Investigating the Effect of Mandibular Advancement Devices on Snoring in Obstructive Sleep Apnea Patients

Gruenspan, Grant 1, 2; Saha, Shumit 1, 2; Meisami, Tina 2, 3; Yadollahi, Azadeh 1, 2

1. Institute of Biomaterials and Biomedical Engineering, University of Toronto, Canada; 2. Toronto Rehabilitation Institute-University Health Network, Canada; 3. Faculty of Dentistry, University of Toronto, Canada

Background: Obstructive sleep apnea (OSA) is a respiratory disorder which occurs due to the repetitive collapse of the pharyngeal airway during sleep. A proven treatment for mild to moderate OSA is mandibular advancement devices. Mandibular advancement devices work by moving the lower jaw forward to open up the pharyngeal airway. Snoring, which is mainly caused by narrowing in the pharyngeal airway, may also change with mandibular advancement devices. As snoring is highly associated with OSA, it can be conceivable that mandibular advancement devices have an effect on snoring sounds features. However, the effect of mandibular advancement on snoring has not been previously investigated. Thus, the aim of this research is to conduct a study to determine the effect of mandibular advancement on snoring in OSA patients.

Method: The research was conducted in the oral surgery clinic located at Toronto Rehabilitation Institute. In this study, 20 OSA patients who had undergone mandibular advancement were included. Before treatment, snoring sounds were recorded using a wearable monitoring device during sleep. Then, the recording was repeated in multiple increments of the mandibular advancement device. From the recording, we extracted acoustic features such as intensity and frequency components (formant frequency, spectral centroid, and peak frequency). Independent T-test or Wilcoxon Signed Rank test, based on normality of the data distribution, was used to compare the sound features from before to after the treatment.

Preliminary Results: Data from 1 female subject, BMI: 43.7 kg/m2 and apnea/hypopnea index: 47.9 events/hour was investigated. The mandibular advancement device advanced the mandible by 1.5 mm. This advancement resulted in a significant decrease from before to after treatment in the following snoring sound features: duration (1.07 ± 0.44 vs. 0.86 ± 0.31 s, p<0.001), intensity (4.31 x 108 ± 1.74 x 108 vs. 2.11 x  108 ± 1.17 x 108 J2, p<0.001), first and second formant frequencies (433.58 ± 35.74 vs. 415.97 ± 38.26 Hz, p<0.001; 1330.8 ± 144.97 vs. 1223.5 ± 233.68 Hz, p<0.001), pitch frequency (135.86 ± 35.7 vs. 121.56 ± 27.13 Hz, p<0.001), and spectral centroid (743.08 ± 73.88 vs. 635.61 ± 75.97 Hz, p<0.001). 

Significance: Our results indicate that snoring sound features are reduced from before to after mandibular advancement. Once validated in a larger population, mandibular advancement devices can be used to treat habitual snoring in OSA patients.