title: Cone-beam computed tomography evaluation on the changes in condylar long axis according to asymmetric setback in sagittal split ramus osteotomy patients.
abstract: OBJECTIVE
  To determine whether the condylar rotation is affected by asymmetric setback in patients undergoing sagittal split ramus osteotomy.
  
  
  METHODS
  Thirty patients who underwent bilateral sagittal split ramus osteotomy setback surgery were divided into the two groups, symmetric setback and asymmetric setback, according to the right/left difference of setback amount (<2.0, ≥2.0 mm). Condylar long axis changes were evaluated using the three-dimensional superimposition of before and immediately after surgery cone-beam computed tomography volume images. Evaluations were performed separately in lesser setback and greater setback side in patients undergoing asymmetric setback, whereas both side condyles were evaluated together in patients undergoing symmetric setback. Condylar axis changes on axial view were correlated with setback amount or right/left setback difference using Pearson correlation analysis.
  
  
  RESULTS
  In general, the condylar axis change occurred in a pattern of inward rotation. The condyles in patients undergoing symmetric setback showed 3.4° rotation in average. In case of asymmetric setback, the lesser setback side showed larger value (4.3°) than the greater setback side (2.3°) with a statistical significance. In the correlation analysis, setback amount showed no significant correlation with the condylar axis changes in both groups. However, correlation with right/left setback difference showed a positive correlation in lesser setback side of patients undergoing asymmetric setback.
  
  
  CONCLUSIONS
  The findings of this study indicate that large amount of setback alone does not contribute to the change in condylar long axis, but asymmetric setback might cause a change in condylar long axis, particularly on the lesser setback side.
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Lim
authors.forename: Tingting
authors.initials: T
authors.lastname: Jiang
authors.forename: Min-Hee
authors.initials: MH
authors.lastname: Oh
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Kook
authors.forename: Jin-Hyoung
authors.initials: JH
authors.lastname: Cho
authors.forename: Hyeon-Shik
authors.initials: HS
authors.lastname: Hwang
mesh_terms: D000293:Adolescent; D000328:Adult; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008313:Malocclusion, Angle Class III / Q000000981:diagnostic imaging* / Q000601:surgery*; D008335:Mandibular Condyle / Q000000981:diagnostic imaging* / Q000601:surgery*; D059229:Osteotomy, Sagittal Split Ramus / Q000379:methods*; D056910:Republic of Korea; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Asymmetric setback; Condyle; Cone-beam computed tomography; Sagittal split ramus osteotomy