title: [A study of ultrasound images under 3 different functional mandibular positions in young females].
abstract: OBJECTIVE
  The aim of this study was to establish the average of superfacial masseter muscle of young females with normal occlusion, and further supply a clue for dentists to evaluate the muscle function of patients with malocclusion.
  
  
  METHODS
  Totally 31 young females were investigated in this study, whose mean age was 21 years and 4 months old. Ultrasound technique was applied to obtain the ultrasound parameters of images, including area, width, mean thickness, maximal thickness of the cross-section and the length of the vertical-section of the masseter muscle under relaxing, maximal clenching and maximal protruding condition. The data were analyzed using ANOVA analysis.
  
  
  RESULTS
  The mean value and standard deviation of every parameter were figured out and it was found that there was a significant difference between relaxing and maximal clenching as well as maximal protruding.
  
  
  CONCLUSIONS
  The result indicates that ultrasonic technique is an effective method for describing superfacial masseter muscle morphology and diagnosing its function.
authors.affiliation: West China College of Stomatology, Sichuan University.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Che
authors.forename: Songjiao
authors.initials: S
authors.lastname: Luo
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Li
mesh_terms: D000328:Adult; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008334:Mandible / Q000502:physiology; D008406:Masseter Muscle / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D009119:Muscle Contraction; D009126:Muscle Relaxation; D014463:Ultrasonography