title: Evaluation of Mandibular Anatomy Associated With Bad Splits in Sagittal Split Ramus Osteotomy of Mandible.
abstract: OBJECTIVE
  This study aimed to identify risk factors associated with bad splits during sagittal split ramus osteotomy by using three-dimensional computed tomography.
  
  
  METHODS
  This study included 8 bad splits and 47 normal patients without bad splits. Mandibular anatomic parameters related to osteotomy line were measured. These included anteroposterior width of the ramus at level of lingula, distance between external oblique ridge and lingula, distance between sigmoid notch and inferior border of mandible, mandibular angle, distance between inferior outer surface of mandibular canal and inferior border of mandible under distal root of second molar (MCEM), buccolingual thickness of the ramus at level of lingula, and buccolingual thickness of the area just distal to first molar (BTM1) and second molar (BTM2).
  
  
  RESULTS
  The incidence of bad splits in 625 sagittal split osteotomies was 1.28%. Compared with normal group, bad split group exhibited significantly thinner BTM2 and shorter sigmoid notch and inferior border of mandible (P <0.05). However, for BTM1 and buccolingual thickness of the ramus at level of lingula, there was no statistical difference between the 2 groups. Mandibular angle, anteroposterior width of the ramus at level of lingula, external oblique ridge and lingula, and MCEM were not significantly different between the groups.
  
  
  CONCLUSIONS
  This study suggests that patients with shorter ramus and low thickness of the buccolingual alveolar region distal to the second molar had a higher risk of bad splits. These anatomic data may help surgeons to choose the safest surgical techniques and best osteotomy sites.
authors.affiliation: *School of Dentistry, Chonnam National University,†Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital,‡Department of Oral and Maxillofacial Surgery§Department of Dental Material, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Korea.
authors.forename: Tongyue
authors.initials: T
authors.lastname: Wang
authors.forename: Jeong Joon
authors.initials: JJ
authors.lastname: Han
authors.forename: Hee-Kyun
authors.initials: HK
authors.lastname: Oh
authors.forename: Hong-Ju
authors.initials: HJ
authors.lastname: Park
authors.forename: Seunggon
authors.initials: S
authors.lastname: Jung
authors.forename: Yeong-Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Kook
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging* / Q000601:surgery*; D059229:Osteotomy, Sagittal Split Ramus / Q000009:adverse effects* / Q000379:methods*; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult