title: Transverse dentoalveolar changes after slow maxillary expansion.
abstract: BACKGROUND
  In this study, we evaluated the transverse dentoalveolar changes in the maxillary first molar region after early treatment with the quad-helix appliance.
  
  
  METHODS
  Seventy-three consecutive patients (39 boys, 34 girls) who had phase 1 quad-helix treatment were evaluated with cone-beam computed tomography scans taken before phase 1 (mean age, 9.2 years) and phase 2 (mean age, 11.9 years) treatments. Buccal bone thickness, buccal cortical plate thickness, lingual bone thickness, alveolar width, palatal width, and intermolar width were measured by using standardized orientations.
  
  
  RESULTS
  Slow palatal expansion with the quad-helix decreased buccal bone thickness (1.6 mm ± 0.8), and increased lingual bone thickness (1.6 mm ± 1.3) and alveolar width (0.5 mm ± 1.0). Intermolar widths and palatal widths increased 6.5 mm ± 2.9 and 3.9 mm ± 1.8, respectively. At the beginning of phase 2, approximately one third of the patients showed little or no buccal cortical plate on at least 1 side. Patients retained with the Hawley demonstrated some relapse tendencies; patients without retention had the greatest relapse tendencies.
  
  
  CONCLUSIONS
  Early treatment with the quad-helix appliance proved to be highly effective in increasing intermolar, palatal, and alveolar widths. The teeth moved through the alveolus, leading to substantial decreases in buccal bone thickness and increases in lingual bone thickness.
authors: Orthodontic Department, Baylor College of Dentistry, Texas A&M Health Science Center, Dallas, Texas 75246, USA.
authors: Jared K
authors: JK
authors: Corbridge
authors: Phillip M
authors: PM
authors: Campbell
authors: Reginald
authors: R
authors: Taylor
authors: Richard F
authors: RF
authors: Ceen
authors: Peter H
authors: PH
authors: Buschang
mesh_terms: D000293:Adolescent; D000539:Alveolar Process / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D000704:Analysis of Variance; D015519:Bone Density; D002508:Cephalometry; D002648:Child; D054893:Cone-Beam Computed Tomography; D003724:Dental Arch / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008437:Maxilla; D008963:Molar / Q000000981:diagnostic imaging; D010155:Palatal Expansion Technique / Q000295:instrumentation; D021362:Palate, Hard / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012008:Recurrence; D018709:Statistics, Nonparametric; D016896:Treatment Outcome