title: Influence of the lateral pterygoid muscle on traumatic temporomandibular joint bony ankylosis.
abstract: BACKGROUND
  The pathogenesis of traumatic TMJ ankylosis remains unclear. This study aimed to verify the role of the lateral pterygoid muscle in the pathogenesis of traumatic temporomandibular joint (TMJ) bony ankylosis.
  
  
  METHODS
  Eight 6-month-old male sheep were used in this study. Bilateral TMJ osteotomies were performed to induce sagittal fractures of the mandibular condyle. The lateral one-fourth segment of the disc was removed to establish a model of TMJ bony ankylosis. Subsequently, the function of the left and right lateral pterygoid muscles was blocked (experimental group) or maintained (control group), respectively. At 12 weeks postoperatively, animals were sacrificed and TMJ complex samples were evaluated by gross observation, spiral computed tomography (CT), micro-CT, and histological examinations.
  
  
  RESULTS
  Gross observation revealed bony ankylosis in the control TMJs and fibrous adhesions in the experimental TMJs. Spiral CT and micro-CT demonstrated that, compared to the experimental group, the control group showed calcified callus formation in the joint space and roughened articular surfaces after new bone formation, which protruded into the joint space. Maximum mediolateral and anteroposterior condylar diameters were significantly larger in the control group than in the experimental group. Micro-CT also showed that the primary growth orientation of new trabeculae was consistent with the direction of lateral pterygoid traction in the control group, but not in the experimental group. Histological examination showed fibro-osseous ankylosis in the control group, but not in the experimental group.
  
  
  CONCLUSIONS
  The lateral pterygoid simulates the effects of distraction osteogenesis, which is an important factor in the pathogenesis of TMJ bony ankylosis during the healing of sagittal condylar fractures.
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China.
authors.forename: Tian-Ge
authors.initials: TG
authors.lastname: Deng
authors.affiliation: Department of Stomatology, 451th Hospital of the People's Liberation Army, 269 East Youyi Road, Xi'an, 710049, China.
authors.forename: Chang-Kui
authors.initials: CK
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China.
authors.forename: Lin-Lin
authors.initials: LL
authors.lastname: Zhang
authors.affiliation: Department of Endodontics and Restorative Dentistry, School of Stomatology, Tianjin Medical University, Tianjin, 300070, China.
authors.forename: Li-Geng
authors.initials: LG
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China.
authors.forename: Hong-Zhi
authors.initials: HZ
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China. yxding@fmmu.edu.cn.
authors.forename: Yu-Xiang
authors.initials: YX
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Military Stomatology, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral Surgery, School of Stomatology, The Fourth Military Medical University, 145 West Changle Road, Xi'an, 710032, China. hukaijin2015@126.com.
authors.forename: Kai-Jin
authors.initials: KJ
authors.lastname: Hu
mesh_terms: D000818:Animals; D000844:Ankylosis / Q000150:complications*; D008297:Male; D008335:Mandibular Condyle; D011626:Pterygoid Muscles / Q000473:pathology*; D012756:Sheep; D013704:Temporomandibular Joint; D013705:Temporomandibular Joint Disorders / Q000150:complications*
keywords: Animal model; Distraction osteogenesis; Lateral pterygoid muscle; Sagittal fracture of mandibular condyle; Temporomandibular joint ankylosis