Three-dimensional changes to the upper airway after maxillomandibular advancement with counterclockwise rotation: a systematic review and meta-analysis

The aim of this study was to evaluate the effect of counterclockwise (CCW) rotation and maxillomandibular advancement (MMA) on the upper airway space using three-dimensional images. An electronic search was performed in the PubMed, Cochrane Library, Scopus, Virtual Health Library, Web of Science, and OpenGrey databases (end date July 2016); a hand-search of primary study reference lists was also conducted. The inclusion criteria encompassed computed tomography evaluations of the upper airway spaces of adult patients undergoing orthognathic surgery with CCW rotation and MMA. The articles were evaluated for risk of bias with a tool for before-and-after studies. A meta-analysis was performed with the mean differences using a random-effects model. Heterogeneity was assessed with the Q-test and the I2 index. The meta-analysis revealed significant (P < 0.001) increases in both the total airway volume (effect size of 6832 mm3 and confidence interval of 5554-8109 mm3) and the minimum axial area (effect size of 92 mm2 and confidence interval of 70-113 mm2). The heterogeneity was low in both comparisons (I2 = 38% and 7%, respectively). The technique of mandibular advancement with CCW rotation produced significant increases in the volumes and areas of the upper airway spaces.