Methods To fill the root canals of the primary teeth using the four different materials: zinc oxide eugenol paste, ZOE and Ca(OH)_2 paste,ZOE iodoform paste, ZOE and Ca(OH)_2 iodoform paste. Investigate the therapeutic effect after two years.

• 方法用几种根管充填材料(ZOE糊剂、ZOE+Ca(OH)2糊剂、ZOE+碘仿糊剂、ZOE+Ca(OH)2+碘仿糊剂)对乳牙进行根管充填,观察两年后的疗效。