Experimental occlusal interferences. Part II. Masseteric EMG responses to an intercuspal interference

Area of Science:

• Biomedical Engineering
• Neuroscience
• Dental Occlusion

Background:

• Intercuspal interferences can alter neuromuscular control of mastication.
• Understanding jaw muscle coordination is crucial for diagnosing and treating occlusal disorders.

Purpose of the Study:

• To investigate the effect of a unilateral intercuspal interference on bilateral masseter muscle activity during forceful clenching.
• To analyze the coordination patterns of masseter electromyographic activity in response to occlusal disturbances.
• To explore the relationship between occlusal interference, muscle activity, and mandibular motion.

Main Methods:

• A rigid unilateral intercuspal interference was introduced in 12 subjects.
• Bipolar surface electromyograms of masseter muscles were recorded during forceful clenching.
• Electromyographic data were analyzed for amplitude and duration.
• Mandibular movements were clinically observed.

Main Results:

• Significant reduction in myoelectric clenching activity was observed on the side opposite the interference.
• Complex, non-linear coordination of bilateral masseteric activity amplitude was found.
• Motor facilitation occurred on the side of the interference, while motor inhibition occurred on the contralateral side.
• Frontal plane rotatory motions of the mandible were clinically observed.

Conclusions:

• Unilateral occlusal interferences induce asymmetric masseter muscle activity patterns.
• Jaw clenching on an interference leads to complex neuromuscular responses and altered mandibular kinematics.
• These findings have implications for understanding the effects of occlusal disharmony on masticatory function.