title: Analysis of stress distribution on fixation of bilateral sagittal split ramus osteotomy with resorbable plates and screws using the finite-element method.
abstract: OBJECTIVE
  To determine the most appropriate stress distribution in fixation with resorbable screws and plates after bilateral sagittal split ramus osteotomy using the finite-element method.
  
  
  METHODS
  This experimental study was performed on simulated human mandibles using computer software. The osteotomy line was applied to the simulated model and experimental loads of 75, 135, and 600 N were exerted on the model in accordance with the vector of occlusal force. The distribution pattern of stress was assessed and compared in 8 fixation methods: 1 resorbable screw, 2 resorbable screws in a vertical pattern, 2 resorbable screws in a horizontal pattern, 3 resorbable screws in an L pattern, 3 resorbable screws in a backward-L pattern, 1 miniplate with 2 screws, 1 miniplate with 4 screws, and 2 parallel miniplates with 4 screws each.
  
  
  RESULTS
  Among the simulated fixations, 2 parallel miniplates showed the greatest primary stability and the single screw and the 2-hole miniplate showed the least tolerance to posterior forces.
  
  
  CONCLUSIONS
  This study showed the 2-miniplate/4-hole plate pattern was the strongest and the single-screw and 2-hole plate patterns were the weakest of fixations in this bilateral sagittal split ramus osteotomy model. The finite-element method showed that polymer-based resorbable screws and plates (polyglycolic acid and d,l-polylactide acid) provide satisfactory primary stability in this model.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Buali Hospital, Azad University of Medical Sciences, Tehran, Iran.
authors.forename: Farzin
authors.initials: F
authors.lastname: Sarkarat
authors.forename: Mohammad Hosein Kalantar
authors.initials: MH
authors.lastname: Motamedi
authors.forename: Behnam
authors.initials: B
authors.lastname: Bohluli
authors.forename: Nima
authors.initials: N
authors.lastname: Moharamnejad
authors.forename: Shirin
authors.initials: S
authors.lastname: Ansari
authors.forename: Hale
authors.initials: H
authors.lastname: Shahabi-Sirjani
mesh_terms: D020341:Absorbable Implants; D001696:Biomechanical Phenomena; D001732:Bite Force; D001860:Bone Plates; D001863:Bone Screws; D019245:Compressive Strength; D003198:Computer Simulation; D003799:Dental Stress Analysis / Q000379:methods*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D019248:Jaw Fixation Techniques / Q000295:instrumentation*; D019344:Lactic Acid; D008334:Mandible / Q000502:physiology* / Q000601:surgery; D059229:Osteotomy, Sagittal Split Ramus; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid