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Updated: May 22, 2026
03:46
Rodent Model of Masseter Volumetric Muscle Loss for Studying Bioengineering Materials
Published on: May 31, 2024
Increased vertical dimension effects on masseter muscle fiber phenotype during maturation
Charles Widmer1, Vo Danh Nguyen, Harmeet Chiang
1Department of Orthodontics, University of Florida College of Dentistry, Gainesville, FL 32610-0444, USA. widmer@dental.ufl.edu
The Angle Orthodontist
|May 4, 2012
Summary
Increasing the vertical dimension of occlusion (VDO) in mice altered myosin heavy chain (MyHC) protein expression in masseter muscles. Specifically, MyHC IIb expression changed in deep regions, indicating muscle plasticity.
Area of Science:
- Muscle physiology
- Biochemistry
- Dental occlusion
Background:
- Myosin heavy chain (MyHC) protein isoforms determine muscle fiber type and function.
- Changes in masticatory muscle MyHC expression may occur in response to altered occlusal conditions.
Purpose of the Study:
- To investigate the impact of a clinically relevant increase in vertical dimension of occlusion (VDO) on mouse masseter muscle MyHC protein expression.
Main Methods:
- Six male CD-1 mice underwent a 10% bite opening, with controls matched for age.
- Masseter muscle cryosections were analyzed at 7 and 14 days post-intervention.
- Muscle fiber phenotype proportions and size were assessed in specific regions.
Main Results:
- Control masseter muscles showed increased MyHC IIb proportion in posterior regions by day 14.
- The bite opening group did not exhibit this MyHC IIb increase.
- MyHC IIa proportion decreased in the anterior region after 14 days of bite opening.
Conclusions:
- The masseter muscle demonstrates selective plasticity in MyHC IIb protein expression in deep regions following a VDO increase.
- These findings suggest adaptive changes in masticatory muscle fiber type in response to altered occlusion.
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