Three-dimensional analysis of lip and chin movements during mastication with artificial nasal obstruction

This study aimed to investigate the effects of nasal obstruction on the coordinated movement of perioral tissues during mastication using a motion capture system.

Twelve healthy adult participants were instructed to chew gum only on their habitual masticatory side for 30 s, with and without nasal obstruction. Nasal obstruction was induced by blocking nasal breathing with a nose clip. Movements of the upper and lower lips, left and right corners of the mouth, and chin during gum chewing were measured using a motion capture system, and the differences between participants with and without nasal obstruction were compared. Multilevel linear model analysis was used to evaluate inter-individual and intra-individual variations in lip and chin movements, both with and without nasal obstruction.

The chin chewing cycle duration was significantly longer in participants with nasal obstruction. The chewing cycle distance of the upper lip was significantly shorter in participants with nasal obstruction. The intra-individual variation in the chewing cycle distance of the chin and lips increased with nasal obstruction, whereas the inter-individual variation decreased.

Nasal obstruction causes unstable yet uniform movements of the chin and lips during mastication, while also restricting upper-lip movement. Our results indicate that nasal obstruction may significantly affect mandibular and lip movements during mastication. These findings highlight the importance of nasal breathing in maintaining stable perioral movements during mastication. This study provides new insights that could inform clinical strategies for managing oral function in individuals with nasal obstruction.