title: [The stress distribution of the temporomandibular joint under four types of inter-arch elastics--a three dimentional finite element model analysis].
abstract: OBJECTIVE
  To analyze the influence of four types (class II long elastic, class II short elastic, class III long elastic, class III short elastic) of inter-arch elastics on the stress distribution and displacement of temporomandibular joint (TMJ).
  
  
  METHODS
  To reconstruct a three-dimensional element model of left craniofacial bones with TMJ, maxilla, mandible and dentition with MBT straight wire appliance by CT images, Mimics, Ansys software. The influence of four types elastic on the model was analyzed by simulating the clinical conditions.
  
  
  RESULTS
  The stress distribution and displacement of TMJ under four types of elastics have been acquired. The stress distributed rule of condition 1 and 2 was similar, compression stress centred on the frontal surface of the condyle, while stretching stress centred on the posterior surface. The stress distributed rule of condition 3 and 4 was similar too, the frontal surface of the condyle was most stretching stress, while posterior surface was most compression stress. The displacement of the condyle of condition 1 and 2 was overall forward and downward with a clockwise rotation, the displacement of the condyle of condition 3 and 4 was overall backward and upward with a anticlockwise rotation.
  
  
  CONCLUSIONS
  Class II long elastic and short elastic, class III long elastic and short elastic, the stress distributed rule was similar, the strength under short elastics was gentle under the same strength value. Overall displacement was downward and forward under class II elastics, the condyloid made a clockwise rotation. Overall displacement was upward and backward under class III elastics, the condyloid made a counterclockwise rotation.
authors.affiliation: Dept. of Orthodontics, Hospital of Stomatology, Jilin University, Changchun 130021, China.
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.forename: Ya-ning
authors.initials: YN
authors.lastname: Xiang
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Ke-feng
authors.initials: KF
authors.lastname: Guo
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
mesh_terms: D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D008334:Mandible; D008437:Maxilla; D013704:Temporomandibular Joint