Impact on the Pharyngeal Airway Space of Different Orthognathic Procedures for the Prognathic Mandible: A Literature Review

Dentofacial deformity refers to deviations from normal facial proportions and dental relationships that are severe enough to be handicapping. These anomalies involve many aspects of patients life and are sometimes also associated with a reduction of pharyngeal airspace (PAS). This episode of pharyngeal airway collapse effects breathing function of the patients. This leads to a condition called Obstructive Sleep Apnea ( OSA). So patients who are undergoing orthognathic surgery should be screened for excessive daytime spmnolence, snoring, increased BMI and medical conditions related to OSA. OSA may be better following a maxillomandibular advancement surgery or may be worsened or developed after mandibular setback surgery. The purpose of this study is to review the changes of PAS and its important related structures such as hyoid bone, the tongues and soft palate after orthognathic surgery in dentofacial deformity patients. The change of head posture, the adaptation and the stability of PAS are also considered. Moderate evidence was found that PAS changes at the level of nasopharyngeal, oropharyngeal and hypopharyngeal. A statistical difference was found between BSSO& IVRO after treatment of mandibular prognathism. The results indicate that bimaxillary surgery in class 3 patients has less unfavourable effects, so it is considered as superior surgery compared to mandibular setback surgery.