Efficacy of the twin-block appliance for pediatric obstructive sleep apnea: an updated systematic review and meta-analysis

OBJECTIVE: To provide an updated and robust assessment of the efficacy of the Twin-Block appliance in the treatment of pediatric obstructive sleep apnea (OSA). A previous meta-analysis indicated a potential benefit, but was limited by the quality of available evidence and is now outdated. This study aims to synthesize all current evidence, including recent high-quality randomized controlled trials (RCTs). METHODS: This systematic review and meta-analysis was conducted following PRISMA guidelines. A comprehensive search of PubMed, Embase, Cochrane Library, and Web of Science was performed up to October 2025. We included RCTs, non-randomized controlled trials (NRCTs), and case series evaluating the effect of the Twin-Block appliance on respiratory parameters in children (< 18 years) with OSA. The primary outcome was the change in the Apnea-Hypopnea Index (AHI). A random-effects model was used to calculate the pooled Mean Difference (MD) and 95% Confidence Intervals (CIs). Sensitivity analyses were performed, and the risk of bias was assessed using design-specific tools (RoB 2, ROBINS-I, and the JBI Critical Appraisal Checklist). RESULTS: Eight studies, comprising a total of 259 patients, were included in the systematic review. The meta-analysis of seven studies (n = 219) demonstrated that Twin-Block therapy resulted in a statistically significant and clinically meaningful reduction in AHI (pooled MD: -6.68, 95% CI: -8.76 to -4.60; p < 0.0001). Significant heterogeneity was observed across studies (I² = 89.1%). A recent high-quality RCT, while not poolable due to a different outcome measure, provided mechanistic evidence by showing a significant increase in oropharyngeal airway volume with Twin-Block treatment compared to a control group. The findings remained robust in sensitivity and leave-one-out analyses. CONCLUSION: This updated meta-analysis provides strengthened evidence that the Twin-Block appliance is an effective treatment for reducing the severity of OSA in appropriately selected children. The therapeutic effect is likely mediated by structural enlargement of the upper airway. Despite the heterogeneity and limitations in the primary literature, these findings support the consideration of the Twin-Block appliance as a viable non-surgical intervention for pediatric OSA, particularly in patients with mandibular retrognathia. Future large-scale RCTs are warranted to confirm these findings and establish long-term effectiveness.