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Changes in rabbit jaw-muscle activity parameters in response to reduced masticatory load
T Grünheid1, P Brugman, A Zentner
1Department of Orthodontics, Academic Centre for Dentistry Amsterdam (ACTA), Research Institute MOVE, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands. t.gruenheid@acta.nl
The Journal of Experimental Biology
|February 16, 2010
Summary
Reduced masticatory load significantly lowers jaw muscle activity, particularly the masseter muscle, in rabbits. This effect is most noticeable in the weeks after dietary changes and primarily impacts chewing-related muscle contractions.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Physiology
Background:
- Mastication is a complex neuromuscular process influenced by food properties.
- Long-term effects of altered masticatory load on jaw muscle activity profiles remain unclear.
Purpose of the Study:
- To investigate how reduced masticatory load affects the daily habitual activity profiles of jaw muscles.
- To determine the impact of softer food on the masseter, temporalis, and digastric muscles in rabbits.
Main Methods:
- Telemetric electromyograms (EMG) of jaw muscles were recorded in male rabbits (7-20 weeks old).
- Experimental group received softer pellets from 8 weeks of age, compared to controls.
- Muscle activity quantified by duty time, burst number, and burst length relative to maximum activity levels.
Main Results:
- The masseter muscle showed significantly lower daily duty time and burst number in the experimental group.
- These reductions were observed at 5% and 10% of maximum activity within two weeks of dietary change.
- The temporalis and digastric muscles' activity characteristics were not significantly affected by altered food hardness.
Conclusions:
- Reduced masticatory load decreases neuromuscular activity in force-generating jaw-closing muscles.
- The effect is most pronounced shortly after dietary changes and specific to chewing contractions.
- The masticatory system exhibits limited diet-specific long-term adaptations in jaw muscle activity profiles.
