title: Evaluation of the Transverse Displacement of the Proximal Segment After Bilateral Sagittal Split Ramus Osteotomy With Different Lingual Split Patterns and Advancement Amounts Using the Finite Element Method.
abstract: OBJECTIVE
  To evaluate transverse displacement of the proximal segment after bilateral sagittal split ramus osteotomy (BSSO) advancement with different lingual split patterns and advancement amounts and to determine the influential factors related to mandibular width.
  
  
  METHODS
  A 3-dimensional finite element model of the mandible including the temporomandibular joint was created for a presurgical simulation and for BSSO with lingual split patterns I (T1; Hunsuck split) and II (T2; Obwegeser split). The mandible was advanced 3 mm (A3) and 8 mm (A8) and fixated with a conventional titanium plate. Ansys software was used to measure the linear distances of the interproximal segments and to analyze the transverse displacement distribution of proximal segments after applying the load of masticatory muscle force groups.
  
  
  RESULTS
  After surgical simulation, T1A3, T1A8, T2A3, and T2A8 showed increased transverse widths (mean, 2.99, 4.70, 2.36, and 4.42 mm, respectively). For transverse augmentation, there was a statistically significant difference between the 2 different mandibular advancement amounts in T1 and in T2 (P ≤ .000), but no significant differences was observed between T1 and T2 (P ≥ .058). The maximum transverse displacement distribution in the proximal segment was measured around the gonial area, and the early contact area was found near the border between the horizontal and sagittal osteotomy lines.
  
  
  CONCLUSIONS
  Transverse displacements of proximal segments occur after BSSO advancement with T1 and T2 and transverse augmentation has statistically meaningful effects depending on the amount of advancement; however, no differences in transverse augmentation between T1 and T2 were identified. The fulcrum caused by the early contact between the proximal and distal segments could be an influential factor related to mandibular width.
authors.affiliation: Resident, Department of Orthognathic surgery, Tianjin Stomatological Hospital of Nankai University, Tianjin, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Dai
authors.affiliation: Professor, Department of Orthognathic Surgery, Tianjin Stomatological Hospital of Nankai University, Tianjin, China. Electronic address: houmin8181@sina.com.
authors.forename: Min
authors.initials: M
authors.lastname: Hou
authors.affiliation: Resident, Department of Orthognathic surgery, Tianjin Stomatological Hospital of Nankai University, Tianjin, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Ma
authors.affiliation: Attending Physician, Department of Orthognathic Surgery, Tianjin Stomatological Hospital of Nankai University, Tianjin, China.
authors.forename: Da-Li
authors.initials: DL
authors.lastname: Song
authors.affiliation: Assistant Professor, Department of Orthodontics, Tianjin Stomatological Hospital of Nankai University, Tianjin, China.
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: Zhang
authors.affiliation: Postgraduate Student, Department of Mechanical Engineering, Tianjin University, Tianjin, China.
authors.forename: Wei-Yuan
authors.initials: WY
authors.lastname: Zhou
mesh_terms: D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D019186:Mandibular Advancement / Q000379:methods*; D008953:Models, Anatomic; D059229:Osteotomy, Sagittal Split Ramus / Q000379:methods*; D017063:Outcome Assessment, Health Care; D057234:Preoperative Period