title: Postoperative changes in mandibular position after mandibular setback surgery via the surgery-first approach in relation to the increase of vertical dimension and the amount of mandibular setback.
abstract: OBJECTIVE
  This study aimed to compare preoperatively predicted rotational relapse with actual post-treatment mandibular position after mandibular setback surgery via the surgery-first approach and to evaluate the effect of the increase of vertical dimension (VD) on surgical occlusion and the amount of mandibular setback on postoperative mandibular positional changes.
  
  
  METHODS
  Twenty-nine patients who underwent bilateral sagittal split ramus osteotomy for mandibular prognathism were evaluated by using lateral cephalograms, which had been obtained preoperatively, immediately postoperatively, and immediately after debonding. Increase of VD on surgical occlusion was measured preoperatively. We estimated the mandibular forward movement resulting from the postoperative mandibular anticlockwise rotation during postoperative orthodontic treatment and compared it with the actual post-treatment mandibular position.
  
  
  RESULTS
  The actual postoperative mandibular forward movement (2.1 mm) was significantly greater compared with the forward movement (1 mm) predicted preoperatively (P < .01). The postoperative mandibular forward movement was greater in the groups with greater VD increase (>1.5 mm) or greater mandibular setback (>10 mm), even though there was no statistically significant difference.
  
  
  CONCLUSIONS
  These results suggest that additional postoperative relapse may occur with mandibular rotational relapse, and VD increase and the amount of mandibular setback may affect post-treatment mandibular position in surgery-first orthodontic treatment.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Chonnam National University Hospital, Gwangju, Republic of Korea.
authors.forename: Jeong Joon
authors.initials: JJ
authors.lastname: Han
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Jong-Hyon
authors.initials: JH
authors.lastname: Chong
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Sun-Youl
authors.initials: SY
authors.lastname: Ryu
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Hee-Kyun
authors.initials: HK
authors.lastname: Oh
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Hong-Ju
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Seunggon
authors.initials: S
authors.lastname: Jung
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, Gwangju, Republic of Korea. Electronic address: Mskook2@gmail.com.
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Kook
mesh_terms: D000328:Adult; D002508:Cephalometry; D005260:Female; D006801:Humans; D008297:Male; D009971:Orthodontics, Corrective; D059229:Osteotomy, Sagittal Split Ramus; D011378:Prognathism / Q000000981:diagnostic imaging / Q000601:surgery*; D012008:Recurrence; D056910:Republic of Korea; D016896:Treatment Outcome; D014716:Vertical Dimension