Evaluation of Airway Dimensions Following Mandibular Setback with Surgery-First Orthognathic Versus Conventional Orthognathic Approach.

BACKGROUND: To evaluate changes in airway dimensions following mandibular setback with conventional orthognathic approach (COA) and surgery-first orthognathic approach (SFOA).
MATERIALS AND METHODS: Treatment records of 20 patients who underwent mandibular setback with SFOA/COA were divided into two groups (COA and SFOA, ten patients in each group). Acoustic pharyngometry values were obtained at T0 (01 week prior to surgery), T1 (01-month post-surgery) and T2 (01-year post-surgery). Percentage change in mean volume and area was obtained at T1 (T1-T0) to evaluate airway changes and at T2 (T2-T1) to compare relapse of airway changes in both groups. Changes in airway per mm setback at T1 (T1-T0) and T2 (T2-T1) were also obtained in both groups.
RESULTS: For both parameters, SFOA showed greater reduction at T1 and greater relapse at T2 as compared to COA. The reduction in airway volume at T1 was 0.56 mm/mm setback in COA compared to 1.06 mm/mm setback in SFOA (P-value > 0.05). The relapse in airway volume at T2 was 0.15 mm/mm setback in COA compared to 0.25 mm/mm setback in SFOA (P-value > 0.05). The reduction in area at T1 was 0.062 mm/mm setback in COA compared to 0.110 mm/mm setback in SFOA (P-value > 0.05). The relapse in area at T2 was 0.016 mm/mm setback in COA compared to 0.034/mm setback in SFOA (P-value < 0.05).
CONCLUSION: In setback cases, SFOA has greater airway reduction immediate post-surgically and greater relapse at 01-year follow-up. Predicting these changes at diagnostic and treatment planning stage may prevent potential adverse events on airway. © The Association of Oral and Maxillofacial Surgeons of India 2020.