[1] Zhejiang Univ, Sch Med, Affiliated Hosp 1, Dept Stomatol, Hangzhou 310003, Zhejiang, Peoples R China
[2] Zhejiang Univ, Sch Med, Affiliated Hosp 1, Dept Gastroenterol, Hangzhou 310003, Zhejiang, Peoples R China
[3] Red Corss Hosp, Dept Stomatol, Hangzhou 310003, Zhejiang, Peoples R China