Two-Year Postoperative Upper Airway Cone-Beam Computed Tomographic Outcomes Based on a Verified Upper Airway Analysis Following Bimaxillary Orthognathic Surgery

Abstract

Upper airway (UA) assessment after orthognathic surgery should rely on a verified method of UA analysis. Therefore, the authors applied a new validated UA evaluation method to determine the effect of bimaxillary surgery (BMS) on UA parameters and hyoid bone and epiglottis displacement evaluated immediately and 2years after surgery. A retrospective cohort study was implemented of patients without obstructive sleep apnea who had undergone BMS for maxillomandibular deficiencies. A new validated UA cone-beam computed tomographic (CBCT) analysis, based on stable anatomic landmarks, was applied to CBCT scans acquired before initiation of treatment (T0), immediately after surgery (T1), and 2years postoperatively (T2). A quality assessment was performed before analysis. The primary predictor variable consisted of time points during treatment (T0, T1 and T2), and UA volumes, cross-sectional area (CSA), and hyoid bone and epiglottis displacement were the outcome variables. Descriptive statistics and t test were performed and the P value was set at .05. Fifty patients (16 men and 34 women) with a mean age of 25.7±8.2years at time of surgery were included. CBCT scans were acquired at T0 (20±9months before surgery), T1 (14±2days after surgery), and T2 (30±6months after surgery). Immediately after surgery (T1 vs T0), BMS resulted in a statistically relevant UA volume increase of 26%. At 2-year follow-up (T2 vs T0), UA volume showed a statistically relevant increase by 20%. CSA increased by approximately 26 and 19% (P<.001) at T1 versus T0 and T2 versus T0, respectively. Two years after surgery, epiglottis displacement was 2mm(P<.001) and hyoid bone displacement was 3mm(P<.001) in a cranial direction and hyoid bone anterior displacement measured 3mm(P<.001). Based on an objective, standardized, and validated CBCT UA analysis, BMS was associated with increased UA volume and CSA measures evaluated immediately and 2years after surgery.