Dental arch dimension and palatal morphology in children and adolescents with mouth breathing: a systematic review and meta-analysis

Mouth breathing (MB) may negatively affect facial and dental morphology in children, potentially causing malocclusion and other abnormalities. However, its effects, such as narrowing of the dental arches and a higher palatal vault, remain controversial. This study aimed to evaluate dental arch and palatal morphology in MB children, vital for orthodontic diagnosis and treatment planning. A search was conducted in MEDLINE, Embase, Cochrane Library, LILACS, and Scopus for studies published until December 2025. The review included clinical trials and observational studies comparing dental dimensions in MB and normal breathing (NB) children under 18, using plaster or 3D dental casts. Two independent reviewers screened titles, abstracts, and full texts, with data analysed using Revman software. Of 7,995 studies identified, 13 studies were included in the meta-analysis. The results indicated a significant reduction in upper intercanine width (UICW; p = 0.02) and intermolar widths (UIMW; p = 0.01, LIMW; p = 0.02) in MB children. However, the lower ICW (p = 0.54), palatal width (at canines; p = 0.09, at primary second molars; p = 0.36, at permanent first molars; p = 0.13) and palatal depth at canines (p = 0.82) and first premolars (p = 0.13) were comparable between both groups. Palatal depth at second premolar and molar positions (p = 0.0001, p = 0.04, respectively) and posterior crossbite frequency (p < 0.00001) were higher in MB group. MB children exhibit narrower upper arches at canines and molars, with decreased width only at molars in the lower arch. Furthermore, MB children tend to exhibit deeper palate in the posterior region, and there is an increased prevalence of posterior crossbite among them.