title: Are there risk factors for osseous mandibular inferior border defects after bilateral sagittal split osteotomy?
abstract: OBJECTIVE
  Bone defects of the inferior mandibular border (osseous inferior border defects) can cause unesthetic postoperative outcomes after bilateral sagittal split osteotomy (BSSO). The aim of this study was to estimate the frequency of osseous inferior border defects after BSSO and to identify risk factors for this complication.
  
  
  METHODS
  This retrospective study included consecutive patients who underwent BSSO for mandibular retrognathia. The primary outcome was the presence/absence of osseous inferior border defects. Predictors included the mandibular movement, rotation of the occlusal plane, postoperative proximal segment position, pattern of lingual fracture, occurrence of bad split, and presence of third molars.
  
  
  RESULTS
  The study sample consisted of 200 patients and had a mean follow-up of 13 months. The mean mandibular advancement and rotation was respectively 5.8 mm and 5.4° clockwise. Osseous inferior border defects were present in 7.0% of splits and in 12.5% of patients. Significant risk factors for inferior border defects included increased advancement, increased clockwise rotation, cranial rotation of the proximal segment, and a split originating in the lingual cortex.
  
  
  CONCLUSIONS
  In conclusion, osseous inferior border defects occur significantly more often in cases with large mandibular advancement, increased clockwise rotation of the occlusal plane, malpositioning of the proximal segment, and a split originating in the lingual cortex.
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. J.P.R. van Merkesteyn), Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: J P
authors.initials: JP
authors.lastname: Verweij
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. J.P.R. van Merkesteyn), Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: J G
authors.initials: JG
authors.lastname: van Rijssel
authors.affiliation: Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands; Mathematical Institute, Leiden University, Leiden, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Fiocco
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. J.P.R. van Merkesteyn), Leiden University Medical Center, Leiden, The Netherlands; Department of Oral and Maxillofacial Surgery, Amphia Hospital, Breda, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Mensink
authors.affiliation: Department of Oral and Maxillofacial Surgery, Amphia Hospital, Breda, The Netherlands.
authors.forename: P J J
authors.initials: PJ
authors.lastname: Gooris
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. J.P.R. van Merkesteyn), Leiden University Medical Center, Leiden, The Netherlands. Electronic address: J.P.R.van_Merkesteyn@lumc.nl.
authors.forename: J P R
authors.initials: JP
authors.lastname: van Merkesteyn
mesh_terms: D000293:Adolescent; D000328:Adult; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D008964:Molar, Third / Q000473:pathology; D059229:Osteotomy, Sagittal Split Ramus / Q000009:adverse effects*; D011862:Radiography, Panoramic; D063173:Retrognathia / Q000000981:diagnostic imaging / Q000601:surgery; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: Inferior border defect; Orthognathic surgery; Risk; Sagittal split osteotomy