Spontaneous Activation of the Masseter Muscle in Balance Tasks: The Functional Relationship Between Postural Control and the Stomatognathic System in Healthy Adults.

BACKGROUND

The functional relationship between postural control and the stomatognathic system is being increasingly investigated.

AIM: This study aimed to document spontaneous electromyographic (EMG) activation of the masseter muscle during balance tasks in healthy subjects and to investigate the relationships between temporomandibular disorder (TMD) symptom severity, masseter pain threshold, and head position with balance performance.

METHODS

In this cross-sectional study, 90 healthy university students aged 18-30 years were included. TMD symptoms were assessed using the Fonseca Anamnestic Index (FAI) and the Clinical Examination Form. Pressure pain threshold (PPT), craniovertebral angle (CVA), and masseter muscle activation (superficial EMG) were measured. Static and dynamic balance performance was analyzed with the Korebalance System. All measurement tools had established validity and reliability.

RESULTS

Using Spearman correlation analysis, there was no significant correlation between TMD symptom severity and balance performance (P > 0.05), while a negative correlation was found between masseter muscle pressure pain threshold and balance scores (P < 0.05). A weak negative correlation (P = 0.025) was found between forward head posture (FHP) and static balance with eyes open. The most striking finding was that spontaneous masseter activation was observed in almost all participants during balance tasks.

CONCLUSION

This study demonstrated significant relationships between spontaneous masseter EMG activation during balance tasks and postural control parameters in healthy individuals. Additionally, correlations between masseter sensitivity, head posture measures, and balance performance suggest a potential neuromuscular interaction between the stomatognathic system and postural control. These findings are exploratory and hypothesis-generating, and further studies are required to clarify this potential relationship.