# Superior Orbicularis Oris Muscle Activity in Children
## 4 Discussion
The advantage of sEMG is its non-invasiveness, as it uses surface electrodes located on the skin surface, which is absolutely necessary in research on children [40]. It should be noted, however, that the use of surface electrodes in patients with clefts has some disadvantages, such as the ability to detect electrical potentials not only of underlying muscle activity, but also of surrounding connective tissue, skin thickness, and nearby nerves. This environment may have been different in these patients and may have accounted for the observed changes. When interpreting the study results it is also important to remember that patients with CLP had malocclusions. Moreover, 50% of children with BCCLP had incompetent lip seal. These factors may also contribute to variations in EMG pattern of the superior orbicularis or muscle. In our study the electromyographical values of the upper orbicularis or muscle during saliva swallowing were significantly greater in children with BCCLP and abnormal lip seal compared to the subjects with BCCLP and lip competence. Similarly, [PERSON] et al. [22] stated that in a cleft lip and palate group, patients with insufficient lip seal produced the highest EMG potentials during saliva swallowing. What is more, [PERSON] and [PERSON] [41] demonstrated that EMG recordings of the upper lip in children with lip incompetence were significantly higher than in normal children when measuring lip closure, chewing, and swallowing. It is known that abnormal craniofacial growth may contribute to severe occlusal disorders, which in turn could be a cause of muscle dysfunction [42]. Our findings suggest that the prevalence of malocclusions in patients with bilateral CLP is comparatively high. Many studies have focused on EMG analysis of muscles in the masticatory system in patients with malocclusion. It was confirmed that improper occlusion has a significant impact on muscle electrical activity [35; 37; 43; 44; 42]. For these reasons, it should be emphasized that altered EMG activity of the upper lip that was observed in children with repaired cleft may also be the result of the presence of malocclusions or abnormal lip seal. For better understanding the upper lip EMG results during speech it is important to consider some details on speech disorders in patients with CLP. The major speech problems observed in children with cleft lip and palate include velopharyngeal inadequacy (VPI), hypernasality, nasal air emissions (audible and inaudible), weakness of production of high-pressure consonants, and compensatory articulation errors [45; 46]. It should be noted that patients with CLP may present with articulation errors patterns as follows: developmental, obligatory and compensatory [46]. The children with developmental articulation errors they have problems producing sounds (articulation) and sound patterns (phonologicalprocesses) after the age of expected mastery. Obligatory articulation errors are produced given abnormal structures, causing the deformation of the sound. These errors include hypernasality, nasal emission and weak pressure consonants which can be associated with VPI, oronasal fistula and short utterances. Compensatory misarticulations refer to changes in placement of sounds to offset the anomalous structure. Usually, the child with repaired cleft is still trying to produce sounds using abnormal habits to \"compensate\" for previous structural deficiencies. The most prevalent compensatory articulation errors in patients with CLP include glottal stops, pharyngeal stops, pharyngeal fricatives, nasal fricatives, laryngeal fricatives, mid-dorsum palatal stops, and pharyngeal plosives [46; 47]. In our study, children produced the bilabial phonemes /p/, /b/ and /m/ with the vowel /a/. These consonants differ according to the manner of articulation and pressure requirements. Thus, plosives sounds, such as /p/ and /b/ involve complete obstruction of the airstream followed by a rapid release that is heard as a plosion. This required a high air pressure in the oral mouth.