作者单位:Peoples Liberat Army Gen Hosp, Inst Stomatol, 28 Fuxing Rd, Beijing 100853, Peoples R China[1]Fourth Mil Med Univ, State Key Lab Mil Stomatol, 145 Western Changle Rd, Xian 710032, Shaanxi[2]Fujian Med Univ, Teaching Hosp, Xiamen Stomatol Hosp, Dept Endodont, 1309 Lvling Rd, Xiamen 361003[3]