Variability and reliability of muscle activity measurements during chewing

Area of Science:

• Biomechanical Engineering
• Neuroscience
• Dental Science

Background:

• Understanding masseter muscle function is crucial for diagnosing and treating various jaw disorders.
• Assessing the reliability of electromyography (EMG) measurements during chewing is essential for clinical applications.

Purpose of the Study:

• To evaluate the variability and reliability of masseter muscle activity during habitual and deliberate unilateral chewing in healthy, dentate volunteers.
• To assess the reproducibility of EMG measurements across multiple sessions under standardized conditions.

Main Methods:

• EMG activity and kinematic data of masseter muscles were recorded over three consecutive days.
• Jaw exercises included maximum voluntary contraction, habitual chewing, and unilateral chewing (left and right).
• Asymmetry Index (AI) and Deliberate Chewing Index (DCI) were calculated to quantify muscle activity and side-specificity.

Main Results:

• Masseter muscle activity demonstrated good to excellent reproducibility, with intra-class correlation coefficients (ICCs) ranging from 0.68 to 0.93.
• Significant individual differences in bilateral masseter activation strategies were observed during both habitual and deliberate unilateral chewing.
• Side-specific DCI scores confirmed distinct activation patterns for left and right unilateral chewing.

Conclusions:

• Standardized EMG recordings provide reliable and reproducible measurements of masseter muscle activity during chewing.
• Individual variability in chewing strategies does not compromise the reliability of EMG measurements.
• These findings support the use of EMG in clinical settings for assessing masseter muscle function and chewing dynamics.