Myosin heavy chain mRNA isoforms in masseter muscle before and after orthognathic surgery.
OBJECTIVE
Orthognathic surgery leads to changed jaw position and force vector of mastication to which the muscles must adapt. The aim of the present study was to determine the relative expression of myosin heavy chain (MyHC) messenger RNA (mRNA) isoforms in different types of human masseter muscle fiber under consideration of change in the number of occlusal contacts before and 6 months after surgery.


METHODS
Muscle biopsies were taken from the anterior and posterior parts of both sides in 30 patients with prognathic and retrognathic mandibles. Specific mRNA MyHC analysis was made by real-time polymerase chain reaction to quantify the isoforms I, IIa, and IId/x.


RESULTS
There was a shift in the relative content from type I (46% before, 37% after) to type IIa (29% before, 42% after). This shift correlates with number of teeth in occlusion.


CONCLUSIONS
Correlation between isoform shift and number of teeth in occlusion indicates higher mastication force which stabilizes the treatment result.
Harzer
Winfried
W
Department of Orthodontics, School of Dentistry, Medical Faculty, University Clinics Carl Gustav Carus, Technical University, Dresden, Germany. winfried.harzer@uniklinikum-dresden.de
Worm
Margret
M
Gedrange
Tomasz
T
Schneider
Matthias
M
Wolf
Peter
P
D000222:Adaptation, Physiological / Q000235:genetics; D000328:Adult; D001483:Base Sequence; D001732:Bite Force; D003766:Dental Occlusion; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000737:chemistry* / Q000502:physiology; D008409:Mastication; D018995:Myosin Heavy Chains / Q000737:chemistry* / Q000235:genetics; D024461:Myosin Type I; D024462:Myosin Type II; D056948:Orthognathic Surgical Procedures; D011184:Postoperative Period; D011378:Prognathism / Q000601:surgery; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000737:chemistry; D063173:Retrognathia / Q000601:surgery
D020033:Protein Isoforms; D012333:RNA, Messenger; D024461:Myosin Type I; D024462:Myosin Type II; D018995:Myosin Heavy Chains