This study aimed to investigate the clinical, skeletal, pharyngeal airway, and sleep characteristics of skeletal Class III subjects with and without obstructive sleep apnea (OSA).

A retrospective case–control study was conducted in 46 subjects (18 with OSA and 28 without OSA). Medical records, cephalometric analyses, cone-beam computed tomography, Thai versions of the Epworth Sleepiness Scale, modified STOP-Bang Questionnaire (SBQ), and sleep study results were evaluated.

The OSA group predominantly comprised males and exhibited higher body mass index (BMI) and larger neck circumference. Sleep analysis showed that subjects with OSA had higher modified SBQ scores, higher snoring level, increased light sleep, and reduced REM sleep stages compared with non-OSA subjects. Among skeletal variables, only mandibular length (Go–Gn) was significantly shorter in the OSA group. Pharyngeal airway revealed a longer uvula, increased airway length, and narrower lateral dimensions of the upper segment of pharyngeal airway. Univariable analysis identified male sex, BMI >25 kg/m², neck circumference >40 cm, modified SBQ score ≥3, snoring, and mandibular length < 80 mm as factors associated with OSA. In multivariable logistic regression analysis, male sex ( adjusted OR  = 8.11, 95%CI : 1.10–59.51, p  = 0.040) and mandibular length < 80 mm ( adjusted OR  = 8.40, 95%CI : 1.05–67.17, p  = 0.045) remained significantly associated with OSA.

Within skeletal Class III subjects, OSA was associated with male sex and shorter mandibular length, while differences in regional airway morphology were observed in the unadjusted analyses. Integrating clinical and imaging parameters may provide complementary information for identifying skeletal Class III patients at increased risk of OSA.