title: Biomechanical evaluation of magnesium-based resorbable metallic screw system in a bilateral sagittal split ramus osteotomy model using three-dimensional finite element analysis.
abstract: OBJECTIVE
  The aim of this study was to evaluate the stress distribution of a magnesium (Mg)-based resorbable screw system in a bilateral sagittal split ramus osteotomy (BSSO) and to compare its biomechanical stability with those of titanium (Ti)-based and polymer (IN)-based systems.
  
  
  METHODS
  A 3-dimensional BSSO model (10-mm advancement and setback) was constructed with Mimics. Bicortical screw fixation using Ti, IN, and Mg screws was performed with 4 different geometries of fixation. With an occlusal load of 132 N on the lower first molar, the von Mises stress (VMS) distribution was calculated using ANSYS.
  
  
  RESULTS
  The VMS distribution of Mg was more similar to that of Ti than to that of IN. In all cases, the highest VMS was concentrated on the screw at the most posterior and superior area. Stress was distributed mainly around the screw holes (cancellous bone) and the retromolar area (cortical bone). In the advancement surgery, fixation with 5 Mg screws (5A-Mg, 99.810 MPa at cortical bone) showed biomechanical stability, whereas fixation with the same number of IN screws did not (5A-IN, 109.021 MPa at cortical bone). In the setback surgery, although the maximum VMSs at cortical bone for Mg, IN, and Ti were lower than 108 MPa (yield strength of cortical bone), Mg screws showed more favorable results than IN screws because the maximum VMSs of Mg at cancellous bone were lower than those of IN.
  
  
  CONCLUSIONS
  The Mg-based resorbable screw system is a promising alternative to the IN-based system.
authors.affiliation: Clinical Assistant Professor, Department of Dentistry, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Clinical Assistant Professor, Department of Oral and Maxillofacial Surgery, Kyunghee University School of Dentistry, Seoul, Korea.
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Clinical Assistant Professor, Department of Dentistry, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Kang-Mi
authors.initials: KM
authors.lastname: Pang
authors.affiliation: Professor, Department of Materials Science and Engineering, Seoul National University, Seoul, Korea.
authors.forename: Hyoun-Ee
authors.initials: HE
authors.lastname: Kim
authors.affiliation: Associate Professor, Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul, Korea.
authors.forename: Soung-Min
authors.initials: SM
authors.lastname: Kim
authors.affiliation: Professor, Department of Oral and Maxillofacial Surgery, Seoul National University School of Dentistry, Seoul, Korea. Electronic address: leejongh@plaza.snu.ac.kr.
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Lee
mesh_terms: D020341:Absorbable Implants; D001863:Bone Screws; D003198:Computer Simulation; D003799:Dental Stress Analysis / Q000379:methods; D055119:Elastic Modulus; D020342:Finite Element Analysis; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008274:Magnesium; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation*; D011108:Polymers; D033081:Shear Strength; D014025:Titanium
chemical_list: D011108:Polymers; D014025:Titanium; D008274:Magnesium