title: Evaluation of masseter muscle electromyography after surgical extraction of third molar.
abstract: OBJECTIVE
  The aims of this study were to evaluate the results of electromyographies (EMGs) of the masseter muscle after mandibular third molar surgery and to determine the relationships between clinical variables and EMG results.
  
  
  METHODS
  Seventy patients were included in the study. The parameters of the patients' masseter muscles were measured using EMG prior to operation and 7 and 21 days post-operation. Clinical variables were also recorded before and after the third molar surgeries.
  
  
  RESULTS
  When the masseter muscle EMG results from the tooth-extracted side were compared with those from the non-extracted (control) side, significant differences in the areas of voltage, power spectral densities and median frequencies (p = 0.011, 0.017 and 0.041, respectively) were found 7 days postoperatively. Additionally, there were significant associations between some clinical variables (i.e. postoperative swelling, bone reduction and pericoronitis) and the EMG results 7 days postoperatively, (p < 0.05). However, there were no significant differences 21 days postoperatively.
  
  
  CONCLUSIONS
  This study revealed that the postoperative changes in EMG activities were transient. Although there have been controversies about the reliability of EMG, this study showed that some EMG variables could be used to evaluate postoperative changes in masseter muscle activity.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Collage of Dentistry, Gangneung-Wonju National University, Jibyun-dong, Gangneung, Gangwon-do, 210-702, Republic of Korea.
authors.forename: Chan-Woo
authors.initials: CW
authors.lastname: Kim
authors.forename: Seong-Gon
authors.initials: SG
authors.lastname: Kim
authors.forename: Sung-Wook
authors.initials: SW
authors.lastname: Park
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Chee
mesh_terms: D000293:Adolescent; D000328:Adult; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008334:Mandible / Q000601:surgery; D008406:Masseter Muscle / Q000503:physiopathology*; D008875:Middle Aged; D008964:Molar, Third / Q000601:surgery*; D011183:Postoperative Complications / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted; D014081:Tooth Extraction; D014095:Tooth, Impacted / Q000601:surgery*; D055815:Young Adult