title: Changes in the computed tomography (pixel) value of mandibular ramus bone and fixation screws after sagittal split ramus osteotomy.
abstract: The purpose of this retrospective study was to evaluate the changes in computed tomography (CT) values of ramus bone and screws after sagittal split ramus osteotomy (SSRO) setback surgery. The subjects were 64 patients (128 sides) who underwent bilateral SSRO setback surgery. They were divided into six groups according to the fixation plate type used and the use or not of self-setting α-tricalcium phosphate (Biopex): group 1: titanium plate and screws; group 2: titanium plate and screws with Biopex; group 3: poly-l-lactic acid (PLLA) plate and screws; group 4: PLLA plate and screws with Biopex; group 5: uncalcined and unsintered hydroxyapatite particles and poly-l-lactic acid (uHA/PLLA) plate and screws; group 6: PLLA/uHA plate and screws with Biopex. CT values (pixel values) of the lateral cortex, medial cortex, osteotomy site, and screws were measured preoperatively, immediately after surgery, and 1 year postoperatively using horizontal CT images at the mandibular foramen taken parallel to the Frankfort horizontal plane. There were significant differences in the time-course change of pixel values for the lateral cortex (P<0.0001) and the osteotomy site (P<0.0001) among the six groups. This study suggests that the fixation plate type and use of bone alternative material may affect bone quality during the process of bone healing after SSRO.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan. Electronic address: kueki@yamanashi.ac.jp.
authors.forename: K
authors.initials: K
authors.lastname: Ueki
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Moroi
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Iguchi
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Kosaka
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ikawa
authors.affiliation: Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo-shi, Yamanashi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yoshizawa
mesh_terms: D000293:Adolescent; D000328:Adult; D001672:Biocompatible Materials; D001860:Bone Plates; D001863:Bone Screws; D002508:Cephalometry; D006801:Humans; D007564:Japan; D008875:Middle Aged; D059229:Osteotomy, Sagittal Split Ramus; D011378:Prognathism / Q000000981:diagnostic imaging* / Q000601:surgery*; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D014025:Titanium; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D001672:Biocompatible Materials; D014025:Titanium
keywords: Absorbable plate and screws; Bone healing; Computed tomography (CT) value; Sagittal split ramus osteotomy