Search

Objective: To test a novel sensor for assessing lip function. Methods: The electromyographic (EMG) activity of the upper orbicularis oris muscle (OOM), lip‐closing pressure (LP) and intraoral baro‐pressure (IP) were simultaneously recorded in 20 healthy subjects (10 women and 10 men) by using a novel composite sensor (CS). Subjects performed the lip‐closure, blow and suck tasks. EMG activity of the upper and lower OOMs was recorded using conventional surface electrodes to evaluate the accuracy of CS electrodes. The subjects also rated the user‐friendliness of the CS. Results: Integrated EMG signals recorded using the CS and conventional electrodes from the upper OOM were highly correlated (r = 0.77 ± 0.12 in women and r = 0.81 ± 0.10 in men). The signal‐to‐noise ratio was higher with the CS than with the conventional electrodes. The mean LP during maximum lip closure, blowing and sucking ranged between 2 and 6 kPa in women and between 5 and 7 kPa in men. The corresponding IPs in women were 0.0 ± 0.5, 3.2 ± 1.4 and −4.4 ± 2.6 kPa, respectively, and in men were −0.5 ± 1.4, 4.9 ± 1.8 and −5.6 ± 2.8 kPa, respectively. All subjects rated the recording technique as excellent or good. Conclusion: The CS was highly user‐friendly and accurate in recording the EMG activity of the OOM and could simultaneously measure the LP and IP. Therefore, it could be an effective tool for evaluating lip function. [ABSTRACT FROM AUTHOR]

• A new method for recording buccinator activity deep in the face has been tested. • The new electrode is small, can be easily set at the right place, and is contamination free. • The buccinator pulls at the corner of the mouth, assisting forceful closure. • Functional activity patterns were identical to those by intramuscular electrodes. • The new electrode can be utilized for studies on chewing. The buccinator (BUC) is an important muscle for oral function. Since it lies deep in the facial skin, recording its activity is difficult; thus, studies on its function are limited. We developed a method to access the deep facial muscles from the mucosal side. The aim of this study was to test the reliability of the new recording method for the BUC and to investigate the BUC behavior in typical facial functions. To evaluate the new method, BUC activities were recorded simultaneously with a gel-type electrode on the skin and the newly developed surface electrode on the buccal mucosa. Electromyographic (EMG) activities in function, such as chewing and swallowing, along with the activities of the lower orbicularis oris (OO), zygomaticus major, masseter, and digastric muscles, were compared using the two recording methods. EMG activities among various tasks were compared using normalized values based on those obtained during maximum lip closure (MaxLC). The new surface electrode was made of gold plates on a thin plastic fixed to a stainless-steel wire frame and weighed less than 1 g. The BUC activity recorded from the mucosa was the highest during a corner-pulling task and was low during clenching. The BUC was active during MaxLC, similar to the OO, and the BUC activity pattern among tasks recorded from the mucosa was identical to that reported by previous studies using intramuscular electrodes. The new electrode evaluated the BUC activities quantitatively, and the recordings by the new electrode were free from contamination. The findings of this study confirmed the reliability of the new BUC recording method. It could be easily placed correctly within seconds, without the need for cleansing or sterilizing the skin. The BUC and OO were active during a MaxLC task, indicating that the BUC assists lip closure by pulling the corners of the mouth. The basic facial functions evaluated, including chewing, were similar to those studied by intramuscular electrodes. [ABSTRACT FROM AUTHOR]