Purpose: The therapy with mandibular advancement devices (MADs) represents a treatment option for patients with obstructive sleep apnea (OSA). The literature does not provide evidence regarding the most effective mandibular advancement; therefore, the aim of this systematic review with meta-regression was to investigate the effectiveness of different mandibular advancement amounts in reducing apnea-hypopnea index (AHI) in OSA patients.
Methods: An electronic search was performed in MEDLINE, Cochrane Database, Google Scholar Beta, ISI Web of Knowledge, Scopus, and LILACS to select randomized controlled trials (RCTs) investigating the efficacy of MADs in reducing AHI in adult OSA patients. Inclusion criteria were the diagnosis of OSA and success evaluation performed with a polysomnography, follow-up of maximum 12 months, and protrusion amount reported as a percentage of the maximum mandibular advancement. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. The success rate of each study was computed: [(mean AHI at baseline-mean AHI after treatment)/mean AHI at baseline].
Results: Thirteen RCTs performing advancements from 50 to 89 % of maximum mandibular protrusion were included. The meta-regression analysis showed that advancement amounts higher than 50 % do not significantly influence the success rate (Q = 0.373, p = 0.541). According to the GRADE score system, the quality of evidence resulted to be moderate.
Conclusion: The AHI improvement resulted to be not proportional to the mandibular advancement increase. It is plausible that the success of the therapy is influenced by a combination of variables that need closer study.
Keywords: Mandibular advancement device; Obstructive sleep apnea; Sleep disordered breathing; Sleep disorders; Temporomandibular disorders.