BACKGROUND: Oral torus assessment is recommended as a part of routine craniofacial examination in patients with obstructive sleep apnoea (OSA). However, there are conflicting studies on whether oral torus is associated with OSA and whether it affects OSA therapy. OBJECTIVE: This study aimed to systematically review the effects of mandibular torus on OSA and its treatment. METHODS: The PubMed, Embase and Cochrane Library databases were searched up to 15 July 2024. Studies that included patients with oral torus and examined the diagnosis and severity of OSA (Apnoea-Hypopnea Index [AHI], oxygen saturation, blood pressure and patient-reported outcomes), and studies that examined the effectiveness of OSA treatment in patients with oral torus were included. PRISMA guidelines were followed for data extraction. RESULTS: Eleven studies with 1372 patients were included in the study. Patients with mandibular torus were found to have a relative risk of 1.9 (95% CI = 0.9
4.1) for OSA. The pooled mean difference in AHI between patients with and without mandibular torus was 1.6 (95% CI = -5.3
8.6). Large mandibular torus was found to be associated with mild and moderate OSA but not with severe OSA. A greater reduction in AHI after mandibular advancement device or soft-tissue OSA surgery can be achieved in patients with torus. However, the difference was not significant when compared to patients without it. CONCLUSION: Patients with mandibular torus are more likely to have OSA. Larger mandibular torus may be associated with mild or moderate OSA but not severe OSA. Mandibular torus does not impede OSA treatment.