Abstract

Initial mandibular position might be a key factor leading to rapid therapeutic outcome in oral appliance therapy for patients with obstructive sleep apnea (OSA). The purpose of this study was to investigate the effects of an adjustable oral appliance on nasal resistance in 7 nonapneic patients. Upright and supine nasal resistance was measured for each subject with an adjustable oral appliance in place in 3 mandibular positions: most retruded (MAX0), maximum protrusion (MAX100), and 67% of MAX100 (MAX67). A significant decrease in upright and supine nasal resistance was observed between MAX0 and MAX67 (P < .01), and between MAX0 and MAX100 (P < .01), but not between MAX67 and MAX100. In addition, there was a positive correlation between the nasal resistance at MAX0 and the nasal resistance change from MAX0 to MAX67 (P < .01), indicating that when the mandible was advanced from MAX0 to MAX67, the more nasal resistance at MAX0, the greater the reduction in nasal resistance at MAX67. These findings suggest that MAX67 might be indicated as the initial mandibular position and that gradual anterior titration of mandibular position beyond MAX67 would give OSA patients rapid therapeutic effects by reducing the nasal resistance. Moreover, OSA patients with augmented nasal resistance at MAX0 might have a greater reduction in nasal resistance in response to MAX67 in oral appliance therapy.