AIM: To conduct a systematic review to evaluate and consolidate the existing evidence on the relationship between mouth breathing and P-OSA.
DESIGN: The research question was framed using the PEO format. A comprehensive literature search was conducted through MEDLINE via PubMed, EMBASE, Scopus, LILACS, Web of Science, Cochrane and OVID up to September 2025. Study quality was assessed, and data were managed using Distiller SR software.
RESULTS: The search identified 3722 articles. After removing duplicates, the articles were screened and reviewed, of which 13 studies - 2 cross-sectional and 11 cohort-met inclusion criteria for qualitative analysis. Most studies reported a significant correlation between mouth breathing and OSA severity, with some identifying mouth breathing as a predictor of persistent OSA after adenotonsillectomy. However, variability in diagnostic methods contributed to inconsistent findings.
CONCLUSION: The available literature suggests that mouth breathing is closely linked to P-OSA, playing a key role in both early diagnosis and ongoing assessment of treatment efficacy. Recognizing mouth breathing as an early marker of P-OSA underscores the need for vigilant assessment by healthcare providers.