title: Oral myofunctional and electromyographic evaluation of the orbicularis oris and mentalis muscles in patients with class II/1 malocclusion submitted to first premolar extraction.
abstract: OBJECTIVE
  The aim of this study was to assess the presence of oral myofunctional alterations before and after first premolar extraction in Class II/1 malocclusion patients that could endanger the long-term dental arch stability.
  
  
  METHODS
  The study was performed by means of morphological, functional and electromyographic analyses in 17 Class II/1 malocclusion patients (group T) and 17 Class I malocclusion patients (group C -control), both groups with 12-30-year age range (mean age: 20.93 +/- 4.94 years).
  
  
  RESULTS
  Data analyzed statistically by Student's t-test showed a significant decrease (p<0.05) in the maxillary and mandibular dental arch perimeters after orthodontic treatment, but lip posture at rest did not present statistically significant differences after treatment (p>0.05). The Kruskal-Wallis test analyzed data from lip posture (orbicularis oris muscle) at rest and during swallowing, as well as the mentalis muscle behavior during the above-mentioned function, not showing statistically significant differences (p>0.05) after treatment (groups T1 and T2). However, group T differed significantly from group C (p<0.05). Lip posture during swallowing showed statistically significant differences (p<0.05) for subjects submitted to orthodontic therapy when compared to data acquired before the treatment. The electromyographic analysis confirmed these data.
  
  
  CONCLUSIONS
  Found myofunctional alterations observed after the orthodontic treatment in Class II/1 malocclusion seemed to jeopardize the long-term orthodontic stability, making recurrence possible.
authors.affiliation: Federal University of São Paulo, São Paulo, SP, Brazil. denize@prudenet.com.br
authors.forename: Denize Ramirez
authors.initials: DR
authors.lastname: de Souza
authors.forename: Tatiana Adamov
authors.initials: TA
authors.lastname: Semeghini
authors.forename: Lucio Benedito
authors.initials: LB
authors.lastname: Kroll
authors.forename: Fausto
authors.initials: F
authors.lastname: Berzin
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000601:surgery; D003679:Deglutition / Q000502:physiology; D003724:Dental Arch / Q000473:pathology; D004576:Electromyography; D005152:Facial Muscles / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008046:Lip / Q000503:physiopathology*; D008297:Male; D008312:Malocclusion, Angle Class II / Q000503:physiopathology* / Q000628:therapy; D009971:Orthodontics, Corrective / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D014081:Tooth Extraction; D055815:Young Adult