Comparison of Sleep Quality Across Different Sagittal Skeletal Patterns in Orthodontic Patients

Background/Objectives: Sagittal skeletal patterns are associated with upper airway dimensions, which may influence breathing during sleep and potentially relate to sleep quality. We hypothesized that global Thai-Pittsburgh Sleep Quality Index (Thai-PSQI) scores would differ among skeletal Class I (Sk-I), Class II (Sk-II), and Class III (Sk-III) groups. Methods: This cross-sectional study was conducted at the Department of Orthodontics, Faculty of Dentistry, Thammasat University, from June 2023 to March 2024. Ninety-three patients aged 18–50 years presenting to initiate orthodontic treatment were classified by ANB angle as Sk-I (0.5–5.1°), Sk-II (>5.1°), or Sk-III (<0.5°), with 31 participants per group. Sleep quality was assessed using the Thai-PSQI; scores > 5 indicated poor sleep quality. Sex, age, and BMI were analyzed as demographic variables. Results: Mean global PSQI scores were 6.42 ± 2.71, 6.68 ± 3.39, and 6.26 ± 2.46 for Sk-I, Sk-II, and Sk-III, respectively. Global PSQI scores did not differ significantly among skeletal groups (H = 0.024, p = 0.988, ε2 < 0.001). Overall, 55.9% of participants were poor sleepers, and the distribution of good and poor sleepers did not differ among groups (χ2 = 1.134, p = 0.567, Cramer’s V = 0.110). No significant associations were observed between global PSQI and sex, age, or BMI (p = 0.279, 0.848, and 0.948, respectively). Conclusions: No statistically significant differences in subjective sleep quality were identified among the three sagittal skeletal groups in this sample.