Accuracy of Predicting the Pharyngeal Airway Space on the Cephalogram After Mandibular Setback Surgery

PurposeThe aim of the present study was to evaluate the accuracy of a formula predicting the change of pharyngeal airway space (PAS) on the cephalogram after mandibular setback surgery.Patients and MethodsTwenty-nine female adults with mandibular prognathism underwent surgery by bilateral sagittal split ramus osteotomy. The postoperative anteroposterior (A-P) PAS dimension was calculated from the change of C3-Me (distance between the anteroinferior point of the third cervical vertebra and menton) using 2 cephalograms taken before treatment and at 1 year after surgery. The regression equation used was y = −21.105 + 0.402x (y: PAS; x: C3-Me; r = 0.854).ResultsThe predicted and measured values were nearly same on average, and the difference between both ranged within ±1.5 mm for each case individually.ConclusionThis study suggested that the postoperative A-P PAS dimension can be predicted from the change in C3-Me, matching the amount of the mandibular setback.