title: Which kind of frontal mandibulotomy is the smartest? A biomechanical study.
abstract: OBJECTIVE
  Retrospective clinical evaluation and biomechanical tests were performed to compare the primary stability and the rate of pseudarthrosis formation after irradiation for two types of mandibular split osteotomies: the stairstep osteotomy (SSO) and the straight-line osteotomy (SLO).
  
  
  METHODS
  The postoperative occurrence of pseudarthrosis was retrospectively analysed in 46 non-consecutive clinical cases of SSO and SLO between 2003 and 2013. Biomechanical tests were performed on 12 standardised synthetic mandibles (Synbone) to compare the SSO and SLO approaches. Two 2.0 mm monocortical miniplates (Medartis) were used for osteosynthesis. The artificial mandible specimens were loaded to 300 N on the Mandibulator test bench while interfragmentary motion was measured using the PONTOS optical measurement device.
  
  
  RESULTS
  The retrospective clinical analysis showed a rate of pseudarthrosis of 19% in the SLO group versus only 5% in the SSO group (p = 0.17). In the biomechanical investigation, the average interfragmentary movement was 14.3 ± 7.70 for the SLO group and 4.57 ± 2.33 for the SSO group under a maximum load of 300 N, resulting in a statistically significant difference between the two approaches (p = 0.014).
  
  
  CONCLUSIONS
  To minimise the rate of postoperative pseudarthrosis formation, SSO is superior to SLO for mandibular split procedures, because SSO provides greater resistance to vertical loads and allows less interfragmentary movement.
  
  
  METHODS
  2C (Outcomes research).
authors.affiliation: Department of Oral and Maxillofacial Surgery, Universitätsklinikum Aachen, RWTH Aachen, Germany. Electronic address: timm.steiner@gmx.de.
authors.forename: T
authors.initials: T
authors.lastname: Steiner
authors.affiliation: Department of Oral and Maxillofacial Surgery, Universitätsklinikum Aachen, RWTH Aachen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Raith
authors.affiliation: Department of Otorhinolaryngology, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Scherer
authors.affiliation: Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Mücke
authors.affiliation: Department of Oral and Maxillofacial Surgery, Universitätsklinikum Aachen, RWTH Aachen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Torsiglieri
authors.affiliation: Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: N H
authors.initials: NH
authors.lastname: Rohleder
authors.affiliation: Department of Plastic Surgery, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Eder
authors.affiliation: Department of Urology, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Grohmann
authors.affiliation: Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kesting
authors.affiliation: Department of Otorhinolaryngology, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Bier
authors.affiliation: Department of Oral and Maxillofacial Surgery, Klinikum rechts der Isar, Technische Universität München, Germany.
authors.forename: K-D
authors.initials: KD
authors.lastname: Wolff
authors.affiliation: Department of Oral and Maxillofacial Surgery, Universitätsklinikum Aachen, RWTH Aachen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Hölzle
mesh_terms: D001696:Biomechanical Phenomena; D001732:Bite Force; D001860:Bone Plates; D001863:Bone Screws; D057918:Fiducial Markers; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008334:Mandible / Q000528:radiation effects / Q000601:surgery*; D008953:Models, Anatomic; D009068:Movement; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation / Q000379:methods*; D011183:Postoperative Complications; D011878:Radiotherapy; D012189:Retrospective Studies; D013314:Stress, Mechanical; D014945:Wound Healing / Q000502:physiology
keywords: 3D Optical measurement; Biomechanics; Experimental testing; Mandibulotomy; Pseudarthrosis