**10. Complications**

### **10.1 Airway problems**

Treatment of cleft patients with class III malocclusion that results out of the combination of maxillary hypoplasia and intermaxillary disorder is usually achieved by maxillary advancement, mandibular setback, and clockwise rotation of the maxillomandibular complex. While maxillary advancement is associated with increased upper airway cavity, in contrast, mandibular setback is associated with reduction of airways with outcomes such as postoperative airway blockage, snoring, hypopnea (slow respiration), and obstructive sleep apnoea [65, 66]. Additionally, a pharyngeal flap may contribute to the airway-related difficulties that are encountered during operation or in the postoperative period. When the three-dimensional (3D) pharyngeal airway cavity of cleft patients in their pre- or post-pubertal periods were compared to a control group, Karia et al. [66] found significantly smaller airway sizes in the cleft group. The total airway volume increased from the pre-pubertal to the post-pubertal periods in both groups, but the reason for this outcome in the cleft group was not anteroposterior growth as in the case of the control group, but in contrast, associated with vertical airway growth. Especially in bilateral cleft patients, significantly reduced pharyngeal airway cavity in comparison to individuals without clefts was also confirmed in a CBCT study [67].

A prospective study by Chang et al. [68] examined the airway changes in cleft patients who received maxillary advancement and mandibular setback treatments by not only CBCT but also polysomnographic examination. Regarding the airway changes after orthognathic surgery, it was found that there was no significant difference in sleep-related respiratory functions, but the snoring index was improved.
