Assessment of Posterior Pharyngeal Airway Changes After Orthognathic Surgery Using Barium Sulfate.

Introduction:  Obstructive sleep apnea (OSA), caused by airway narrowing, is likely to occur if the mandibular plane to hyoid distance is greater than 15.4 mm and the posterior airway space (PAS) is less than 11 mm. OSA may be caused by mandibular deficit, bimaxillary retrusion, increased lower facial height, extended soft palate, a large tongue base, and a posteroinferiorly positioned hyoid bone. Snoring and drowsiness during exercise are symptoms of OSA, which is a risk factor for high blood pressure, heart disease, and stroke, and these can result in car crashes. However, orthognathic surgery can improve dental occlusion and aesthetics by adjusting facial bone position, shape, and size. When bones move, the position and tension of soft tissues change. These novel soft tissue interactions, especially when anteroposterior, change the face's appearance and PAS dimensions. This study uses barium sulfate paste to enhance lateral cephalograms before and after orthognathic surgery to assess posterior pharyngeal airway changes.

Materials And Methods:  Barium sulfate was mixed with water to make a paste for the tongue's dorsum. A preoperative digital lateral cephalogram was obtained, and a postoperative evaluation was conducted six weeks after the procedure. In the cephalostat, the Frankfort horizontal and median planes were aligned parallel to the floor, and a radiograph was taken after the breathing cycle to standardize the hyoid bone location. Preoperative lateral cephalogram analysis using Burstone's hard tissue landmarks confirmed skeletal class II or III deformities. First, the narrowest part of the posterior pharyngeal airway was measured. Second, the narrowest portion between the soft palate and posterior pharyngeal wall parallel to the Frankfort horizontal plane was measured preoperatively, and the procedure was repeated six weeks postop.

Results:  Complexity characterizes the pharyngeal airway, which, along with the surrounding structures, facilitates the bodily functions of eating, talking, and breathing. The pharyngeal airway is located behind the nose, mouth, and larynx, and adjusting the jaws changes the size and structure of the pharyngeal airway and surrounding soft tissues, which may affect breathing. A statistically significant change is detected in the posterior palatal and posterior lingual airways after different orthognathic operations. After the mandible is moved forward, both the posterior palatal and posterior lingual airways enlarge. Furthermore, the soft palate exhibits slight decreases in length, thickness, and angle. Additionally, there is an anterosuperior displacement of the hyoid bone. Following maxillary superior impaction, mandibular autorotation is seen in a counterclockwise direction, which has the same result as that of mandibular advancement.

Conclusion:  It is essential to consider these soft tissue changes when planning orthognathic procedures, as alterations in the pharyngeal airway may impact the patient's postoperative breathing and overall health. Patients with OSA or those at risk of developing it should be closely evaluated and managed appropriately during the surgical planning process.