title: Change of mRNA amount of myosin heavy chain in masseter muscle after orthognathic surgery of patients with malocclusion.
abstract: BACKGROUND
  Surgical correction of malocclusion changes the force to moment ratio of masticatory muscles inserting at the mandible caused by shortening, lengthening and rotation of the bone following osteotomy. During muscle adaptation the expression of mRNA for the myosin heavy chain (MyHC) of type I and type II fibres may be changed.
  
  
  METHODS
  The adaptation of the masseter muscle was investigated at the mRNA level in 10 patients 6 months after orthognathic surgery in the mandible. The competitive polymerase chain reaction (cPCR) is a suitable method for quantification of MyHC mRNA. For application of this minimal invasive method an amount of 35 mg muscle tissue was sufficient.
  
  
  RESULTS
  6 month postoperatively there was a deficiency of about 87% of MyHC mRNA for fibre type I and II in both groups of patients. The deficiency in patients with mesial position of the mandible was higher but not significant different to patients with distal malocclusion.
  
  
  CONCLUSIONS
  Patients should use the postoperative interval for training their masticatory muscles. This improves the stability of treatment result and prevents relapse.
authors.affiliation: Department of Orthodontics, Technical University of Dresden, Germany. gedrange@uni-greifswald.de
authors.forename: Tomas
authors.initials: T
authors.lastname: Gedrange
authors.forename: Cordula
authors.initials: C
authors.lastname: Büttner
authors.forename: Matthias
authors.initials: M
authors.lastname: Schneider
authors.forename: Günter
authors.initials: G
authors.lastname: Lauer
authors.forename: Ronald
authors.initials: R
authors.lastname: Mai
authors.forename: Ronald
authors.initials: R
authors.lastname: Oppitz
authors.forename: Winfried
authors.initials: W
authors.lastname: Harzer
mesh_terms: D000328:Adult; D002508:Cephalometry; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000601:surgery; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D008406:Masseter Muscle / Q000737:chemistry*; D008437:Maxilla / Q000000981:diagnostic imaging; D018995:Myosin Heavy Chains / Q000032:analysis* / Q000235:genetics; D010027:Osteotomy / Q000009:adverse effects*; D012333:RNA, Messenger / Q000032:analysis*; D011859:Radiography
chemical_list: D012333:RNA, Messenger; D018995:Myosin Heavy Chains