title: Computer Image-Guided Template for Horizontal Advancement Genioplasty.
abstract: BACKGROUND
  Horizontal advancement genioplasty can be extremely rewarding for microgenia. However, it is challenging for even very experienced surgeon to determine the three-dimensional position of the distant bone fragment during the operation. This study aimed to apply and evaluate computer-aided design (CAD) and computer-aided manufacturing techniques for horizontal advancement genioplasty to improve surgical accuracy.
  
  
  METHODS
  Seven patients with microgenia were prospectively enrolled in the study. Preoperative and postoperative computed tomography (CT), photographs, and lateral cephalograms were performed. Computer-aided design was done based on preoperative CT data, and then surgical templates (cutting guide templates and fixation templates) were designed accordingly to guide horizontal advancement genioplasty. All surgeries were performed by junior surgeons. The accuracy of the authors' method was evaluated by the relative error (the mean value of discrepancy between postoperative CT and preoperative design at 6 points selected randomly/preoperative design movement × 100%), Pg position error (postoperative Pg Advancement - preoperative CAD Pg Advancement)/preoperative CAD Pg Advancement × 100%), and Me position error (postoperative Me downward movement - preoperative CAD Me downward movement)/preoperative CAD Me downward movement × 100%). They are all calculated by Geomagic automatically.
  
  
  RESULTS
  All 7 patients were satisfied with their aesthetic outcomes. The average absolute relative error is 1.8%. The average absolute Pg position error is 1.9% and the average absolute Me position error value is 1.3%.
  
  
  CONCLUSIONS
  The authors' study showed that applying computer-assisted techniques for horizontal advancement genioplasty provided accurate surgical result. With this technique, best result for horizontal advancement genioplasty could be achieved by even inexperienced surgeons.
authors.affiliation: *The Craniofacial Center One, Plastic Surgery Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China†Plastic and Reconstructive Surgery, Stanford, Palo Alto, CA.
authors.forename: Jia
authors.initials: J
authors.lastname: Qiao
authors.forename: Xi
authors.initials: X
authors.lastname: Fu
authors.forename: Lai
authors.initials: L
authors.lastname: Gui
authors.forename: Sabine
authors.initials: S
authors.lastname: Girod
authors.forename: Gordon K
authors.initials: GK
authors.lastname: Lee
authors.forename: Feng
authors.initials: F
authors.lastname: Niu
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D002680:Chin / Q000002:abnormalities* / Q000601:surgery; D017076:Computer-Aided Design; D004955:Esthetics, Dental; D005260:Female; D063172:Genioplasty / Q000379:methods*; D006801:Humans; D008297:Male; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult