The short- and long-term changes of upper airway and alar in nongrowing patients treated with Mini-Implant Assisted Rapid Palatal Expansion (MARPE): a systematic review and meta-analysis

Objective This study aims to assess the short- and long-term changes in the upper airway and alar width after mini-implant -assisted rapid palatal expansion (MARPE) in nongrowing patients. Methods Five electronic databases (PubMed, Scopus, Embase, Web of Science, and Cochrane Library) were searched up to 2 August, 2023 based on the PICOS principles. The main outcomes were classified into three groups: 1) nasal cavity changes, 2) upper airway changes and 3) alar changes. The mean difference (MD) and 95% confidence intervals (CI) were used to assess these changes. Heterogeneity tests, subgroup analyses, sensitivity analyses, and publication bias were also analyzed. Result Overall, 22 articles were included for data analysis. Nasal cavity width (WMD: 2.05 mm; 95% CI: 1.10, 3.00) and nasal floor width (WMD: 2.13 mm; 95% CI: 1.16, 3.11) increased significantly. While palatopharyngeal volume (WMD: 0.29 cm 3 , 95% CI: -0.44, 1.01), glossopharyngeal volume (WMD: 0.30 cm 3 , 95% CI: -0.29, 0.89) and hypopharyngeal volume (WMD: -0.90 cm 3 ; 95% CI: -1.86, 0.06) remained unchanged, nasal cavity volume (WMD: 1.24 cm 3 , 95% CI: 0.68, 1.81), nasopharyngeal volume (MD: 0.75 cm 3 , 95% CI: 0.44, 1.06), oropharyngeal volume (WMD: 0.61 cm 3 , 95% CI: 0.35, 0.87), and total volume of the upper airway (WMD: 1.67 cm 3 , 95% CI: 0.68, 2.66) increased significantly. Alar width (WMD: 1.47 mm; 95% CI: 0.40, 2.55) and alar base width (WMD: 1.54 mm; 95% CI: 1.21, 1.87) also increased. Conclusion MARPE can increase nasal cavity width, nasal cavity volume, nasopharyngeal volume and oropharyngeal volume for nongrowing patients, but has no significant effect on hypopharyngeal volume. In addition, the alar width also increased. However, the studies included in this meta-analysis were mainly retrospective, nonrandomized and small in number, so the findings should be interpreted with caution and high-quality RCTs need to be studied.