title: Postsurgical stability after mandibular setback surgery with minimal orthodontic preparation following upper premolar extraction.
abstract: OBJECTIVE
  To compare patterns of surgical change and postsurgical relapse between patients with mandibular setback surgery with minimal orthodontic preparation (MS-MO) and those with sufficient orthodontic preparation (MS-SO) after upper premolar extraction (UPE).
  
  
  METHODS
  Twenty-six patients were allocated to 2 groups based on the duration of presurgical orthodontic preparation: MS-MO/UPE (n = 15; 5.53 ± 3.14 months) and MS-SO/UPE (n = 11; 13.00 ± 5.33 months). Lateral cephalograms were taken during the initial examination (T0), at splint removal (4 weeks after surgery; T1), and immediately after debonding (T2). To evaluate the surgical changes (T1 vs. T0) and relapse (T2 vs. T1), linear, angular, and dental measurements were used and analyzed using paired t test and independent t test.
  
  
  RESULTS
  Although there was no significant difference in skeletodental patterns at T0 between the 2 groups, the MS-MO/UPE group showed a significantly larger amount of mandibular setback than the MS-SO/UPE group from T0 to T1. The 2 groups exhibited significant anterior and superior movement of the mandible from T1 to T2. However, the MS-MO/UPE group manifested greater counterclockwise rotation and forward movement of the mandible than the MS-SO/UPE group. Owing to such relapse of the mandible, the MS-MO/UPE group exhibited limited retraction of the upper incisors, whereas the MS-SO/UPE group showed slight labioversion of the upper incisors.
  
  
  CONCLUSIONS
  Compared with the MS-SO/UPE group, the MS-MO/UPE group showed a larger amount of surgical setback and greater postsurgical counterclockwise rotation and forward movement of the mandible.
authors.affiliation: Former Assistant Professor, Department of Orthodontics, Seoul National University Bundang Hospital, Seongnam, South Korea; Private Practice, Seongnam, South Korea.
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Kim
authors.forename: Nam-Ki
authors.initials: NK
authors.lastname: Lee
authors.forename: Pil-Young
authors.initials: PY
authors.lastname: Yun
authors.forename: Sang-Woon
authors.initials: SW
authors.lastname: Moon
authors.forename: Young-Kyun
authors.initials: YK
authors.lastname: Kim
mesh_terms: D000367:Age Factors; D001641:Bicuspid / Q000601:surgery*; D002508:Cephalometry / Q000379:methods; D002680:Chin / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor / Q000473:pathology; D019248:Jaw Fixation Techniques / Q000295:instrumentation; D008297:Male; D008313:Malocclusion, Angle Class III / Q000473:pathology / Q000601:surgery; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D008437:Maxilla / Q000473:pathology; D009068:Movement; D017090:Occlusal Splints; D009971:Orthodontics, Corrective / Q000379:methods*; D011378:Prognathism / Q000473:pathology / Q000601:surgery; D012008:Recurrence; D012189:Retrospective Studies; D012399:Rotation; D013997:Time Factors; D014081:Tooth Extraction / Q000379:methods*; D016896:Treatment Outcome; D014716:Vertical Dimension; D055815:Young Adult