Evaluation of displacements and stress changes in the maxillo-mandibular complex with fixed functional appliance skeletally anchored on mandible using miniplates: A finite element study

OBJECTIVES: Fixed functional appliances (FFA) have been used for correction class II malocclusion but cause proclination of teeth. Recently, few studies have advocated the use of skeletal anchorage along with FFAs to prevent this side effect. The purpose of the study was to evaluate the stress distribution and displacements produced by miniplate anchored Forsus-fatigue resistant device on the maxilla, mandible, and the dentition in a Class II malocclusion patient by finite element analysis. MATERIALS AND METHODS: Cone beam computed tomography of a class II division 1 patient indicated for FFA was used to construct a 3D finite element model using MIMICS 8.11 and Hypermesh 13.0 software. Various material properties, boundary, and loading conditions were then applied. The model was analyzed for principal stress and von Mises stress in maxilla, mandible, and their dentition using ANSYS 12.1 software. RESULTS: In the mandible, maximum principal and von Mises stresses were seen in the cortical bone area in the symphyseal region, whereas mandibular teeth showed comparatively lesser stresses. In the maxilla, higher principal and von Mises stresses were seen in the maxillary molar region compared to the maxillary cortical bone. The entire mandible was displaced antero-inferiorly, whereas the maxilla showed a postero-superior displacement. CONCLUSION: Using skeletally anchored FFA results in more stresses and displacements in the skeletal structures compared to the dentition.