title: 3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation.
abstract: BACKGROUND
  Bioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy. Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.
  
  
  METHODS
  Bicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.
  
  
  RESULTS
  Measuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral-medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.
  
  
  CONCLUSIONS
  In 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Ju Hong Jeon), Seoul Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Jee Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Jin Young Choi), Seoul National University Dental Hospital, Seoul, Republic of Korea.
authors.forename: Soung Min
authors.initials: SM
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Ju Hong Jeon), Seoul Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Bu Kyu
authors.initials: BK
authors.lastname: Lee
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Ju Hong Jeon), Seoul Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Ju Hong
authors.initials: JH
authors.lastname: Jeon
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Jin Young Choi), Seoul National University Dental Hospital, Seoul, Republic of Korea. Electronic address: omsljh@gmail.com.
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Kim
mesh_terms: D020341:Absorbable Implants; D000293:Adolescent; D000328:Adult; D001672:Biocompatible Materials / Q000737:chemistry; D001863:Bone Screws; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D008335:Mandibular Condyle / Q000000981:diagnostic imaging*; D061330:Multidetector Computed Tomography / Q000379:methods / Q000706:statistics & numerical data; D019340:Osteotomy, Le Fort / Q000379:methods; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation*; D011378:Prognathism / Q000601:surgery; D012189:Retrospective Studies; D012399:Rotation; D014025:Titanium / Q000737:chemistry; D055815:Young Adult
chemical_list: D001672:Biocompatible Materials; D014025:Titanium
keywords: Bioabsorbable screw; Sagittal split ramus osteotomy; Three dimensional image