontic treatment with and without rapid maxillary expansion (RME).
  
  
  METHODS
  Lateral and frontal cephalograms of 138 patients treated with RME and 148 controls treated without RME were used to measure pretreatment (T(1)) and posttreatment (T(2)) intermolar (IM) distance, lateronasal width (LNW), H-MP, and TL. Medical histories were used to collect demographic information, history of mouth breathing, difficulty breathing through the nose, and previous adenotonsillectomy. Groups were group-matched for age and gender. Descriptive statistics were calculated. Group means were compared using t-tests and chi-square statistics. Reliability was estimated using intraclass correlations and kappa statistics. Statistical significance was set at P < .05.
  
  
  RESULTS
  At T(1), the RME group showed smaller LNW (24.83 ± 1.99 vs 26.18 ± 2.05) and IM (50.17 ± 2.3 vs 51.58 ± 2.83). The distance from H-MP was longer in the RME group (15.69 ± 3.95 vs 13.86 ± 3.4). Mean changes (T(2) - T(1)) in the RME group were increased LNW (+2.48 ± 1.38 vs +0.94 ± 1.11 for the non-RME group) and IM (+3.21 ± 1.72 vs +0.98 ± 1.67). The mean change (T(2) - T(1)) in H-MP for the RME group was -0.68 ± 3.67 compared with +1.1 ± 2.96 for the non-RME group. Mean changes for TL were not statistically significant. No significant differences were noted at T(2) between groups for LNW, H-MP, or TL.
  
  
  CONCLUSIONS
  In this sample, RME produced significant changes in H-MP, and TL was unaffected.
authors.affiliation: Department of Orthodontics, School of Dental Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Austin
authors.initials: A
authors.lastname: Phoenix
authors.forename: Manish
authors.initials: M
authors.lastname: Valiathan
authors.forename: Suchitra
authors.initials: S
authors.lastname: Nelson
authors.forename: Kingman P
authors.initials: KP
authors.lastname: Strohl
authors.forename: Mark
authors.initials: M
authors.lastname: Hans
mesh_terms: D000293:Adolescent; D000403:Airway Resistance; D016022:Case-Control Studies; D002508:Cephalometry; D016009:Chi-Square Distribution; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006928:Hyoid Bone / Q000033:anatomy & histology*; D008297:Male; D008334:Mandible / Q000033:anatomy & histology; D009058:Mouth Breathing / Q000628:therapy*; D009296:Nasal Cavity / Q000033:anatomy & histology; D010155:Palatal Expansion Technique; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D014059:Tongue / Q000033:anatomy & histology