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Electromyography and bite force studies of muscular function and dysfunction in masticatory muscles
Swedish Dental Journal. Supplement
|January 1, 1986
Summary
This study investigated electromyographic (EMG) activity and bite force in patients with painful masseter muscles. Lidocaine injections reduced muscular discomfort and altered EMG-force relationships, suggesting potential therapeutic benefits for masseter pain.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Musculoskeletal Research
Background:
- Painful masseter muscles can significantly impact masticatory function and quality of life.
- Understanding the relationship between muscle activity (electromyography) and bite force is crucial for diagnosing and treating jaw muscle disorders.
- Previous research has explored these relationships, but the effects of interventions like local anesthetics require further investigation.
Purpose of the Study:
- To analyze electromyographic (EMG) activity versus bite force during isometric contractions in patients with painful masseter muscles and healthy controls.
- To evaluate the effects of lidocaine and saline injections on EMG-force relationships and perceived discomfort.
- To compare masticatory force utilization during chewing tasks between patient and control groups.
Main Methods:
- Isometric contractions of masseter, anterior temporalis, and trapezius muscles were recorded alongside bite force measurements.
- Double-blind intramuscular injections of lidocaine or saline were administered to patients' masseter muscles.
- EMG-force relationships were analyzed using regression, and chewing performance was assessed via amplitude probability distribution analysis.
Main Results:
- Regression analyses revealed steeper EMG-force slopes at higher force levels for the masseter muscle, potentially due to recruitment patterns.
- Lidocaine injections, but not saline, reduced the steepness of the EMG-force relationship at low force levels in the masseter muscle.
- Patients exhibited greater relative masticatory forces during almond chewing compared to controls, and both groups reported reduced discomfort post-injection, with lidocaine showing a more immediate effect.
Conclusions:
- The study elucidates the complex EMG-force dynamics in painful masseter muscles and highlights the differential effects of lidocaine and saline.
- Lidocaine demonstrates potential in modulating neuromuscular activity and alleviating muscular discomfort in masseter pain conditions.
- Findings suggest altered masticatory strategies in patients and provide insights into the neurophysiological underpinnings of jaw muscle pain.