# Superior Orbicularis Oris Muscle Activity in Children
## 4 Discussion
As the intraoral pressure in subject with a cleft is usually insufficient patients with CLP and/or velopharyngeal dysfunction (VPD) have problems producing these consonants. The incapacity to create and/or preserve adequate amount of intraoral pressure for production of plosion may lead to changes in placement of generation this type of sounds, called compensatory articulation errors. In these articulation errors patterns, the manner of articulation is usually maintained, while the place of production is abnormally posteriorized. On the contrary, nasal sounds including /m/ are created with acoustic energy being displaced concurrently to oral and nasal cavities. These sounds do not need pressure build-up [47]. Based on the above considerations, it would be expected the reduction of the EMG potentials of the upper orbicularis oris muscle in patients with CLP during the production of the plosives sounds /p/ and /b/. On the other hand, it can be supposed that the EMG activity of the upper lip is higher in cases when the lips do not close in the rest position and increased scope of movement is necessary to achieve contact between the lips for the production of the bilabial phonemes /p/, /b/ and /m/. These situations may be the result of occlusal discrepancies, such as negative overjet. For these reasons, we must remember that our upper lip EMG results during speech movement tasks should be interpreted with caution. More additional studies in this area are needed to support and clarify these findings. As mentioned earlier, it is significant that the increased electrical potentials of the upper orbicularis oris muscle in patients with BCCLP may indicate the greater force of contraction after surgical lip reconstruction to underlying structures [48], which may consequently affect maxillofacial growth. Particularly important seems to be the much greater electromyographic activity of the upper lip when swallowing saliva, because, although it is a very short-term activity, it is repeated up to 3000 times a day [1; 49]. Previous studies [20; 26; 27; 28; 29] have shown that the restraining effect of increased labial pressure due to lip repair may disturb normal facial morphology by inhibiting maxillary sagittal growth in subjects with unilateral complete CLP. However, no such findings have been reported for patients with BCCLP. The most obvious cephalometric characteristic in adult patients with unoperated bilateral CLP is the protrusion of the premaxilla and prolabium, which results in excessive convexity of the midface and a significant shortening in the nasal columnella [17; 50]. The increased backpressure produced by the repaired orbicularis oris muscle can help correct the premaxillary protruding position, which results in an essential reduction in facial convexity. Such a long-lasting restraining effect on the projected premaxilla is usually beneficial, except when extreme lip pressure, an unfavorable growth pattern, or both retropositions the midface profile beyond the permissible sagittal limits [19; 31; 32]. In light of the above, it should be noted that the results of our study do not directly allow to conclude an association between EMG activity of the upper lip in patients with repaired clefts and maxillary growth and facial aesthetics. However, to support the hypothesis that the hyperactivity of the superior orbicularis oris muscle in children surgically treated for CLP may affect facial growth/aesthetics we analyzed electromyographic potentials of the upper lip during saliva swallowing within the BCCLP group. An analysis of the EMGvalues of the upper orbicularis or muscle showed that the upper lip electrical activity in children with BCCLP and concave facial profile was significantly higher than in patients with straight or convex profile. Moreover, patients with CLP and class III malocclusion, as well as patients with negative overjet produced significantly greater EMG potentials during saliva swallowing. A further complementary study would be necessary to support and discuss these findings.