Abstract
Background: Chronic anemia and craniofacial changes associated with transfusion-dependent β-thalassemia (TDT) may influence upper airway function and occlusal development. However, evidence regarding mouth breathing, STOP-Bang questionnaire findings, and associated occlusal characteristics in adults with TDT remains limited. Objective: To investigate associations between mouth breathing and STOP-Bang questionnaire findings while exploring malocclusion characteristics and other oral functional features among adults with TDT. Participants and Methods: We conducted a cross-sectional study that included 153 adults with TDT. STOP-Bang classified OSA screening risk; clinical examinations and interviews assessed dentofacial, functional, and patient-reported characteristics. Group comparisons used chi-square or exact tests with Benjamini–Hochberg correction. Firth-penalized logistic regression evaluated a three-item score comprising snoring, observed apnea, and high blood pressure, modeling open bite and mouth breathing as outcomes. Models adjusted for age, sex, BMI, and hemoglobin, followed by mutual adjustment for the other oral feature. Adjusted full-score models were retained as sensitivity analyses. Significance was set at p < 0.05 or FDR-adjusted q < 0.05. Results: Among 153 adults, 113 (73.9%) had low STOP-Bang scores and 40 (26.1%) scored ≥3. Vertical occlusal relationships differed between groups (q = 0.033), with open bite observed in 30.0% versus 12.4%. Mouth breathing was more frequent in the higher-score group (80.0% versus 35.4%; q < 0.001). In exploratory reduced-score analyses, open bite was associated with higher scores after core adjustment (aOR 1.68, 95% CI 1.04–2.75; p = 0.036). The estimate attenuated following additional adjustment for mouth breathing (aOR 1.50, 95% CI 0.86–2.58; p = 0.147), while mouth breathing remained associated after adjustment for open bite (aOR 3.40, 95% CI 2.08–5.95). Conclusions: Among adults with TDT, mouth breathing was associated with STOP-Bang questionnaire findings, while vertical occlusal relationships differed between score groups. Anterior open bite showed a significant association in the core-adjusted reduced-score model, which attenuated following adjustment for mouth breathing without excluding an association. Objective sleep assessments are needed to clarify the clinical significance of these findings.