[Efficacy of oral appliance therapy of obstructive sleep apnea and hypopnea syndrome in different periods of treatment].

OBJECTIVE: To investigate the long-term efficacy of oral appliance treating of obstructive sleep apnea and hypopnea syndrome (OSAHS) in different periods of treatment.

METHODS: A total of 55 patients were included in the study. Patients were all diagnosed with OSAHS by overnight polysomnography and all received oral appliance (OA) as the therapy. The OA positioned the mandible at 60%-70% of the maximal mandible advancement position and created a 4-5 mm incisor separation. The patients were instructed to wear the appliance during sleep, 6-8 hours per day, for 5-7 days per week. They were divided into four groups by the period of treatment, including less than 1 year group; 1-2 years group; 2-6 years group and 6-9 years group. The polysomnographic study was used to investigate the efficacy of the four groups. The outcome measures included the score on the apnea-hypopnea index (AHI), the longest apnea time and the lowest oxygen saturation (LSaO2) levels during an overnight sleep.

RESULTS: The AHI decreased significantly in all the four groups. The less than 1 year group decreased from 24.50 (14.65, 54.05) to 7.40 (2.12,10.00) events/h (P<0.001); The 1-2 years group decreased from 19.50 (12.15, 39.23) to 1.80 (0.70, 6.58) events/h (P=0.001); The 2-6 years group decreased from 25.00 (11.41, 42.60) to 4.50 (1.35, 7.90) events/h (P=0.001); The 6-9 years group decreased from 26.2 (16.95, 47.45) to 4.00 (1.90, 26.70) events/h (P=0.043). The longest apnea decreased significantly in less than 1 year group, 1-2 years group and 2-6 years group. The longest apnea decreased from 57.00 (37.70, 61.50) to 25.00 (15.90, 33.50) seconds (P<0.001) in the less than 1 year group, from 41.00 (25.50, 62.26) to 13.10 (0.00, 22.10) seconds (P=0.001) in the 1-2 year group and from 42.50 (30.35, 58.15) to 15.60 (0.00, 28.10) seconds (P=0.003) in the 2-6 year group. The LSaO2 levels increased significantly in the less than 1 year group and 2-6 years group. The LSaO(2) levels rose significantly in the less than 1 year group, from 74.18%±7.96% to 84.06%±7.67% (P=0.001), and in the 2-6 years group, from 76.71%±10.98% to 84.06%±4.64% (P=0.006), The LSaO2 levels did not increase significantly in the 1-2 years and 6-9 years groups. Kruskal-Wallis test showed that there were no statistically significant differences in the AHI, longest apnea time and LSaO(2) in 4 the groups.

CONCLUSION: The oral appliance is an effective therapy for patients with OSAHS in the long-term treatment. However, it's recommended to make appointments with patients as a follow-up supervision whether there is any efficacy decrease. And the oral appliance should be replaced if necessary.