Aim: The use of maxillary protraction appliances (MPAs) and Facemask (FM), with or without a rapid maxillary expansion (RME), have become a routine orthopaedic treatment procedure for the treatment of Class III in growing individuals; several authors have suggested that maxillary protraction could have a positive impact on airway dimensions. The purpose of this systematic review and meta-analysis was to assess the efficacy of maxillary protraction appliances (MPAs), with or without a rapid maxillary expansion (RME), on airway dimensions in children in mixed or early permanent dentition.
Materials and methods: An electronic search was performed on PubMed, Medline, Scopus, The Cochrane Library, EMBASE and the System for Information on Grey Literature in Europe until November 30th, 2019. The Newcastle-Ottawa (NOS) scale was used to assess the studies' quality. Review Manager 5.3 (provided by the Cochrane Collaboration) was used to synthesize the effects on airway dimensions.
Results: After full text assessment, 8 studies were included in the qualitative and quantitative synthesis. NOS scores ranged 6 to 9 indicating high quality. The effects of two therapeutic protocols were compared, treatment with MPAs only (113 subjects treated - 65 controls) and the treatment with MPAs + RME (137 subjects treated- 87 controls). The MPAs only treatment group displayed a significantly increase in nasopharyngeal airway dimension at PNS-AD1 (random: mean difference, 1.39 mm, 95% CI, 0.32 mm, 2.47 mm, p= 0.01) and at PNS-AD2 (random: mean difference, 1.70 mm, 95% CI, 1.14 mm, 2.26 mm, p= 0.00001). No statistically significant changes were found post treatment in MPAs + RME treatment groups at PNS-AD1 (P= 0.15), PNS-AD2 (P= 0.17), McNamara's upper pharynx (MPAs + RME P= 0.05, MPAs P= 0.99) and McNamara lower pharynx (MPAs + RME P= 0.25, MPAs P= 0.40).
Conclusion: MPAs only treatment can increase the pharyngeal thickness after treatment both at PNS-A1 and PNS-AD2. MPA+ RME had no effect on sagittal widths compared with controls, but the effect on the transverse dimension could not be assessed.