title: Electromyographic and ultrasonographic characterization of masticatory function in individuals with normal occlusion.
abstract: OBJECTIVE
  To characterize the motor control of the masseter and temporal muscles and the morphology of the masseter muscles during mastication in individuals with normal occlusion and to verify the consistency between surface electromyography (sEMG) and ultrasound (USD).
  
  
  METHODS
  Participants were 22 adults, of both genders, with no alterations of the oral myofuntional system. The procedures performed included sEMG of the masseter (MM) and temporal (TM) muscles and USD of the MM, each during three tasks: resting condition and maximum voluntary dental clench with and without cotton rolls.
  
  
  RESULTS
  The following statistical tests were used: Kolmogorov-Smirnov, paired t-test and Spearman correlation (significance level of 5%). The sEMG data indicated a significant difference between the MM and TM during the maximum voluntary clench with and without cotton rolls, and the TM was more active than the TM in both clenching tasks. No significant difference was observed between the sides of the face when assessed with sEMG or USD. A significant positive correlation between the exams was observed for the left maximum voluntary dental clench with and without cotton rolls, and a trend toward significance was found for the right maximum dental clench without cotton rolls.
  
  
  CONCLUSIONS
  The comparison of sEMG to USD for the investigation of muscle function reveals important information about the physiology of skeletal muscles. The results of the present study suggest a correlation between sEMG and USD, i.e., between increased electrical activity and the corresponding increase in muscle thickness.
authors.affiliation: Programa de Pós-graduação, Doutorado, em Ciências da Reabilitação, Departamento de Fisioterapia, Fonoaudiologia e Terapia Ocupacional, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: Laura Davison
authors.initials: LD
authors.lastname: Mangilli
authors.forename: Fernanda Chiarion
authors.initials: FC
authors.lastname: Sassi
authors.forename: Renato Antônio
authors.initials: RA
authors.lastname: Sernik
authors.forename: Clarice
authors.initials: C
authors.lastname: Tanaka
authors.forename: Claudia Regina Furquim de
authors.initials: CR
authors.lastname: Andrade
mesh_terms: D000328:Adult; D001732:Bite Force; D003766:Dental Occlusion; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000000981:diagnostic imaging* / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D015203:Reproducibility of Results; D013703:Temporal Muscle / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D055815:Young Adult