Abstract: PURPOSE: To compare the changes of sleep-breathing parameters and sleep quality before and after treatment of Class Ⅱ malocclusion in adolescents. METHODS: Forty-eight adolescent patients were selected for functional orthodontic treatment. Portable sleep breathing monitor and Pittsburgh sleep quality index(PSQI) were used before treatment, 1 month and 10 months after treatment, in order to compare the results of apnea and hypopnea index(AHI), obstructive apnea index(OAI), central apnea index(CAI), number of hypoventilation (HI), oxygen reduction index (ODI), minimum oxygen index(LSpO₂) and sleep quality index. SPSS 16.0 software package was used for data analysis. RESULTS: After 1 month of functional appliance use, AHI, HI and ODI were significantly decreased than those before treatment, while LSpO₂ was significantly increased (P<0.01), but there was no significant difference in OAI and CAI (P>0.05). AHI, OAI, CAI, HI, ODI and LSpO₂ 10 months after treatment were significantly different from those before and 1 month after treatment(P<0.01). The sleep duration, quality, efficiency, and sleep disturbance and daytime dysfunction were not different from one month than before treatment (P>0.05), and related sleep quality scores were different from ten months after treatment compared with pre-treatment and one month after treatment(P<0.01). AHI, OAI, HI, ODI and LSpO₂ were positively correlated with sleep quality in patients(P<0.01). CONCLUSIONS: Functional treatment of Class Ⅱ adolescents can improve sleep breathing situation and sleep quality of patients.

Key words: Adolescent Class Ⅱ malocclusion, Functional appliance, Portable sleep monitor, Pittsburgh sleep quality scale