Abstract: Objective To investigate the effects of mandibular advancement device (MAD) on interleukin 1β (IL-1β), interleukin 6 (IL-6)and tumor necrosis factor α (TNF-α) in palatopharyngeal tissue and plasma of rabbits with obstructive sleep apnea hypopnea syndrome (OSAHS), and to provide a theoretical basis for the clinical treatment of OSAHS. 
Methods A total of 30 male New Zealand rabbits were randomly divided into three groups. The OSAHS model was induced in OSAHS group and MAD group. The animals were equipped with MADs in MAD group and no treatment was given in the control group. All the animals were kept to sleep in supine position for 8 weeks (4-6 h/d). The expression of inflammatory factors in plasma was determined by enzyme linked immunosorbent assay (ELISA), and the expression of inflammatory factors in palatopharyngeal tissue was determined by immunohistochemistry (IHC) and real-time quantitative polymerase chain reaction (qRT-PCR). 
Results The results of ELISA showed that the levels of IL-1β, IL-6 and TNF-α in OSAHS group were significantly higher than those in the control group and MAD group (P＜0.05). There was no significant difference in levels of IL-1β, IL-6 and TNF-α between the control group and MAD group (P＞0.05). The results of qRT-PCR showed that the gene expression of inflammatory factors in palatopharyngeal tissues was significantly higher in OSAHS group than in the control group and MAD group. IHC showed that positive cells for TNF-α in palatopharyngeal tissue were significantly higher in OSAHS group than those in the control group and MAD group. 
Conclusion MAD can rescue the systemic and palatopharyngeal inflammation caused by OSAHS.

Key words: sleep apnea, obstructive, orthodontic appliances, interleukin 1β, tumor necrosis factor α