title: Long-term 3-dimensional stability of mandibular advancement surgery.
abstract: OBJECTIVE
  To evaluate 3-dimensional changes in the position of the condyles, rami, and chin from 1 to 3 years after mandibular advancement surgery.
  
  
  METHODS
  This prospective observational study used pre- and postoperative cone-beam computed tomograms of 27 subjects with skeletal Class II jaw relation and normal or deep overbite. An automatic technique of cranial base superimposition was used to assess positional and bone remodeling changes that were visually displayed and quantified using 3-dimensional color maps. Analysis of covariance with presence of genioplasty, age at time of surgery, and gender as explanatory variables was used to estimate and test adjusted mean changes for each region of interest.
  
  
  RESULTS
  The chin rotated downward and backward 1 to 3 years after surgery. Changes of at least 2 mm were observed in 17% of cases. Mandibular condyles presented with displacements or bone remodeling of at least 2 mm on the anterior surface (21% of cases on the left side and 13% on the right), superior surface (8% on right and left sides), and lateral poles (17% on left side and 4% on right). Posterior borders of the rami exhibited symmetric lateral or rotational displacements in 4% of cases.
  
  
  CONCLUSIONS
  In the hierarchy of surgical stability, mandibular advancement surgery is considered one of the most stable surgical procedures. However, 1 to 3 years after surgery, approximately 20% of patients had 2- to 4-mm changes in horizontal and vertical chin positions or changes in condylar position and adaptive bone remodeling.
authors.affiliation: Department of Orthodontics, School of Dentistry, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Franco
authors.forename: Lucia Helena S
authors.initials: LH
authors.lastname: Cevidanes
authors.forename: Ceib
authors.initials: C
authors.lastname: Phillips
authors.forename: Paul Emile
authors.initials: PE
authors.lastname: Rossouw
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Turvey
authors.forename: Felipe de Assis R
authors.initials: Fde A
authors.lastname: Carvalho
authors.forename: Leonardo K de
authors.initials: LK
authors.lastname: Paula
authors.forename: Cátia Cardoso A
authors.initials: CC
authors.lastname: Quintão
authors.forename: Marco Antonio O
authors.initials: MA
authors.lastname: Almeida
mesh_terms: D000328:Adult; D000367:Age Factors; D016723:Bone Remodeling / Q000502:physiology; D002508:Cephalometry / Q000379:methods; D002680:Chin / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D063172:Genioplasty / Q000379:methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008137:Longitudinal Studies; D008297:Male; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging / Q000601:surgery; D008334:Mandible / Q000000981:diagnostic imaging; D019186:Mandibular Advancement / Q000379:methods*; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D059229:Osteotomy, Sagittal Split Ramus / Q000379:methods; D057887:Overbite / Q000000981:diagnostic imaging / Q000601:surgery; D011446:Prospective Studies; D012008:Recurrence; D012399:Rotation; D012737:Sex Factors