Background: Obstructive sleep apnea (OSA) is associated with endothelial dysfunction. In the current study, we assessed the effect of long-term modified Herbst mandibular advancement splint (MAS) treatment on OSA, oxidative stress markers, and on endothelial function (EF).
Methods: A total of 16 subjects participated (11 men and 5 women; mean [± SD] age, 54.0 ± 8.3 years; mean body mass index, 28.0 ± 3.1 kg/m2), 12 of whom completed the 1-year evaluation. Apnea severity, levels of oxidative stress markers, and EF were assessed after 3 months and 1 year of receiving treatment. For comparison, 6 untreated patients underwent two evaluations 9 months apart, and 10 non-OSA individuals were assessed once as a reference group. The results are presented as the mean ± SD.
Results: The mean apnea-hypopnea index (AHI) decreased significantly from 29.7 ± 18.5 events/h before treatment to 17.7 ± 11.1 events/h after 3 months of treatment and 19.6 ± 11.5 events/h after 1 year of treatment (p < 0.005 for both). The mean Epworth sleepiness scale score decreased significantly from 12.4 ± 6.0 before treatment to 10.2 ± 6.6 after 3 months of treatment and 7.8 ± 3.8 after 1 year of treatment (p < 0.001 for both). The mean EF improved significantly from 1.77 ± 0.4 before treatment to 2.1 ± 0.4 after 3 months of treatment (p < 0.05) and 2.0 ± 0.3 after 1 year of treatment (p = 0.055), which were similar to the values of the reference group. Thiobarbituric acid-reactive substance (TBARS) levels decreased from 18.8 ± 6.2 nmol malondialdehyde (MDA)/mL before treatment to 15.8 ± 3.9 MDA/mL after 3 months of treatment (p = 0.09) and 15.5 ± 3.2 nmol MDA/mL after 1 year of treatment (p < 0.05). There was a correlation between the improvement in AHI and in EF or TBARS levels (r = 0.55; p = 0.05). The untreated control group remained unchanged.
Conclusions: The Herbst MAS may be a moderately effective long-term treatment for patients with OSA. EF improved to levels that were not significantly different than reference levels, even though apneic events were not completely eliminated. We think that these data are encouraging and that they justify the performance of larger randomized controlled studies.