[1] Hunan Normal Univ, Hunan Prov Peoples Hosp, Dept Oral & Maxillofacial Surg, Changsha 410005, Hunan, Peoples R China
[2] Hunan Normal Univ, Affiliated Hosp 1, Changsha 410005, Hunan, Peoples R China
[3] Xin Cheng Hosp Gu Zhang Cty, Zhuzhou, Hunan Province, Peoples R China
[4] Univ Utah, Sch Med, Dept Family & Prevent Med, Salt Lake City, UT 84112 USA
[5] Univ Maryland, Sch Med, Dept Epidemiol & Publ Hlth, Baltimore, MD 21201 USA
[6] Hunan Normal Univ, Div Int, Changsha 410005, Hunan, Peoples R China