title: Biomechanical analysis of fractures in the mandibular neck (collum mandibulae).
abstract: After treatment of fractures in the neck of the mandible by means of immobilization of the dentition, often more or less severe manifestations of malocclusion remain. It was hypothesized that this is caused by an altered articulation in the jaw joint on the affected side. Furthermore, it was hypothesized that an anteriorly displaced condyle, as observed frequently as a side effect of the treatment, is caused by pull of the lateral pterygoid muscle, despite maxillomandibular fixation. Intervention experiments were performed in silico to test these hypotheses. With a biomechanical model of the human masticatory system alterations were applied mimicking a fractured mandibular neck and configurations that had been observed after healing. It was predicted that the altered articulation in the jaw joint caused asymmetrical jaw movements despite symmetrical muscle activation. The jaw was predicted to close with an open bite similar to clinical observations. The predicted laterodeviations, however, were not in accordance with clinical observations. Despite maxillo-mandibular fixation the lateral pterygoid muscle was able to pull the mandibular condyle out of its fossa in anterior direction. Consequently, despite some methodological limitations, in general the predictions corroborated the hypotheses.
authors.affiliation: Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), MOVE Research Institute Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands. Electronic address: j.koolstra@acta.nl.
authors.forename: Jan Harm
authors.initials: JH
authors.lastname: Koolstra
authors.affiliation: Department of Oral and Maxillofacial Surgery/Oral Pathology, VU University Medical Center/Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: Sofie C
authors.initials: SC
authors.lastname: Kommers
authors.affiliation: Department of Oral and Maxillofacial Surgery/Oral Pathology, VU University Medical Center/Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
authors.forename: Tymour
authors.initials: T
authors.lastname: Forouzanfar
mesh_terms: D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000503:physiopathology; D003198:Computer Simulation; D017102:Fracture Healing / Q000502:physiology; D006801:Humans; D019248:Jaw Fixation Techniques; D004204:Joint Dislocations / Q000503:physiopathology; D008335:Mandibular Condyle / Q000293:injuries / Q000503:physiopathology; D008337:Mandibular Fractures / Q000503:physiopathology*; D008954:Models, Biological; D024343:Open Bite / Q000503:physiopathology; D011626:Pterygoid Muscles / Q000503:physiopathology; D016059:Range of Motion, Articular / Q000502:physiology; D013314:Stress, Mechanical; D013701:Temporal Bone / Q000503:physiopathology; D013704:Temporomandibular Joint / Q000503:physiopathology; D019224:Temporomandibular Joint Disc / Q000503:physiopathology
keywords: Biomechanics; Collum fractures; Dysocclusion