title: Effects of Class II activator and Class II activator high-pull headgear combination on the mandible: a 3-dimensional finite element stress analysis study.
abstract: BACKGROUND
  The aim of this study was to evaluate the effects of the Class II activator and the Class II activator high-pull headgear (HG) combination on the mandible with 3-dimensional (3D) finite element stress analysis.
  
  
  METHODS
  A 3D finite element model of the mandible was constructed from a dry human mandible. To investigate the effects of the Class II activator, a 3D model of the lower part of this appliance was constructed and fixed on the mandibular model. The Class II activator high-pull headgear model was established as described, and an extraoral traction force of 350 g was directed from the middle of the Class II activator to the top of the mandibular condyle. The stress regions were studied with the finite element method.
  
  
  RESULTS
  The regions near the muscle attachment areas were affected the most. The inner part of the coronoid process and the gonial area had the maximum stress values.
  
  
  CONCLUSIONS
  Both functional appliances can cause morphologic changes on the mandible by activating the masticatory muscles to change the growth direction.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey. culusoy77@hotmail.com
authors.forename: Cağri
authors.initials: C
authors.lastname: Ulusoy
authors.forename: Nilüfer
authors.initials: N
authors.lastname: Darendeliler
mesh_terms: D000202:Activator Appliances; D003198:Computer Simulation; D003799:Dental Stress Analysis / Q000379:methods*; D005115:Extraoral Traction Appliances; D020342:Finite Element Analysis; D006801:Humans; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible / Q000254:growth & development* / Q000502:physiology; D008410:Masticatory Muscles / Q000502:physiology; D008954:Models, Biological