title: Jaw-stretch reflex is weaker in patients after orthognathic surgery.
abstract: OBJECTIVE
  The jaw-stretch reflex (JSR) was studied in both patients and healthy participants in order to investigate the possible long-term impact of orthognathic surgery on the motor function of the masticatory system.
  
  
  METHODS
  JSR was measured in patients before surgery (PC), 1year after surgery (PS) and in healthy controls (HC) (N=31 in each group). JSR was evoked by a standardized stretch device and recorded bilaterally from masseter and anterior temporalis muscles using surface electromyography (EMG).
  
  
  RESULTS
  The peak-to-peak amplitude (which was normalized to pre-stimulus EMG activity) of JSRs in PC and PS were significantly smaller than in HC (P<0.001; P<0.001). The onset latency in PS was significantly longer compared with HC (P<0.05). The duration of JSR in PS was significantly longer than in HC and PC (P<0.001; P<0.05).
  
  
  CONCLUSIONS
  Patients with dentofacial deformities are characterized by reduced JSR amplitude. The delayed onset and elongated duration of JSR might be potential indicators of a long-term surgical impact on the motor function of the masticatory system.
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D2, 9220 Aalborg, Denmark.
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Section of Clinical Oral Physiology, School of Dentistry, University of Aarhus, Vennelyst Boulevard 9, DK-8000 Aarhus C, Denmark; Center of Functionally Integrative Neuroscience (CFIN), MindLab, Aarhus University Hospital, 44 Norrebrogade, Aarhus, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Svensson
authors.affiliation: Department of Oral & Maxillofacial Surgery, Aalborg Hospital, Aalborg, Denmark.
authors.forename: Janek Dalsgaard
authors.initials: JD
authors.lastname: Jensen
authors.affiliation: Department of Oral & Maxillofacial Surgery, Aalborg Hospital, Aalborg, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Jensen
authors.affiliation: Department of Oral & Maxillofacial Surgery, Aalborg Hospital, Aalborg, Denmark.
authors.forename: Bjarne
authors.initials: B
authors.lastname: Neumann
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D2, 9220 Aalborg, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.affiliation: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D2, 9220 Aalborg, Denmark; Department of Oral & Maxillofacial Surgery, Aalborg Hospital, Aalborg, Denmark. Electronic address: kelun@hst.aau.dk.
authors.forename: Kelun
authors.initials: K
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D063169:Dentofacial Deformities / Q000503:physiopathology* / Q000601:surgery*; D004576:Electromyography; D005260:Female; D006801:Humans; D007568:Jaw / Q000503:physiopathology*; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology*; D057909:Orthognathic Surgery; D010147:Pain Measurement; D012026:Reflex, Stretch / Q000502:physiology*; D011795:Surveys and Questionnaires; D013703:Temporal Muscle / Q000503:physiopathology*
keywords: Dentofacial deformities; Electromyography; Jaw-stretch reflex; Masticatory muscles; Orthognathic surgery; Physiology