Masticatory muscle function affects the pathological conditions of dentofacial deformities

Tomohiro Yamada, Goro Sugiyama, Yoshihide Mori

Research output: Contribution to journalReview articlepeer-review

17 Citations (Scopus)


The causes of dentofacial deformities include various known syndromes, genetics, environmental and neuromuscular factors, trauma, and tumors. Above all, the functional effects of muscles are important, and deformation of the mandible is often associated with a mechanical imbalance of the masticatory muscles. With the vertical position of the face, weakness of the sling of the masseter muscle and medial pterygoid muscle causes dilatation of the mandibular angle. In patients with a deep bite, excessive function of the masticatory muscles is reported. Myosin heavy chain (MyHC) properties also affect jawbone morphology. In short-face patients, the proportion of type II fibers, which are fast muscles, is high. The proportions of muscle fiber types are genetically determined but can be altered by postnatal environmental factors. Orthognathic surgery may results in the transition of MyHC to type II (fast) fibers, but excessive stretching enhances the release of inflammatory mediators and causes a shift toward a greater proportion of slow muscle fibers. This feature can be related to postoperative relapse. Bones and muscles are in close crosstalk, and it may be possible to use biochemical approaches as well as biomechanical considerations for the treatment of jaw deformities.

Original languageEnglish
Pages (from-to)56-61
Number of pages6
JournalJapanese Dental Science Review
Issue number1
Publication statusPublished - Dec 2020

All Science Journal Classification (ASJC) codes

  • General Dentistry


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