ReviewImpact on the upper airway space of different types of orthognathic surgery for the correction of skeletal class III malocclusion: A systematic review and meta-analysis

- Two-jaw surgery caused a smaller reduction in the PNS-CSA, EP-CSA, nasopharynx volume and upper airway total volume compared with one-jaw surgery.
- Bimaxillary surgery promotes less decrease on the upper airway than mandibular setback surgery alone for the correction of the skeletal class III malocclusion.

ObjectiveThis study is aimed at assembling, through a systematic review and meta-analysis, scientific evidence related to the effects of mandibular setback (MdS) surgery and bimaxillary surgery for the correction of Class III malocclusion on the cross-sectional area (CSA) and volume of the upper airway as assessed using CT.MethodsAn electronic search was conducted on Cochrane Library, EMBASE, PubMed, Scopus and Web of Science up to June 20, 2016. The inclusion criteria were prospective or retrospective studies, with the aim of comparing the impact on the upper airway space of orthognathic surgery for the treatment of the skeletal class III malocclusion. The methodological index for non-randomized studies (MINORS) was chosen as the evaluation instrument and Revman5.3 was used for the meta-analysis.ResultsA total of 1213 studies were retrieved, of which only 18 met the eligibility criteria. The results of meta-analysis showed that the mean decrease in the upper airway volume after MdS surgery was 3.24 cm3 [95%CI (−5.25,-1.23), p = 0.85]; the mean decrease in minimum CSA after a combined surgery of maxillary advancement with mandibular setback (MdS + MxA) was 27.66 mm2 [95%CI (−52.81,−2.51), p = 0.51], but there was no significant decrease in upper airway volume (mean 0.86 cm3); comparison between MdS + MxA and isolated MdS showed significant differences in the CSA of the posterior nasal spine plane (PNS) and epiglottis plane (EP); statistically significant differences in nasopharynx volume (P < 0.0001) and upper airway total volume (P = 0.002) were observed, but no statistically meaningful variations existed in oropharynx volume (P = 0.08) and hypopharynx volume (P = 0.64).ConclusionThe results of this study suggest that bimaxillary surgery promotes less decrease on the upper airway than mandibular setback surgery alone for the correction of the skeletal class III malocclusion.