title: Asymmetric maxillary protraction for unilateral cleft lip and palate patients using finite element analysis.
abstract: OBJECTIVE
  Unilateral cleft lip and palate (UCLP) patients frequently present with an asymmetry in the nasomaxillary complex and a maxillary hypoplasia. The aim of this study was to investigate biomechanic effects of asymmetric maxillary protraction in UCLP patients using finite element method.
  
  
  METHODS
  A finite element model of a UCLP patient's skull was generated using data from spiral computed tomographic scans. On the basis of this finite element model, three groups of orthopedic forces were loaded. All forces were applied in a direction that was 30 degrees downward and forward to the occlusal plane on the region of the alveolar of the maxillary canine. The value of orthopedic force was 5 N in cleft side and 5 N in noncleft side (group A), 6 N in cleft side and 5 N in noncleft side (group B), and 7 N in cleft side and 5 N in noncleft side (group C), respectively.
  
  
  RESULTS
  All 3 groups were effective in promoting maxilla forward. In group B, the displacement difference between the cleft side and the noncleft side was the smallest. The largest value difference between the cleft side and the noncleft side was found in group C.
  
  
  CONCLUSIONS
  Maxillary protraction with a loading of 6 N in the cleft side and 5 N in the noncleft side produced the most favorable outcome. It can be suggested that it might be advantageous to perform asymmetric maxillary protraction on UCLP patients.
authors.affiliation: From the Department of Orthodontics, Ninth People's Hospital, School of Stomatology, Shanghai key Laboratory of Stomatology, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Zhengxi
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Pan
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
authors.forename: Zhenqi
authors.initials: Z
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Shen
mesh_terms: D000293:Adolescent; D002971:Cleft Lip / Q000000981:diagnostic imaging*; D002972:Cleft Palate / Q000000981:diagnostic imaging*; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008437:Maxilla / Q000002:abnormalities*; D036542:Tomography, Spiral Computed