The Effects of Oral Appliance Therapy on Masseter Muscle Activity in Obstructive Sleep Apnea
Condition: Obstructive Sleep Apnea
MeSH terms: Apnea; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
Study type: Interventional

Summary: 
      Previous studies have shown that contractions of the jaw-closing masseter muscle (MAS) often
      occur shortly after respiratory events during sleep in obstructive sleep apnea (OSA)
      patients. Although it has been hypothesized that such non-specific motor activations may
      contribute to restoration of a compromised upper airway during respiratory events, proper
      physiological understanding of MAS contractions in patients with OSA is lacking. MAS
      contractions are usually associated with the termination of respiratory events, but these
      contractions do not always occur after respiratory events. Therefore, the above-stated
      hypothesis that "non-specific motor activations of the jaw-closing masseter muscle (MAS) may
      contribute to restoration of a compromised upper airway during respiratory events" is not
      accepted yet. Further, Kato et al. concluded from a recent study that MAS contraction is an
      orofacial manifestation of a general motor reaction to arousal occurring during sleep in OSA
      patients. This suggests that MAS contraction after a respiratory event is dependent on the
      arousal response rather than on the respiratory events per se.
    

Detailed description: 
      OSA patients will be invited for participation in this study when they fulfil the
      predetermined inclusion criteria and exclusion criteria. The number of OSA patients that will
      be included for this study will be 25 based on a power analysis with a power of 80% and a
      significance level of 5% (two-sided). Informed consent will be obtained by signing form
      approved by the ethics board of the Université de Montréal.

      The patients will be instructed to wear the mandibular advancement appliance (MAA) every
      night upon delivery. After a habituation period of three to six months patients will undergo
      two follow-up polysomnographic (PSG) recordings (see below).

      The study has a randomized controlled crossover design, in which two experimental conditions
      (with MAA in situ versus without MAA in situ) will be compared in random order. A washout
      period of one week will be used for the MAA therapy.The study consists of three PSG
      recordings per patient: a baseline recording for the inclusion/exclusion of patients, and two
      follow-up recordings. The first and second follow-up nights will be used to establish, in a
      random order, the baseline for masseter muscle activity and arousals, and the effects of the
      MAA on these parameters. The two follow-up recordings will be performed within one week.

      The ambulatory follow-up PSG recordings will be obtained at home. The mounting will be
      performed by a trained sleep technician. PSG recordings are made using surface electrodes
      according to the standard technical protocol used in previous OSA studies at the same
      laboratory.

      The PSG recordings will be scored manually in 30-s epochs, and standard sleep and respiratory
      outcome variables will be obtained. All data analyses will be performed under blind
      conditions for the PSG recordings (with or without an MAA in situ) by one technician.
    

Intervention name(s): mandibular advancement appliance
Intervention type(s): Device
Intervention description(s): mandibular advancement appliance
Other intervention name(s): mandibular advancement splint; oral appliance; mandibular repositioning splint; mandibular repositioning appliance
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Other
Keywords: obstructive sleep apnea; oral appliance; therapy; masseter muscle activity; randomized controlled trial; mandibular advancement device; mandibular advancement appliance; arousals