title: [Three-dimensional finite element analysis of maxillary incisor retraction with step-shaped vertical closing loop].
abstract: OBJECTIVE
  To investigate the displacement and stress distribution of upper incisors in three-dimensional (3D) space controlled by step-shaped vertical closing loop.
  
  
  METHODS
  The maxillary teeth and alveolar bone of a volunteer with normal occlusion were scanned with 3D spiral CT. Modeling and calculation were only carried out on right upper central incisor, lateral incisor and their alveolar bone in order to simplify the procedures. A 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was developed using Ansys finite element package. Finally, a 3D finite element model of archwire-brackets-upper incisors and periodontal tissues was established based on mirror symmetry principle. The displacement of maxillary incisors and stress distribution in periodontal tissues were analyzed.
  
  
  RESULTS
  When step-shaped vertical closing loop was simply drew back 1 mm, the maximum displacement of upper central incisor in labial and lingual direction were 5.29 × 10(-2) and 0.71 × 10(-2) mm; 10.47 × 10(-3) and 10.20 × 10(-3) mm in gingival and occlusal direction, 10.26 × 10(-3) and 1.63 × 10(-3) mm in medial and distal direction; the maximum displacement of upper lateral incisor in labial and lingual direction were 3.31 × 10(-2) and 0.41 × 10(-2) mm, 10.52 × 10(-3) and 5.10 × 10(-3) mm in gingival and occlusal direction, 6.29 × 10(-3) and 4.64 × 10(-3) mm in medial and distal direction, the displacement trend of them were moving lingually and gingivally similar to bodily movement. The stress peach of upper central incisor, periodontal ligament and alveolar bone were 31.35, 2.52 and 4.64 MPa, the stress peach of upper lateral incisor, periodontal ligament and alveolar bone were 19.59, 1.28 and 4.12 Mpa, the stress distribution of them were similar and the periodontal ligament buffered the stress imposed on the tooth.
authors: Department of Orthodontics, Sun Yat-sen University, Guangzhou, China.
authors: Sheng
authors: S
authors: Zhang
authors: Li-xiang
authors: LX
authors: Mai
authors: Cong-hua
authors: CH
authors: Liu
authors: Da-wei
authors: DW
authors: Wang
mesh_terms: D000539:Alveolar Process / Q000502:physiology; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000502:physiology*; D008437:Maxilla / Q000502:physiology*; D008954:Models, Biological; D010519:Periodontium / Q000502:physiology; D013314:Stress, Mechanical; D036542:Tomography, Spiral Computed; D019228:Tooth Crown / Q000502:physiology; D014085:Tooth Migration; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*