Objective To investigate the changes of upper airway of obstructive sleep apnea syndrome（OSAS） patients after the treatment of Silensor snoreguard. Methods 42 patients with OSAS were treated with dental appliance. Cephalometric analysis was carried out to compare the changes of upper airway before and after the treatment. Results SPP-SPPW increased from（9.10±2.25） mm to（12.24±2.61） mm. PAS increased from（8.99±3.20） mm to（11.24±3.79） mm. CL decreased from（26.26±6.04） mm to（14.37±8.14） mm. H-MP decreased from（21.27±6.12） mm to（12.14±5.89） mm. V-RGn decreased from（55.15±5.61） mm to（51.63±5.87） mm. OPAA increased from（7.01±1.54） mm2 to（7.85±1.61） mm2. HPAA increased from（3.02±0.89） mm2 to（3.61±1.61）mm2. Conclusion Dental appliance worked with the effect of enlarging upper airway.
