1. Department of Respiratory Disease, Zhongshan People's Hospital, Zhongshan, Guangdong 528403, P.R. China
2. Dental Implant and Restoration Centre, Zhongshan People's Hospital, Zhongshan, Guangdong 528403, P.R. China
3. Department of Respiratory Disease, Ji'an First People's Hospital, Ji'an, Jiangxi 343099, P.R. China
4. The Second Department of Respiratory Disease, Jiangxi Provincial People's Hospital, The First Affiliated Hospital of Nanchang Medical College, Nanchang, Jiangxi 330006, P.R. China