Three forms of therapy interventions were used in this parallel-group study. First, an individually fabricated MAD with an adjustable protrusive mandibular position at a constant vertical dimension was used. Second, nCPAP of the REMstar Pro system was used (Respironics, Herrsching, Germany). Third, a thin (< 1 mm), hard acrylic-resin palatal splint with only a partial palatal coverage was used as a placebo.