# Superior Orbicularis Oris Muscle Activity in Children
###### Abstract  
The aim of this cross-sectional study was to evaluate the electromyographic activity of the superior orbicularis or muscle both in children surgically treated for bilateral complete cleft lip and palate (BCCLP) as well as in subjects without BCCLP. The study comprised 77 children aged 6.6 to 12.5 years. All the patients with clefts had previously undergone lip and palate surgery. The upper lip electromyographic (EMG) assessments were made with a DAB-Bluetooth device (Zebris Medical GmbH, Germany) at rest, while swallowing saliva, protruding lips and compressing lips. EMG measurements were also made when the subjects produced phonemes /p/./b/, and /m/ with the vowel /a/. The Mann-Whitney U test was applied to statistically analyze the EMG values. Significantly higher median upper lip EMG activity under working conditions such as swallowing saliva, lip compression, and production of the phoneme /p/ with the vowel /a/ was observed in patients with BCCLP compared to those without a cleft. The results of the study showed that the upper lip muscle activity increases in children with BCCLP when swallowing saliva, compressing lips and during some speech movement tasks. This may be important in the aspect of the effect of surgical lip repair on the craniofacial growth. bilateral cleft; cleft lip and palate; dentofacial deformities; facial growth; multidisciplinary cleft treatment; surgical lip repair; superior orbicularis or muscle; surface electromyography +
Footnote †: journal: Clinical Medicine  
Long-term postoperative effects and the severity of age-related abnormalities pose a major challenge to clinicians dealing with the interdisciplinary treatment of patients with clefts including oral and maxillofacial surgeons and orthodontists. Major complications include hypoplasia of the maxilla, collapse of the maxillary buccal segments with a subsequent posterior crossbite, and premaxillary protrusion following a distorted facial profile [17; 18]. Surgical lip repair is a very important procedure consisting in the immediate reconstruction of the cleft face and brings psychological benefits to the patient's family [19]. Moreover, it should also be noted that lip repair may affect the final morphology of the maxilla and midface [20; 21]. In 1977 [PERSON] and [PERSON] forwarded the thesis that primary lip reconstruction always results in a certain degree of labial tension which is transferred as pressure to the underlying jaw. Recent studies have also shown that electromyographic (EMG) activity of the superior orbicularis or muscle was higher following lip repair during swallowing saliva [22; 23] and speech [24]. The authors suggested that the superior orbicularis or muscle exerted a restrictive pressure effect on maxillary growth [22; 23; 24; 25]. In unilateral complete CLP, this effect is usually negative because it excessively restricts maxillary anterior displacement [20; 21; 26; 27; 28; 29; 30]. However, the restraining lip repair effect may to some extent be desirable for facial growth in patients with bilateral CLP. In complete bilateral clefts, the increased backward pressure produced by the repaired orbicularis or muscle is fundamental to the retropositioning of the protruded premaxilla, which results in an essential reduction in facial convexity [17; 19; 31; 32]. It should also be noted that the orbicularis or muscle has important functions in the stomatognathic system associated with food ingestion, facial expression or speech articulation [33] and abnormal lip activity during these functions may represent an additional factor threatening the integrity of underlying dentofacial structures. In light of the above, it is essential to determine the electrical activity of the upper orbicularis or muscle during different functional conditions in subjects with CLP that have undergone cleft lip and palate surgery. Electromyography (EMG) is a tool that investigates muscle function by recording the electric signals coming from the muscles [34].