Reliability of electromyographic activity vs. bite-force from human masticatory muscles

Area of Science:

• Biomechanics
• Neurophysiology
• Dental Science

Background:

• The reproducibility of electromyographic (EMG) activity relative to static bite force in masticatory muscles is not well understood.
• Understanding this relationship is crucial for developing accurate mechanical models of the human masticatory system.

Purpose of the Study:

• To evaluate the reliability of EMG activity in relation to static bite force in humans.
• To determine the consistency of EMG measurements during different biting tasks.

Main Methods:

• Eighty-four subjects performed unilateral static bites at varying forces and positions on molars and incisors across two sessions.
• Surface EMG activity was recorded bilaterally from temporalis, masseter, and suprahyoid muscles.
• Intraclass correlation coefficients (ICCs) were calculated to assess reliability, with ICC ≥ 0.60 indicating good reliability.

Main Results:

• The slopes of EMG activity versus bite force were reliable for temporalis and masseter muscles during both molar and incisor biting.
• ICCs for jaw-closing muscles during molar biting ranged from 0.58 to 0.93.
• ICCs for jaw-closing muscles during incisor biting ranged from 0.56 to 0.86, with some lower values for contralateral temporalis muscles.
• Suprahyoid muscle reliability showed wide confidence intervals, often including zero.

Conclusions:

• EMG activity in the temporalis and masseter muscles demonstrates good reliability in relation to static bite force.
• These findings support the use of EMG activity and bite force measurements for validating mechanical models of the masticatory system.