The effect of maxillary protraction, with or without rapid palatal expansion, on airway dimensions: A systematic review and meta-analysis.

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.