Electromyographic analysis of the upper lip in nose and mouth breathers

Correpondence to: Michelle Santos Vianna-Lara Rua Francisco Rocha, 62, conj. 409 Batel – Curitiba – Paraná Brazil CEP 80420-130 Phone: 55 (41) 3014-0947 Fax: 55 41 271-1405 E-mail: [email protected] Abstract The purpose of this research was to compare the electromyographic (EMG) activity of the superior belly of orbicularis oris muscle between individuals with Class II Division 1 malocclusion, nose breathers (Group 1) and mouth breathers (Group 2), having as a comparative parameter a control group of individuals with clinically normal occlusion (Group 3). The EMG recordings were obtained in resting position and in 16 movements. A statistically significant difference between Groups 1 and 2 was observed during puffing out with flaccid cheeks, dispelling of the lips’ angle and saliva deglutition; between Groups 1 and 3 during puffing out with flaccid cheeks, posterior right and left clenching and saliva deglutition; between 2 and 3 during posterior right and left clenching. According to the normalized data the malocclusion groups (Groups 1 and 2) have a similar muscle behavior but when they are compared with the normal occlusion group there was a statistically significant difference between them. It can be concluded that, for this sample, the breathing mode did not influence the muscular behavior of the subjects with Class II division 1 malocclusion and that subjects with normal occlusion have more competent lips than the ones with Class II division 1 malocclusion.