Is adjustability advantageous in mandibular advancement appliances in the treatment of sleep-disordered breathing?

Mandibular advancement appliances (MAD) that can adjust the amount of mandibular protrusion in response to treatment results are becoming popular with dentists who treat sleep-disorder breathing. Clinicians commonly assume that they are more efficacious and more comfortable to wear than monoblock appliances. An adjustable MAD was compared with one that stabilized the mandible at 70% of the protrusive path. There was not a significant difference in their overall efficacy. The adjustable MAD appeared to be more effective in the more severe cases, presumably due to the greater mandibular advancement; the nonadjustable MAD appeared to be more effective in the less severe cases, presumably due to the greater mandibular stabilization. Existing research was examined and biomechanical principles were considered. Insufficient research exists to definitely evaluate the pros and cons of adjustability vs. stability. There does not appear to be sufficient evidence to support the assumption that adjustable MADs are more efficacious or more comfortable to wear than monoblock appliances.