Abstract: Objective: To improve the constructure of the common mandibular advancement appliance and evaluate the clinical effect of the modified oral appliance on the treatment of mild to moderate OSA. Methods: Forty patients with mild to moderate OSA(5＜AHI＜30) diagnosed by polysomnography (PSG) were included in the study. All subjects were divided into the experimental group and the control group randomly. The PSG was monitored for all subjects before and after 3 months treatment respectively. The diversity was calculated between two groups on the basis of the AHI, LSaO₂, and sleep structures recorded by PSG. At the same time, the subjective symptom was collected by questionnaire. Results: Compared to pretreatment, 40 patients responded to the appliance therapy. Apnea hypopnea index in 18 patients of the experimental group was reduced by 50%, the efficiency was 90%, significantly higher than the control group. Lowest arterial oxygen saturation improved significantly in two groups (P<0.05) . The N1% was shorter and the N2% and N3% were longer compared with preoperative status in the experimental group (P<0.05). Disordered sleep patterns in the control group improved not obviously. Falling of snore guards didn't occur in the experimental group. Conclusion: Modified oral appliance is more effective in the treatment of mild to moderate OSA than traditional mandibular advancement appliance.

Key words: Sleep apnoea hypopnea syndrome, Obstructive , Modified oral appliance, Polysomnography.