The aims of this overview are to evaluate the three-dimensional effects of orthopaedic treatment (OT) and myofunctional therapy (MT) on the enlargement of the upper airways (UA).

A search of the MEDLINE/PubMed and EMBASE databases was conducted up to July 2022 and completed by hand search. After selection of the title and abstract, systematic reviews (SR) dealing with the impact of OT and/or MT on UA containing only controlled studies were included. The methodological quality of the SR was assessed by the AMSTAR-2, Glenny and ROBIS tools. A quantitative analysis was done with Review Manager 5.4.1.

Ten SR were included. The risk of bias was judged low for one SR according to ROBIS. Two SR presented a high level of evidence according to AMSTAR-2. In the quantitative analysis and about the orthopaedic mandibular advancement therapies (OMA), while a significant increase in superior (SPS) [(Mean difference (MD): 1.19; CI 95% [0.59; 1.78]; P<0.0001)] and middle (MPS) pharyngeal space [(MD: 1.10; CI 95% [0.22; 1.98]; P=0.01)] existed in the short-term for both OMA, it was greater for removable. On the other hand, there was no significant change in the inferior pharyngeal space (IPS). Four other SR targeted the short-term efficacy of class III OT. Only treatments with face mask (FM) or face mask+rapid maxillary expansion (FM+RME) allowed a significant increase in SPS [(MD FM: 0.97; CI 95% [0.14; 1.81]; P=0.02/MD FM+RME: 1.54; CI 95% [0.43; 2.66]; P=0.006)]. This was neither the case for chin cup nor in all cases in IPS. The last two SR explored the effectiveness of RME, whether or not associated with bone anchorage, on the dimensions of the UA or on the reduction of the apnoea/hypopnea index (AHI). A significant superiority of the effects of the devices with mixed or only bone anchorages existed concerning the width of the nasal cavity, the nasal airflow and the reduction of the nasal resistance. But, the qualitative analysis showed no significant reduction in AHI after RME.

Despite the heterogeneity of the included systematic reviews and their unfortunately not always low risk of bias, this synthesis showed that orthopaedics could provide some short-term improvement in AU dimensions, mainly in the upper and middle areas. Indeed, no devices improved the IPS. Class II orthopaedics improved SPS and MPS; class III orthopaedics, except for the chin cup, improved only SPS. RME, optimised with bone or mixed anchors, mostly improved the nasal floor.