Obstructive sleep apnoea (OSA) is a common, chronic condition that affects breathing during sleep. The gold standard for treatment is continuous positive airway pressure (CPAP) which is often not well-tolerated. Mandibular repositioning appliances (MRDs) are an alternative that dentists may be requested to provide.The purpose of this audit is to evaluate the effectiveness of an MRD in improving the Oxygen Desaturation Index (ODI) and Epworth Sleepiness Scale (ESS). A total of 52 patients diagnosed with OSA in an NHS hospital respiratory clinic were fitted with an MRD. Analysis of the digitally recorded oximeter signals was recorded among other treatment outcomes before and 6-8 weeks after the fit of the appliance.The meta-analysis of the audit data showed supportive evidence for MRD treatment in OSA patients. There was a statistically significant reduction in ODI and ESS. The audit population consisted of 138 patients (91 men, 47 women; mean age: 49.49 ± 11.93 years). The ODI outcomes improved significantly, from 10.68 to 6.58 (p <0.02). The ESS improved significantly from 9.46 to 6.02 (p <0.01).This audit demonstrates that MRDs are effective and should be considered as an alternative to CPAP in some specific OSA phenotypes.