title: Comparison of skeletal stability after sagittal split ramus osteotomy among mono-cortical plate fixation, bi-cortical plate fixation, and hybrid fixation using absorbable plates and screws.
abstract: OBJECTIVE
  The purpose of this study was to examine skeletal stability and plate breakage after sagittal split ramus osteotomy (SSRO) with the mono-cortical plate fixation, bi-cortical plate fixation, and hybrid fixation techniques using absorbable plates and screws.
  
  
  METHODS
  A total of 76 Japanese patients diagnosed with mandibular prognathism with and without maxillary deformity were divided into 3 groups randomly. A total of 28 patients underwent SSRO with mono-cortical plate fixation, 23 underwent SSRO with bi-cortical plate fixation, and 25 underwent SSRO with hybrid fixation. Skeletal stability and horizontal condylar angle were analyzed by axial, frontal, and lateral cephalograms from before the operation to 1 year postoperatively. Breakage of the plate and screws was observed by 3-dimensional computed tomography (3DCT) immediately after surgery and after 1 year.
  
  
  RESULTS
  Although there was a significant difference between the mono-cortical plate fixation group and hybrid fixation group regarding right MeAg in T1 (P = 0.0488) and occlusal plane in T1 (P = 0.0346), there were no significant differences between the groups for the other measurements in each time interval. In 2 cases, namely, 6 sides in the mono-cortical plate fixation group, breakage of the absorbable plate was found by 3DCT. However, there was no breakage in the bi-cortical plate fixation group and hybrid fixation group.
  
  
  CONCLUSIONS
  This study results suggested that there were no significant differences in the postoperative skeletal stability among the 3 groups, and bi-cortical fixation as well as hybrid fixation was a reliable and useful method to prevent plate breakage even if an absorbable material was used.
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan. Electronic address: kueki@yamanashi.ac.jp.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ueki
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Moroi
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Kunio
authors.initials: K
authors.lastname: Yoshizawa
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Hotta
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Tsutsui
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Fukaya
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Hiraide
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takayama
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Tatsuta
authors.initials: T
authors.lastname: Tsunoda
authors.affiliation: Department of Oral and Maxillofacial Surgery (Head: Prof. Dr. K Ueki), Division of Medicine, Interdisciplinary Graduate School, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, 409-3898, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D000328:Adult; D001860:Bone Plates; D001863:Bone Screws; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery; D008875:Middle Aged; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation / Q000379:methods*; D011378:Prognathism / Q000601:surgery; D011475:Prosthesis Failure; D011859:Radiography; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Absorbable plate; Bi-cortical plate fixation; Hybrid fixation; Mono-cortical plate fixation; Sagittal split ramus osteotomy