title: Three-dimensional finite element analysis of the deformation of the human mandible: a preliminary study from the perspective of orthodontic mini-implant stability.
abstract: OBJECTIVE
  The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI).
  
  
  METHODS
  Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each model. Mandibular deformation under premolar and molar clenching was simulated. Comparisons were made between peri-orthodontic mini-implant compressive strain (POMI-CSTN) under clenching and orthodontic traction forces (150 g and 200 g).
  
  
  RESULTS
  Three models with different mandibular plane angles demonstrated different functional deformation characteristics. The compressive strains around the OMI were distributed mesiodistally rather than occlusogingivally. In model A, the maximum POMI-CSTN under clenching was observed at the mesial aspect of #46 (1,401.75 microstrain [µE]), and similar maximum POMI-CSTN was observed under a traction force of 150 g (1,415 µE).
  
  
  CONCLUSIONS
  The maximum POMI-CSTN developed by clenching failed to exceed the normally allowed compressive cortical bone strains; however, additional orthodontic traction force to the OMI may increase POMI-CSTN to compromise OMI stability.
authors.affiliation: Division of Orthodontics, Department of Dentistry, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sun-Hye
authors.initials: SH
authors.lastname: Baek
authors.forename: Hyun-Suk
authors.initials: HS
authors.lastname: Cha
authors.forename: Jung-Yul
authors.initials: JY
authors.lastname: Cha
authors.forename: Yoon-Shik
authors.initials: YS
authors.lastname: Moon
authors.forename: Sang-Jin
authors.initials: SJ
authors.lastname: Sung
keywords: Anatomy; Finite element method; Neuromuscular force; Orthodontic mini-implant; Stability