Do subjects with forced lip closure have different perioral and jaw muscles activity?

Objective: To evaluate the activity of mentalis (MN), buccinator (BC), and suprahyoid (SH) muscles among participants with different lip competence. Methods: Sixty-three participants were classified clinically and assigned to the following groups of 21 each: 1) competent lips (competent), 2) incompetent lips (incompetent), or 3) forced lip closure (forced). Activity was recorded at rest, swallowing, speaking, reciprocal compression of the lips, and chewing. Results: MN activity in incompetent was significantly higher than competent at rest, and it was significantly higher in incompetent and forced when compared with competent during swallowing (p<.05). No differences among incompetent and forced were observed (p>.05). During speaking, reciprocal compression of the lips, and chewing, MN activity did not show significant differences among groups. BC and SH activity did not show significant differences (p>.05). Conclusion: MN activity during swallowing can be considered a relevant biomarker to differentiate between forced and competent participants.