# Superior Orbicularis Oris Muscle Activity in Children
## 4 Discussion  
This is the first study to evaluate the electrical potentials of the upper orbicularis on muscle in children who had been operated on for bilateral complete cleft lip and palate. Our analysis included only those surgically treated for bilateral CLP based on a similar operating protocol with a limited number of surgeons involved, thus ensuring sample homogeneity and reducing the number of confounders. The experiment showed increased EMG activity of the superior orbicularis on muscle in children with BCCLP during saliva swallowing, lip compression and when producing the phoneme /p/ associated with the vowel /a/. As no similar studies on participants with bilateral CLP has been carried out it is difficult to compare our results with any others. Nevertheless, a few studies of lip electromyography in patients treated surgically for unilateral cleft lip and palate have been performed. In a recent study, [PERSON] et al. (2013) analyzed the electrical activity of the upper orbicularis on muscle in patients aged 6 to 13 years. Their research cohort comprised 45 children operated on for unilateral complete CLP. These were compared to 40 control subjects. The data obtained in our study is consistent with the results reported by [PERSON] et al., who found that the EMG activity of the upper orbicularis on muscle while swallowing saliva and compressing the lips was significantly higher in the cleft group than in the patients with no CLP. In addition, the authors observed that upper lip EMG potentials both at rest and while speaking were comparable in both groups. They suggested that the increased activity of the repaired upper lip during saliva swallowing and lip compression in patients with unilateral complete CLP could affect facial morphology. [PERSON] et al. (2013) researched the function of the upper lip in children with CLP aged between 7 and 12. Children with CLP studied by [PERSON] et al. with regard  
Figure 4: EMG potentials of the upper lip [μV/μV%] during production of the phoneme /p/ with the vowel /a/ in the noncleft group (NCG) and the cleft group (CG); \({}^{*}p<0.05\). to cleft type constituted mixed sample (children with unilateral and bilateral CLP). There were no differences in the EMG potentials of the upper lip at rest between patients with and without clefts, while the EMG activity of the upper lip during saliva swallowing in children with clefts was significantly greater than in the subjects without CLP. The authors concluded that the upper orbicularis or muscle exerts a limiting pressure on the growth of the jaw during swallowing. [PERSON] et al. [24] observed that the electrical potentials of the upper lip during speech and nonspeech movement tasks were higher in patients aged 15-23 with repaired unilateral cleft lips and/or palate compared with the subjects without clefts. The authors suggested that increased lip activity during function in patients with CLP may impact on their facial growth. [PERSON] et al. [38] measured the EMG activity of the upper lip in children aged 6 to 12 years surgically treated for unilateral cleft lip and palate. They found significantly higher scores for the electrical potentials of the upper orbicularis or muscle at rest and when saliva swallowing in the cleft group, while electromyographic values during speech were similar in both subjects with clefts, and in children without a cleft. It should be noted that the similar levels we observed between children with BCCLP and in those without BCCLP regarding EMG activity of the upper orbicularis or muscle at rest contradict the findings described by [PERSON] et al. This may be due to differences in the selection criteria of the studied groups. In other words, this study included children with normal and abnormal lip seal (as [PERSON] et al. and [PERSON] et al. ), while [PERSON] et al. evaluated patients with clinically short upper lips and insufficient lip seal. Our research made use of surface electromyography (sEMG).