title: [Finite element analysis of different load mode on tooth movement for space closure in patient with bimaxillary protrusion].
abstract: OBJECTIVE
  To investigate the stress distribution on the maxillary anterior teeth retracted with sliding mechanics and micro-implant anchorage using different retraction hook heights and positions.
  
  
  METHODS
  DICOM image data including maxilla and upper teeth were obtained with cone-beam CT. The three-dimensional finite element model was constructed using Mimics software. Brackets and archwire model were constructed using Creo software. The models were instantiated using Pro/Engineer software. Abaqus software was used to simulate the sliding mechanics by loading 2 N force on 0, 2, 4, 6, 8, 10 mm retraction hooks and three different positions, repectively. Rotation of the occlusal plane, the initial displacement and stress distribution of teeth were analyzed.
  
  
  RESULTS
  Lingual rotation of maxillary central incisor(0.021°), gingival movement of the maxillary first molar(0.005 mm), and clockwise rotation of the maxillary occlusal plane(0.012°) were observed when the force application point located at the archwire level (0 mm). In contrast, 0.235° labial rotation of the maxillary central incisor, 0.015 mm occlusal movement of the maxillary first molar, and 0.075° anti-clockwise rotation of the maxillary occlusal plane were observed when the force application point located at the higher level(10 mm retraction hook). The more the force application point was located posteriorly at the archwire level, the less lingual rotation of the maxillary central incisor and the more buccal displacement of maxillary first molar was observed.
  
  
  CONCLUSIONS
  Maxillary anterior tooth rotation and retraction, vertical displacement of posterior segment, and rotation of the occlusal plane could be controlled by adjusting the height and position of the retraction hook in space closure using miniscrew and sliding mechanics.
authors.affiliation: Department of Orthodontics, School of Stomatology Lanzhou University, Lanzhou 730030, China.
authors.forename: X B
authors.initials: XB
authors.lastname: Zhang
authors.affiliation: Department of Orthodontics, School of Stomatology Lanzhou University, Lanzhou 730030, China.
authors.forename: Y F
authors.initials: YF
authors.lastname: Yin
authors.affiliation: Department of Orthodontics, School of Stomatology Lanzhou University, Lanzhou 730030, China.
authors.forename: H M
authors.initials: HM
authors.lastname: Yao
authors.affiliation: Department of Stomatology, Jiuquan City People's Hospital, Jiuquan Gansu 735000, China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Han
authors.affiliation: Department of Orthodontics, School of Stomatology Lanzhou University, Lanzhou 730030, China.
authors.forename: N
authors.initials: N
authors.lastname: Wang
authors.affiliation: Department of Orthodontics, School of Stomatology Lanzhou University, Lanzhou 730030, China.
authors.forename: Z L
authors.initials: ZL
authors.lastname: Ge
mesh_terms: D054893:Cone-Beam Computed Tomography; D003817:Dentition; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging; D008437:Maxilla; D008963:Molar / Q000000981:diagnostic imaging; D057887:Overbite / Q000628:therapy*; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*