title: The effect of cleft maxillary distraction osteogenesis on the levator veli palatini and velopharyngeal function.
abstract: BACKGROUND
  Le Fort I maxillary distraction with the rigid external distraction (RED) device is performed to correct severe midface retrusion in cleft patients, but it may adversely affect velopharyngeal function.
  
  
  OBJECTIVE
  This study aims to investigate the angular changes in the levator veli palatini (LVP) and its influence on velopharyngeal function after maxillary distraction using 3-dimensional computed tomography (3D CT) scan volume rendered images.
  
  
  METHODS
  This was a retrospective study of 12 patients. Group 1 had no velopharyngeal function deterioration and group 2 had velopharyngeal function deterioration. Preoperative and 1 year postoperative CT scans were analyzed with Mimics v10 software. Segmentation of the LVP and the nasopharyngeal airway was performed and volumetric images were obtained. Six measurements were made: (1) the angle between the levator plane and the Frankfort horizontal, (2) the angle between the levator plane and the soft palate plane, (3) the angle between the 2 LVP muscles, (4) the pharyngeal depth, and (5, 6) the movement of the inferior pharyngeal point with respect to the horizontal and vertical planes. The independent samples t test, Mann-Whitney test, and paired t tests were used for statistical analyses (P < 0.05).
  
  
  RESULTS
  Group 2 had statistically significant reduction in the angle between the levator plane and Frankfort horizontal as well as the soft palate plane. Group 1 had a statistically significant increase in the pharyngeal depth and movement of the inferior pharyngeal point with respect to the horizontal plane.
  
  
  CONCLUSIONS
  A decrease in the angle between the levator plane and the Frankfort horizontal or the soft palate plane was associated with velopharyngeal function deterioration.
authors.affiliation: *Craniofacial Center, Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan †Cleft and Craniofacial Center, Department of Plastic, Reconstructive and Aesthetic Surgery, Kandang Kerbau Women's and Children's Hospital, Singapore, Singapore ‡Department of Orthodontics and Craniofacial Dentistry, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
authors.forename: Philip Kuo-Ting
authors.initials: PK
authors.lastname: Chen
authors.forename: Yong-Chen
authors.initials: YC
authors.lastname: Por
authors.forename: Eric Jein-Wein
authors.initials: EJ
authors.lastname: Liou
authors.forename: Frank Chun-Shin
authors.initials: FC
authors.lastname: Chang
mesh_terms: D002648:Child; D002972:Cleft Palate / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D003679:Deglutition / Q000502:physiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D019857:Osteogenesis, Distraction / Q000379:methods*; D010160:Palate, Soft / Q000601:surgery*; D010614:Pharynx / Q000601:surgery*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed