Rationale: Mouth breathing increases upper airway collapsibility, leading to decreased efficacy of obstructive sleep apnea (OSA) treatments. We hypothesized that the use of mandibular advancement devices (MAD) increases mouth breathing, and thus, using an adhesive mouthpiece (AMT) to prevent mouth breathing in combination with MAD can improve the treatment efficacy. Objectives: To evaluate the efficacy of MAD + AMT in comparison with MAD alone. Methods: A prospective crossover pilot study was designed to test this hypothesis. Briefly, adult participants with an apnea-hypopnea index (AHI) between 10 and 50 events/h at the screening visit were randomized to no treatment (baseline), MAD treatment, AMT treatment, and MAD + AMT treatment. As a primary analysis, absolute AHI was compared between MAD and MAD + AMT arms. Secondary analyses included quantifying the percent change in AHI, percentage of complete (AHI < 5 events/h) and incomplete (5-10 events/h) responders, and the efficacy of AMT alone in comparison with other treatment arms. Results: A total of 21 participants were included (baseline AHI = 24.3 ± 9.9 events/h). The median AHI (interquartile range) in the MAD and MAD + AMT arms were 10.5 (5.4-19.6) events/h and 5.6 (2.2-11.7) events/h (P = 0.02), respectively. A total of 76% of individuals achieved an AHI of <10 events/h in the MAD + AMT arm versus 43% in the MAD arm (P < 0.01). Finally, the observed effect was similar in moderate to severe OSA (AHI ⩾ 15 events/h) in terms of absolute reduction and treatment responders, and AMT alone did not significantly reduce the AHI compared with baseline. Conclusions: A combination of an adhesive mouthpiece and MAD is a more effective therapy than MAD alone. These findings may help improve clinical decision making in sleep apnea.
Keywords: mandibular advancement; mouth breathing; obstructive sleep apnea; oral appliance.