Effects of rapid maxillary expansion on upper airway morphology and respiratory function: a scoping review
Authors
Luca Esposito, Francesca Calò, Aia Amin, Sabrina Ardizzone, Antonino Manti, Andrea Palermo, Lucia Memè
Abstract
Background: Transverse maxillary deficiency in growing patients has been linked to decreased nasal cavity dimensions, heightened nasal airway resistance, and an increased incidence of mouth breathing. Rapid maxillary expansion (RME) is a well-established orthopedic intervention for addressing maxillary constriction, and its possible influence on upper airway morphology and respiratory function has attracted growing interdisciplinary interest.
Objective: To systematically review and synthesize the available evidence concerning the impact of RME on the morphology of the upper airway and respiratory parameters, with particular emphasis on alterations in the nasal cavity, modifications of the pharyngeal airway, and associated functional respiratory outcomes.
Methods: A scoping review was conducted by searching PubMed, Embase, and Web of Science for studies published between 2011 and 2026 evaluating morphological and/or functional respiratory outcomes following RME. Randomized clinical trials, prospective and retrospective clinical studies, and case series were eligible. Records were screened at title/abstract and full-text levels based on predefined criteria, and data were charted by outcome domain, including airway morphology (CT/CBCT), nasal airflow and resistance (e.g., rhinomanometry), pulmonary function (spirometry), and patient-reported respiratory outcomes.
Results: Sixteen studies met the inclusion criteria. Most studies reported enlargement of the nasal cavity after RME, particularly in the inferior/anterior regions, and reductions in nasal airway resistance when assessed by rhinomanometry. Improvements were more frequently reported among mouth-breathing patients and those with baseline nasal obstruction. In contrast, pharyngeal airway findings were heterogeneous, and spirometry outcomes were assessed in fewer studies and were generally inconsistent and of modest magnitude.
Conclusions: Available evidence indicates that RME reliably improves nasal airway morphology and nasal breathing, whereas its effects on the pharyngeal airway and pulmonary function remain variable. RME may provide adjunctive respiratory benefits in selected growing patients with compromised nasal breathing; however, standardized longitudinal studies are needed to clarify long-term outcomes and clinical relevance.
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