Methods:Primary dental root canal was simulated with silica gel tubes, one end sealed and the other end open. The tubes were filled Zinc-Oxide-Eugenol(ZOE), Ca(OH) 2 and iodoform respectively with sterile conditions.

• 方法 :以一端封闭 ,另一端开放的硅胶管模拟乳牙根管 ,无菌条件下分别充填氧化锌丁香油糊剂 ,氢氧化钙糊剂和碘仿糊剂。