Functional Factors

     and SAS
  a.1. Indications
         Oral Appliance
   a.3.1. AHI
   a.3.2. Sleep Quality 
   a.3.4. Snoring
   a.3.5. Blood Pressure
   a.3.6. Upper Airway 
             Resistance Syndrome
   a.3.7. Side Effects
   a.4.1. Anatomical Factors
   a.4.2. Functional Factors
   a.4.3. Sleep Position 
         Periodontal Disease
         Heart Disease
         Metabolic Syndrome
Functional factors include respiratory instability, lax tissues surrounding the oropharynx, and deficient contraction of the pharyngeal dilator muscles [8]. The device is successful for obstructive and mixed apneas, but not suitable for central apnea [21, 59], which can occur upon loss of neural chest and abdominal respiratory drive even if the muscles are active and the upper airway is patent [36]. Oral appliances appear to be less effective when the respiratory disturbance index exceeds 40 to 50 per hour, or AHI of > 60 [67]. A recent study reported that the success rate of oral appliance therapy correlated inversely to disease severity [20]. The reasons for the poor beneficial effect in severe cases remain unresolved.