Appliances Therapy in Obstructive Sleep Apnoea: A Systematic Review and Meta-Analysis

Obstructive sleep apnea (OSA) is a recurrent partial or complete obstruction of the upper airway during sleep caused by narrowing or collapse of the pharyngeal wall. It leads to microstimulation and oxyhemoglobin desaturation, resulting in sleepiness and loud snoring. OSA negatively affects the cardiovascular system and may contribute to neurocognitive impairment. The aim of this systematic review is to evaluate the effectiveness and efficacy of appliance therapy in obstructive sleep apnea. The effectiveness was assessed by using the Apnea Hypopnea Index (AHI). An electronic search of the Cochrane Library, PubMed, and Google Scholar was conducted between 1998 and 2021. Articles were independently assessed by three reviewers. The quality of a randomised control trial (RCT) is assessed using the Cochrane risk of bias method. The tool GRADE was used to achieve the desired level of confidence for each outcome reported. Several studies used continuous positive airway pressure (CPAP), mandibular advancement devices (MAD), and tongue retention devices (TRD). The meta-analysis included a total of six papers that met the inclusion criteria. Results showed that CPAP significantly improved AHI compared with an oral appliance (random effects: difference in means = 8.40, 95% CI = 7.21 to 9.60). It was also found that oral appliance (OA) therapy significantly improved AHI compared with baseline before appliance therapy (random effects: mean difference = 13.40, 95% CI = 10.87 to 15.93; p.00001). For mild to moderate OSA, CPAP is considered the gold standard. Our meta-analysis of six RCTs found favorable evidence for OSA patients receiving oral devices; however, they were less effective than CPAP. A subgroup analysis found that MAD may be a beneficial treatment for mild to moderate OSA patients who do not respond to CPAP. The findings suggest that oral appliances may be an effective treatment for OSA, especially in patients with mild to moderate OSA.