title: [Comparison of effect of the mandible setbacked by SSRO and IVRO on gnathostomatic system].
abstract: OBJECTIVE
  To compare the effect of the mandible setbacked by sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) on gnathostomatic system.
  
  
  METHODS
  27 cases with mandibular prognathism were treated, 16 received SSRO and 11 IVRO. Their occlusal force and masticatory efficiency were measured preoperatively and at 3 and 6 months after operation. The condylar positions were assessed by radiography before surgery and at 6 months postoperatively.
  
  
  RESULTS
  In three months postoperatively, the occlusal force and masticatory efficiency of IVRO group was decreased more than that of SSRO group. At six months postoperatively, the occlusal force and masticatory efficiency of SSRO group recovered quicker than IVRO group and better than that of before operation. In IVRO group, the occlusal force approached the preoperative level, the masticatory efficiency was better than preoperative value. 26/32 (81.2%) condyles were relatively retropositioned in SSRO group, 14/22 (63.6%) condyles were relatively forward positioned in IVRO group.
  
  
  CONCLUSIONS
  The function recovery time after surgery was shorter in SSRO group. The masticator muscles were detached in varying degree and the bone segments healed slowly, the effect on gnathostomatic system was greater and recovery time after surgery was longer in the IVRO group.
authors.affiliation: Department of Oral Maxillofacial Surgery, School of Stomatology, Hubei Medical University, Wuhan 430070, China.
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Dong
authors.forename: Z
authors.initials: Z
authors.lastname: Li
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D019248:Jaw Fixation Techniques; D008297:Male; D008334:Mandible / Q000002:abnormalities / Q000503:physiopathology / Q000601:surgery*; D008409:Mastication / Q000502:physiology; D008410:Masticatory Muscles / Q000503:physiopathology / Q000601:surgery; D019647:Oral Surgical Procedures / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D016896:Treatment Outcome