Masticatory muscle function after unilateral condylar fractures: a prospective and quantitative electromyographic...

Area of Science:

• Oral and Maxillofacial Surgery
• Biomechanics
• Neuromuscular Function

Background:

• Unilateral condylar fractures can impact masticatory muscle function.
• Conservative treatment is common, but long-term functional outcomes require investigation.

Purpose of the Study:

• To evaluate changes in masticatory muscle activity after conservative treatment of unilateral condylar fractures.
• To assess the functional recovery and potential long-term distortions in muscle activity.

Main Methods:

• Electromyographic (EMG) recordings of masticatory muscles (temporal, masseter) were taken at 3 time points: immediately after treatment (T0), and 4 (T1) and 8 (T2) months post-trauma.
• Subjects performed maximal voluntary contractions and natural chewing tasks.
• Activity was analyzed on both the fractured (ipsilateral) and opposite (contralateral) sides.

Main Results:

• Significant increases in maximal voluntary contraction for temporal and contralateral masseter muscles were observed from T0 to T2.
• Anterior temporal muscle activity increased during natural chewing, with shorter, stronger contractions on the ipsilateral side.
• Masseter muscle activity was consistently stronger contralaterally during natural chewing, with a tendency towards contralateral chewing preference.

Conclusions:

• Improved masticatory muscle function, particularly in temporal muscles, indicates healing and pain relief.
• Persistent contralateral masseter dominance suggests a permanent functional distortion, possibly due to reflex suppression on the fracture side.