(HealthDay)—For individuals with obstructive sleep apnea (OSA) treated with an optimally titrated mandibular advancement splint, normalization of the respiratory effort index derived from vertical mandibular movements (MM-REI) reflects the efficacy of the appliance, according to a study published online Nov. 6 in Chest. Jean-Benoit Martinot, M.D., from the CHU UCL Namur Site Sainte-Elisabeth in Belgium,