title: Impact of the mandibular divergence on the position of the inferior alveolar nerve and mylohyoid nerve: a computed tomography study and its relevance to bilateral sagittal split osteotomy.
abstract: OBJECTIVE
  Bilateral sagittal split osteotomy (BSSO) is the most common procedure used to treat mandibular deformities. BSSO procedures include the Epker technique and the Dal Pont technique which are the most frequently used. Because of the intramandibular pathway of the inferior alveolar nerve (IAN), neurosensory disturbance of the lower lip and chin is the most common complication of BSSO. This study performed quantitative measurements from computed tomographic (CT) data obtained on dry human mandibles. The main aim of the study was to evaluate if mandibular divergence can predict the position of the IAN and the mylohyoid nerve (MHN) to prevent nerve injury.
  
  
  METHODS
  After CT and 3D reconstruction of 65 dry mandibles, 30 measurements were made on 3 planes for each hemi-mandible. This allowed analysis of the IAN and MHN pathways. Three groups of hemi-mandibles were created depending on their divergence, and a statistical analysis was performed.
  
  
  RESULTS
  Eight out of the 30 measurements showed a significant difference among the 3 groups. There was no significant difference for the remaining 22 measurements.
  
  
  CONCLUSIONS
  The IAN seems to have a more superior position in the groups of mandibular hypo- and hyper-divergence. Orthognathic surgeons should use a more superficial retromolar bone incision in these cases. Finally, the Epker technique would be safer for preserving the MHN in normo- and hypo-divergent patients.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Hôpital Erasme, Université Libre de Bruxelles, Route de Lennik, Brussels, Belgium. oth.olivier@gmail.com
authors.forename: Olivier
authors.initials: O
authors.lastname: Oth
authors.forename: Stéphane
authors.initials: S
authors.lastname: Louryan
authors.forename: Serge
authors.initials: S
authors.lastname: Van Sint Jan
authors.forename: Marcel
authors.initials: M
authors.lastname: Rooze
authors.forename: Régine
authors.initials: R
authors.lastname: Glineur
mesh_terms: D006801:Humans; D008334:Mandible / Q000000981:diagnostic imaging* / Q000294:innervation* / Q000601:surgery; D008340:Mandibular Nerve / Q000033:anatomy & histology*; D063168:Mandibular Osteotomy; D012016:Reference Values; D014057:Tomography, X-Ray Computed