title: Orthodontic intrusion of maxillary incisors: a 3D finite element method study.
abstract: OBJECTIVE
  In orthodontic treatment, intrusion movement of maxillary incisors is often necessary. Therefore, the objective of this investigation is to evaluate the initial distribution patterns and magnitude of compressive stress in the periodontal ligament (PDL) in a simulation of orthodontic intrusion of maxillary incisors, considering the points of force application.
  
  
  METHODS
  Anatomic 3D models reconstructed from cone-beam computed tomography scans were used to simulate maxillary incisors intrusion loading. The points of force application selected were: centered between central incisors brackets (LOAD 1); bilaterally between the brackets of central and lateral incisors (LOAD 2); bilaterally distal to the brackets of lateral incisors (LOAD 3); bilaterally 7 mm distal to the center of brackets of lateral incisors (LOAD 4).
  
  
  CONCLUSIONS
  Stress concentrated at the PDL apex region, irrespective of the point of orthodontic force application. The four load models showed distinct contour plots and compressive stress values over the midsagittal reference line. The contour plots of central and lateral incisors were not similar in the same load model. LOAD 3 resulted in more balanced compressive stress distribution.
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Armando Yukio
authors.initials: AY
authors.lastname: Saga
authors.affiliation: Associação Brasileira de Odontologia, Ponta Grossa, Paraná, Brazil.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maruo
authors.affiliation: Department of Civil Engineering, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Marco André
authors.initials: MA
authors.lastname: Argenta
authors.affiliation: Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Ivan Toshio
authors.initials: IT
authors.lastname: Maruo
authors.affiliation: Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Orlando Motohiro
authors.initials: OM
authors.lastname: Tanaka
mesh_terms: D054893:Cone-Beam Computed Tomography; D020342:Finite Element Analysis; D006801:Humans; D007180:Incisor; D008437:Maxilla; D010513:Periodontal Ligament