Effect of oral appliance on endothelial function in sleep apnea.

OBJECTIVES: This study evaluated the effects of mandibular advancement device (MAD) on serum levels of nitric oxide derivatives and endothelial function by endothelium-dependent flow-mediated dilation (FMD) in obstructive sleep apnea syndrome (OSAS). METHODS: Thirty patients with moderately severe-to-severe OSAS who desired MAD and 15 healthy controls were prospectively enrolled. FMD was measured by high-resolution B-mode ultrasonography, while serum NO x level from peripheral blood samples was measured by ELISA. All subjects participated in the sleep studies, which were repeated 2 months after MAD in OSAS patients. RESULTS: Serum NO x level and FMD were lower in patients with OSAS than in controls prior to MAD. Serum NO x levels in 19 of 30 patients with OSAS, the designated MAD responders, increased from 11.8 ± 5.8 µM pre-MAD to 22.7 ± 4.9 µM post-MAD. The FMD increased from 5.9 ± 4.6 pre-MAD to 10.5 ± 4.8 post-MAD. For the 11 unresponsive patients, serum NO x and FMD remained impaired after MAD. CONCLUSIONS: Successful treatment of OSAS with MAD can restore serum levels of NO x and FMD. CLINICAL RELEVANCE: Endothelial function can be improved following effective treatment of OSAS using MAD.