Correlation Between Severity of Obstructive Sleep Apnea and Dental Arch Form in Adults

<b>Objectives:</b> This study examines the relationship between maxillary morphology and the severity of obstructive sleep apnea (OSA) in adults, with a focus on intermolar distance (IMD) and palatal height (PH) as predictive factors. <b>Methods:</b> A retrospective observational study was conducted at private orthodontic practices in Sydney, Australia. A total of 100 adults (50 OSA patients and 50 controls) were included. OSA diagnosis and severity were confirmed via hospital-based polysomnography. Digital maxillary models were analyzed using the Medit Link software (version 3.2.0; Medit Corp., Seoul, Republic of Korea), and IMD and PH were measured. Statistical analyses included one-way ANOVA and linear regression modeling, with adjustments for age and sex. <b>Results:</b> The OSA group exhibited significantly narrower IMD (28.96-35.01 mm) and higher PH (21.68-29.56 mm) compared to the control group (IMD: 36.35-41.50 mm; PH: 18.57-23.51 mm). A negative correlation was observed between IMD and PH across all groups. Linear regression analysis demonstrated a strong association between these craniofacial parameters and OSA severity (R² = 0.76, <i>p</i> < 0.001). IMD was negatively correlated with the Apnea-Hypopnea Index (AHI) (<i>p</i> = 0.003), while PH was positively correlated (<i>p</i> < 0.001). The inclusion of demographic variables did not significantly enhance the predictive model. <b>Conclusions:</b> Maxillary morphology associates with OSA severity, with narrower IMD and greater PH linked to higher AHI.