Functional brain network alterations in a rat model of dental malocclusion.

BACKGROUND

Malocclusion has been associated with alterations in central nervous system function; however, the effects of persistent abnormal occlusal input on whole-brain functional organization remain poorly understood. This study aimed to investigate functional brain network reorganization associated with unilateral anterior crossbite (UAC) in rats.

METHODS

Fourteen female rats were used, seven of which were treated with left-sided UAC at 6 weeks old and the other seven served as sham-operation controls. Resting-state functional magnetic resonance imaging data were acquired at 26 weeks old. Regional activity in the proprioceptive pathway was assessed, followed by graph theoretical analysis of whole-brain functional networks.

RESULTS

UAC rats exhibited altered regional activity in the right ventral posteromedial thalamus (p = 0.023) and primary somatosensory cortex (p < 0.001), contralateral to the modeling side. Network analysis revealed significantly higher normalized clustering coefficient (p = 0.014) and small-worldness (p = 0.006) in the UAC group compared with controls. Furthermore, UAC rats showed enhanced functional connectivity within a subnetwork (p = 0.023) in which the right amygdala exhibited the greatest number of altered connections. In addition, abnormal regional activity was also detected in the right amygdala of UAC rats (p = 0.039).

CONCLUSION

Long-term UAC in rats is associated with alterations in whole-brain functional network organization. These findings provide new insights into the central neural responses associated with abnormal occlusal input.