Tongue strength, hard palate morphology and adenotonsillar hypertrophy in schoolchildren with early mixed dentition: a cross-sectional study

BACKGROUND: Adenotonsillar hypertrophy (ATH) relates to airway obstruction and orofacial changes in children. Whether adenoid hypertrophy (AH), palatine tonsil hypertrophy (PTH), and combined ATH were associated with distinct patterns of hard palate morphology and tongue function in the early mixed dentition remains unclear. METHODS: This cross-sectional study examined 420 schoolchildren aged 6-8 years in central Vietnam. AH was defined by the Fujioka adenoid-nasopharynx ratio (ANR > 0.6) and PTH by Brodsky grades 3-4; tongue strength was measured with the Iowa Oral Performance Instrument, and hard palate morphology by digital dental-cast analysis. Multivariable regression (adjusted for age, sex, BMI, lip-seal at rest, and school location) analyzed individual measures; modified Poisson regression analyzed a co-occurring phenotype (structural alteration plus low tongue strength). Univariable comparisons applied Benjamini-Hochberg false-discovery-rate (FDR) correction. RESULTS: Enlarged lymphoid tissue was present in 65.2% of children (AH only 19.3%, PTH only 32.6%, combined ATH 13.3%); tapered arch (31.0%), high-arch palate (20.0%), and low tongue strength (35.0%) were common. Nominally, AH was associated with a deeper, shorter palate, and PTH with a narrower tapered arch and lower tongue strength; but none survived FDR correction (smallest q = 0.16). In adjusted models, combined ATH was associated with a smaller anterior maxillary angle (β = -3.76°; 95% CI -6.22 to -1.29; p = 0.003) and palatal vault module (β = -0.54; -1.02 to -0.05; p = 0.032), each decreasing with adenotonsillar burden (both trends p ≤ 0.020). The co-occurring phenotype (77 children; 18.3%) became more common with burden (PTH only aPR 1.77, p = 0.040; combined ATH aPR 1.87, p = 0.048; trend aPR 1.38 per level, p = 0.020). CONCLUSIONS: Adenotonsillar hypertrophy was common in schoolchildren with mixed dentition. AH and PTH showed distinct patterns of palate and tongue alteration, although these did not survive FDR correction and remain exploratory. Combined ATH and greater adenotonsillar burden were consistently associated with maxillary arch narrowing; the co-occurrence alteration was also more frequent with higher burden. These findings support including palatal morphology and tongue function in orofacial screening during the mixed dentition, pending longitudinal confirmation.